Presentation of an oil refinery
Source: Wikipedia, the free encyclopedia (www.wikipedia.com)
View of the Tosco (ex Valero, originally Shell) Martinez oil refinery
Definition
An oil refinery is an industrial process plant where crude oil is processed and refined into
useful petroleum products.
Contents
1.
2.
3.
4.
5.
6.
7.
8.
9.
Operation
Products of oil refinery
Safety and environmental concerns
Common process units found in a refinery
Specialized end product units
Co-plant siting
History
See also
External links
1. Operation
Raw oil or unprocessed ("crude") oil is not very useful in the form it comes in out of the
ground. It needs to be broken down into parts and refined before use in a solid material such
as plastics and foams, or as petroleum fossil fuels as in the case of automobile and airplane
engines.
Oil can be used in so many various ways because it contains hydrocarbons of varying
molecular masses and lengths such as paraffins, aromatics, naphthenes (or cycloalkanes),
alkenes, dienes, and alkynes.
Crude oil is separated into fractions by fractional distillation. The heavier fractions that
merge from the bottom of the fractionating column are often broken up (cracked) to make
more useful products.
Hydrocarbons are molecules of varying length and complexity made of hydrogen and
carbon. Their various structures give them their differing properties and thereby uses. The
trick in the oil refinement process is separating and purifying these. All these different
hydrocarbons have a different boiling point, which means they can be separated by
distillation.
Once separated and any contaminants and impurities have been removed, the oil can be
either sold without any further processing, or smaller molecules such as isobutane and
propylene or butylenes can be recombined to meet specific octane requirements by processes
such as alkylation or less commonly, dimerization. Octane can also be improved by catalytic
reforming, which strips hydrogen out of hydrocarbons to produce aromatics, which have
much higher octane ratings. Intermediate products such as gasoils can even be reprocessed
to break heavy, long-chained oil into lighter short-chained oil, by various forms of cracking
such as Fluid Catalytic Cracking, Thermal Cracking, and Hydrocracking. The final step in
gasoline production is the blending of fuels with different octane ratings, vapor pressures
and other properties to meet product specifications.
2. Products of oil refinery









Asphalt
Diesel fuel
Fuel oils
Gasoline
Kerosene
Liquid petroleum gas (LPG)
Lubricating oils
Paraffin wax
Tar
3. Safety and environmental concerns
Oil refineries can become very large and
sprawling complexes with vast numbers of
pipes running throughout the facility. The
refining process can cause many different
chemicals to be released into the atmosphere
- consequently a notable odor may
accompany the presence of a refinery.
Environmental groups have lobbied many
governments to increase restrictions on how
much material refineries can release, and
many refineries have installed equipment
and changed practices to lessen the
environmental impact. In the United States,
there is strong pressure to prevent the development of new refineries, and none have been
built in the country for more than three decades. Many existing refineries have been
expanded during that time however.
Environmental and safety concerns mean that oil refineries are usually located a safe
distance away from major urban areas. Nevertheless, there are potentially dangerous
exceptions to this rule, a particularly notable one being the Santa Cruz refinery 1 (Tenerife,
Spain), which is sited in a densely-populated city center and next to the only two major
evacuation routes in and out of the city.
4. Common process units found in a refinery










Atmospheric Distillation Unit: distills crude oil into fractions;
Vacuum Distillation Unit: further distills residual bottoms after atmospheric
distillation;
Naphtha Hydrotreater Unit: desulfurizes naphtha from atmospheric distillation;
Catalytic Reformer Unit: uses hydrogen to break long chain hydrocarbons into lighter
elements that are added to the distiller feedstock;
Distillate Hydrotreater Unit: desulfurizes distillate (diesel) after atmospheric
distillation;
Fluid Catalytic Converter Unit
Dimerization Unit
Isomerization Unit
Gas storage units for propane and similar gaseous fuels at pressure sufficient to
maintain in liquid form - these are usually spherical
Storage tanks for crude oil and finished products, usually cylindrical, with some sort
of vapor enclosure and surrounded by an earth berm to contain spills
5. Specialized end product units
These units will blend various feedstocks, mix appropriate additives, provide short term
storage, and prepare for bulk loading to trucks, barges, product ships, and railcars.

Gaseous fuels such as propane are stored and shipped in liquid form under pressure
in specialized railcars to distributors.







Liquid fuels blending (producing automotive and aviation grades of gasoline,
kerosene, various aviation turbine fuels, and diesel fuels, adding dyes, detergents,
antiknock additives, oxygenates, and anti-fungal compounds as required). Shipped
by barge, rail, and tanker ship. May be shipped regionally in dedicated pipelines to
point consumers, particularly aviation jet fuel to major airports, or piped to
distributors in multi-product pipelines using product separators called "pigs".
Lubricants (produces light machine oils, motor oils, and greases, adding viscosity
stabilizers as required), usually shipped in bulk to an offsite packaging plant.
Wax, used in the packaging of frozen foods, among others. May be shipped in bulk to
a site to prepare as packaged blocks.
Sulfuric acid finishing and shipping. This is a useful industrial material, usually
prepared as oleum, a byproduct of sulfur removal from fuels.
Bulk tar shipping for offsite unit packaging for use in tar-and-gravel roofing.
Asphalt unit. Prepares bulk asphalt for shipment.
Asphalt concrete unit. Mixes asphalt with aggregate on demand to truck hot for local
road surfacing use.
6. Co-plant siting
Frequently a chemical plant will be sited adjacent to a refinery, utilizing intermediate
products as feedstocks for the production of specialized materials such as plastics and
various toxic materials used in agribusiness
7. History
The world's first oil refinery opened at Ploieşti, Romania in 1856. Several other refineries
were built at that location with investment from United States companies before being taken
over by Nazi Germany during World War II. Most of these refineries were bombarded by the
US Air Force in Operation Tidal Wave, August 1, 1943.
Another early example is Oljeön preserved as a museum at the UNESCO world heritage site
Engelsberg. It started operation in 1875 and is part of the Ecomuseum Bergslagen.
The largest oil refinery in the world is in Ras Tanura, Saudi Arabia, owned by Saudi Aramco.
The city was originally built as a sea port, but actually developed because of the huge
refinery area. For most of the 20th century the largest refinery of the world was that of
Abadan in Iran.
Cracking (chemistry)
In petroleum geology and chemistry, cracking is the process whereby complex organic
molecules (e.g. kerogens or heavy hydrocarbons) are converted to simpler molecules (e.g.
light hydrocarbons) by the breaking of carbon-carbon bonds in the precursors. The rate of
cracking and the end products are strongly dependent on the temperature and presence of
any catalysts.
Contents
1. Applications
1.1. Fluid Catalytic Cracking
1.2. Hydrocracking
1.3. Steam Cracking
2. Chemistry
2.1. Catalytic Cracking
2.2. Thermal Cracking
3. History
1. Applications
In an oil refinery cracking processes allow the production of "light" products (such as LPG
and gasoline) from heavier crude oil distillation fractions (such as gas oils) and residues.
Fluid Catalytic Cracking (FCC for short) produces a high yield of gasoline and LPG while
hydrocracking is a major source of jet fuel, gasoline components and LPG. Thermal cracking
is currently used to "upgrade" very heavy fractions ("upgrading", "visbreaking"), or to
produce light fractions or distillates, burner fuel and/or petroleum coke. Two extremes of
the thermal cracking in terms of product range are represented by the high-temperature
process called steam cracking or pyrolysis (ca. 750 to 900 °C or more) which produces
valuable ethylene and other feeds for the petrochemical industry, and the mildertemperature delayed coking (ca. 500 °C) which can produce, under the right conditions,
valuable needle coke, a highly crystalline petroleum coke used in the production of
electrodes for the steel and aluminum industries.
1.1. Fluid Catalytic Cracking
Fluid catalytic cracking is a commonly used process and a modern oil refinery will typically
include a cat cracker, particularly refineries in the USA due to the high demand for gasoline.
The process was first used in around 1942, and employs a powdered catalyst. Initial process
implementations were based on a low activity alumina catalyst and a reactor where the
catalyst particles were suspended in a rising flow of feed hydrocarbons in a fluidized bed.
In newer designs, cracking takes place using a very active zeolite-based catalyst in a shortcontact time vertical or upward sloped pipe called the "riser". Pre-heated feed is sprayed into
the base of the riser via feed nozzles where it contacts extremely hot fluidized catalyst at 1230
to 1400 °F (665 to 760 °C). The hot catalyst vaporizes the feed and catalyzes the cracking
reactions that break down the high molecular weight oil into lighter components including
LPG, gasoline, and diesel. The catalyst-hydrocarbon mixture flows upward through the riser
for just a few seconds and then the mixture is separated via cyclones. The catalyst-free
hydrocarbons are routed to a main fractionator for separation into fuel gas, LPG, gasoline,
light cycle oils used in diesel and jet fuel, and heavy fuel oil.
During the trip up the riser, the cracking catalyst is "spent" by reactions which deposit coke
on the catalyst and greatly reduce activity and selectivity. The "spent" catalyst is disengaged
from the cracked hydrocarbon vapors and sent to a stripper where it is contacted with steam
to remove hydrocarbons remaining in the catalyst pores. The "spent" catalyst then flows into
a fluidized-bed regenerator where air (or in some cases air plus oxygen) is used to burn off
the coke to restore catalyst activity and also provide the necessary heat for the next reaction
cycle, cracking being an endothermic reaction. The "regenerated" catalyst then flows to the
base of the riser, repeating the cycle.
The gasoline produced in the FCC unit has an elevated octane rating but is less chemically
stable compared to other gasoline components due to its olefinic profile. Olefins in gasoline
are responsible for the formation of polymeric deposits in storage tanks, fuel ducts and
injectors. The FCC LPG is an important source of C3-C4 olefins and isobutane that are
essential feeds for the alkylation process.
1.2. Hydrocracking
Hydrocracking is a catalytic cracking process assisted by the presence of an elevated partial
pressure of hydrogen. The products resulted are saturated hydrocarbons; depending on the
process severity (temperature, pressure, catalyst activity) these products range from ethane,
LPG to heavier hydrocarbons comprising mostly of isoparaffins. Hydrocracking is normally
facilitated by a bifunctional catalyst that is capable of rearranging and breaking hydrocarbon
chains as well as adding hydrogen to aromatics and olefins to produce naphthenes and
alkanes.
Major products from hydrocracking are jet fuel, relatively high octane rating gasoline
fractions and LPG. All these products have a very low content of sulfur and contaminants.
1.3. Steam Cracking
Steam cracking is a petrochemical process in which saturated hydrocarbons are broken down
into smaller, often unsaturated, hydrocarbons. It is the principal industrial method for
producing the lighter alkenes (or commonly olefins), including ethene (or ethylene) and
propene (or propylene).
In steam cracking, a gaseous or liquid hydrocarbon feed is diluted with steam and then
briefly heated in a furnace. Typically, the reaction temperature is very hot—over 900°C—but
the reaction is only allowed to proceed for a few tenths of a second before being quenched by
contact with a colder fluid.
The products produced in the reaction depend on the composition of the feed, the
hydrocarbon to steam ratio and on the cracking temperature & furnace residence time. Light
hydrocarbon feeds (such as ethane, LPGs or light naphthas) give product streams rich in the
lighter alkenes, including ethylene, propylene, and butadiene. Heavier hydrocarbon (full
range & heavy naphthas as well as other refinery products) feeds give some of these, but also
give products rich in aromatic hydrocarbons and hydrocarbons suitable for inclusion in
gasoline or fuel oil. The higher cracking temperature (also referred to as severity) favours the
production of ethene and benzene, whereas lower severity produces relatively higher
amomunts of propene, C4-hydrocarbons and liquid products.
The process also results in the slow deposition of coke, a form of carbon, on the reactor walls.
This degrades the effectiveness of the reactor, so reaction conditions are designed to
minimize this. Nonetheless, a steam cracking furnace can usually only run for a few months
at a time between de-cokings.
2. Chemistry
"Cracking" breaks larger molecules into smaller ones. This can be done with a thermic or
catalytic method. The thermal cracking process follows a homolytic mechanism, that is,
bonds break symmetrically and thus pairs of free radicals are formed. The catalytic cracking
process involves the presence of acid catalysts (usually solid acids such as silica-alumina and
zeolites) which promote a heterolytic (asymmetric) breakage of bonds yielding pairs of ions
of opposite charges, usually a carbocation and the very unstable hydride anion. Carbonlocalized free radicals and cations are both highly unstable and undergo processes of chain
rearrangement, C-C scission in position beta (i.e., cracking) and intra- and intermolecular
hydrogen transfer or hydride transfer. In both types of processes, the corresponding reactive
intermediates (radicals, ions) are permanently regenerated, and thus they proceed by a selfpropagating chain mechanism. The chain of reactions is eventually terminated by radical or
ion recombination.
2.1. Catalytic Cracking
Catalytic cracking uses a catalyst to aid the process of breaking down large hydrocarbon
molecules into smaller ones. During this process, less reactive and therefore more stable and
longer lived intermediate cations accumulate on the catalysts' active sites generating deposits
of carbonaceous products generally (and in many cases inappropriately) known as coke.
Such deposits need to be removed (usually by controlled burning) in order to restore catalyst
activity.
2.2. Thermal Cracking
In thermal cracking elevated temperatures are used. An overall process of
disproportionation can be observed, where "light", hydrogen-rich products are formed at the
expense of heavier molecules which condense and are depleted of hydrogen.
A large number of chemical reactions take place during steam cracking, most of them based
on free radicals. Computer simulations aimed at modeling what takes place during steam
cracking have included hundreds or even thousands of reactions in their models. The major
sorts of reactions that take place, with examples, include:






Initiation reactions, where a single molecule breaks apart into two free radicals. Only
a small fraction of the feed molecules actually undergo initiation, but these reactions
are necessary to produce the free radicals that drive the rest of the reactions. In steam
cracking, initiation usually involves breaking a chemical bond between two carbon
atoms, rather than the bond between a carbon and a hydrogen atom.
CH3CH3 → 2 CH3•
Hydrogen abstraction, where a free radical removes a hydrogen atom from another
molecule, turning the second molecule into a free radical.
CH3• + CH3CH3 → CH4 + CH3CH2•
Radical decomposition, where a free radical breaks apart into two molecules, one an
alkene, the other a free radical. This is the process that results in the alkene products
of steam cracking.
CH3CH2• → CH2=CH2 + H•





Radical addition, the reverse of radical decomposition, in which a radical reacts with
an alkene to form a single, larger free radical. These processes are involved in
forming the aromatic products that result when heavier feedstocks are used.
CH3CH2• + CH2=CH2 → CH3CH2CH2CH2•
Termination reactions, which happen when two free radicals react with each other to
produce products that are not free radicals. Two common forms of termination are
recombination, where the two radicals combine to form one larger molecule, and
disproportionation, where one radical transfers a hydrogen atom to the other, giving
an alkene and an alkane.
CH3• + CH3CH2• → CH3CH2CH3
CH3CH2• + CH3CH2• → CH2=CH2 + CH3CH3
3. History
The first thermal cracking method, the Burton process, was invented by William M. Burton;
the oil industry first using it to produce gasoline in 1913.
Catalytic cracking, based upon a process developed by Dr. Alex Golden Oblad at Standard
Oil of Indiana has been used from around 1936. Typical catalysts include alumina, silica,
zeolites, and various types of clay.
Gasoline
Petrol (petroleum spirit) redirects here. For the seabird, see petrel, spelled with an 'e'.
Gasoline, as it is known in North America, or petrol (abbreviated from petroleum spirit), in
many Commonwealth countries (sometimes also called motor spirit) is a petroleum-derived
liquid mixture consisting primarily of hydrocarbons, used as fuel in internal combustion
engines. The term gasoline is commonly used within the oil industry, even within companies
that are not American. The word "gasoline" is commonly shortened in colloquial usage to
"gas" (see other meanings). The term mogas, short for motor gasoline, for use in cars is used
to distinguish it from avgas, aviation gasoline used in (light) aircraft. This should be
distinguished in usage from genuinely gaseous fuels used in internal combustion engines
such as LPG.
Contents
1. Chemical analysis and production
1.1. Volatility
1.2. Octane rating
2. Dangers
3. Energy content
4. Additives
4.1. Lead
4.2. MMT
4.3. Oxygenate blending
5. History
5.1. Pharmaceutical
5.2. Etymology
5.3. World War II and octane
6. Current use
1. Chemical analysis and production
Gasoline is produced in oil refineries. These days, material that is simply separated from
crude oil via distillation, called natural gasoline, will not meet the required specifications (in
particular octane rating; see below) for modern engines, but these streams will form part of
the blend.
The bulk of a typical gasoline consists of hydrocarbons with between 5 and 12 carbon atoms
per molecule.
The various refinery streams that are blended together to make gasoline all have different
characteristics. Some important streams are:
 Reformate, produced in a catalytic reformer with a high octane and high aromatics
content, and very low olefins (alkenes).





Cat Cracked Gasoline or Cat Cracked Naphtha, produced from a catalytic cracker,
with a moderate octane, high olefins (alkene) content, and moderate aromatics level.
Here, "cat" is short for "catalyst".
Hydrocrackate (Heavy, Mid, and Light), produced from a hydrocracker, with
medium to low octane and moderate aromatic levels.
Natural Gasoline (has very many names), directly from crude oil with low octane,
low aromatics (depending on the crude oil), some naphthenes (cycloalkanes) and
zero olefins (alkenes).
Alkylate, produced in an alkylation unit, with a high octane and which is pure
paraffin (alkane), mainly branched chains.
Isomerate (various names) which is made by isomerising Natural Gasoline to increase
its octane rating and is very low in aromatics and benzene content.
Note: The terms used here are not always the correct chemical terms. Typically they are old
fashioned, but they are the terms normally used in the oil industry. The exact terminology
for these streams varies by oil company and by country.
Overall a typical gasoline is predominantly a mixture of paraffins (alkanes), naphthenes
(cycloalkanes), aromatics and olefins (alkenes). The exact ratios can depend on:
 the oil refinery that makes the gasoline, as not all refineries have the same set of
processing units.
 the crude oil used by the refinery on a particular day.
 the grade of gasoline, in particular the octane.
These days, gasoline in many countries has tight limits on aromatics in general, benzene in
particular, and olefins (alkene) content. This is increasing the demand for high octane pure
paraffin (alkane) components, such as alkylate, and is forcing refineries to add processing
units to reduce the benzene content.
Gasoline can also contain some other organic compounds: such as organic ethers,
(deliberately added) plus small levels of contaminants, in particular sulfur compounds such
as disulfides and thiophenes. Some contaminants, in particular mercaptans and hydrogen
sulfide must be removed because they cause corrosion in engines.
1.1. Volatility
Gasoline is more volatile than diesel or kerosene, not only because of the base constituents,
but because of the additives that are put into it. The final control of volatility is often via
blending of butane. The desired volatility depends on the ambient temperature: In hotter
climates, gasoline components of higher molecular weight and thus lower volatility are used.
In Australia the volatility limit changes every month and differs for each main distribution
center, but most countries simply have a summer, winter and perhaps intermediate limit.
The maximum volatility of gasoline in many countries has been reduced in recent years to
reduce the fugitive emissions during refueling.
Volatility standards may be relaxed (allowing more gasoline components into the
atmosphere) during emergency anticipated gasoline shortages. For example, on 31 August
2005 in response to Hurricane Katrina, the United States activated an early switch to "winter
gasoline" which has a volatility limit exceeding the usual summertime standard. As
mandated by EPA administrator Stephen L. Johnson, this "fuel waiver" was made effective
through 15 September 2005. Though relaxed volatility standards negatively impact ozone
and other air quality criteria, higher volatility gasoline (which contains less additives than
gasoline whose volatility has been artificially lowered) essentially increases a nation's
gasoline supply.
1.2. Octane rating
The most important characteristic of gasoline is its octane rating, which is a measure of how
resistant gasoline is to premature detonation (knocking). It is measured relative to a mixture
of 2,2,4-trimethylpentane (an isomer of octane) and n-heptane. An 87-octane gasoline has the
same knock resistance as a mixture of 87% isooctane and 13% n-heptane. The octane rating
system was developed by the chemist Russell Marker.
2. Dangers
Many of the non-aliphatic hydrocarbons naturally present in gasoline (especially aromatic
ones like benzene), as well as many anti-knocking additives, are carcinogenic. Because of
this, any large-scale or ongoing leaks of gasoline pose a threat to the public's health and the
environment, should the gasoline reach a public supply of drinking water. The chief risks of
such leaks come not from vehicles, but from gasoline delivery truck accidents and leaks from
storage tanks. Because of this risk, most (underground) storage tanks now have extensive
measures in place to detect and prevent any such leaks, such as sacrificial anodes. Gasoline is
rather volatile (meaning it readily evaporates), requiring that storage tanks on land and in
vehicles be properly sealed. But the high volatility also means that it will easily ignite in cold
weather conditions, unlike diesel for example. However, certain measures must be in place
to allow appropriate venting to ensure the level of pressure is similar on the inside and
outside. Gasoline also reacts dangerously with certain common chemicals; for example,
gasoline and crystal Drāno (sodium hydroxide) react together in a spontaneous combustion.
Gasoline is also one of the sources of pollutant gases. Even gasoline which does not contain
lead or sulfur compounds produces carbon dioxide, nitrogen oxides, and carbon monoxide
in the exhaust of the engine which is running on it.
Through misuse as an inhalant, gasoline also contributes to damage to health. "Petrol
sniffing" is a common way of obtaining a high for many people and has become epidemic in
many poorer communities such as with Indigenous Australians. In response, Opal fuel has
been developed by the BP Kwinana Refinery in Australia, and contains only 5% aromatics
(unlike the usual 25%) which inhibits the effects of inhalation.
3. Energy content
Gasoline contains about 45 megajoules per kilogram (MJ/kg)
Volumetric energy density of some fuels compared to gasoline:
fuel type
MJ/L
BTU/imp gal
BTU/US gal
gasoline
LPG
ethanol
methanol
gasohol (10% ethanol + 90% gasoline)
diesel
29.0
22.16
19.59
14.57
28.06
40.9
150,000
114,660
101,360
75,420
145,200
176,000
125,000
95,475
84,400
62,800
120,900
147,000
Research octane
number (RON)
91–98
115
129
123
93/94
N/A (see cetane)
A high octane fuel such as LPG has a lower energy content than lower octane gasoline,
resulting in an overall lower power output at the regular compression ratio an engine ran at
on gasoline. However, with an engine tuned to the use of LPG (ie. via higher compression
ratios such as 12:1 instead of 8:1), this lower power output can be overcome. This is because
higher-octane fuels allow for a higher compression ratio - this means less space in a cylinder
on its combustion stroke, hence a higher cylinder temperature, less wasted hydrocarbons
(therefore less pollution and wasted energy), and therefore higher power levels coupled with
less pollution overall because of the greater efficiency.
Note that the main reason for the lower energy content (per litre) of LPG in comparison to
gasoline is that is has a lower density. Energy content per kilogram is higher than for
gasoline (higher hydrogen to carbon ratio). In lay terms, we burn mass, not volume!
As an interesting side note different countries have some variation in what RON is standard
for gasoline, or petrol. In the UK, ordinary premium unleaded petrol is always 95 RON
whereas super unleaded is usually 97-98 RON. In the US, octane ratings in fuels can vary
between 87 AKI (92 RON) for regular, through 90 (95) for mid-grade (European Premium),
up to 93/94 for premium unleaded or E10 (Super in Europe)
4. Additives
4.1. Lead
The mixture known as gasoline when used in high compression internal combustion
engines, has a tendency to explode early ( pre-ignition pre-detonation) causing a disturbing
"engine knocking" (also called "pinging") noise. Early research into this effect was led by
A.H. Gibson and Harry Ricardo in England and Thomas Midgley and Thomas Boyd in the
United States. The discovery that lead additives modified this behavior led to the
widespread adoption of the practice in the 1920s and hence more powerful higher
compression engines. The most popular additive was tetra-ethyl lead. However, with the
recognition of the environmental damage caused by the lead, and the incompatibility of lead
with catalytic converters, this practice began to wane in the 1980s. Most countries are
phasing out leaded fuel; different additives have replaced the lead compounds. The most
popular additives include aromatic hydrocarbons, ethers and alcohol (usually ethanol or
methanol).
In the U.S., where lead has been blended with gasoline, primarily to boost octane levels,
since the early 1920s, standards to phase out leaded gasoline were first implemented in 1973.
In 1995, leaded fuel accounted for only 0.6 % of total gasoline sales and less than 2,000 tons of
lead per year. Effective January 1, 1996, the Clean Air Act banned the sale of the small
amount of leaded fuel that was still available in some parts of the country for use in on-road
vehicles. (Fuel containing lead may continue to be sold for off-road uses, including aircraft,
racing cars, farm equipment, and marine engines.) The ban on leaded gasoline was
presumed to lower levels of lead in people's bloodstream and led to thousands of tons of
lead being removed from the air.
A side effect of the lead additives was protection of the valve seats from erosion. Many
classic car's engines have needed modification to use lead-free fuels since leaded fuels
became unavailable.
Gasoline, as delivered at the pump, also contains additives to reduce internal engine carbon
buildups, improve combustion, and to allow easier starting in cold climates.
4.2. MMT
Methylcyclopentadienyl manganese tricarbonyl (MMT) has been used for many years in
Canada and recently in Australia to boost octane. It also helps old cars designed for leaded
fuel run on unleaded fuel without need for additives to prevent valve problems.
There are currently ongoing debates as to whether or not MMT is harmful to the
environment and toxic to humans.
4.3. Oxygenate blending
Oxygenate blending adds oxygen to the fuel in oxygen-bearing compounds such as MTBE,
ethanol and ETBE, and so reduces the amount of carbon monoxide and unburned fuel in the
exhaust gas, thus reducing smog. In many areas throughout the US oxygenate blending is
mandatory. For example, in Southern California, fuel must contain 2% oxygen by weight.
The resulting fuel is often known as reformulated gasoline (RFG) or oxygenated gasoline.
MTBE use is being phased out due to issues with contamination of ground water. In some
places it is already banned. Ethanol and to a lesser extent the ethanol derived ETBE are a
common replacements. Especially ethanol derived from biomatter such as corn, sugar cane
or grain is frequent, this will often be referred to as bio-ethanol. An ethanol-gasoline mix of
10% ethanol mixed with gasoline is called gasohol. An ethanol-gasoline mix of 85% ethanol
mixed with gasoline is called E85. The most extensive use of ethanol takes place in Brazil,
where the ethanol is derived from sugarcane. Over 3,400 million US gallons (13,000,000 m³)
of ethanol mostly produced from corn was produced in the United States in 2004 for fuel use,
and E85 is fast becoming available in many of the United States. The use of bioethanol, either
directly or indirectly by conversion of such ethanol to bio-ETBE, is encouraged by the
European Union Biofuels Directive.
5. History
Long-term U.S. gasoline prices, 1990-2005 (adjusted for inflation using the U.S. CPI).
5.1. Pharmaceutical
Before internal combustion engines were invented in the mid-1800s, gasoline was sold in
small bottles as a treatment against lice and their eggs. In those early times, the word "Petrol"
was a trade name. This treatment method is no longer common, due to the inherent fire
hazard and risk of dermatitis and that gasoline is a carcinogen where continued contact
might develop cancerous growths.
The word petrol may be derived from Old French pétrole, meaning petroleum: see
Etymology.
Petrol is also abused as a psychoactive inhalant.
5.2. Etymology
The word "gasolene" was coined in 1865 from the word gas and the chemical suffix -ine/ene. The modern spelling was first used in 1871. The shortened form "gas" was first recorded
in American English in 1905. Although, Gasoline originally referred to any liquid offered for
sale, sold or used as the fuel for a gasoline-powered engine, but does not include diesel fuel
or liquefied gas. Methanol racing fuel would have been classed as a type of gasoline.
The word "petrol" was first used in reference to the refined substance as early as 1892 (it
previously referred to unrefined petroleum), and was registered as a trade name by English
wholesaler Carless, Capel & Leonard.
Bertha Benz got petrol for her famous drive from Mannheim to Pforzheim and back from
chemists' shops. In Germany petrol is called Benzin but this is not related to her name but to
the chemical Benzine.
Recent U.S. gasoline prices, 2003-2005 (not adjusted for inflation).
5.3. World War II and octane
One interesting historical issue involving octane rating took place during WWII. Germany
received nearly all its oil from Romania, and set up huge distilling plants in Germany to
produce gasoline from coal. In the US the oil was not "as good" and the oil industry had to
invest heavily in various expensive boosting systems. This turned out to have benefits. The
US industry started delivering fuels of ever-increasing octane ratings by adding more of the
boosting agents and the infrastructure was in place for post war octane agents additive
industry. Good crude oil was no longer a factor during wartime and by war's end, American
aviation fuel was commonly 130 to 150 octane. This high octane could easily be used in
existing engines to deliver much more power by increasing the compression delivered by the
superchargers. The Germans, relying entirely on "good" gasoline, had no such industry, and
instead had to rely on ever-larger engines to deliver more power.
However, German aviation engines were of the direct fuel injection type and could use
methanol-water injection and nitrous oxide injection, which gave 50% more engine power for
five minutes of dogfight. This could be done only five times or after 40 hours run-time and
then the engine would have to be rebuilt. Most German aero engines used 87 octane fuel
(called B4), while some high-powered engines used 100 octane (C2/C3) fuel.
This historical "issue" is based on a very common misapprehension about wartime fuel
octane numbers. There are two octane numbers for each fuel, one for lean mix and one for
rich mix, rich being always greater. So, for example, a common British aviation fuel of the
later part of the war was 100/125. The misapprehension that German fuels have a lower
octane number (and thus a poorer quality) arises because the Germans quoted the lean mix
octane number for their fuels while the Allies quoted the rich mix number for their fuels.
Standard German high-grade aviation fuel used in the later part of the war (given the
designation C3) had lean/rich octane numbers of 100/130. The Germans would list this as a
100 octane fuel while the Allies would list it as 130 octane.
After the war the US Navy sent a Technical Mission to Germany to interview German
petrochemists and examine German fuel quality. Their report entitled "Technical Report 14545 Manufacture of Aviation Gasoline in Germany" chemically analyzed the different fuels
and concluded that "Toward the end of the war the quality of fuel being used by the German
fighter planes was quite similar to that being used by the Allies".
6. Current use
The United States uses 360 million US liquid gallons (1.36 billion litres) of gasoline each day.
Western countries have among the highest usage rates per head, while eastern developing
nations as China typically have the highest usage per square mile/kilometer. Some
countries, e.g. in Europe, impose heavy fuel taxes on fuels such as gasoline, leading to
greater efficiency and economy in car design.
Diesel
This article is about the fuel. For other uses see diesel (disambiguation)
Diesel or Diesel fuel is a specific fractional distillate of fuel oil (mostly petroleum) that is
used as fuel in a diesel engine invented by German engineer Rudolf Diesel. The term
typically refers to fuel that has been processed from petroleum, but increasingly, alternatives
such as biodiesel or biomass to liquid (BTL) or gas to liquid (GTL) diesel that are not derived
from petroleum are being developed.
Contents
1. Petroleum diesel
1.1. Chemical composition
2. Synthetic diesel
3. Biodiesel
4. Uses
1. Petroleum diesel
A vintage diesel station in a factory's yard
Diesel is produced from petroleum, and is sometimes called petrodiesel (or, less seriously,
dinodiesel) when there is a need to distinguish it from diesel obtained from other sources. As
a hydrocarbon mixture, it is obtained in the fractional distillation of crude oil between 250 °C
and 350 °C at atmospheric pressure. Petrodiesel is considered to be a fuel oil and is about
18% heavier than gasoline.
Diesel typically weighs about 7.1 pounds (lb) per US gallon (gal.) (850 grams per liter (g/l)),
whereas gasoline weighs about 6.0 lb per US gal. (720 g/l), or about 15% less. When burnt
diesel typically releases about 147,000 British thermal units (BTU) per US gal. (40.9
megajoules (MJ) per liter), whereas gasoline releases 125,000 BTUs per US gal. (34.8 MJ/l),
also about 15% less.
Diesel is generally simpler to refine than gasoline and often costs less (although price
fluctuations often mean that the inverse is true; for example, the cost of diesel traditionally
rises during colder months as demand for heating oil, which is refined much the same way,
rises).
Diesel fuel, however, often contains higher quantities of sulfur. In Europe, emission
standards and preferential taxation have both forced oil refineries to dramatically reduce the
level of sulfur in diesel fuels. In contrast, the United States has long had "dirtier" diesel,
although more stringent emission standards have been adopted with the transition to ultralow sulfur diesel (ULSD) occurring in 2006 (see also diesel exhaust). US diesel fuel typically
also has a lower cetane number (a measure of ignition quality) than European diesel,
resulting in worse cold weather performance and some increase in emissions.
High levels of sulfur in diesel are harmful for the environment. It prevents the use of
catalytic diesel particulate filters to control diesel particulate emissions, as well as more
advanced technologies, such as nitrogen oxide (NOx) adsorbers (still under development), to
reduce emissions. However, lowering sulfur also reduces the lubricity of the fuel, meaning
that additives must be put into the fuel to help lubricate engines. Biodiesel is an effective
lubricity additive.
Diesel contains approximately 18% more energy per unit of volume than gasoline, which,
along with the greater efficiency of diesel engines, contributes to fuel economy (distance
traveled per volume of fuel consumed).
In the maritime field various grades of diesel fuel are used.
1.1. Chemical composition
Petroleum derived diesel is composed of about 75% saturated hydrocarbons (primarily
paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including
naphthalenes and alkylbenzenes).
2. Synthetic diesel
Wood, straw, corn, garbage, and sewage-sludge may be dried and gasified. After
purification the so called Fischer Tropsch process is used to produce synthetic diesel. Other
attempts use enzymatic processes and are also economic in case of high oil prices. Synthetic
diesel may also be produced out of natural gas in the GTL process. Such synthetic diesel has
30% less particulate emissions than conventional diesel (US- California).
3. Biodiesel
Biodiesel can be obtained from vegetable oil and animal fats (bio-lipids, using
transesterification). Biodiesel is a non-fossil fuel alternative to petrodiesel. It can also be
mixed with petrodiesel in any amount in modern engines, though it is a strong solvent and
can cause problems in some cases. There have been reports that a diesel-biodiesel mix results
in lower emissions than either can achieve alone. A small percentage of biodiesel can be used
as an additive in low-sulfur formulations of diesel to increase the lubricating ability that is
lost when the sulfur is removed.
Chemically, biodiesel consists of alkyl (usually methyl) esters instead of the alkanes and
aromatic hydrocarbons of petroleum derived diesel. However, biodiesel has combustion
properties very similar to regular diesel, including combustion energy and cetane ratings.
4. Uses
Diesel fuel is very similar to heating oil which used in central heating. In both Europe and
the United States, taxes on diesel fuel are higher than on heating oil, and in those areas,
heating oil is marked with dye and trace chemicals to prevent and detect tax fraud. Similarly,
"untaxed" diesel is available in the United States, which is available for use primarily in
agricultural applications such as for tractor fuel. This untaxed diesel is also dyed red for
identification purposes, and should a person be found to be using this untaxed diesel fuel for
a typically taxed purpose (such as "over-the-road", or driving use), the user can be fined
$10,000 USD on the spot. Also, in the United Kingdom and Ireland it is known as red diesel,
and is also used by agricultural vehicles. The term DERV (short for "diesel engined road
vehicle") is also used in the UK as a synonym for diesel fuel.
Diesel is used in diesel engines, a type of internal combustion engine. Rudolf Diesel
originally designed the diesel engine to use coal dust as a fuel, but oil proved more effective.
Diesel engines are used in cars, trucks, motorcycles, boats and locomotives.
Packard diesel motors were used in aircraft as early as 1927, and Charles Lindbergh flew a
Stinson SM1B with a Packard Diesel in 1928. A Packard diesel motor designed by L.M.
Woolson was fitted to a Stinson X7654, and in 1929 it was flown 1000 km non-stop from
Detroit to Langley, VA. In 1931, Walter Lees and Fredrick Brossy set the nonstop flight
record flying a Bellanca powered by a Packard Diesel for 84h 32m.
The very first diesel-engine automobile trip was completed on January 6, 1930. The trip was
from Indianapolis to New York City - a distance of nearly 800 miles (1300 km). This feat
helped to prove the usefulness of the internal combustion engine. The following year Dave
Evans drove his Cummins Diesel Special to a nonstop finish in the Indianapolis 500, the first
time a car had completed the race without a pit stop. That car and a later Cummins Diesel
Special are on display at the Indianapolis Motor Speedway Hall of Fame Museum.
Westport claims to have invented a process called Westport-Cycle with comparable
efficiency using natural gas and petrodiesel.
Fischer-Tropsch process
The Fischer-Tropsch process is a catalyzed chemical reaction in which carbon monoxide and
hydrogen are converted into liquid hydrocarbons of various forms. Typical catalysts used
are based on iron and cobalt. The principal purpose of this process is to produce a synthetic
petroleum substitute.
Contents:
1. Original process
2. History
3. Utilization
1. Original process
The original Fischer-Tropsch process is described by the following chemical equation:
The mixture of carbon monoxide and hydrogen is called synthesis gas or syngas. The
resulting hydrocarbon products are refined to produce the desired synthetic fuel.
The carbon dioxide and carbon monoxide is generated by partial oxidation of coal and
wood-based fuels. The utility of the process is primarily in its role in producing fluid
hydrocarbons or hydrogen from a solid feedstock, such as coal or solid carbon-containing
wastes of various types. Non-oxidative pyrolysis of the solid material produces syngas
which can be used directly as a fuel without being taken through Fischer-Tropsch
transformations. If liquid petroleum-like fuel, lubricant, or wax is required, the FischerTropsch process can be applied. Finally, if hydrogen production is to be maximized, the
water gas shift reaction can be performed, generating only carbon dioxide and hydrogen and
leaving no hydrocarbons in the product stream. Fortunately shifts from liquid to gaseous
fuels are relatively easy to make.
2. History
Since the invention of the original process by the German researchers Franz Fischer and
Hans Tropsch, working at the Kaiser Wilhelm Institute in the 1920s, many refinements and
adjustments have been made, and the term "Fischer-Tropsch" now applies to a wide variety
of similar processes (Fischer-Tropsch synthesis or Fischer-Tropsch chemistry)
The process was invented in petroleum-poor but coal-rich Germany in the 1920s, to produce
liquid fuels. It was used by Germany and Japan during World War II to produce alternative
fuels. Germany's yearly synthetic oil production reached more than 90 million tons in 1944.
After the war captured German scientists continued to work on synthetic fuels in the United
States in Operation Paperclip.
3. Utilization
Currently, two companies have commercialised their FT technology. Shell in Bintulu,
Malaysia, uses natural gas as a feedstock, and produces primarily low-sulfur diesel fuels.
Sasol in South Africa uses coal as a feedstock, and produces a variety of synthetic petroleum
products. The process is today used in South Africa to produce most of the country's diesel
fuel from coal by the company Sasol. The process was used in South Africa to meet its energy
needs during its isolation under Apartheid. This process has received renewed attention in
the quest to produce low sulfur diesel fuel in order to minimize the environmental impact
from the use of diesel engines.
The FT process is an established technology and already applied on a large scale, although its
popularity is hampered by high capital costs, high operation and maintenance costs, and the
relatively low price of crude oil. In particular, the use of natural gas as a feedstock only
becomes practical when using "stranded gas", i.e. sources of natural gas far from major cities
which are impractical to exploit with conventional gas pipelines and LNG technology;
otherwise, the direct sale of natural gas to consumers would become much more profitable.
There are several companies developing the process to enable practical exploitation of socalled stranded gas reserves. It is expected by geologists that supplies of natural gas will
peak 5-15 years after oil does.
There are large coal reserves which may increasingly be used as a fuel source during oil
depletion. Since there are large coal reserves in the world, this technology could be used as
an interim transportation fuel if conventional oil were to become more expensive.
Combination of biomass gasification (BG) and Fischer-Tropsch (FT) synthesis is a very
promising route to produce renewable or ‘green’ transportation fuels.
In Sept. 2005, Pennsylvania governor Edward Rendell announced a venture with Waste
Management and Processors Inc. -- using technology licensed from Shell and Sasol -- to build
an FT plant that will convert so-called waste coal (leftovers from the mining process) into
low-sulfur diesel fuel at a site outside of Mahanoy City, northwest of Philadelphia. The state
of Pennsylvania has committed to buy a significant percentage of the plant's output and,
together with the U.S. Dept. of Energy, has offered over $140 million in tax incentives. Other
coal-producing states are exploring similar plans. Governor Brian Schweitzer of Montana has
proposed developing a plant that would use the FT process to turn his state's coal reserves
into fuel in order to help alleviate the United States' dependence on foreign oil.
One issue that has yet to be addressed in the emerging discussion about large-scale
development of synthetic fuels is the enormous increase in primary energy use and carbon
emissions inherent in conversion of gaseous and solid carbon sources to a usable liquid form.
Recent work by the National Renewable Energy Laboratory indicates that full fuel cycle
greenhouse gas emissions for coal-based synfuels are nearly twice as high as their
petroleum-based equivalent. Emissions of other pollutants are vastly increased as well,
although many of these emissions can be captured during production. Carbon sequestration
has been suggested as a mitigation strategy for greenhouse gas emissions. However, while
sequestration is already in limited use, the science and economics around large-scale
sequestration strategies are, as yet, unconvincing.
Biodiesel
Biodiesel sample
Biodiesel is fuel made from renewable resources such as vegetable oils or animal fats. It is
biodegradable and non-toxic, and has significantly fewer emissions than petroleum-based
diesel (petro-diesel) when burned. Biodiesel functions in current diesel engines, and is a
possible candidate to replace fossil fuels as the world's primary transport energy source.
With a flash point of 150 °C, Biodiesel is classified as a non-flammable liquid by the
Occupational Safety and Health Administration. This property makes a vehicle fueled by
pure biodiesel far safer in an accident than one powered by petroleum diesel or the
explosively combustible gasoline. Precautions should be taken in very cold climates, where
biodiesel may gel at higher temperatures than petroleum diesel.
Biodiesel can be distributed using today's infrastructure, and its use and production is
increasing rapidly (especially in Europe, the United States, and Asia). Fuel stations are
beginning to make biodiesel available to consumers, and a growing number of transport
fleets use it as an additive in their fuel. Biodiesel is generally more expensive to produce than
petroleum diesel, although this differential may diminish due to economies of scale and the
rising cost of petroleum.
Contents:
1. History
2. Fuel quality, standards and properties
3. Production
3.1. Base oils
3.2. Efficiency and economic arguments
4. Availability
4.1. Brazil
4.2. Canada
4.3. Germany
4.4. United States
1. History
Transesterification of a vegetable oil was conducted as early as 1853, by scientists E. Duffy
and J. Patrick, many years before the first diesel engine became functional. Rudolf Diesel's
prime model, a single 10 ft (3 m) iron cylinder with a flywheel at its base, ran on its own
power for the first time in Augsburg, Germany on August 10, 1893. In remembrance of this
event, August 10 has been declared International Biodiesel Day. Diesel later demonstrated
his engine and received the "Grand Prix" (highest prize) at the World Fair in Paris, France in
1900. This engine stood as an example of Diesel's vision because it was powered by peanut
oil—a biofuel, though not strictly biodiesel, since it was not transesterified. He believed that
the utilization of a biomass fuel was the real future of his engine. In a 1912 speech, Rudolf
Diesel said, "the use of vegetable oils for engine fuels may seem insignificant today, but such
oils may become, in the course of time, as important as petroleum and the coal-tar products
of the present time."
During the 1920s, diesel engine manufacturers altered their engines to utilize the lower
viscosity of the fossil fuel (petrodiesel) rather than vegetable oil, a biomass fuel. The
petroleum industries were able to make inroads in fuel markets because their fuel was much
cheaper to produce than the biomass alternatives. The result was, for many years, a near
elimination of the biomass fuel production infrastructure. Only recently have environmental
impact concerns and a decreasing cost differential made biomass fuels such as biodiesel a
growing alternative.
In the 1990s, France launched the local production of biodiesel fuel (known locally as diester)
obtained by the transesterification of rapeseed oil. It is mixed to the proportion of 5% into
regular diesel fuel, and to the proportion of 30% into the diesel fuel used by some captive
fleets (public transportation). Renault, Peugeot, and other manufacturers have certified truck
engines for use with up to this partial biodiesel. Experiments with 50% biodiesel are
underway.
From 1978 to 1996, the U.S. National Renewable Energy Laboratory experimented with using
algae as a biodiesel source in the "Aquatic Species Program". A recent paper from Michael
Briggs at the UNH Biodiesel Group, offers estimates for the realistic replacement of all
vehicular fuel with biodiesel by utilizing algae that has a greater than 50% natural oil
content.
2. Fuel quality, standards and properties
Biodiesel is a clear amber-yellow liquid with a viscosity similar to petrodiesel, the industry
term for diesel produced from petroleum. It can be used as an additive in formulations of
diesel to increase the lubricity of pure ultra-low sulfur petrodiesel (ULSD) fuel. Much of the
world uses a system known as the "BD factor" to state the amount of biodiesel in any fuel
mix, in contrast to the "BA" system used for bioalcohol mixes. For example, 20% biodiesel is
labeled BD20. Pure biodiesel, 100%, is referred to as BD100. If the "D" is dropped (B100, B20,
B5, etc.), it becomes difficult to differentiate the label from that of bioalcohol fuel.
The common international standard for biodiesel is EN 14214.
There are additional national specifications. The standard ASTM D 6751, which is the most
common standard referenced in the United States. In Germany, the requirements for
biodiesels are fixed in a DIN standard. There are standards for three different varieties of
biodiesel, which are made of different oils:
 RME (rapeseed methyl ester, according to DIN E 51606)
 PME (vegetable methyl ester, purely vegetable products, according to DIN E 51606)
 FME (fat methyl ester, vegetable and animal products, according to DIN V 51606)
The standards ensure that the following important factors in the fuel production process are
satisfied:
 Complete reaction.
 Removal of glycerin.
 Removal of catalyst.
 Removal of alcohol.
 Absence of free fatty acids.
Basic industrial tests to determine whether the products conform to the standards typically
include gas chromatography, a test that verifies only the more important of the variables
above. More complete testings are more expensive. Fuel meeting the quality standards is
very non-toxic, with a toxicity rating (LD50) of greater than 50 ml/kg. This toxicity rating
would mean that an average 60 kg person would need to consume more than 3 liters to cause
death 50% of the time, making biodiesel ten times less toxic than table salt.
Biodiesel can be mixed with petroleum diesel at any concentration in most modern engines,
although it has the disadvantage of degrading rubber gaskets and hoses in vehicles
manufactured before 1992. Biodiesel is a better solvent than petrodiesel and has been known
to break down deposits of residue in the fuel lines of vehicles that have previously been run
on petroleum. Fuel filters may become clogged with particulates if a quick transition to pure
biodiesel is made, but biodiesel cleans the engine in the process.
In a study at a U.S. military base, a biodiesel blend was used as a replacement for heating oil
at housing on the base. Due to the solvent power of biodiesel, residues that had been present
in fuel tanks for decades were dissolved. The particulate component of the residues caused
repeated clogging of fuel strainers, requiring repeated replacement, cleaning, and in some
cases installation of higher capacity filters. Due to the relatively smaller surface area and
service life of fuel tanks in motor vehicles and mobile equipment, filter clogging is less
prevalent but still a factor to be considered.
Environmental benefits in comparison to petroleum based fuels include:
 Biodiesel reduces emissions of carbon monoxide (CO) by approximately 50% and
carbon dioxide by 78.45% on a net lifecycle basis because the carbon in biodiesel
emissions is recycled from carbon that was already in the atmosphere, rather than
being new carbon from petroleum that was sequestered in the earth's crust. (Sheehan,
1998)
 Biodiesel contains fewer aromatic hydrocarbons: benzofluoranthene: 56% reduction;
Benzopyrenes: 71% reduction.
 It also eliminates sulfur emissions (SO2), because biodiesel does not include sulfur.
 Biodiesel reduces by as much as 65% the emission of particulates, small particles of
solid combustion products.
 Biodiesel does produce more NOx emissions than petrodiesel, but these emissions
can be reduced through the use of catalytic converters. The increase in NOx

emmisions may also be due to the higher cetane rating of biodiesel. Properly
designed and tuned engines may eliminate this increase.
Biodiesel has a higher cetane rating than petrodiesel, and therefore ignites more
rapidly when injected into the engine.
Pure biodiesel (BD100 or B100) can be used in any petroleum diesel engine, though it is more
commonly used in lower concentrations. Some areas have mandated ultra-low sulfur
petrodiesel, which reduces the natural viscosity and lubricity of the fuel due to the removal
of sulfur and certain other materials. Additives are required to make ULSD properly flow in
engines, making biodiesel one popular alternative. Ranges as low as 2% (BD2 or B2) have
been shown to restore lubricity. Many municipalities have started using 5% biodiesel (BD5 or
B5) in snow-removal equipment and other systems.
Since biodiesel is more often used in a blend with petroleum diesel, there are fewer formal
studies about the effects on pure biodiesel in unmodified engines and vehicles in day-to-day
use. Fuel meeting the standards and engine parts that can withstand the greater solvent
properties of biodiesel is expected to--and in reported cases does--run without any
additional problems than the use of petroleum diesel.
The flash point of biodiesel (150°C) is significantly higher than that of petroleum diesel
(64°C) or gasoline (−45 °C). The gel point of biodiesel varies depending on the proportion of
different types of esters contained. However, most biodiesel, including that made from
soybean oil, has a somewhat higher gel and cloud point than petroleum diesel. In practice
this often requires the heating of storage tanks, especially in cooler climates.
3. Production
Chemically, biodiesel comprises a mix of mono-alkyl esters of long chain fatty acids. The
most common form uses methanol to produce methyl esters, though ethanol can be used to
produce an ethyl ester biodiesel. A byproduct of the transesterification process is the
production of glycerol. A lipid transesterification production process is used to convert the
base oil to the desired esters and remove free fatty acids. After this processing, unlike
straight vegetable oil, biodiesel has combustion properties very similar to those of petroleum
diesel, and can replace it in most current uses.
3.1. Base oils
Soybeans are used as a source of biodiesel
A variety of biolipids can be used to produce biodiesel. These include:
 Virgin oil feedstock; rapeseed and soybean oils are most commonly used, though
other crops such as mustard, palm oil, hemp and even algae show promise;
 Waste vegetable oil (WVO);
 Animal fats including tallow, lard, yellow grease and as a byproduct from the
production of Omega-3 fatty acids from fish oil.
Worldwide production of vegetable oil and animal fat is not yet sufficient to replace liquid
fossil fuel use. Furthermore, some environmental groups (notably the Natural Resources
Defense Council), object to the vast amount of farming and the resulting over-fertilization,
pesticide use, and land use conversion that would be needed to produce the additional
vegetable oil.
Many advocates suggest that waste vegetable oil is the best source of oil to produce
biodiesel. However, the available supply is drastically less than the amount of petroleumbased fuel that is burned for transportation and home heating in the world. According to the
United States Environmental Protection Agency (EPA), restaurants in the US produce about
300 million US gallons (1,000,000 m³) of waste cooking oil annually. Although it is
economically profitable to use WVO to produce biodiesel, it is even more profitable to
convert WVO into other products such as soap. Hence, most WVO that is not dumped into
landfills is used for these other purposes. Animal fats are similarly limited in supply, and it
would not be efficient to raise animals simply for their fat. However, producing biodiesel
with animal fat that would have otherwise been discarded could replace a small percentage
of petroleum diesel usage.
The estimated transportation fuel and home heating oil use in the United States is about
230,000 million US gallons (0.87 km³) (Briggs, 2004). Waste vegetable oil and animal fats
would not be enough to meet this demand. In the United States, estimated production of
vegetable oil for all uses is about 23,600 million pounds (12,000,000 t) or 3,000 million US
gallons (11,000,000 m³)), and estimated production of animal fat is 11,638 million pounds
(5,000,000 t). (Van Gerpen, 2004)
For a truly renewable source of oil, crops or other similar cultivatable sources would have to
be considered. Plants utilize photosynthesis to convert solar energy into chemical energy. It
is this chemical energy that biodiesel stores and is released when it is burned. Therefore
plants can offer a sustainable oil source for biodiesel production. Different plants produce
usable oil at different rates. Some studies have shown the following annual production:
 Soybean: 40 to 50 US gal/acre (40 to 50 m³/km²)
 Rapeseed: 110 to 145 US gal/acre (100 to 140 m³/km²)
 Mustard: 140 US gal/acre (130 m³/km²)
 Jatropha: 175 US gal/acre (160 m³/km²)
 Palm oil: 650 US gal/acre (610 m³/km²)
 Algae: 10,000 to 20,000 US gal/acre (10,000 to 20,000 m³/km²)
There is ongoing research into finding more suitable crops and improving oil yield. Using
the current yields, vast amounts of land and fresh water would be needed to produce
enough oil to completely replace fossil fuel usage.
Soybeans are not a very efficient crop solely for the production of biodiesel, but their
common use in the United States for food products has led to soybean biodiesel becoming
the primary source for biodiesel in that country. Soybean producers have lobbied to increase
awareness of soybean biodiesel, expanding the market for their product.
In Europe, rapeseed is the most common base oil used in biodiesel production. In India and
southeast Asia, the Jatropha tree is used as a significant fuel source, and it is also planted for
watershed protection and other environmental restoration efforts. Malaysia and Indonesia
are starting pilot-scale production from palm oil.
Specially bred mustard varieties can produce reasonably high oil yields, and have the added
benefit that the meal leftover after the oil has been pressed out can act as a effective and
biodegradable pesticide.
The production of algae to harvest oil for biodiesel has not been undertaken on a commercial
scale, but working feasibility studies have been conducted to arrive at the above yield
estimate. In addition to a high yield, this solution does not compete with agriculture for food,
requiring neither farmland nor fresh water.
3.2. Efficiency and economic arguments
According to a study written by Drs. Van Dyne and Raymer for the Tennessee Valley
Authority, the average US farm consumes fuel at the rate of 82 litres per hectare (8.75 US
gallons per acre) of land to produce one crop. However, average crops of rapeseed produce
oil at an average rate of 1,029 L/ha (110 US gal/acre), and high-yield rapeseed fields produce
about 1,356 L/ha (145 US gal/acre). The ratio of input to output in these cases is roughly
1:12.5 and 1:16.5. Photosynthesis is known to have an efficiency rate of about 16% and if the
entire mass of a crop is utilized for energy production, the overall efficiency of this chain is
known to be about 1%. This does not compare favorably to solar cells combined with an
electric drive train. Biodiesel outcompetes solar cells in cost and ease of deployment.
However, these statistics by themselves are not enough to show whether such a change
makes economic sense.
Additional factors must be taken into account, such as: the fuel equivalent of the energy
required for processing, the yield of fuel from raw oil, the return on cultivating food, and the
relative cost of biodiesel versus petrodiesel. A 1998 joint study by the U.S. Department of
Energy (DOE) and the U.S. Department of Agriculture (USDA) traced many of the various
costs involved in the production of biodiesel and found that overall, it yields 3.2 units of fuel
product energy for every unit of fossil fuel energy consumed. That measure is referred to as
the energy yield. A comparison to petroleum diesel, petroleum gasoline and bioethanol
using the USDA numbers can be found at the Minnesota Department of Agriculture website.
In the comparison petroleum diesel fuel is found to have a 0.843 energy yield, along with
0.805 for petroleum gasoline, and 1.34 for bioethanol. The 1998 study used soybean oil
primarily as the base oil to calculate the energy yields. It is conceivable that higher oil
yielding crops could increase the energy yield of biodiesel. The debate over the energy
balance of biodiesel is ongoing, however.
Some nations and regions that have pondered transitioning fully to biofuels have found that
doing so would require immense tracts of land if traditional crops are used. Considering
only traditional plants and analyzing the amount of biodiesel that can be produced per unit
area of cultivated land, some have concluded that it is likely that the United States, with one
of the highest per capita energy demands of any country, does not have enough arable land
to fuel all of the nation's vehicles. Other developed and developing nations may be in better
situations, although many regions cannot afford to divert land away from food production.
For third world countries, biodiesel sources that use marginal land could make more sense,
e.g. honge nuts grown along roads.
More recent studies using a species of algae that has oil contents of as high as 50% have
concluded that as little as 28,000 km² or 0.3% of the land area of the US could be utilized to
produce enough biodiesel to replace all transportation fuel the country currently utilizes.
Further encouragement comes from the fact that the land that could be most effective in
growing the algae is desert land with high solar irradiation, but lower economic value for
other uses and that the algae could utilize farm waste and excess CO2 from factories to help
speed the growth of the algae.
The direct source of the energy content of biodiesel is solar energy captured by plants during
photosynthesis. The website www.biodiesel.co.uk discusses the positive energy balance of
biodiesel:
When straw was left in the field, biodiesel production was strongly energy positive, yielding 1
GJ biodiesel for every 0.561 GJ of energy input (a yield/cost ratio of 1.78).
When straw was burned as fuel and oilseed rapemeal was used as a fertilizer, the yield/cost
ratio for biodiesel production was even better (3.71). In other words, for every unit of energy
input to produce biodiesel, the output was 3.71 units (the difference of 2.71 units would be
from solar energy).
Biodiesel is becoming of interest to companies interested in commercial scale production as
well as the more usual home brew biodiesel user and the user of straight vegetable oil or
waste vegetable oil in diesel engines. Homemade biodiesel processors are many and varied.
Alcohol fuel
The use of alcohol as a fuel for internal combustion engines, either alone or in combination
with other fuels, has been given much attention mostly because of its possible environmental
and long-term economical advantages over fossil fuel.
Both ethanol and methanol have been considered for this purpose. While both can be
obtained from petroleum or natural gas, ethanol may be the most interesting because many
believe it to be a renewable resource, easily obtained from sugar or starch in crops and other
agricultural produce such as grain, sugarcane or even lactose. Since ethanol occurs in nature
whenever yeast happens to find a sugar solution such as overripe fruit, most organisms have
evolved some tolerance to ethanol, whereas methanol is toxic. When 10% alcohol fuel is
mixed into gasoline, the result is known as gasohol. When 85% alcohol fuel is mixed into
gasoline, the result is known as E85. Other experiments involve butanol, which can also be
produced by fermentation of plants.
Alcohol is also increasingly used as an oxygenate for gasoline, as a replacement for MTBE.
Contents:
1. Alcohol Fuels
1.1. Ethanol
1.2. Methanol
2. Other alcohols: butanol and propanol
3. Alcohol and hydrogen
4. Alternate sources
5. Economics of corn ethanol in the U.S.
6. Net fuel energy balance
6.1. Energy balance in the United States
7. Arguments and criticisms
7.1. Air pollution
7.2. Fire safety
7.3. Greenhouse gases
7.4. Renewable resource
7.5. Dependency on foreign oil and international crime
7.6. Statism
7.7. Cost
8. Alcohol fuel in Brazil
8.1. Ethanol production basics
8.2. Electricity from bagasse
8.3. Program statistics
8.4. Effect on oil consumption
8.5. Environmental effect
8.6. Social implications
8.7. Politics
9. U.S. National security
1. Alcohol Fuels
Proposals to use alcohol as a fuel are generally concerned with its use in transportation,
chiefly as a total or partial replacement for gasoline in cars and other road vehicles.
However, other less conventional approaches have been advanced, such as the use of alcohol
in fuel cells, either directly or as a feedstock for hydrogen production. To have a net energy
gain, it is critical that detailed energy and input stock analyses be performed. Currently, all
studies indicate a net energy loss in the production of Alcohol Fuel versus equivalent oil
products. This is due to the use of petrochemicals for pesticides, fertilizers, and operation of
farm and other machinery in the processing of the feed stock. Without a net energy gain,
reduction in the use of Oil etc. does not occur!
Fuel alcohols can be produced from a variety of crops, such as hemp, kenaf, sugarcane, sugar
beets, maize, barley, potatoes, cassava, sunflower, eucalyptus, etc. Two countries have
developed significant bio-alcohol programs: Brazil (ethanol from sugarcane) and Russia
(methanol from eucalyptus). Ethanol for industrial use is often made synthetically from
petroleum feedstock, typically by the catalytic hydration of ethylene with sulfuric acid as the
catalyst. This process is cheaper than the production by fermentation. It can also be obtained
via ethene or acetylene, from calcium carbide, coal, oil gas, and other sources.
Agricultural alcohol for fuel requires substantial amounts of cultivable land with fertile soils
and water. It is hardly an option for densely occupied and industrialized regions like
Western Europe. For example, even if Germany were to be entirely covered with sugarcane
plantations, it would get only half of its present energy needs (including fuel and electricity),
and even that only if we assume that sugarcane would grow in Germany at all. However, if
the fuel alcohol is made of the stalks, wastes, clippings, straw, corn cobs, and other crop field
trash, then no additional land is needed. However using these sources for this purpose
would require additional replacement animal feedstock, fertilizers and electric power plant
fuels.
1.1. Ethanol
Ethanol can be derived from corn, wheat, potato wastes, cheese whey, rice straw, sawdust,
urban wastes, paper mill wastes, yard clippings, molasses, sugar cane, seaweed, surplus food
crops, and other cellulose waste. Petroleum is also used to make industrial ethanol.
Ethanol, which is the same chemical as the alcohol in alcoholic beverages, can reach 96%
purity by volume by distillation, and is as clear as water. This is enough for straight-ethanol
combustion. For blending with gasoline, purities of 99.5 to 99.9% are required, depending on
temperature, to avoid separation. These purities are produced using additional industrial
processes. Ethanol in water is an azeotropic mixture which cannot be purified beyond 96%
by distillation. Today, the most widely used purification method is a physical adsorption
process using molecular sieves. Ethanol is flammable and pure ethanol burns more cleanly
than many other fuels. Assuming it is derived from biomass, the combustion of ethanol
produces no net carbon dioxide. When fully combusted, its combustion products are only
carbon dioxide and water which are also the by-products of regular cellulose waste
decomposition. For this reason, it is favoured for environmentally conscious transport
schemes and has been used to fuel public buses. However, pure ethanol reacts with or
dissolves certain rubber and plastic materials and cannot be used in unmodified engines.
Additionally, ethanol has a much higher octane rating (about 115) than ordinary gasoline,
requiring changes to the compression ratio or spark timing to obtain maximum benefit. To
change a gasoline-fueled car into an pure-ethanol-fueled car, larger carburetor jets (about 3040% larger by area) are needed. (Methanol requires an even larger increase in area, to
roughly 50% larger.) A cold starting system is also needed to ensure sufficient vaporization
for temperatures below 15 °C (59 °F) to maximize combustion and minimize uncombusted
nonvaporized ethanol. If 10 to 30% ethanol is mixed with gasoline, no engine modification is
typically needed. Many modern cars can run on the mixture very reliably.
A mixture containing gasoline with approximately 10% ethanol is known as gasohol. It was
introduced nationwide in Denmark, and in 1989, Brazil produced 12 billion litres of fuel
ethanol from sugar cane, which was used to power 9.2 million cars. It is also commonly
available in the Midwest of the United States and is the only type of gasoline allowed to be
sold in the state of Minnesota. The most common gasohol variant is "E10", containing 10%
ethanol and 90% gasoline. Other blends include E5 and E7. These concentrations are
generally safe for recent, unmodified automobile engines, and some regions and
municipalities mandate that the locally-sold fuels contain limited amounts of ethanol. One
way to measure alternative fuels in the US is the "gasoline-equivalent gallons" (GEG). In
2002, the U.S. used as fuel an amount of ethanol equal to 137 petajoules (PJ), the energy of
1.13 billion US gallons (4,280,000 m³) of gasoline. This was less than 1% of the total fuel used
that year.
The term "E85" is used for a mixture of 15% (by volume) gasoline and 85% ethanol. This
mixture has an octane rating of about 105. This is down significantly from pure ethanol but
still much higher than normal gasoline. The addition of a small amount of gasoline helps the
engine under cold start conditions. E85 does not always contain exactly 85% ethanol. In
winter, especially in colder climates, additional gasoline is added (to facilitate cold start). E85
has traditionally been similar in cost to gasoline, but with the large oil prices seen during
2005 it has become common to see E85 sold for as much as $0.70 less per gallon than
gasoline, making it highly attractive to the small but growing number of motorists with cars
capable of burning it. With no real hope of large long-term reductions in oil prices, the long
term cost-competitiveness (even without tax subsidies) of E85 seems assured.
Beginning with the model year 1999, an increasing number of vehicles in the world are
manufactured with engines which can run on any gasoline from 0% ethanol up to 85%
ethanol without modification. Many light trucks (a class containing minivans, SUVs and
pickup trucks) are designed to be dual fuel or flexible fuel vehicles, since they can
automatically detect the type of fuel and change the engine's behavior, principally air-to-fuel
ratio and ignition timing to compensate for the different octane levels of the fuel in the
engine cylinders.
In the past, when farmers distilled their own ethanol, they sometimes used radiators as part
of the still. The radiators often contained lead, which would get into the ethanol. Lead
entered the air during the burning of contaminated fuel, possibly leading to neural damage.
However this was a minor source of lead since tetraethyl lead was used as a gasoline
additive. Today, ethanol for fuel use is produced almost exclusively from purpose built
plants eliminating any use of lead.
In Brazil and the United States, the use of ethanol from sugar cane and grain as car fuel has
been promoted by government programs. Some individual U.S. states in the corn belt began
subsidizing ethanol from corn (maize) after the Arab oil embargo of 1973. The Energy Tax
Act of 1978 authorized an excise tax exemption for biofuels, chiefly gasohol. The excise tax
exemption alone has been estimated as worth US$1.4 billion per year. Another U.S. federal
program guaranteed loans for the construction of ethanol plants, and in 1986 the U.S. even
gave ethanol producers free corn.
In August 2005, President Bush signed a comprehensive energy bill which included a
requirement to increase the production of ethanol and biodiesel from 4 to 7.5 billion US
gallons (15,000,000 to 28,000,000 m³) within the next ten years. It is expected that in the short
term the majority of this increase will come from ethanol produced from corn.
1.2. Methanol
Methanol, too, has been considered as a fuel, mainly in combination with gasoline. It has
received less attention than ethanol, however, because it has a number of problems of its
own. Its main advantage is that it can be easily manufactured from methane (the chief
constituent of natural gas) as well as by pyrolysis of many organic materials. A problem with
pyrolysis is that it is only economically feasible on an industrial scale, so it is not advisable to
try and produce methanol from renewable resources like wood on a small (personal use)
scale. In any case, high temperatures are involved, with some risk of fire; furthermore,
methanol is highly toxic, so great care should be taken at all times not to ingest methanol,
spill it onto exposed skin, or inhale the fumes.
However, unlike ethanol, methanol is a toxic product; extensive exposure to it could lead to
permanent health damage, including blindness. US maximum allowed exposure in air (40
h/week) are 1900 mg/m³ for ethanol, 900 mg/m³ for gasoline, and 260 mg/m³ for methanol.
It is also quite volatile and therefore would increase the risk of fires and explosions. Besides
the increased fire and explosion risks, higher volatility means more evaporative emissions.
Both in the atmosphere and in the liver, methanol is oxidized into two highly potent toxins:
formaldehyde (used as a preservative for dead organic matter in laboratories), and formic
acid (the poison found in ant stings). Catalytic converters would usually break down these
two toxins in a manner similar to the sulfur, nitrogen, or carbon monoxide molecules which
they normally dispose of if it were not for the fact that catalytic converters operate below the
required temperature until the vehicle has gone 5 to 10 miles (10 to 15 km).
It is possible to overcome this environmental issue in two ways. Firstly, there is the very
expensive option of adding more catalyst to the converter's aluminium honeycomb. But the
catalysts themselves just happen to be the metals platinum, palladium, and rhodium - all of
which are very rare and expensive to purchase. As an example, palladium costs about $200
per ounce, the equivalent of $3,200 per pound or £4,000 (€5,500) per kilogram. Also, platinum
costs even more: $935 per ounce, $15,000 per pound, or £18,700 or €26,200 per kilogram. That
is why catalytic converters contain so little catalyst: the catalysts themselves are too
expensive to be used generously enough to be as effective as they were meant to be.
Alternatively, an electric heater (for home conversion, an glow plug from an old diesel
engine) would serve to preheat the converter a bit more rapidly than an engine by itself
would by idling for 5 or 10 minutes. The catalytic converter would still be operating below
the required temperature for some time, but less than in an unmodified vehicle, thus cutting
pollution levels significantly. Note that hybrid vehicles will be easier to modify this way
because they already have battery systems that can supply sufficient power to heat the
catalyst sufficiently, whereas conventional cars may need electrical modifications to enable
this.
An additional problem of methanol is that its energy content is only 45% that of gasoline
(75% of ethanol).
Nevertheless, a drive to add a significant percentage of methanol to gasoline got very close
to implementation in Brazil, following a pilot test set up by a group of scientists involving
adding blending gasoline with methanol between 1989 and 1992. The larger-scale pilot
experiment that was to be conducted in São Paulo was vetoed at the last minute by the city's
mayor, out of concern for the health of gas station workers (who are mostly illiterate and
could not be expected to follow safety precautions). As of 2005, the idea has not resurfaced.
Since 1965, pure methanol was used in United States Auto Club competition for its series,
and today used by many short track organisations, especially midget and sprint cars, Champ
Car, and until 2005, Indy cars, primarily for safety reasons.
A seven-car crash on the second lap of the 1964 Indianapolis 500 resulted in USAC's decision
to mandate methanol. Eddie Sachs and Dave McDonald died in the crash when their
gasoline-fueled cars exploded. Johnny Rutherford was also involved, in a methanol-fueled
car which also leaked following the crash, and while this car burned from the impact of the
first fireball, it formed a much lesser inferno than the gasoline cars. That testimony and
pressure from the Indianapolis Star writer George Moore, led to the 1965 alcohol fuel
mandate.
Currently, the Indy Racing League uses pure methanol (M100). In 2006, the IRL will switch
to a 10% ethanol / 90% methanol (M90 or E10) mix, before switching to an all-ethanol mix
(E100) in 2007.
2. Other alcohols: butanol and propanol
Although not as common as ethanol and methanol, other fuel alcohols have been considered,
notably butanol and propanol. These alcohols are toxic, although considerably less toxic than
methanol, and considerably less volatile. In particular, butanol has a high flashpoint of 35 °C,
which is a benefit for fire safety, but a difficulty for starting engines, particularly in cold
weather. (In comparison, ethanol has a flashpoint of 13 °C; methanol has a flashpoint of 11
°C; and propanol has a flashpoint of 15 °C.)
The fermentation processes to produce these heavy alcohols from cellulose are fairly tricky to
execute, and the Weizmann organism (Clostridium acetobutylicum) used to perform these
conversions produces an extremely bad smell that must be considered when designing and
locating a fermentation plant.
One advantage shared by all four alcohols is octane rating. Butanol has the additional
attraction that its energy per kilogram is closer to gasoline than the other alcohols (while still
retaining over 25% higher octane rating).
As of 2005, production of all four alcohols from petroleum is cheaper than fermentation and
extraction from biomass, but this is expected to change as fermentation and extraction
processes become more efficient while petroleum becomes more expensive.
3. Alcohol and hydrogen
A view is emerging that current consumers of fossil fuels should move to using hydrogen as
a fuel, creating a new so-called hydrogen economy. However, hydrogen is not a fuel source
in and of itself. Rather, it is merely an intermediate energy storage medium existing between
an energy source (be it solar power, biofuels, and nuclear power) and the place where the
energy will be used. Because hydrogen in its gaseous state takes up a very large volume
when compared to other fuels, logistics becomes a very difficult problem. One possible
solution is to use ethanol to transport the hydrogen, then liberate the hydrogen from its
associated carbon in a hydrogen reformer and feed the hydrogen into a fuel cell.
Alternatively, some fuel cells can be directly fed by ethanol or methanol. As of 2005, fuel cells
are able to process methanol more efficiently than ethanol.
In early 2004, researchers at the University of Minnesota announced that they had invented a
simple ethanol reactor that would take ethanol, feed it through a stack of catalysts, and
output hydrogen suitable for a fuel cell. The device uses a rhodium-cerium catalyst for the
initial reaction, which occurs at a temperature of about 700 °C. This initial reaction mixes
ethanol, water vapor, and oxygen and produces good quantities of hydrogen. Unfortunately,
it also results in the formation of carbon monoxide, a substance that "chokes" most fuel cells
and must be passed through another catalyst to be converted into carbon dioxide. (The
odorless, colorless, and tasteless carbon monoxide is also a significant toxic hazard if it
escapes through the fuel cell into the exhaust, or if the conduits between the catalytic sections
leak.) The ultimate products of the simple device are roughly 50% hydrogen gas and 30%
nitrogen, with the remaining 20% mostly composed of carbon dioxide. Both the nitrogen and
carbon dioxide are fairly inert when the mixture is pumped into an appropriate fuel cell.
Once the carbon dioxide is released back into the atmosphere, where it can be reabsorbed by
plant life. No net carbon dioxide is released, though it could be argued that while it is in the
atmosphere, it does act as a greenhouse gas.
EEI has developed a new method for producing butanol from biomass. This process involves
the use of two separate micro-organisms in sequence to minimize production of acetone and
ethanol byproducts. Interestingly, this process produces recoverable amounts of hydrogen as
well as butanol.
4. Alternate sources
Sugar cane grows in the extreme southern United States, but not in the cooler climates where
corn is dominant. However, many regions that currently grow corn are also appropriate
areas for growing sugar beets. Some studies indicate that using these sugar beets would be a
much more efficient method for making ethanol in the U.S. than using corn.
In the 1980s, Brazil seriously considered producing ethanol from cassava, a major food crop
with massive starchy roots. However yields were lower than sugarcane, and the processing
of cassava was considerably more complex, as it would require cooking the root to turn the
starch into fermentable sugar. The babaçu plant was also investigated as a possible source of
alcohol.
There is also growing interest in the use of waste biomass as a source for alcohol other types
of fuel. New technologies such as cellulose to ethanol production could provide much higher
positive energy ratios of 2 to 3 times more energy in ethanol produced than input. Cellulose
to ethanol production could also run on any cellulose source from farm waste, hay/grass,
basically any plant matter including wood, cardboard and paper. Theoretically farms could
produce fuel without sacrificing food production, because all that is needed is the left over
plant matter after harvesting. Cellulose to ethanol production is still in development and has
seen limited use in industrial ethanol production. The biggest challenges in using cellulose as
a feedstock is the treatment and disposal of process waste and the conversion of C5 sugars
(these are typically unconverted adding to the waste treatment demand). Unlike grain based
processes which produce a by-product known as distillers grain with minimal waste
treatment needs, cellulosic processes are typically effluent and waste treatment intensive.
Distiller grain is a protein enriched animal feed with much higher nutritional value than
natural grain and is typically priced at less than half that of natural grain. It therefore tends
to be a desirable product for animal feeders. Approximately one-third of grain usage in the
production of ethanol in modern plants is recovered as distillers grain.
At this time, most of the different processes for converting biomass into ethanol and other
fuels are very complicated and not particularly efficient. A few processes have seen
increasing buzz, including thermal depolymerization (though that process produces what is
described as light crude oil).
It is possible to decompose cellulose into sugar in strong or weak solutions of sulphuric acid,
but this process also decomposes and wastes perhaps half the potential sugar content and
creates large amounts of acidic waste, so scientists are searching for more efficient and less
polluting enzymatic and microbial processes for breaking down cellulose into sugar.
Another approach under development is to gasify biomass by heating it in an oxygen-poor
environment. This yields hydrogen, methane and carbon monoxide as well as
noncombustible carbon dioxide and nitrogen compounds. Bacterial cultures have been
isolated that can convert the reactive gasses into ethanol, which is then distilled out of the
liquid medium.
5. Economics of corn ethanol in the U.S.
While the energy balance of ethanol production is controversial and estimates vary widely,
the economics are more certain. Ethanol production from corn costs $1.10 per US gallon (290
$/m²). This figure takes into account a government subsidy of $0.214 per US gallon (57
$/m²). Additionally, corn farmers receive subsidies equivalent to about $0.61 per US gallon
(161 $/m²) of ethanol. Finally, the government subsidizes $0.54 per US gallon (143 $/m²) of
ethanol sold as fuel. Totaling these subsidies and including the $1.10 cost of production gives
$2.464 per US gallon (651 $/m²) of ethanol.
The national trade deficit (USA) has risen to an all time high of $686 billion. Most of this rise
has been attributed to the record high prices of crude oil ($67/barrel). Domestic production
of ethanol for fuel has the potential to ease this deficit.
6. Net fuel energy balance
To be viable, an alcohol-based fuel economy should have positive net fuel energy balance.
Namely, the total fuel energy expended in producing the alcohol — including fertilizing,
farming, harvesting, transport, fermentation, distillation, and distribution, as well as the fuel
used in building the farm and fuel plant equipment — should not exceed the energy contents
of the product.
This is a controversial subject charged with potential bias. Much of it depends on what is
included and what is excluded from the calculation, particularly when compared with the
energy balance of the production of gasoline itself. Analyses are greatly complicated by
various methods of accounting for the energy value coproducts and consideration of
alternate uses of the feedstock. Not surprisingly, this debate has been at best inconclusive to
date.
Switching to a system with negative fuel energy balance would only increase the
consumption of non-alcohol fuels. Such a system would only be worth considering as a way
of exploiting non-alcohol fuels that may not be suitable for transportation use, such as coal,
natural gas, or biofuel from crop residues. (Indeed, many U.S. proposals assume the use of
natural gas for distillation.) However, many of the expected environmental and
sustainability advantages of alcohol fuels would not be realized in a system with negative
fuel balance.
Even a positive but small energy balance would be problematic: if the net fuel energy
balance is 50%, then, in order to eliminate the use of non-alcohol fuels, it would be necessary
to produce two units of alcohol for each unit of alcohol delivered to the consumer.
In this regard, geography is the decisive factor. In tropical regions with abundant water and
land resources, such as Brazil, the viability of production of ethanol from sugarcane is no
longer in question; in fact, the burning of sugarcane residues (bagasse) generates far more
energy than needed to operate the ethanol plants, and many of them are now selling electric
energy to the utilities. Also, in countries with abundant hydroelectric power, the net fuel
energy balance of the cycle could be improved to some extent by using electricity in the
production, e.g. for milling and distillation.
The picture is quite different for other regions, such as the United States, where the climate is
too cool for sugarcane. In the U.S., agricultural ethanol is generally obtained from grain,
chiefly maize, and the net fuel energy balance of that route is still critical.
6.1. Energy balance in the United States
One study has concluded that the use of corn ethanol for fuel would have a negative net
energy balance. Namely, the total energy needed to produce ethanol from grain — including
fermentation, fertilizing, fuel for farm tractors, harvesting and transporting the grain,
building and operating an ethanol plant, and the natural gas used to distill corn sugars into
alcohol — exceeds the energy content of ethanol. However, all subsequent studies have
concluded that ethanol production yields more energy than it consumes (most agree on a
ratio of 1.34:1).
Using old data greatly affects the outcome in these studies. According to the USDA, farms
have become more energy efficient since 1978 due in large part to replacing gasoline
powered equipment with more fuel-efficient diesel engines. Total farm energy use peaked in
1978 at 2,244 trillion Btu (2.368 EJ), but by 2000 had dropped to about 1,600 trillion Btu (1.7
EJ). In the meantime, corn production rose from an average of 110 bushels per acre (6.9
Mg/ha) in 1980 to 140 bushels per acre (8.8 Mg/ha) in 2000.
A study by Cornell University ecology professor David Pimentel seemed to confirm this
conclusion. Pimentel's study was disputed by other specialists, forcing him to revise his
figures. Still, in August 2003 (and again in March 2005), he stated in a Cornell bulletin that
production of ethanol from corn takes 29% more energy than it produces, ethanol from
switch grass requires 45% more energy and ethanol from wood biomass requires 57% more
energy that it produces. However, he concluded yield was 218 US gallons per acre (204
m³/km²) of gasoline equivalent, due to the energy in ethanol being only 66% that of gasoline.
Pimentel also calculated it corn (maize) production requires about 115 US gallons per acre
(108 m³/km²) of gasoline equivalent. Thus, he calculated a net energy production of 103 US
gallons per acre (96 m³/km²), while his studies somehow all concluded a net energy loss in
producing ethanol. Critics of Pimentel's study cite questionable deductions, for example;
1,000,000 Btu per acre (260 kJ/m²) for labor, 5,656,000 Btu per acre (1474 kJ/m²) for
machinery, as well as additional deductions for steel and concrete production and
construction of ethanol refineries, while not saying from where these numbers were derived.
(Shapouri, Hosein, James A. Duffield, Michael Wang. The Energy Balance of Corn Ethanol: An
Update. USDA: Office of the Chief Economist; Office of Energy Policy and New Uses.
Washington, DC. July, 2002)
Pimentel’s work has been largely criticized and discredited by subsequent studies.
It is only fair to hold gasoline to the same standard that ethanol is being put through. The
focus of the USDA report, and others, was on ethanol and the energy balance equation, but
according to a report by the Minnesota Department of Agriculture, when taking into account
the energy needed to extract, transport and refine crude oil into gasoline, the final energy
product of gasoline has an energy ratio of 0.805. That means ethanol production is 81% more
energy efficient than gasoline.
(Groschen http://www.mda.state.mn.us/Ethanol/balance.html )
Continuous refinements to ethanol production procedures have much improved the
benefit/cost ratio, and most studies of modern systems indicate that they now have a
positive net energy balance. Also, when ethanol is mixed with water vapor and converted
into hydrogen, it does not need to be as pure as when it is used in a combustion engine,
making the process more efficient.
Many other studies of corn ethanol production have been conducted, with greatly varied net
energy estimates. Most indicate that production requires energy equivalent to 1/2, 2/3, or
more of the fuel produced to run the process. A 2002 report by the United States Department
of Agriculture concluded that corn ethanol production in the U.S. has a net energy value of
1.34, meaning 34% more energy was produced than what went in. This means that 75%
(1/1.34) of each unit produced is required to replace the energy used in production. The
study also concluded that the energy used to produce and convert the ethanol was from
abundant domestic sources, with only 17% of the energy used coming from liquid fuels,
therefore, for every 1 unit of energy from of liquid fuel used, such as gasoline or diesel fuel,
there was a gain of 6.34 units of energy. MSU Ethanol Energy Balance Study: Michigan State
University, May 2002. This comprehensive, independent study funded by MSU shows that
corn ethanol production has a net energy value of 1.56: it produces 56% more energy per unit
volume of ethanol than it consumes. Nevertheless, as noted earlier, these relatively small
energy gains are problematic, for they imply that between 2.79 (assuming net energy value
1.56) and 3.94 (assuming net energy value 1.34) units of ethanol must be produced for each
unit of ethanol that can be sold to consumers. Actual net energy values might be improved
by measures such as burning corn stalks (which are not fermentable using current
technology) to run some parts of the corn ethanol production process that currently consume
petroleum, gas, or ethanol (similarly to the way bagasse is currently burned to produce
energy to run the ethanol production facilities in Brazil). As of 2005, ethanol production from
corn has a long way to go (or requires a great rise in the cost of petroleum) before it will
become economically viable without government subsidies.
7. Arguments and criticisms
The use of alcohol as fuel is advocated with various arguments, mainly relating to its
beneficial effects on the local and global environment, its independence from foreign oil, and
its economic advantages. Critics generally dispute those arguments, claim that the switch
would be expensive, and object to perceived need for increased government subsidies, taxes,
and regulations.
7.1. Air pollution
There has long been widespread acknowledgement that ethanol is a cleaner-burning fuel
than gasoline. Ethanol has far fewer standard regulated pollutants such as carbon monoxide
and hydrocarbons, compared with plain gasoline in equivalent tests. See, for example, the air
pollution and environmental studies listed at the Renewable Fuels Association website
http://www.ethanolrfa.org/pubs.shtml
There has been concern about increased evaporative smog-forming hydrocarbon emissions.
For example, the conservative organization RPPI claims that "adding ethanol to gasoline will
at best have no effect on air quality and could even make it worse. Studies show ethanol
could even increase emissions of nitrogen oxides and volatile organic compounds, which are
major ingredients of smog." Other critics have argued that the beneficial effects of ethanol
can be achieved with other cheaper additives made from petroleum.
It is important to distinguish the issues. Ethanol in a blend with gasoline replaces tetra ethyl
lead, benzene and MTBE -- all of which are additives that are meant to raise octane levels.
Ethanol, with an octane rating of 110, far surpasses regular gasoline and precludes needs for
other dangerous additives. However, ethanol can increase vapor pressure of gasoline
causing increased evaporative emissions which, on balance, are far less serious than lead,
benzene or MTBE.
Ethanol as a straight fuel is far cleaner than gasoline in its own right and this has been
recognized from the dawn of the automotive age. See, for instance, Kovarik's "Fuel of the
Future" http://www.radford.edu/~wkovarik/lead
7.2. Fire safety
Ethanol appears to be less of a fire hazard than gasoline; while methanol, being more
volatile, is somewhat more prone to fire and explosions. However, since ethanol and
methanol dissolve in water (rather than floating on it like gasoline) their fires can be
extinguished with ordinary water hoses.
One of the problems with accidental combustion of pure ethanol is that it burns with a dim,
blue flame, with invisible smoke. Methanol flames are dim enough to be considered invisible
in daylight. Blending significant amounts of gasoline produces a highly visible flame; small
quantities of dye can also produce this effect.
7.3. Greenhouse gases
A separate (and perhaps more important) benefit of switching to an ethanol fuel economy
would be the decreased net output of the greenhouse gas carbon dioxide (CO2), since all the
CO2 that would be liberated in the manufacture and consumption of ethanol would have to
be absorbed by the plantations. In constrast, the burning of fossil fuels injects massive
amounts of "new" CO2 into the atmosphere, without creating a corresponding sink.
Needless to say, this advantage will be accrued only with agricultural ethanol, not with
ethanol derived from petroleum — which, due to its much smaller cost, presently accounts
for most of the alcohol produced for industrial consumption. This point must be taken into
account when estimating the cost of the switch.
However, this assumes processes such as distillation of ethanol and production of fertiliser
which require large amounts of energy would be done without using fossil fuels.
7.4. Renewable resource
According to its proponents, another advantage of (agricultural) alcohol as a fuel is that it is
a renewable energy source that will never be exhausted; whereas an economy based on fossil
fuels will sooner or later collapse when the world runs out of oil.
However, David Pimentel disputes that "ethanol production from corn" is a renewable
energy source. However, Pimentel's studies have been widely discredited, and also fails to
compare other viable sources of ethanol such as Sugar_beets and Sugarcane.
7.5. Dependency on foreign oil and international crime
A somewhat related (but more compelling) argument is that developed regions like the
United States and Europe consume much more fossil fuels than they can extract from their
territory, therefore becoming dependant upon foreign suppliers as a result. As such, this
dependency has become a major cause of oil wars and coups d'etat initiated by Western
powers, and attendant misery and human rights violations in certain oil-producing countries
allied with the West. Even if the energy balance is negative, US production involves mostly
domestic fuels such as natural gas and coal, so the impact on oil importation is still positive.
7.6. Statism
Some critics, mainly on ideological grounds, dislike the idea of an ethanol economy because
they see it as leading to increased government subsidy for corn-growing agribusiness, and
statism. The Archer Daniels Midland Corporation of Decatur, Illinois, better known as ADM,
the world's largest grain processor, produces 40% of the ethanol used to make gasohol in the
U.S. The company and its officers have been eloquent in their defense of ethanol and
generous in contributing to both political parties.
Tax Incentives for ethanol and petroleum: U.S. General Accounting Office, September 2000.
This study examines subsidies historically given to the oil industry and to the ethanol
industry and finds that the amounts of those to the oil industry are far higher. At the same
time, this study applies only to historical subsidies and doesn't investigate the question of
what the case would be if petroleum fuels were substantially replaced by ethanol.
7.7. Cost
Some economists have argued that using bioalcohol as a petroleum substitute is
economically infeasible because the energy required to grow the corn and other crops used
as fuel is greater than the amount ultimately produced. They argue that government
programs that mandate the use of bioalcohol are simply agricultural subsidies enacted to
gain votes from heavily agricultural states, especially Iowa. However, this reflects a lack of
understanding of the motor fuel industry; production of gasoline also requires more energy
input than the fuel itself provides, but the trade-off is worthwhile because it converts less
portable forms of energy (electricity for pumps, burning off crude oil for heat at refineries,
etc.) into a high-value (portable, easily used) form of energy. As of 2005, ethanol production
has actually become much more energy-efficient than gasoline production, with energy
inputs as low as 70% of the energy value of the ethanol produced.
8. Alcohol fuel in Brazil
An early poster promoting alcohol fuel warns Brazilians not to mix standard petrol with alcohol fuel, and not to use alcohol in
unconverted engines
In Brazil, ethanol is produced from sugar cane which is a more efficient source of
fermentable carbohydrates than corn as well as much easier to grow and process. Brazil has
the largest sugarcane crop in the world, which, besides ethanol, also yields sugar, electricity,
and industrial heating. Sugar cane growing requires little labor, and government tax and
pricing policies have made ethanol production a very lucrative business for big farms. As a
consequence, over the last 25 years sugarcane has become one of the main crops grown in the
country.
8.1. Ethanol production basics
Sugarcane is harvested manually or mechanically and shipped to the distillery (usina) in
huge specially built trucks. There are several hundred distilleries throughout the country;
they are typically owned and run by big farms or farm consortia and located near the
producing fields. At the mill the cane is roller-pressed to extract the juice (garapa), leaving
behind a fibrous residue (bagasse). The juice is fermented by yeasts which break down the
sucrose into CO2 and ethanol. The resulting "wine" is distilled, yielding hydrated ethanol
(5% water by volume) and "fusel oil". The acidic residue of the distillation (vinhoto) is
neutralized with lime and sold as fertilizer. The hydrated ethanol may be sold as is (for
ethanol cars) or be dehydrated and used as a gasoline additive (for gasohol cars). In either
case, the bulk product was sold until 1996 at regulated prices to the state oil company
(Petrobras). Today it is no longer regulated.
One ton (1,000 kg) of harvested sugarcane, as shipped to the processing plant, contains about
145 kg of dry fiber (bagasse) and 138 kg of sucrose. Of that, 112 kg can be extracted as sugar,
leaving 23 kg in low-valued molasses. If the cane is processed for alcohol, all the sucrose is
used, yielding 72 liters of ethanol. Burning the bagasse produces heat for distillation and
drying, and (through low-pressure boilers and turbines) about 288 MJ of electricity, of which
180 MJ is used by the plant itself and 108 MJ sold to utilities.
The average cost of production, including farming, transportation and distribution, is
US$0.63 per US gallon (US$0.17/L); gasoline prices in the world market is about US$ 1.05 per
US gallon (US$0.28/L). The alcohol industry, entirely private, was invested heavily in crop
improvement and agricultural techniques. As a result, average yearly ethanol yield increased
steadily from 300 to 550 m³/km² between 1978 and 2000, or about 3.5% per year.
8.2. Electricity from bagasse
Sucrose accounts for little more than 30% of the chemical energy stored in the mature plant;
35% is in the leaves and stem tips, which are left in the fields during harvest, and 35% are in
the fibrous material (bagasse) left over from pressing.
Part of the bagasse is currently burned at the mill to provide heat for distillation and
electricity to run the machinery. This allows ethanol plants to be energetically self-sufficient
and even sell surplus electricity to utilities; current production is 600 MW for self-use and
100 MW for sale. This secondary activity is expected to boom now that utilities have been
convinced to pay fair price (about US$10/GJ) for 10 year contracts. The energy is especially
valuable to utilities because it is produced mainly in the dry season when hydroelectric dams
are running low. Estimates of potential power generation from bagasse range from 1,000 to
9,000 MW, depending on technology. Higher estimates assume gasification of biomass,
replacement of current low-pressure steam boilers and turbines by high-pressure ones, and
use of harvest trash currently left behind in the fields. For comparison, Brazil's Angra I
nuclear plant generates 600 MW (and it is often off line).
Presently, it is economically viable to extract about 288 MJ of electricity from the residues of
one ton of sugarcane, of which about 180 MJ are used in the plant itself. Thus a medium-size
distillery processing 1 million tons of sugarcane per year could sell about 5 MW of surplus
electricity. At current prices, it would earn US$ 18 million from sugar and ethanol sales, and
about US$ 1 million from surplus electricity sales. With advanced boiler and turbine
technology, the electricity yield could be increased to 648 MJ per ton of sugarcane, but
current electricity prices do not justify the necessary investment. (According to one report,
the World bank would only finance investments in bagasse power generation if the price
were at least US$19/GJ.)
Bagasse burning is environmentally friendly compared to other fuels like oil and coal. Its ash
content is only 2.5% (against 30-50% of coal), and it contains no sulfur. Since it burns at
relatively low temperatures, it produces little nitrous oxides. Moreover, bagasse is being sold
for use as a fuel (replacing heavy fuel oil) in various industries, including citrus juice
concentrate, vegetable oil, ceramics, and tyre recycling. The state of São Paulo alone used 2
million tons, saving about US$ 35 million in fuel oil imports.
8.3. Program statistics
Except where noted, the following data apply to the 2003/2004 season.
land use:
45,000 km² in 2000
labor:
1 million jobs (50% farming, 50% processing)
Sugarcane:
344 million metric tons (50% sugar, 50% alcohol)
sugar:
23 million tons (30% is exported)
ethanol:
14 million m³ (7.5 anhydrous, 6.5 hydrated; 2.4% is exported)
dry bagasse: 50 million tons
electricity:
1350 MW (1200 for self use, 150 sold to utilities) in 2001
The labor figures are industry estimates, and do not take into account the loss of jobs due to
replacement of other crops by sugarcane.
8.4. Effect on oil consumption
Most cars in Brazil run either on alcohol or on gasohol; only recently dual-fuel ("Flex Fuel")
engines have become available. Most gas stations sell both fuels. The market share of the two
car types has varied a lot over the last decades, in response to fuel price changes. Ethanolonly cars were sold in Brazil in significant numbers between 1980 and 1995; between 1983
and 1988, they accounted for over 90% of the sales. 80% of the cars produced in Brazil in 2005
where dual-fuel, comparing to only 17% in 2004.
Ethanol-fuelled small planes for farm use have been developed by giant Embraer and by a
small Brazilian firm (Aeroálcool), and are currently undergoing certification.
Domestic demand for alcohol grew between 1982 and 1998 from 11,000 to 33,000 cubic
metres per day, and has remained roughly constant since then. In 1989 more than 90% of the
production was used by ethanol-only cars; today that has reduced to about 40%, the
remaining 60% being used with gasoline in gasohol-only cars. Both the total consumption of
ethanol and the ethanol/gasohol ratio are expected to increase again with deployment of
dual-fuel cars.
Presently the use of ethanol as fuel by Brazilian cars - as pure ethanol and in gasohol replaces gasoline at the rate of about 27,000 cubic metres per day, or about 40% of the fuel
that would be needed to run the fleet on gasoline alone. However, the effect on the country's
oil consumption was much smaller than that. Although Brazil is a major oil producer and
now exports gasoline (19,000 m³/day), it still must import oil because of internal demand for
other oil byproducts, chiefly diesel fuel (which cannot be easily replaced by ethanol).
8.5. Environmental effect
The improvement in air quality in big cities in the 1980s, following the widespread use of
ethanol as car fuel, was evident to everyone; as was the degradation that followed the partial
return to gasoline in the 1990s.
However, the ethanol program also brought a host of environmental and social problems of
its own. Sugarcane fields are traditionally burned just before harvest, in order to remove the
leaves and kill snakes. Therefore, in sugarcane-growing parts of the country, the smoke from
burning fields turns the sky gray throughout the harvesting season. As winds carry the
smoke into nearby towns, air pollution goes critical and respiratory problems soar. Thus, the
air pollution which was removed from big cities was merely transferred to the rural areas
(and multiplied). This practice has been decreasing of late, due to pressure from the public
and health authorities. In Brazil, a recent law has been created in order to ban the burning of
sugarcane fields, and machines will be used to harvest the cane instead of people. This not
only solves the problem of pollution from burning fields, but such machines have a higher
productivity than people.
Many nations have produced alcohol fuel with no destruction to the environment.
Advancements in fertilizers and natural pesticides have eliminated the need to burn fields.
With condensed agriculture, like hydroponics and greenhouses, less land is used to grow
more crops.
Some question the viabiliy of biofuels like ethanol as total replacements for gasoline/crude
oil. We cannot replace all our food-growing fields with fuel-growing fuels. Authors like
George Monbiot fear the marketplace will convert crops to fuel for the rich while the poor
starve while as well as biofuels causing environmental problems.
8.6. Social implications
The ethanol program also led to widespread replacement of small farms and varied
agriculture by vast seas of sugarcane monoculture. This led to a decrease in biodiversity and
further shrinkage of the residual native forests (not only from deforestation but also through
fires caused by the burning of adjoining fields). The replacement of food crops by the more
lucrative sugarcane has also led to a sharp increase in food prices over the last decade.
Since sugarcane only requires hand labor at harvest time, this shift also created a large
population of destitute migrant workers who can only find temporary employment as cane
cutters (at about US$3 to 5 per day) for one or two months every year. This huge social
problem has contributed to political unrest and violence in rural areas, which are now
plagued by recurrent farm invasions, vandalism, armed confrontations, and assassinations.
8.7. Politics
The Brazilian alcohol program has been often criticized for many motives, including
excessive land use, environmental damage, displacement of food crops, reliance on miserywage temporary labor, statism and dependency on government subsidies, etc..
Until 1996, the Brazilian oil company (Petrobras) was forced to buy ethanol from the private
distilleries and sell it to gas station chains, both as pure (hydrated) ethanol and gasohol.
Nowadays Petrobras only buy ethanol as a anti-knocking additive. However, for lack of
internal demand, Petrobras is virtually forced to sell its surplus gasoline in the international
market at a rather low price, US$ 0.13/liter. Since the domestic market price is about US$
0.50/liter, Petrobras could increase its revenue by over 1 billion US$ per year if the ethanol
program were cancelled. Petrobras also produces methyl-tert-butyl ether (MTBE), a
compound that could replace ethanol in gasohol as an anti-knocking and anti-pollution
additive. However, it is unlikely that this replacement will happen as although MTBE is
cheaper than ethanol, it is also mostly derived from methanol that is a byproduct of the
natural gas industry; therefore, apart from being carcinogenic, MTBE is also non-renewable
(since it is made from crude oil-derived methane.)
On the other hand, the sugarcane agribusiness sector is politically powerful and so far it has
successfully defended the program from its critics. The positive effect of the program on
Brazil's overstrained foreign trade speaks louder than all its environmental and social
problems.
9. U.S. National security
It is believed by some (including former CIA director James Woolsey and Frank Gaffney,
President Reagan's undersecretary of defense) that oil consumption in the U.S. contributes in
a large way to the funding of terrorism. Oil is the primary source of revenue for many mideast countries. Many of these countries are thought to harbor and/or fund terrorist
organizations. The use of alternative fuels would divert money away from these nations.
Ideally, instead of funding terrorism, this money would then be used to fuel the U.S.
economy.
10. External links




















Ethanol Facts, provided by the National Corn Growers Association.
U.S. Department of Energy: Biomass Program.
U.S. Department of Energy: Clean Cities. Includes info on flexible fuel vehicles.
Zen Alcohol Stoves. Includes info on alcohol fuels for stove use.
Ethanol as Fuel - Documentation that Ethanol consumes more energy to make than is
derived from its burning.
American Coalition for Ethanol: www.ethanol.org. Advocacy group.
Methanol Institute: Article about methanol in race cars.
How To Run Your Car On Alcohol Fuel - A 1982 book, now published online, with
information on converting gasoline cars to use ethanol.
Farm Industry News: Hydrogen Corn Economy. Article about converting ethanol to
hydrogen.
Making Alcohol Fuel - A website that covers the use and production of ethanol as a
fuel.
Cogeneration in Ethanol Plants by P. M. Nastari
CDM Potential in Brazil, by S. Meyers, J. Sathaye et al.
Brazilian Ethanol program (in Portuguese) and its machine translation
UNICA - Brazilian Sugarcane growers assoc. (in Portuguese) and its machine
translation
Renewable Fuel Association
National Ethanol Vehicle Coalition Shows locations of E85 fuel pumps in the USA
Clean Fuels Development Coalition
Pimentel: Ethanol - Inefficient Fuel
Debunking Pimentel: Ethanol - Efficient Fuel
Ethanol Fuel News and Discussion
API gravity
API Gravity is a specific gravity scale developed by the American Petroleum Institute (API)
for measuring the relative density of various petroleum liquids. API gravity is gradated in
degrees on a hydrometer instrument and was designed so that most values would fall
between 10 and 70 API gravity degrees.
The U.S. National Bureau of Standards established the Baumé scale (see degrees Baumé) as
the standard for measuring specific gravity of liquids less dense than water in 1916.
Investigation by the U.S. National Academy of Sciences found major errors in salinity and
temperature controls that had caused serious variations in published values. Hydrometers in
the U.S. had been manufactured and distributed widely with a modulus of 141.5 instead of
the Baumé scale modulus of 140. The scale was so firmly established that by 1921 the remedy
implemented by the American Petroleum Institute was to create the API Gravity scale
recognizing the scale that was actually being used.
The arbitrary formula used to obtain this effect is:
API gravity = (141.5/SG at 60 °F) - 131.5
Sixty degrees Fahrenheit (15 5/9 °C) is used as the normal value for measurements and
further tables give adjustments for temperature.
(See ASTM D1298)
Thus, a heavy oil with a specific gravity of 1.0 (the same specific gravity as pure water)
would have an API gravity of:
(141.5/1.0) - 131.5 = 10.0 degrees API.
Generally speaking higher API gravity degree oil values have a greater commercial value
and lower degree values have lower commercial value. This general rule only holds up to 45
degrees API gravity as beyond this value the molecular chains become shorter and less
valuable to a refinery.
Crude oil is classified as light, medium or heavy, according to its measured API gravity.
 Light crude oil is defined as having an API gravity higher than 31.1 °API
 Medium oil is defined as having an API gravity between 22.3 °API and 31.1 °API
 Heavy oil is defined as having an API gravity below 22.3 °API.
Oil which will not flow at normal temperatures or without dilution is named bitumen and
the API gravity is generally less than 10 °API. Bitumen derived from the oil sands deposits in
the Alberta, Canada area has an API gravity of around 8 °API. It is 'upgraded' to an API
gravity of 31 °API to 33 °API and the upgraded oil is known as synthetic oil.