Cleaner or alternative forms of transportation in conjunction with fuel efficiency are an important area of
development and innovation. With an ever increasing demand for transportation for over great distances the
potential improvements could save huge amounts of money, and reduce effects of vehicle emissions on
environments and alleviate the reliance transportation and society have on fossil fuels. The main areas to consider
are:
What are the negative effects of transportation pollution and why should we care?
What do we have and what are the potential flaws?
What are the methods being employed and developed to improve transport?
What are the negative effects of transportation pollution and why should we care?
The transportation industry is responsible for ≈14% of emissions pollution
(http://en.wikipedia.org/wiki/Greenhouse_Gas). It is responsible of social issues like smog surrounding various major
cities such as Mexico City and Santiago, but the main area of concern is the greenhouse gas emissions and the lack of
efficiency in combustion engines.
Combustion of Fossil Fuels in the US for example account for ≈90% (http://en.wikipedia.org/wiki/Fossil_fuel) of
greenhouse gas emissions. The primary contributors are fossil fuel power stations, which due to vast amounts of
research are becoming far more efficient and less polluting, but the transportation sector is a close second. (2004 for
US and 2006 US): (http://www.globalization101.org/uploads/Image/Energy/Graph-5-US-Fossil-Fuel-Usagesector.jpg)
(http://www.epa.gov/climatechange/emissions/co2_human.html)
Transportation greenhouse emissions are nearly entirely consistent of Carbon Dioxide. Of all CO2 emissions 19.2% is
from is transport industry.
(http://upload.wikimedia.org/wikipedia/commons/e/e0/Greenhouse_Gas_by_Sector.png)
The rise in the concentration of greenhouse gases in atmosphere contributing to Global Warming is referred to as
the “greenhouse effect”. The density of greenhouse gases; namely carbon dioxide, methane and nitrous oxide, in
atmosphere reflects the amount of radiation reflected back upon the earth as it tries to pass through the
atmosphere and off into space. Over time, this effect raises the average temperature of earth.
(http://www.grida.no/images/series/vg-africa/graphics/09-greenhousegases.jpg)
Transportation although a smaller contributor than fossil fuel power plants is also far less efficient, as a result it may
be possible to make greater improvements in transportation accounting for a similar effect on environmental change.
Other Risks due to Tailpipe Pollutants:
Internal combustion engines also release a number of other substances which amalgamate to cause adverse effects
related to smog, most notably:
1. Nitrogen and Oxygen compounds like NO and NO2 can react with other compounds, even moisture creating
nitrous based acidic substances that damage people respiratory systems.
2. Carbon Monoxide, well known for being very difficult to detect (no odour, colour or taste) and fatal. It
isolates and causes oxygen carrying components of blood to become unreactive to incoming oxygen.
3. Volatile organic compounds (VOCs) like Benzene, a carcinogen, are usually only dangerous in the long run.
They are numerous and most are difficult to detect.
4. Particle matter often due to impurities or additives in fuel that are smaller than 10 microns in diameter can
penetrates lungs causing infection or eventually emphysema.
Furthermore this smog density and consequently these risks will only increase over time until improvements are
made. This cannot be permitted to be a permanent solution:
http://www.lesterho.com/blog/wp-content/gallery/mask/p3180417.jpg
In addition to environmental and health effects there are also economic issues to consider. Most of fuel of modern
world in gathered from fossil fuels. Fossil fuels are a finite resource from our perspective as they take hundreds of
thousands of years to build up. This means, like all economic goods as supply becomes constricted/limited prices will
rise rapidly. In addition fossil fuels are the backbone of our society; we are heavily reliant on them:




Distribution/transportation of goods/people.
Extraction of raw materials.
Generation of electricity which is essential to every household.
Household heating.
The list of essential jobs they contribute too is increasingly lengthy. To put out reliance into context:
World Energy Sources
Gas, 23.00%
Nuclear, 6.00%
Biofuels,
0.20%
Biomass, 4.00%
Hydro, 3.00%
Coal, 25.00%
Wind, 0.30%
Other, 1.24%
Oil, 37.00%
Geothermal,
0.20%
Solar, 0.54%
An amalgamation of greenhouse gas emissions, noise pollution, smog’s associated social consequences, economic
benefits, a shift away from fossil fuel reliance, waste energy in internal combustion engines and the demands of the
Kyoto protocol represent “why we should care” about improving the transportation industry.
Before improvements can be made an understanding of “What we have and what is wrong with it?” must be
reached.
http://www.hauteliving.com/wp-content/uploads/2011/11/BMW-i81.jpg
What do we have and what are the potential flaws?
(http://inventors.about.com/library/inventors/blinternalcombustion.htm) In general, fossil fuel based transports
make use of internal combustion engines, to compare performance engines and fuels must first be understood:
There are two main types of internal combustion engine. The 2-stroke engine and the 4-stroke engine, this referee
the procedure of cycle and as a result how complex the engine is.
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Petrol/Gasoline Internal Combustion Engines
Diesel Internal Combustion Engines
Properties and Performance of Fuels
Considering the above pages, there are many flaws in internal combustion engines capacity to efficiently transform
thermal energy to motive energy. This leaves innovators with a number of choices, to improve upon the existing
internal combustion engine (reduce wasted heat e.g. heat loss through exhaust gases) or to come up with totally
new engines and forms of transport. So “What are the methods being employed and developed to improve
transport?”
Petrol/Gasoline Internal Combustion Engines:
The 2-Stroke Petrol Engine is the simpler and cheaper of two types. It has a shorter cycle and less moving parts
making is less expensive to manufacture but as a result it is less efficient. They are generally used for smaller
machines like motorcycles, chainsaws and snow mobiles. The 2-strokes of engine cycle, beginning on down stroke,
consist of:
1. Exhaust gases are expelled via exhaust port as piston moves down. As the piston moves further down,
filtered air and fuel mixture drawn from carburettor through a reed value (only allows flow in one direction)
in the inlet port during the previous stroke is now pressurised by the piston within crankcase. As the piston
converges on the bottom of its oscillation the transfer port allows un-ignited fuel air mixture into
combustion chamber.
2. As the piston moves up it opens the inlet port allowing more fuel air mixture to enter. The transfer port is
then closed, followed by the exhaust port. The mixture in the combustion chamber is compressed to the
optimal point where the spark plug is triggered and the piston is “fired” by the expanding gas, completing
the cycle.
http://www.arthursclipart.org/carmechanic/mechanic/2%20stroke%20engine.gif
Precision is important as the ports are often open at same time, which if not judged correctly would ruin the engine.
It is also one of the reasons it is less efficient. The engine is designed so exhaust and inlet gases never mix.
The 4-Stroke Petrol Engine is used in most cars and trucks, its engine’s cycle is similar to the 2-stroke engine, but:
1. Stroke down to draw new fuel and air mixture into combustion chamber through valve
2. Stroke up that compresses fuel in chamber; ignition of plug is triggered as pressure passes a certain value
3. Stroke as expanding hot air forces piston back down
4. Final upstroke that cleans chamber of ignited hot air and pollutants
(http://upload.wikimedia.org/wikipedia/commons/d/d7/4-Stroke-Engine-with-airflows.gif)
Diesel Internal Combustion Engines:
There are a number of differences in the design of diesel engines. Diesel 2-stroke engines are less common than
there petrol counterpart. A 2-stroke diesel does draw in pre mixed fuel and air mix, instead the fuel is injected into
chamber before the upwards compression stroke. There is also no spark plug; ignition of fuel is achieved via heat
due to rapid compression.
http://static.howstuffworks.com/gif/diesel-two-stroke.gif
A 4-stroke diesel engine varies in that:
1. No fuel is drawn in by the piston’s downward movement, instead, just warm air.
1
1
1
2. A petrol engine only compresses 8 to 12 of original volume, whereas a diesel engine compresses air too 14 to
1
25
of its original volume. This is what causes ignition, the temperature of air due to compression.
3. Petrol engines rely of spark plug and already mixed air and fuel. In a diesel engine the fuel is delivered in 3rd
stroke. There are many delivery methods; in this case fuel is injected as spray into hot air, igniting it.
4. In both cases hot waste gas is ejected.
http://jayant7k.blogspot.com/2006/10/petrol-engine-versus-diesel-engine.html
Properties and Performance of Fuels: Petrol is a lightweight highly volatile fuel, whereas diesel is heavier less
volatile fuel. Diesel is the more effect fuel for a number of reasons. Diesel has a higher energy density; 1 litre of
diesel = 40.8x106 Joules of Energy whereas 1litre of petrol = 34.7 Joules of energy. The relative weight of fuel to
distance travelled improves fuel efficiency.
So considering this theory it is no surprise to discover that during in house testing Isuzu concluded that Diesel engine
has a higher thermal efficiency (proportion of heat converted to motive force) than petrol. Diesel performed at 35%
to 42% efficiency compared with petrol engine of 25% to 30%. Moreover this efficiency translated to 20% to 40%
drop in fuel consumption, especially when driving in slow moving traffic where diesel engines even torque engine
speed characteristics reduce fuel consumption.
(http://www.isuzu.co.jp/world/technology/clean/diesel_gasoline02.html)
Diesel is made of the longer chain hydrocarbons separate during fractional distillation process, and petrol the lighter,
shorter chain hydrocarbons. Because of the post processing required for the extraction and preparation of gasoline
diesel is also cheaper to extract. So consumers and environment could benefit from using diesel, but due to huge
demand for diesel in larger industrial machinery, transportation like container ships or heating in winter months the
price of diesel to consumer has in recent years exceeded petrol. (http://www.factcheck.org/2008/05/diesel-fueland-gasoline-costs/)
To back up this evidence further there are also consumer reviews (http://cars.uk.msn.com/features/greenmotoring/articles.aspx?cp-documentid=147863573) comparing similar vehicles. Although these vehicles often have
some of the measures used to reduce emissions they still help compare engines.
What are the methods being employed and developed to improve transport?
Improving existing transports could be argued as an easier transition for society, especially one as economically
fragile as ours. Many years of research and practice have gone into the combustion engine so we are potentially
more experienced and better equipped to improve that style of engine rather than creating new ones.
On the other hand, given the advances in scientific understanding, mathematical modelling, materials,
manufacturing and our ability to predict the problems we are going to face, that a definitive substitute is required.
Given these advances is likely that fundamental flaws with internal combustion engines could be completely avoided.
But as argued by David Petechuk in his article, this will not be the case within the next decade:
(http://www.scienceclarified.com/dispute/Vol-1/Will-a-viable-alternative-to-the-internal-combustion-engine-existwithin-the-next-decade.html)
“To become a "viable" alternative to the internal combustion engine, alternative technologies must be as
efficient, dependable, and powerful. Furthermore, they must be as competitive in terms of cost to the
consumer. To reach these goals within a decade is not possible given the internal combustion engine’s
current vast superiority in these areas.”
When comparing the following ideas it is important to consider the whole life cycle of vehicle, or as it is more
commonly known when referring to cars “well-to-wheel” emissions. Tailpipe pollutants measure only considers cost
to environment at point of use e.g. driving itself. Instead pollutants from the manufacture, sourcing of raw materials
and disposal of vehicle should be accounted.
With this in mind, these are just a number of the technologies in development or use that help to improve fuel
efficacy and reduce emissions. They consider either:
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Individual aspects of vehicles
The integration of aspects into hybrids
Macroscopic scale efficiency
A more easily accessible guide from a consumer’s perspective can be found here. As there are so many contributing
factors within how efficient a car is it is almost impossible to make an inform decision. Given the huge amount of
success designers and engineers are having in just consumer automotives, the future of transportation may not
seem so fragile.
Individual aspects of vehicles:
Turbo-chargers and Super-chargers: are forced induction systems. Turbo-chargers compress incoming air using
waste exhaust gases whereas super-chargers use the engine itself to compress incoming air. As shown by research
into “Hybrid Compressed Air Cars”, compressing air before it enters the engine can increase efficiency hugely. They
can give improvements to fuel efficiency of ≈7.5%. (http://www.fueleconomy.gov/feg/tech_adv.shtml) A twincharger combines both super chargers and turbo chargers, to further improve fuel efficiency and consistency.
Obviously the viability depends on vehicle. Turbo chargers perform better in terms of fuel economy, but super
chargers offer better throttle response. Twin chargers are most efficient, but are more complex, hence they are
much more expensive.
Using the same principles BMW have released their concept of a “Turbo Steamer”; this uses waste exhaust gases to
power a steam engine which can add to engines power output. This can recycle up to 80% of waste heat energy from
exhaust gases giving a (http://www.bmwheaven.com/index.php/articles-and-reviews-mainmenu-3/bmwinnovations/65-169)
In addition, with a turbo-charger or super-charger direct fuel injection can be installed giving a further ≈4.4%-5.5%
improvement to fuel efficiency. Direct fuel injection, means fuel is injected directly into combustion chamber. By
controlling how and when it is delivered more accurately, optimal “firing” of piston is achieved resulting in better
fuel efficiency.
Regenerative Breaking: A braking system whereby the brake pads rotate and are connected to an electric motor,
braking forces motor to go backwards, generating power that is fed back into car battery. Within the later
mentioned hybrid vehicles this energy is then used to boost engine output through support by electric motor. They
also offer reduced break wear and are most efficient when employed in slow stop-start traffic situations.
There is also a hydraulic variant of regenerative breaking; these are more commonly associated with larger heavy
goods vehicles.
Integrated Starter/Generator (ISG): Automatically switches the engine of a vehicle off when not moving, e.g. traffic
jam, but allows for driving power to be instantly available the moment the vehicle needs to move. It offers ≈8%
increase to fuel efficiency.
Inactive Cylinders: Similar to ISG, when the vehicle is moving slowly and not all cylinders within the engine are
required, they are instead switched off. This can save up ≈7.5% in fuel efficiency.
Materials: Weight has a huge impact of fuel efficacy of a vehicle. Due to improvements in material science, better
materials with optimal strength to weight ratios can be chosen. Within cars already is the use of aluminium, carbon
fibre, magnesium alloys and various plastics. Materials likely to be used in future: Duralumin, age hardened
aluminium; Carbon Nanotubes, an allotrope of carbon that has vastly improved properties due to its intended
atomic structure, a product of research into Buckminster Fullerene.
The negative impact of using new materials, especially alloys, is their use of rare minerals and metal deposits.
Technology with a reliance on rare materials is as unsuitable as fossil fuels if supply of materials cannot meet need.
In-Wheel Motors: placing all integral parts of car drive into wheels themselves; motor, brakes, transmission, steering,
braking among others. Looking at Ford F-150 truck shown at Specialty Equipment Market Association (SEMA) (2008)
the performance of four in-wheel motors was comparable with two of the V8 engine originally within truck. With
600 horsepower generated from just four 30kg motors, the early concept vehicle has a range of 100miles.
Production vehicles would only need two in-wheel engines, promoting them yet further.
There are considerable more benefits, and these are a likely alternative in future, as “Michelin is hoping that its
Active Wheel system will catch on with automakers soon” (http://auto.howstuffworks.com/in-wheel-motor.htm)
Flow Dynamics: Because of greater scientific understanding and the use of computer modelling and air tunnels
designers and engineers are far better equipped to design optimal aerodynamically shaped vehicles. Flow
characteristics have more impact at higher speeds as air resistance and traction become more important. Formular 1
cars are an obvious example of where dynamic flow plays a huge roll. A designed aimed at an economic,
environmentally friendly drive is the Aptera Series 2.
http://www.jasonhharper.com/wpcontent/uploads/2009/03/aptera2e-51.jpg
http://auto.howstuffworks.com/aptera-hybrid.htm
An example of an interesting claim by the makers of Gumbert Apollo is that it could potentially drive along upside
down at speeds above 200mph due to its flow design, and the down-force generated at those speeds. Obviously this
does not account for the loss of traction due to vehicle being upside down, but the possibility remains.
http://www.hidromobil.org/wpcontent/uploads/2011/11/2011-Gumpert-Apollo-S.jpg
http://www.topgear.com/uk/car-news/gumpert-apollo-ceiling
The integration of aspects into hybrids
Hybrids:
Plug-In Hybrids:
Electric Cars:
Hybrid Compressed Air Cars: as previously mentioned, researchers of UK Brunel University claim to have a method
of upgrading existing internal combustion engines o run on compressed air, resulting is 30% less gas consumption
causing a 65miles per gallon, on par with many conventional hybrids. Because this design can be fitted to existing
combustion engines, or integrated into manufacture more easily, it is argued to be a more viable alternative to
conventional hybrids. (http://www.fastcompany.com/blog/ariel-schwartz/sustainability/will-we-see-hybridcompressed-air-car-near-future)
There are also systematic approaches that evaluate the way vehicles are used and look to improve in those areas:
Advanced Control Systems: