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GREEN TECHNOLOGY
BY
Dr.K.Narasimhulu
Ph.D(Biotechnology),M.Tech(Biotechnology), B.Tech(Chemical Engineering), D.S.Tech(Sugar Technology)
Assistant Professor
Department of Biotechnology
NIT Warangal
OPEN ELECTIVE
BIOMASS ENERGY
• What is BIOMASS?
• Biomass is biological material derived from living, or recently living
organisms. In the context of biomass for energy this is often used to
mean plant based material, but biomass can equally apply to both
animal and vegetable derived material.
• Chemical composition
• Biomass is carbon based and is composed of a mixture of organic
molecules containing hydrogen, usually including atoms of oxygen,
often nitrogen and also small quantities of other atoms, including
alkali, alkaline earth and heavy metals.
• Plant material
• The carbon used to construct biomass is absorbed from the atmosphere
as carbon dioxide (CO2) by plant life, using energy from the sun.
• Plants may subsequently be eaten by animals and thus converted into
animal biomass. However the primary absorption is performed by
plants.
• If plant material is not eaten it is generally either broken down by
micro-organisms or burned:
• If broken down it releases the carbon back to the atmosphere, mainly
as either carbon dioxide (CO2) or methane (CH4), depending upon the
conditions and processes involved.
• If burned, the carbon is returned to the atmosphere as CO2.
• There are five basic categories of material:
• Virgin wood, from forestry or from wood processing
• Energy crops: high yield crops grown specifically for energy applications
• Agricultural residues: residues from agriculture harvesting or processing
• Food waste, from food and drink manufacture, preparation and
processing and post-consumer waste
• Industrial waste and co-products from manufacturing and industrial
processes.
Sources of Biomass
•
• The amount of energy released when a given unit of fuel is combusted is
referred to as the energy content of that fuel.
• For example, the energy content of wood is generally in the range of 6 to
18 Mega Joules per kg (MJ/kg) of wood, depending on the moisture
content of the wood.
• Freshly cut wood could have as much as 60% moisture and would have a
relative low energy content (e.g., 6 MJ/kg), whereas oven dried wood
with close to zero moisture content could have up to 18 MJ/kg.
• An average commonly used value for wood is 15 MJ/kg. Representative
values for the energy content of other types of biomass are:
• Grass (fresh cut) ---- 4 MJ/kg
Paper ------------ 17 MJ/kg
Straw ------------ 15 MJ/kg
Dung ------------ 16 MJ/kg
Domestic waste ---- 9 MJ/kg
How Can We Use the Energy in Biomass?
• There are a wide variety of uses for the energy in biomass,
including basic life functions, direct combustion, and
charcoal, liquid fuel, or gaseous fuel production.
Use for Basic Life Functions
• We are all familiar with the use of biomass for basic life functions by all
animals and humans.
• All the food we eat contains biomass, whether vegetables, animals, or
products derived from them.
• The energy in these foods is what sustains life in all living organisms.
• Considerable debate exists about the competing uses of biomass for food
versus energy production.
Direct Combustion of Biomass
• Most biomass is in solid form and can be burned (combusted with
oxygen in air). The combustion process results in the generation of heat
(thermal energy) the same way that burning coal gives off heat.
• The heat generated by the burning of biomass can be used for space
heating (e.g., heating of buildings), for cooking and for heating water.
• It can also be used to boil water to generate steam, which in turn is
used to run a turbine and electric generator to produce electricity in
the same way that coal is used to generate electricity in a coal-fired
power plant.
• The biomass may need a certain amount of processing before burning
(e.g., sorting, drying and size reduction). It may also be mixed with coal
or other types of fuel in the furnace.
Charcoal Production from Biomass and
Combustion
• In addition to water (moisture), wood normally contains chemicals that
volatilize when they are heated.
• During the combustion of wood in air, most of this volatile matter
oxidizes and contributes to the energy being released in the combustion
process.
• However, when wood is heated in the absence of air or oxygen, the
volatile matter is driven off of wood in a process called pyrolysis and the
remaining matter is called charcoal.
• Charcoal is almost pure carbon, with about twice
the energy content per unit mass as the original
wood.
• Therefore, it can burn at much higher
temperatures than wood. However, it takes about
4 to 10 kg of wood to make 1 kg of charcoal.
• In addition, if the volatile gases driven off from
the wood during pyrolysis are not collected and
used, they contribute to greenhouse gas emissions.
Production of Liquid Fuels from Biomass
• Liquid fuels that are produced from biomass are
used to extend crude oil resources by
substituting for gasoline or diesel fuel.
• Although there are different ways of producing
gasoline-like liquid fuels from biomass, the most
common gasoline substitute is ethanol.
• Ethanol Production from Biomass:
• The most common method for producing ethanol from biomass is
through a process known as fermentation, which is an anaerobic
biological process in which sugars are converted to alcohol by the
action of microorganisms such as yeast.
• Fermentation is a technology that has been used for centuries to make
beer and wine. The process requires sugars.
• If the carbohydrates contained in the starting biomass are starch, such
as is found in corn, then the starchy material first has to be converted
to sugars.
• The most common crop used in the United States for making ethanol
for gasoline additive is corn, whereas in tropical countries such as
Brazil, the crop of choice is sugar cane.
• Biodiesel Production from Biomass: Biodiesel is normally produced
from vegetable oils, animal fats, or greases.
• The process involves the use of a catalyst and alcohol. The catalyst is
typically sodium hydroxide or potassium hydroxide, which is dissolved
in methyl alcohol.
• Any type of vegetable oil or used cooking oil can be used to make
biodiesel; most biodiesel today is made from soybean oil.
• Biodiesel production from algae is still in the experimental stage. Algae
are expected to produce from 10 to 100 times more biodiesel
compared with soybeans and other seed crops.
Production of Gaseous Fuels from Biomass
• It is well known that anaerobic digestion of organic matter produces
organic gas, mostly methane.
• Examples of natural processes are the production of landfill gas in
municipal landfills and the burping of cows.
• Biomass can also be converted to biogas under controlled conditions in
what is known as a digester.
• The organic matter used for this purpose is often animal waste such
as manure.
• The anaerobic digestion is basically a biological
process carried out by bacteria in the absence of
oxygen.
• Biogas can also be produced from solid biomass by
chemical means similar to the way town (or coal)
gas is produced from coal.
• Biogas can be used in many applications similar to
natural gas, including cooking, space heating,
industrial heat, and electricity production.
Production of biomass
electricity
What is biomass power?
• Electricity that is produced as a result of utilizing surplus biomass
sources into energy is considered biomass power. Biomass combusted in
a boiler produces steam. This steam drives a turbine generator that
produces electricity. This electricity will be fed into the high voltage
transmission grid to be transported to end-users.
• What are the types of biomass used in a biomass power generation
facility?
• The principal source of biomass are rice husk, woody biomass such as
Julie flora, casurina, other agro residues such as stalks/cobs/shells,
sugarcane trash, cotton stalks, mustard stalks, groundnut shells etc.
Why produce power from biomass?
• Generating power through the use of biomass
represents the cost-effective and cleanest way to
provide renewable electricity in biomass potential
regions with high levels of biomass resources and its
processing activity.
•
Furthermore, use of this resource helps become
more energy independent and use of a locally
derived fuel provides employment and direct
economic benefit to local communities.
What is the potential of power generation
from biomass ?
• The estimated power potential from surplus agro
residues in the country is about 17,000 MW.
•
In addition about 5000 MW of power can be
produced, if the sugar mills in the country switch
over to modern techniques of cogeneration.
• Biomass can be converted into electric power through several methods.
• The most common is direct combustion of biomass material, such as
agricultural waste or woody materials.
• Other options include gasification, pyrolysis, and anaerobic digestion.
• Gasification produces a synthesis gas with usable energy content by
heating the biomass with less oxygen than needed for complete
combustion.
• Pyrolysis yields bio-oil by rapidly heating the biomass in the absence of
oxygen.
• Anaerobic digestion produces a renewable natural gas when organic
matter is decomposed by bacteria in the absence of oxygen.
• Different methods work bet with different types of biomass.
• Typically, woody biomass such as wood chips, pellets, and sawdust are
combusted or gasified to generate electricity.
• Corn Stover and wheat straw residues are baled for combustion or
converted into a gas using an anaerobic digester.
• Very wet wastes, like animal and human wastes, are converted into a
medium-energy content gas in an anaerobic digester.
• In addition, most other types of biomass can be converted into bio-oil
through pyrolysis, which can then be used in boilers and furnaces.
• Woody biomass is commonly used for facility heating in three forms:
whole logs or firewood, wood chips, and wood pellets.
• Systems are available from 6,000 British thermal units (Btu)/hr to
over 100 million Btu/hr.
• Small systems, particularly small- and mid-size pellet and log systems,
are available off-the-shelf from numerous manufacturers.
• Larger pellet systems and wood chip-fired systems are commercially
available from several companies.
• The larger systems typically require both facility modification and
system customization, mainly for integration of the fuel storage and
handling and conveying systems
• Biomass systems require more operator interaction
than other renewable energy systems such as solar
and wind.
• This includes ordering and delivering fuel, removing
ash, and maintaining moving parts.
• Overall, however, biomass heating systems typically
only require a few minutes of attention each day,
plus a few hours per year for annual maintenance.
• Compared to most other renewable energy options
currently available, biomass has the advantage of
dispatchability, meaning it is controllable and available
when needed, similar to fossil fuel heating and electric
generation systems.
• The disadvantage of biomass for facility heating is that the
fuel needs to be purchased, procured, delivered, and stored.
• Biomass combustion also produces emissions, which must be
monitored and controlled to comply with regulations.
•
A biomass heating system is made up of several
key components, which include some combination
of the following items:
•
Fuel storage and handling / conveying
•
Combustor
•
Boiler
•
Fire suppression systems
•
Pumps
•
Fans
•
Exhaust / emissions controls
•
System controls
•
Automatic ash handling (optional)
•
Backup boiler
•
The building facility's heat distribution system.
• All biomass systems require fuel storage space and
usually some sort of fuel handling equipment and
controls.
• A system using wood chips or pellets usually stores
the fuel in a bunker or silo.
• An automated control system conveys the fuel from
the storage area using a combination of belts,
augers, or pneumatic transport.
• The fuel storage volume can be sized to supply a
quantity of fuel that will last from one day up to
several weeks.
• The combustor and boiler can be configured end-to-end or the boiler
can be mounted on top of the combustor.
• The first configuration requires more floor space and the second
requires more vertical clearance.
• Some manufacturers of larger biomass heating equipment make all of
the system components, including the boiler/heat exchanger and the
combustor.
• Others specialize in specific components, like the combustor and fuel
handling systems, and in integrating components into complete
systems.
• A fire suppression system is sometimes used to
prevent fire from spreading from the combustor
back up through the conveyor system where the
wood chips are held in the metering bin.
• For example, this system might include a
temperature sensor mounted on the feed system
just upstream of the combustor as well as a waterdelivery and control system to quench any fire
before it spreads through the feed system.
• In a hydronic system, which uses steam or hot water, pumps
are used to circulate water from the hot water tank to
spaces or buildings being heated by the system, through flow
valves controlled by a thermostat or other temperature
controller.
• Biomass heating systems generally use a combination of
induced-draft and forced-draft fans to control combustion
air into the firebox and to force air through any emissions
controls systems.
• Exhaust systems are used to vent combustion by-products, primary
carbon-dioxide, and water to the atmosphere.
• Emissions controls might include a cyclone or multi-cyclone, a baghouse,
or an electrostatic precipitator (listed in order of increasing capital cost
and effectiveness) to capture particulate matter.
• Cyclones and multi-cyclones can be used as pre-collectors to remove
larger particles upstream of a baghouse (fabric filters) or electrostatic
precipitator.
• Woody biomass typically contains 1% to 5% ash content, which is
non-combustible material.
• To ensure that the system continues functioning properly, this ash
must be removed periodically from the system.
• In some systems, ash is removed manually, using a special rake or
shovel.
• In other systems, augers automatically remove the ash from the
firebox and deliver it to a barrel or other container for disposal.
• Biomass-fired heating systems often include a secondary fossil fuelfired heating unit. This offers several advantages, including:
• Reduced capital costs and increased operating efficiency by undersizing the biomass system
• Reduced uncertainty, as the buildings will still have a heat source even
if the biomass system is down for any reason
• Increased operational flexibility
• Increased fuel options.
How Does it Work?
• Direct combustion is the most common method of producing heat from
biomass.
• In a direct combustion system, the biomass is burned to generate hot
gas, which is either used directly to provide heat or fed into a boiler to
generate hot water or steam.
• In a boiler system, the steam can be used to provide heat for process or
space heating.
• The hot water or steam from the boiler can be used to transfer heat to
a facility through typical space heating methods.
• If the system is used as a combined heat and power system, the boiler
can produce steam to run a turbine and power a generator, and
remaining steam and hot water can then be used for heating.
•
Application
• The type of system best suited to a particular application depends on
many factors, including:
• availability and cost of each type of biomass (e.g. chip, pellet or logs),
• competing fuel cost (e.g. fuel oil and natural gas),
• thermal peak and annual load,
• building size and type,
• space availability,
• operation and maintenance
emissions regulations.
(O&M)
staff
availability,
and
local
Transmission of biomass electricity
• After electricity is produced at power
plants it has to get to the customers
that use the electricity.
• Our cities, towns, states and the entire
country are criss-crossed with power
lines that "carry" the electricity.
• As large generators spin, they produce electricity with a voltage of
about 25,000 volts.
• A volt is a measurement of electromotive force in electricity. This is the
electric force that "pushes" electrons around a circuit.
• "Volt" is named after Alessandro Volta, an Italian physicist who
invented the first battery.
• The electricity first goes to a transformer at the power plant that
boosts the voltage up to 400,000 volts.
• When electricity travels long distances it is better to have it at higher
voltages.
• Another way of saying this is that electricity can be transferred more
efficiently at high voltages.
• The long thick cables of transmission lines
are made of copper or aluminum because
they have a low resistance.
• The higher the resistance of a wire, the
warmer it gets.
• So, some of the electrical energy is lost
because it is changed into heat energy.
• High voltage transmission lines carry
electricity long distances to a substation.
•
The power lines go into substations near businesses, factories
and homes.
•
Here transformers change the very high voltage electricity back
into lower voltage electricity.
•
From these substations (like in the photo to the right),
electricity in different power levels is used to run factories,
streetcars and mass transit, light street lights and stop lights,
and is sent to your neighborhood.
•
In your neighborhood, another small transformer mounted on
pole (see picture) or in a utility box converts the power to even
lower levels to be used in your house.
•
The voltage is eventually reduced to 220 volts for larger
appliances, like stoves and clothes dryers, and 110 volts for
lights, TVs and other smaller appliances.
• When electricity enters your home, it
must pass through a meter.
• A utility company worker reads the
meter so the company will know how
much electricity you used and can bill
you for the cost.
• After being metered, the electricity goes
through a fuse box into your home.
• The fuse box protects the house in case
of problems. When a fuse (or a circuit
breaker) "blows" or "trips" something is
wrong with an appliance or something
was short- circuited.
UNIT-3
• Energy transformation from source to services:
• Energy transformation or energy conversion is the process of
changing one form of energy to another.
• In physics, the term energy describes the capacity to produce certain
changes within a system, without regard to limitations in
transformation imposed by Entropy.
• Changes in total energy of systems can only be accomplished by
adding or removing energy from them, as energy is a quantity
which is conserved (unchanging), as stated by the first law of
thermodynamics.
• Energy in its various forms may be used in
natural processes, or to provide some service
to society such as heating, refrigeration, light,
or performing mechanical work to operate
machines.
• For example, an internal combustion engine
converts the potential chemical energy in
gasoline and oxygen into thermal energy
which, by causing pressure and performing
work on the pistons, is transformed into the
mechanical energy that accelerates the vehicle
(increasing its kinetic energy) and that pushes
it up hills (increasing its gravitational
potential energy)no its not.
• A solar cell converts the radiant energy of
sunlight into electrical energy that can then
be used to light a bulb or power a computer.
There are many different machines and transducers
that convert one energy form into another
•
Thermoelectric (Heat → Electric energy)
•
Geothermal power (Heat→ Electric energy)
•
Heat engines, such as the internal combustion engine used in cars, or the steam engine (Heat
→ Mechanical energy)
•
Ocean thermal power (Heat → Electric energy)
•
Hydroelectric dams (Gravitational potential energy → Electric energy)
•
Electric generator (Kinetic energy or Mechanical work → Electric energy)
•
Fuel cells (Chemical energy → Electric energy)
•
Battery (electricity) (Chemical energy → Electric energy)
• Fire (Chemical energy → Heat and Light)
• Electric lamp (Electric energy → Heat and Light)
• Microphone (Sound → Electric energy)
• Wave power (Mechanical energy → Electric energy)
• Windmills (Wind energy → Electric energy or Mechanical energy)
• Piezoelectrics (Strain → Electric energy)
• Acoustoelectrics (Sound → Electric energy)
• Friction (Kinetic energy → Heat)
• Heater (Electric energy → Heat)
• Light bulb (electricity → light)
•
•
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