readings with assessment in Alternative Energy -- Wind
Energy -- Geothermal Energy -- Hydropower -- Nuclear Energy
Alternative Energy Basics
BIOMASS FOR FUEL
Biomass is organic
material made from plants and animals.
contains stored energy from the sun.
absorb the sun's energy in a process called photosynthesis.
The chemical energy in plants gets passed on to animals and
people that eat them.
is a renewable energy source because we can always grow more trees
and crops, and waste will always exist. Some examples of biomass
fuels are wood, crops, manure, and some garbage.
the chemical energy in biomass is released as heat. If you have
a fireplace, the wood you burn in it is a biomass fuel. Wood waste
or garbage can be burned to produce steam for making electricity,
or to provide heat to industries and homes.
biomass is not the only way to release its energy. Biomass
can be converted to other usable forms of energy like methane
gas or transportation fuels like ethanol and biodiesel. Methane
gas is the main ingredient of natural gas. Smelly stuff, like
rotting garbage, and agricultural and human waste, release
methane gas - also called "landfill gas" or "biogas." Crops
like corn and sugar cane can be fermented to produce the transportation
fuel, ethanol. Biodiesel, another transportation fuel, can
be produced from left-over food products like vegetable oils
and animal fats.
fuels provide about 3 percent of the energy used in the United
States. People in the USA are trying to develop ways to burn
more biomass and less fossil fuels. Using biomass for energy
can cut back on waste and support agricultural products grown
in the United States. Biomass fuels also have a number of
The most common
form of biomass is wood. For thousands of years people have burned
wood for heating and cooking. Wood was the main source of energy
in the U.S. and the rest of the world until the mid-1800s. Biomass
continues to be a major source of energy in much of the developing
world. In the United States wood and waste (bark, sawdust, wood
chips, and wood scrap) provide only about 2 percent of the energy
we use today.
About 84 percent
of the wood and wood waste fuel used in the United States is consumed
by the industry, electric power producers, and commercial businesses.
The rest, mainly wood, is used in homes for heating and cooking.
plants in the wood and paper products industry use wood waste to
produce their own steam and electricity. This saves these companies
money because they don't have to dispose of their waste products
and they don't have to buy as much electricity. The photograph to
the right is of biomass fuel, probably wood chips, being stored
and dried for later use in a boiler.
WASTE, LANDFILL GAS, AND BIOGAS
of biomass is our garbage, also called municipal solid waste (MSW).
Trash that comes from plant or animal products is biomass. Food
scraps, lawn clippings, and leaves are all examples of biomass trash.
Materials that are made out of glass, plastic, and metals are not
biomass because they are made out of non-renewable materials. MSW
can be a source of energy by either burning MSW in waste-to-energy
plants, or by capturing biogas. In waste-to-energy plants, trash
is burned to produce steam that can be used either to heat buildings
or to generate electricity.
In landfills, biomass
rots and releases methane gas, also called biogas or landfill gas.
Some landfills have a system that collects the methane gas so that
it can be used as a fuel source. Some dairy farmers collect biogas
from tanks called "digesters" where they put all of the muck and manure
from their barns. Read about a field trip to a real waste-to-energy
plant or learn about the history of MSW.
ETHANOL AND BIODIESEL
transportation fuels like ethanol
that are made from biomass materials. These fuels are usually blended
with the petroleum fuels - gasoline and diesel fuel, but they can
also be used on their own. Using ethanol or biodiesel means we don't
burn quite as much fossil fuel. Ethanol and biodiesel are usually
more expensive than the fossil fuels that they replace but they
are also cleaner burning fuels, producing fewer air pollutants.
is an alcohol fuel made from the sugars found in grains, such as
corn, sorghum, and wheat, as well as potato skins, rice, sugar cane,
sugar beets, and yard clippings. Scientists are working on cheaper
ways to make ethanol by using all parts of plants and trees. Farmers
are experimenting with "woody crops", mostly small poplar
trees and switchgrass, to see if they can grow them cheaply and
abundantly. Most of the ethanol used in the United States today
is distilled from corn. About 99 percent of the ethanol produced
in the United States is used to make "E10" or "gasohol" a mixture
of 10 percent ethanol and 90 percent gasoline. Any gasoline powered
engine can use E10 but only specially made vehicles can run on E85,
a fuel that is 85 percent ethanol and 15 percent gasoline.
is a fuel made with vegetable oils, fats, or greases - such as recycled
restaurant grease. Biodiesel fuels can be used in diesel engines
without changing them. It is the fastest growing alternative fuel
in the United States. Biodiesel, a renewable fuel, is safe, biodegradable,
and reduces the emissions of most air pollutants.
pollute the air when it is burned, though not as much as fossil
fuels. Burning biomass fuels does not produce pollutants like sulfur,
that can cause acid rain. When burned, biomass does release carbon
dioxide, a greenhouse
gas. But when biomass crops are grown, a nearly equivalent amount
of carbon dioxide is captured through photosynthesis. Each of the
different forms and uses of biomass impact the environment in a
wood - Because the smoke from burning wood contains pollutants
like carbon monoxide and particulate matter, some areas of the country
won't allow the use of wood burning fireplaces or stoves on high
pollution days. A special clean-burning technology can be added
to wood burning fireplaces and stoves so that they can be used even
on days with the worst pollution.
Municipal Solid Waste (MSW) or Wood Waste - Burning municipal
solid waste (MSW or garbage) and wood waste to produce energy, means
that less of it has to get buried in landfills. Plants that burn
waste to make electricity must use technology to prevent harmful
gases and particles from coming out of their smoke stacks. The particles
that are filtered out are added to the ash that is removed from
the bottom of the furnace. Because the ash may contain harmful chemicals
and metals, it must be disposed of carefully. Sometimes the ash
can be used for road work or building purposes. Learn more about
MSW or waste-to-energy plants.
landfill gas or biogas - Collecting and using landfill
and biogas reduces the amount of methane that is released into the
air. Methane is one of the greenhouse gases associated with global
climate change. Many landfills find it cheaper to just burn-off
the gas that they collect because the gas needs to be processed
before it can be put into natural gas pipelines. Learn more about
Since the early 1990s ethanol has been blended into gasoline to
reduce harmful carbon monoxide
Blending ethanol into gasoline also reduces toxic pollutants found
in gasoline but causes more "evaporative emissions" to escape. In
order to reduce evaporative emissions, the gasoline requires extra
processing before it can be blended with ethanol. When burned, ethanol
does release carbon dioxide, a green house gas. But growing plants
for ethanol may reduce greenhouse gases, since plants use carbon
dioxide and produce oxygen as they grow.
Biodiesel is much less polluting than petroleum diesel. It results
in much lower emissions of almost every pollutant: carbon dioxide,
sulfur oxide, particulates, carbon monoxide, air toxics and unburned
hydrocarbons. Biodiesel does have nitrogen oxide emissions that
are about 10 percent higher though. Blending biodiesel into petroleum
diesel can help reduce emissions. Biodiesel contains almost no sulfur
and can help reduce sulfur in diesel fuel used throughout the country.
Sources: Energy Information Administration, Annual Energy Review
2006, June 2007.
Energy Infromation Administration,Renewable Energy Annual 2005,
The National Energy Education Development Project, Intermediate
Energy Infobook, 2006.
The National Energy Education Development Project, Alternative
Fuels: What Car Will You Drive?, 2004.
U.S. Department of Energy, Energy Effciency and Renewable Energy,
Clean Cities Fact Sheet- Low Level Ethanol Fuel Blends
: ENERGY INFORMATION ADMINISTRATION
-- DEPARTMENT OF ENERGY -- KIDS HOME PAGE
YOUR KNOWLEDGE OF THE MATERIAL