What is Biomass?
Biomass is any organic matter-wood, crops, seaweed,
animal wastes-that can be used as an energy source.
Biomass is probably our oldest source of energy. For
thousands of years, people have burned wood to heat their
homes and cook their food.
Biomass gets its energy from the sun. All organic matter
contains stored energy from the sun. During a process
called photosynthesis, sunlight gives plants the energy
they need to convert water, carbon dioxide, and minerals
into oxygen and sugars. The sugars, called carbohydrates,
supply plants (or the animals that eat plants) with
energy. Foods rich in carbohydrates (like spaghetti) are
a good source of energy for the human body!
Biomass is a renewable energy source because its supplies
are not limited. We can always grow trees and crops, and
waste will always exist.
Types of Biomass
We use four types of biomass today-wood and agriculture
products; solid waste; landfill gas and biogas; and
alcohol fuels.
Wood and Agricultural Biomass
Most biomass used today is grown energy. Wood-logs,
chips, bark, and sawdust-accounts for about 75 percent of
biomass energy. But any organic matter can produce
biomass energy. Other biomass sources include
agricultural waste products like fruit pits and corncobs.
Wood and wood waste, along with agricultural waste, is
used to generate electricity. Much of the electricity
generated by biomass is used by the industries making the
waste; it is not distributed by utilities. Paper mills
and sawmills, for example, use much of their waste
products to generate steam and electricity for their use.
However, since they use so much energy, they need to buy
additional electricity from utilities.
Increasingly, timber companies and companies involved
with wood products are seeing the benefits of using their
lumber scrap and sawdust for power generation. This saves
disposal costs and in some areas, may reduce the
companies' utility bills. In fact, the pulp and paper
industries rely on biomass to meet half of their energy
needs.
Other industries that use biomass include lumber
producers, furniture manufacturers, agricultural concerns
like nut and rice growers, and liquor producers.
Solid Waste
There is nothing new about people burning trash. What's
new is burning trash to generate electricity. This turns
waste into a usable form of energy. A ton of garbage
contains about as much heat energy as 500 pounds of coal.
Garbage is not all biomass; perhaps half of its energy
content comes from plastics and rubber.
Power plants that burn garbage for energy are called
waste-to-energy plants. These plants generate electricity
much as coal-fired plants do except that garbage-not
coal-is the fuel used to fire their boilers.
Making electricity from garbage costs more than making it
from coal and other energy sources. The main advantage of
burning solid waste is that it reduces that amount of
garbage dumped in landfills by 60 to 90 percent, and
reduces the cost of landfill disposal.
Landfill Gas
Bacteria and fungi are not picky eaters. They eat dead
plants and animals, causing them to rot or decay. A
fungus on a rotting log is converting cellulose to sugars
to feed itself. Even though this natural process is
slowed in the artificial environment of a landfill, a
substance called methane gas is still produced as the
waste decays.
New regulations require landfills to collect the methane
gas for safety and environmental reasons. Methane gas is
colorless and odorless, but it is not harmless. The gas
can cause fires and explosions if it seeps into homes and
is ignited. Landfills can collect the methane gas, purify
it, and use it as an energy source. Methane, which is the
main ingredient in natural gas, is a good energy source.
Most gas furnaces and gas stoves se methane supplies by
natural gas utility companies. A landfill in Florence,
Alabama recovers 32 million cubic feet of methane gas a
day. The city purifies the gas and pumps it into natural
gas pipelines.
Today, a tiny portion of landfill gas is used to provide
energy. Most is burned of at the landfill. With today's
low natural gas prices, this higher-priced biogas is
rarely economical to collect. Methane, however, is a more
powerful greenhouse gas than carbon dioxide. It is better
to burn landfill methane and change it into carbon
dioxide than releases it into the atmosphere.
Methane can also be produced using energy from
agricultural and human wastes. Biogas digesters are
airtight containers or pits lines with steel or bricks.
Wastes put into the containers are fermented without
oxygen to produce a methane-rich gas. This gas can be
used to produce electricity, or for cooking and lighting.
It is a safe and clean-burning gas, producing little
carbon monoxide and no smoke.
Biogas digesters are inexpensive to build and maintain.
They can be built as family-sized or community-sized
units. They need moderate temperatures and moisture for
the fermentation process to occur.
For developing countries, biogas digesters may be one of
the best answers to many of their energy needs. They can
help reverse the rampant deforestation caused by wood
burning, reduce air pollution, and fertilize over-used
field, as well as produce clean, safe energy for rural
communities.
Use of Biomass
Until the mid-1800s, wood gave Americans 90 percent of
the energy. Today, biomass gives us about 3.2 percent of
the energy we use. Coal, natural gas, and petroleum have
largely replaced biomass. 79 percent of the biomass used
today comes from burning wood and its scraps. The rest
comes from crops, garbage, landfill gas, and alcohol
fuels.
Who uses biomass energy? Industry is the biggest user of
biomass. 77percent of biomass energy are used by
industry. Homes are the next biggest users of biomass
energy. About one-fifth of American homes burn wood for
heating. Three percent of homes use wood as their main
heating fuel. Electric utilities use biomass energy to
produce electricity. One percent of biomass is used to
make electricity. Biomass produces 1.4 percent of the
electricity we use in this country.
Biomass and the Environment
Environmentally, biomass has some advantages over fossil
fuels such as coal and petroleum. Biomass contains little
sulfur and nitrogen, so it does not produce the
pollutants that can cause acid rain. Growing plants for
use a biomass fuels may also help keep carbon dioxide
levels balanced. Plants remove carbon dioxide-one of the
greenhouse gases-from the atmosphere when they grow.
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Seaweed is one of the
elements that, when decomposed, can be used to form
biomass.
Paper factories, like this one, use biomass as their
cheif source of energy. They get this biomass from the
waste that is produced in the paper making process. See
across for more information on this.
Landfill's, like this one, are required to collect the
methane gas that they give off. This gas is highly
explosive but can be used to produce energy.
The most popular residential use of biomass in the home
is burning wood to produce a fire. Here a family keeps
warm from the heat produced through the use of biomass. |
