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 people will always produce garbage.
Using Biomass Energy
Usually we burn wood and
use its energy for heating. Burning, though, is not the only way to convert
biomass energy into a usable energy source. There are four ways:
We can bum biomass in
special plants to produce steam for making electricity, or we can burn it to
provide heat for industries and homes.
Bacteria feed on dead
plants and animals, producing a gas called methane. This is a natural
process that happens whenever waste decays. Methane is the same thing as
natural gas, the gas sold by natural gas utilities.
Adding a yeast to biomass
produces an alcohol called ethanol. This is how wine, beer, and liquor
are made. Wine is just fermented grape juice.
Biomass can be converted
into gas or liquid fuels by using chemicals or heat. In India, cow manure is
converted to methane gas to produce electricity. Methane gas can also be
converted to methanol, a liquid form of methane.
Types of Biomass
We use four types of
biomass today: 1) wood and agricultural products; 2) solid waste; 3) landfill
gas; and 4) alcohol fuels.
Wood and Agricultural
Most biomass used today
is home grown energy. Wood-logs, chips, bark, and sawdust-accounts for about 79
percent of biomass energy. But any organic matter can produce
biomass energy. Other
biomass sources include agricultural waste products like fruit pits and corn
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 (2,000
pounds) of garbage contains about as much heat energy, as pounds of coal.
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 an industrial boiler.
Making electricity from
garbage costs more than making it from coal and other energy sources. The main
advantage of burning solid waste is it reduces the amount of garbage dumped in
landfills by 60 to 90 percent, and reduces the cost of landfill disposal.
Bacteria and fungi are
not picky eaters. They eat dead plants and animals, causing them to rot or
decay. Even though this natural process is slowed in the artificial environment
of a landfill, a substance called methane gas is still produced as the
New regulations require
landfills to collect methane gas for safety and environmental reasons. Methane
gas is colorless and odorless, but it is not harmless. The gas can cause fires
or explosions if it seeps into nearby homes and is ignited.
Landfills can collect the
methane gas, purify it, and then use it as an energy source. Methane, which is
the same thing as natural gas, is a good energy source. Most gas furnaces and
gas stoves use methane supplied by natural gas utility companies. The
city landfill in Florence, Alabama recovers 32 million cubic feet of methane
gas a day. The city purifies the gas and then pumps it into natural gas
Today only a tiny portion
of landfill gas is used to provide energy. Most is burned off at the landfill.
Why? With today's low natural gas prices, this higher-priced "biogas"
has a hard time competing.
Wheat, corn, and other
crops can be converted into a variety of liquid fuels including ethanol and
Using ethanol as a motor
fuel is nothing new. Its use is almost as old as the automobile. In the early
20th century, automobile pioneer Henry Ford advocated using gasohol, a
mixture of ethanol and gasoline, to run his cars.
Today ethanol is a high
cost fuel and its use has become a controversial issue. It is estimated that a
barrel of oil will have to more than double in price before ethanol can compete
with gasoline as a transportation fuel.
In spite of this, the
ethanol industry has continued to grow, mainly because the federal government
exempts ethanol fuels from the federal highway tax. This exemption has been
extended to the year 2000.
Because ethanol is
expensive, and because car engines must be modified to run on pure ethanol,
ethanol is usually mixed with gasoline to produce gasohol. (Cars can run
on gasohol without adjustments.)
Gasohol is 10 percent
ethanol and 90 percent gasoline. In 1994, 12 percent of the nation's motor fuel
consisted of this ethanol and gasoline mixture. However, in some corn-growing
states, gasohol use is as high as 50 percent.
Gasohol does have some
advantages over gasoline. It has a higher octane rating than gasoline (provides
your car with more power), and it is cleaner-burning than unleaded gasoline,
with one-third less carbon monoxide emissions. Gasohol may also help reduce
America's dependence on foreign oil.
Use of Biomass and the Environment
Until the mid-1800s, wood
gave Americans 90 percent of the energy they used. Today biomass gives us only
3.2 percent of the energy we use. Biomass was largely replaced by coal, natural
gas, and petroleum.
Seventy-nine percent of
the biomass we use today comes from burning wood and wood scraps - The rest of
the biomass comes from crops, garbage, landfill gas, and. alcohol fuels.
Who uses biomass energy?
Industry is the biggest user of biomass. Seventy-seven percent of biomass is
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 also
use biomass energy to produce electricity. One percent of biomass is used to
make electricity. Still, biomass produces only a tiny amount of the electricity
we use in this country.
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
cause acid rain. Growing plants for use as biomass fuels may also help keep
global warming in check. That's because plants remove carbon dioxide--one of
the greenhouse gases-from the atmosphere when they grow.