1. 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.
2. 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.
3. 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 Biomass
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 cobs.
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 waste decays.
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 pipelines.
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 methanol.
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.
4. 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.
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 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.