Frequently Asked Questions
(source: State Environmental Resource Center)
Biomass
Q: What is biomass?
A: Biomass is the organic matter produced by plants. The solar energy trapped by these plants can be converted to electricity or fuel.
Q: How is biomass used?
A:
People have used biomass for heating and cooking for thousands of years. With today's technology, plant materials can be used to generate electricity, heat, or liquid fuels for motor vehicles that have substantially lower environmental impacts than traditional fossil fuels.
Q: What are the benefits of using biomass for energy generation?
A: As with many other renewable energy sources, biomass is capable of simultaneously addressing the nation's energy, environmental, and economic needs. Increased use of biomass for energy would lead to reduced greenhouse gas emissions, reduced dependence on foreign oil, an improved U.S. balance of trade, an improved rural economy, and the creation of a major new American industry.
Q: What economic benefits might a biomass program produce for my state?
A: Because biomass feedstocks – the actual crop to be used in energy generation – are typically bulky and costly to transport, conversion facilities will likely be located where the crop is grown. That means local jobs – rural economies will grow because of the development of a local industry to convert biomass to either electricity or transportation fuel. In addition, farmers will see their income rise thanks to the creation of new markets for their products – such as agricultural wastes and crops that can be grown on marginal land. Furthermore, increased investment in biomass conversion technologies can create high-skill, high-wage jobs for the producers of these technologies and the industry or utility that uses them.
Q: What are the environmental benefits of biomass?
A:
The use of biomass energy provides a multitude of environmental benefits. It can help mitigate climate change; reduce acid rain; prevent soil erosion and water pollution; minimize pressure on landfills; provide wildlife habitat; and, help maintain forest health through better management.
The use of biomass will greatly reduce the nation's greenhouse gas emissions. Fossil fuels emit vast quantities of carbon dioxide into the atmosphere upon combustion, carbon that would ordinarily remain trapped underground. Biomass also releases carbon dioxide as it burns, but the plants need CO2 to grow – thus creating a closed-carbon cycle. All the CO2 released during the combustion of biomass materials is recaptured by the growth of these same materials. Unlike fossil fuels, with biomass combustion there is no net increase in carbon dioxide released into the atmosphere. In addition, substantial quantities of carbon can be captured in the soil through biomass root structures, creating a net carbon sink.
Biomass has other environmental benefits as well. The nation has many vast tracts of unused agricultural land – the byproduct of increasingly efficient agricultural techniques – that might otherwise be converted to residential or industrial use. These lands could instead be used to grow biomass crops that will restore soil carbon, reduce erosion and chemical runoff, and enhance wildlife habitat.
Of course not all forms of biomass produce all of these benefits and the use of some forms can actually produce significant environmental damage. Defining environmentally preferable biomass is a crucial step in capturing these benefits.
Q: What impact could biomass really have on our domestic energy supply?
A: Biomass currently provides about 2% of the electricity produced in the U.S., and, according to the American Biomass Association, it could easily supply 20%. As a result of the available land and agricultural infrastructure this country already has, biomass could conceivably replace all of the power that nuclear plants generate and do so in a sustainable fashion.
Q: How is electricity created with biomass?
A: Direct combustion is the simplest and most common method of capturing the energy contained within biomass. Usually these facilities (boilers) produce steam to use either within an industrial process, or to produce electricity directly. They can also produce heat, which is then captured for one purpose or another.
Direct combustion technology is very similar to that used for coal. Biomass and coal can be handled and burned in essentially the same fashion because coal is simply fossilized biomass heated and compressed over millions of years. The process which coal undergoes as it is heated and compressed deep within the earth adds elements like sulfur and mercury to the coal – elements which produce noxious emissions when burned. Since biomass does not contain these dangerous elements, combusting it produces no dangerous emissions.
Gasification is another method to generate electricity from biomass. Instead of simply burning the fuel, gasification captures about 65-70% of the energy in solid fuel (as compared to 20-30% for traditional combustion) by converting it first into combustible gases. This gas is then burned, as if it were natural gas, to create electricity, fuel a vehicle, power industrial applications, or be converted to synthetic fuels.
Q: Is biomass really a renewable source of energy?
A: Yes. If biomass is cultivated and harvested in a way that allows regrowth without depleting nutrient and water resources, it is a renewable resource that can be used to generate energy on demand, with little or no net contributions to global greenhouse gas emissions.
By burning biomass fuels we release no more carbon dioxide than would have been produced in any case by natural processes such as crop and plant decay and no more than will be absorbed by the plants as they regrow. Secondly, provided our consumption of biomass does not exceed our ability to continually supply the biomass feedstock we use, we have a renewable energy source whose use does not substantially disturb the natural biochemical cycle on a human time scale.
Q: Is municipal solid waste (MSW) considered biomass?
A: No. Although MSW is burned in the U.S., Europe, and elsewhere to generate electric power and heat, it contains inorganic materials such as plastics and metals and therefore cannot properly be considered biomass. It also contains a variety of potentially toxic materials such as creosote-treated wood, batteries that contain mercury, and other hazardous products, and therefore cannot be called biomass and is certainly not environmentally sound. MSW incineration also conflicts with recycling goals, diverting resources from more environmentally sound uses.
MSW incineration should be distinguished from landfill methane. Using methane captured from landfills to fuel power plants is far superior to allowing the methane and other air toxics generated by landfills to escape into the atmosphere (where the methane has a global warming potential 21 times that of carbon dioxide) or simply flaring the gas.
For a more extensive list of Frequently Asked Questions relating to biomass and bio-energy, visit the U.S. Department of Energy's Bio-Energy Feedstock Information.
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