REPP-CREST : BIOENERGY

Biomass can be used in a variety of energy conversion processes in order to yield power, heat, steam and fuel.

Biopower can be generated any number of ways, which are detailed in Chapter 4 of this report. Most biopower is generated through a co-firing method or with a traditional steam turbine. In any system, a turbine is stimulated, either by steam or gas. The turbine is connected to a generator which contains magnets which are positioned to ensure repellance, meaning the polar opposites are unable to attract to one another. When callibrated correctly the magnets inside the generator generate a magnetic field. A conductor rod will be passed through the magnetic field, causing electrons in the conductor rod will flow freely thereby creating an electrical current.

The conducting rod is metal, often copper, wound into tight coils to maximize the amount of electricity created. The ends of the coils are connected to an outside transmission station and eventually fed to the grid [1]. Below is a flow chart of the McNeil Generating System in Burlington, Vermont; one of the oldest online biomass generating power plants in the country. It was founded in 1986 and uses woodchips as its primary fuel.

The same power plants that produce power also yield useful steam and heat which can be used to heat residential and commercial buildings. The process of capturing the heat and the steam that is released from the process is called combined-heat-and-power or CHP. Taking advantage of these products can improve the efficiency of the operation by over 35%. Pulp and paper mills in the Southeast, Northeast and Great Lakes region of the U.S. already generate power, steam and heat from biomass. Finland hosts CHP operations that heat homes and businesses. Below is a map of the United States which shows where biomass can hope to be harvested to aid in one of the energy sectors.

Of course, biomass such as wood in fireplaces and kilns also heat homes and provide energy for cooking.
Biomass is the oldest known source of renewable energy—humans have been using it since we discovered fire—and it has high energy content. The energy content of dry biomass ranges from 7,000 Btu/lb for straws to 8,500 Btu/lb for wood [4]. Below is a chart that lists the heat content of different types of biomass, as supplied by the Energy Information Administration. For perspective, it takes about 10,000 Btu to cook a meal. Alternatively, one gallon of gasoline is equivalent to 124,884 btu.

Source: Energy Information Administration, Form EIA-860B (1999), "Annual Electric Generator Report - Nonutility 1999."

Solid biomass can also be converted into liquid fuels that power cars, engines including those in diesel generators, and even industrial operations. Methanol, ethanol, biofuel and biodiesel can all be created from biomass. Methanol is a wood alcohol which is not as efficient as gasoline as a fuel and is mostly used in antifreeze and in the production of other chemicals, such as formaldehyde [5]. For more information on methanol, visit the Methanol Institute.

Ethanol, or ethyl alcohol, is a clear, colorless, flammable oxygenated fuel currently added as a gasoline additive in 30 states to increase octane and lower tailpipe greenhouse gas emissions [6]. It is biodegradable and water soluble. Ethanol (which comes from cellulosic biomass such as corn) is produced through fermentation at either a dry mill or at a wet mill, both displayed below. The dry mill process is simpler than the wet mill process. The wet mill breaks the corn into its components and processes each separately. In addition to ethanol, both processes also create distiller's grain, which is fed to farm animals.

Up to 24% ethanol can be added to gasoline before engine modifications are necessary. A blend known as E85, which is 85% ethanol and 15% gasoline, can be used to power flexible fuel vehicles (FFVs). Many cars on the market today are already built to run on E85. Brazil has had much success converting nearly all of its vehicles to run on E85 made from sugar. It even announced that it would stop importing oil by the end of 2006 [7].

Ethanol has a better environmental profile than gasoline as measured at both the production facility and the tailpipe. Ethanol production plants produce less carbon dioxide, methane and particulates than gasoline refineries, which help meet clean air standards. A blend of 10% ethanol, or E10, yields a 26% reduction in greenhouse gases when compared to gasoline alone [8]. The Senate version of The Energy Policy Act of 2005 includes an ethanol provision that would boost ethanol production to 8 billion gallons from the current level of 3.9 billion gallons by 2012 [9]. For more information on ethanol, please see visit the Renewable Fuels Association website.

Both Diagrams courtesy of the Renewable Fuels Association, Production Processes

Biodiesel is the result of combining alcohol (including ethanol) with oil extracted from soybeans, rapeseed, animal fats, or other biomass. Biodiesel is an American-made fuel that can be produced from any fat or vegetable oil, such as soybean oil often sold as 2% (B2) or 10% (B10) blends with diesel. “Concerns that biodiesel can't perform or flow well in adverse weather are based on myths,” according to Kelly Strebig, a research engineer for the University of Minnesota Center for Diesel Research at Minneapolis, Minnesota [10]. Biodiesel performs very well in cold climates and is being used in airport snowplows and school buses according to an article a Missouri paper. It also burns much cleaner than traditional diesel, making it more environmentally friendly. Seen below are two liters of biodiesel. Some biodiesel companies are even contracting with restaurants to make biodiesel from their used vegetable oils.