BIOMASS What Is It?
Biomass consists of growing plants or the remains of growing things. Examples of biomass include trees, grasses, agricultural wastes, manure, ocean plants, and even garbage.
Wood chips and other woody material can be burned to produce heat, steam or electricity. Farm products such as corn, sugarcane molasses, agricultural residues, or energy crops can be used to produce heat or can be converted to liquids or gases to be used as transportation fuels. Gases formed by decaying biomass can also be collected and used as fuel.
Bagasse, the crushed fibers which remain after the sugar has been removed from the sugarcane, is the largest source of biomass energy in Hawaii. Macadamia nut shells and husks and eucalyptus and kiawe trees are also used as biomass energy sources. Methane gas is collected from manure or from landfills and burned as fuel to produce heat and power. Ethanol, a transportation fuel, is produced on the Mainland primarily from corn. In Hawaii, ethanol can be made from sugarcane molasses, and several companies are also considering producing ethanol from yard and wood wastes or mixed waste paper. Work is also ongoing to Œgasify¹ bagasse and wood chips to produce a fuel for electric power generation or for transportation.
Plants use sunlight for growth in a process called photosynthesis. In this process, the plant combines carbon dioxide from the air and water from the ground to produce oxygen and energy. Energy is stored in the plant in the form of carbohydrates. This energy is released when the plant is burned or converted into a fuel.
When animal waste (manure) is converted into gaseous fuels, the manure is broken down by bacteria through an anaerobic (free of oxygen) process. The resulting gas is burned to generate electricity or heat for on-site use.
Biomass can also be treated with chemicals, converted by microorganisms, or put under high pressures and temperatures to produce liquids, gases, and solids which offer the possibility of replacing petroleum-based fuels.
Sugar factories in Hawaii burn bagasse to provide steam for sugar processing and the generation of electricity. Electricity not needed for factory operations is sold to local utility companies. Ethanol made from sugarcane molasses has been produced in Hawaii and mixed with gasoline to produce fuel for automobiles.
Wood chips and macadamia nut husks and shells are burned by companies in Maui County to provide heat and electricity.
Several private companies, including Unisyn Biowaste Technology in Waimanalo, Oahu, and Happy Hula Hog Farm on Maui, are processing animal waste to produce methane gas. The gas is used for heat and electricity. Unisyn, the first company to use food waste to generate energy, uses its patented anaerobic digestion system processes organic waste not suitable for burning nor allowed in landfills and waste water treatment facilities. By-products include organic fertilizer, which can replace chemical fertilizers, and biogas, which is used to generate electricity and process heat to run the Unisyn system. One ton of food waste produces about 85 cubic meters of biogas, which is approximately 60 percent methane; the rest is mostly carbon dioxide. About 40 Oahu businesses provide Unisyn with their food and animal waste.
H-POWER (Honolulu Project of Waste Energy Recovery), the City and County of Honolulu¹s ³garbage to energy² plant, is burning refuse-derived fuel to provide electricity which is sold to Hawaiian Electric Company. Materials which do not burn, such as glass and metal, are removed and may be recycled In 1993, the plant produces approximately 6 percent of Oahu¹s electricity.
Kapaa Energy Partners, a private company, is collecting methane from the Kapaa landfill on Oahu. The methane is burned to produce electricity which is sold to Hawaiian Electric Company. Heat from the turbine exhaust is used for drying gravel.
Construction of the first phase of a pre-commercial biomass gasification research facility on Maui was completed in late 1994. The facility has successfully demonstrated the technical feasibility of producing fuel gas (biogas) from sugar cane bagasse. The biogas can be utilized in gas turbines for generating electricity and for producing methanol fuel for transportation purposes.
Phase II of the project will add a hot-gas cleanup system and a gas turbine generator for producing electricity. This will demonstrate dependable electrical energy and the capacity for commercial sale. Phase III will add an on-site oxygen plant to enable the production of a synthesis gas and fuel-grade methanol. Conversion of biomass to transportation fuels through gasification has great potential for reducing petroleum consumption in Hawaii and the rest of the country. In addition, the technologies developed during the project will enable the widespread use of a cleaner, self-sustaining energy resource, while also preserving or creating jobs in the agricultural sector.
Most of information contained in this summary was excerpted from a Fact Sheet prepared by the staff of the Energy Division of the State of Hawaii-Department of Business, Economic Development, and Tourism (DBEDT) and published with funding from the U.S. Department of Energy, Grant No. DE-FG49-94R900023. This information does not necessarily reflect the views of the State of Hawaii, the United States Government, or any agency thereof.
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