The following are words, terms and acronyms frequently used in association with waste-to-energy.

Ash. The noncombustible solid by-products of combustion.

Baghouse. An emission control device that consists of an array of fabric filters through which flue gases pass. Particles are trapped and thus prevented from passing into the atmosphere.

Biodegradable material. Any organic material that can be broken down by microorganisms into simpler, more stable compounds. Most organic wastes (e.g., food, paper) are biodegradable.

Biomass. Any organic matter that can be used as fuel to generate energy.

Bottom ash. A relatively coarse, noncombustible residue of combustion that accumulates on the floor or “grate” of a furnace.

Bulky waste. Large wastes such as appliances, furniture, and trees and branches, that cannot be handled by normal MSW processing methods.

BTU. An abbreviation for British Thermal Unit, a measurement of energy. BTU is commonly used to measure the energy content of various fuels. One BTU is the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit.

Clean Air Act Amendments of 1990. A major overhaul of the earlier Clean Air Act of 1970. Changes included requiring a number of industries, including solid waste combustion units, to meet Maximum Achievable Control Technology standards for air emissions.

Combustion. The process by which municipal solid waste is burned in a waste-to-energy plant.

Competitive Bidding (Electricity). A procedure that utilities in many states use to select suppliers of new electric capacity and energy. Under competitive bidding, an electric utility solicits bids from prospective power generators to meet current or future power demands. When offers from independent power producers began exceeding utility needs in the mid-1980s, utilities and state regulators began using competitive bidding systems to select among numerous supply alternatives.

Competitive Bidding (Municipal Solid Waste). A procedure that municipalities use to select vendors to collect and/or dispose of the solid waste within the municipality.

Composting. Biological decomposition of solid organic materials by bacteria, fungi, and other organisms into a soil-like product.

Construction and demolition debris. Waste generated by construction and demolition of buildings, such as bricks, concrete, drywall, lumber, miscellaneous metal parts and sheets, packaging materials, etc.

DOE. An abbreviation for the U.S. Department of Energy. DOE manages programs of research, development and commercialization for various energy technologies, and associated environmental, regulatory and defense programs. DOE announces energy policies and acts as a principal advisor to the President on energy matters.

Electric Capacity. The ability of a power plant to produce a given output of electric energy at an instant in time, measured in kilowatts or megawatts.

Electric Utility. A company that controls the distribution of electricity in a specific state, area or region. Utilities often own and operate electricity generation and transmission facilities.

Emissions. Gases released into the atmosphere.

Environmental Impact Assessment (EIA). An evaluation designed to identify and predict the impact of an action or a project on the environment and human health and well-being. Can include risk assessment as a component, along with economic and land use assessment.

Expansion Unit. The installation of a new boiler at an existing waste-to-energy facility, which increases the waste processing and energy generating capacity at the facility.

The Energy Policy Act of 2005 (EPAct05). A comprehensive federal energy law that provided important incentives to renewable energy producers, including waste-to-energy facilities.

EPA. The abbreviation for the U.S. Environmental Protection Agency. EPA administers federal environmental policies, enforces environmental laws and regulations, performs research, and provides information on environmental subjects.

Fly ash. The particulate matter captured from the flue gas of a municipal waste combustor by the air pollution control system.

Gigawatt. A unit of electric power equal to one billion watts, or one thousand megawatts.

Greenfield Plant. A new electric power generating facility built from the ground up on an undeveloped site.

Hazardous waste. Waste, as defined by the Resource Conservation and Recovery Act, that is reactive, toxic, corrosive, or otherwise dangerous to living things and/or the environment.

Heavy metals. Metals of high atomic weight and density, such as mercury, lead, and cadmium.

Independent Power Producers (IPPs). Private companies that develop, own or operate electric power plants, often fueled by alternative energy sources, such as waste-to-energy, biomass, cogeneration, small hydro, and wind facilities.

Inorganic waste. Waste composed of material other than plant or animal matter, such as sand, dust, glass, and many synthetics.

Kilowatt (kW). A measurement of electric power equal to one thousand watts. Electric power capacity of one kW is sufficient to power 10 100-watt light bulbs.

Kilowatt Hour (kWh). A measurement of energy equal to the energy produced by a 1,000 watt generator in one hour.

Mass-burn. A type of combustion process in which solid waste is burned without sorting or processing being done at the facility.

Megawatt (MW). A unit of electric power equal to one million watts, or 1,000 kilowatts.

Mixed waste. Unsorted materials that have been discarded into the waste stream.

Municipal solid waste (MSW). All solid waste generated in an area except industrial and agricultural wastes, typically from residences, commercial or retail establishments. Sometimes includes construction and demolition debris and other special wastes that may enter the municipal waste stream.

Municipal Solid Waste Collection. The process of picking up wastes from residences, businesses, or a collection point, loading them into a vehicle, and transporting them to a processing, transfer, or disposal site.

Municipal Waste Combustor. Combustion facility that uses MSW as its primary, i.e., at least 70%, fuel source.

Nitrogen Oxides (NOx). Emissions that contribute to the formation of smog.

Organic waste. Technically, waste containing carbon of a natural origin, including paper, wood, food wastes, and yard wastes. The term often means material that is more directly derived from plant or animal sources, and which can generally be decomposed.

Power Purchase Agreement (PPA). A contract entered into by an independent power producer and an electric utility. The power purchase agreement specifies the terms and conditions under which electric power will be generated and purchased. Power purchase agreements require the independent power producer to supply power at a specified price for the life of the agreement.

Processing. Preparing MSW materials for subsequent use or management, using processes such as baling, magnetic separation, crushing, and shredding.

Refuse-derived fuel (RDF). Fuel produced from MSW that has undergone processing. Processing can include separation of recyclables and noncombustible materials, shredding, size reduction, and pelletizing.

Resource recovery. A synonym of waste-to-energy, resource recovery is the extraction and utilization of materials and energy from wastes.

Renewable Energy. Any source of energy that is sustainable and constantly replenished. Energy produced from municipal solid waste is classified as renewable.

Scrubber. An emission control device, used primarily to control acid gases, but also to remove some heavy metals.

Source separation. Setting aside of compostable and recyclable materials from the waste stream before they are collected with other MSW, to facilitate reuse, recycling, and composting.

Sulfur Dioxide (SO2).  A by-product of burning fuels that contain sulfur, e.g., coal, that contributes to acid rain.

Tipping fee.  A fee for unloading or dumping waste at a landfill, transfer station, waste-to-energy facility, or recycling facility.

Tipping floor.  Unloading area for vehicles that are delivering MSW to a waste-to-energy plant.

Waste-to-energy (WTE) plant.  A facility that generates steam and/or electricity through the combustion of municipal solid waste.

Waste-based Energy (WBE).  The process of extracting useful energy from a waste stream.