AIR-COOLED CONDENSER - a heat exchanger that returns steam to a water state, utilizing air circulation fans to force air over finned tubing, through which the turbine's output steam flows. The condensate is then returned to the boiler as feedwater.

COGENERATION - a process that converts a fuel into both useful thermal and electrical energy. The thermal energy may be in the form of steam, hot water, hot air, or any combination of the three.

COMBINED CYCLE PLANT - an electric generating station that produces electricity from a combustion turbine generator (Brayton cycle) and a steam turbine generator (Rankine cycle). The steam is generated using waste heat from the combustion turbine to produce steam in a heat recovery steam generator (HRSG).

COMBUSTION - the burning or rapid oxidation of fuel resulting in the release of energy in the form of heat and light.

CONDENSER - a heat exchanger that returns steam to a water state, utilizing cooling water. The water flows inside tubes with steam on the outside of the tubes. The cooling water may be supplied from a cooling tower or directly from a river, lake, or ocean. The condensate is then returned to the boiler as feedwater.

DRY LOW NOX TECHNOLOGY - a technology that reduces the formation of certain nitrogen oxides during the combustion process without the use of water injection.

ELECTROSTATIC PRECIPITATOR (ESP) - a system used to remove dust and fly-ash from emissions. By maintaining a high voltage potential between the discharge electrodes (wires) and collector plates in the ESP, the units electrostatically charge the particles that are attracted to the neutral collecting plates.

FEEDWATER - the water supply that is purified of excess minerals and other contaminants that is used as the working medium in the steam turbine cycle. The water is heated in the HRSG and converted to steam which expands in the steam turbine, generating electricity. The steam is condensed back into water for use in the HRSG.

GREENFIELD DEVELOPMENT - the development of a project, such as a power plant, for a specific site in which no such facility or operation already exists. The process requires complex negotiations, permitting, and construction planning. InterGen is one of the global power industry's leading developers of greenfield power projects.

GREENHOUSE EFFECT - the presence of trace atmospheric gases make the earth slightly warmer than direct sunlight alone. These gases (carbon dioxide [CO2], methane [CH4], nitrous oxide [N2O], ozone [O3], and water vapor [H2O]) trap some of the sun's radiation as it leaves the earth's surface. CO2, N2O, and O3 are some of the more commonly known "greenhouse gases."

GRID - a system of interconnected power lines at various voltages that allows the transmission of electricity between generators and users.

MEGAWATT (MW) - one thousand kilowatts (1,000 kW) or one million watts (1,000,000).

OPEN-CUT COAL MINE - an above-ground mining tecohnique in which rock covering the coal seam is blasted and removed by large draglines or electric shovels and trucks. Modern equipment and techniques allow open-cut mines to be operated to depths much greater than traditionally possible.

PARTICULATE MATTER - ash, non-combustible materials, and unburned fuel particles that are entrained in the flue gas exiting the boiler. These particulates are collected in the ESP or baghouse for reclamation or disposal.

SUPERCRITICAL BOILER - a steam cycle that has higher than usual steam temperatures and pressures, producing greater electric generation efficiencies and reducing certain emissions.

SEQUENTIAL COMBUSTION - a process in which combustion occurs simultaneously in two chambers in a combustion turbine, increasing efficiencies and significantly lowering the required inlet temperature of the fuel.

TURBINE GENERATOR - a device that employs a turbine, which uses the potential energy in high-pressure steam, hot high-pressure gases, water, or wind to spin a generator. The generator then produces electricity using electromagnetic forces. InterGen facilities use both steam turbines and gas combustion turbines to generate electricity.

WATER-COOLED CONDENSER - a system that returns steam to a water state by passing it through a heat exchanger, through which water circulates to cool the steam. The resultant condensate is recycled as feedwater.