Discovery Guides Areas


Geothermal Energy: Drilling Beneath the Surface of Our Energy Dilemma
(Released September 2009)

  by Ethan Goffman  


Key Citations





Baseline power. Power that supplies a constant energy need, often supplied through coal or nuclear plants, but also supplied by geothermal

Binary plants. Geothermal plants that transfer heat from water to another liquid with a much lower boiling point-a "working fluid." This fluid becomes steam to power a turbine. Binary geothermal is more expensive than other methods but works with lower temperatures

Desuperheater. A device that uses waste heat from geothermal pumps to heat water

Dry steam plants. Geothermal plants that employ hot steam directly into turbines that generate electricity

Enhanced Geothermal Systems (EGS). A method of generating electricity from areas with heat, but no water, deep beneath the earth. EGS involves pumping liquid down one well drilled deep into the earth and using steam retrieved from another deep well

Flash plants. Geothermal plants that "flash" water from between 300 and 700°F (148 and 371°C) at low pressure to become steam, spinning a turbine that generates electricity

Gigawatt-hours. A unit of energy equivalent to the work done by one gigawatt (1 GW) of power expended for one hour. One gigawatt-hour equals 1,000 megawatt-hours or 1,000,000 kilowatt-hours

Kilowatt-hours. A unit of energy equivalent to the work done by one Kilowatt (1 KW) of power expended for one hour. This is more formally expressed in joules: one Kilowatt-hour equals 3,600,000 joules

Megawatt (MW). A unit of energy equal to a million watts. A watt is equal to one joule per second. A Megawatt is not the same as a megawatt-hour, which equals a megawatt expended over an hour

Renewable Portfolio Standards (RPS). Laws that require utilities to obtain a minimum fraction of their energy from renewable sources by a certain date; RPS is a form of environmental target