| A | B |
|---|
| solar cells | device that coverts radiant (solar) energy directly into electrical energy |
| energy efficiency | percentage of total energy input that does useful work and is not converted into low quality , usually useless heat in an energy conversion system |
| life cycle cost | initial cost plus the lifetime operating coat of an economic good |
| net energy | total amount of useful energy available from an energy resource or energy system over its lifetime minus the amount of energy used, automatically wasted, or unnecessarily wasted |
| cogeneration | production of two useful forms of energy, such as high temp heat or steam and electricity, from the same fuel source |
| photovoltaic (PV) cells | solar cells |
| passive solar heating system | absorbs and stores heat from the sun directly within the structure |
| active solar heating system | system that uses solar collectors to capture energy from the sun and store it as heat for space heating and water heating |
| bio fuels | gas or liquid fuels (such as ethyl alcohol ) made from plant material (biomass) |
| biomass | plant materials and animal wastes used as sources of energy |
| geothermal energy | heat transferred from the earth's underground concentrations of dry steam, wet steam, or hot water trapped in fractured or porous rock |
| wet steam | a mixture of steam and water droplets |
| dry steam | steam with no water drplets |
| micropower systems | microturbines, fuel cells, and household solar panels and solar roofs |
| wind turbines | devices for converting wind power into electricity |
| solar-hydrogen revolution | world will shift from carbon-based fossil fuel economies to decarbonized hydrogen economies powered increasingly by solar energy or nuclear fission to produce hydrogen gas from water |
| hydrogen | a colorless, odorless, flammable gas at room temperature |
| power tower | a central reciever system |
| solar power systems | collect and transfer radiant energy from the sun |
