Refers to the internal heat from the earth.

• Geothermal

• Thermal energy

• Molten heat

• Tectonic heat

A rock - forming crystalline mixed silicate which constitute about 60% of the earth's surface.

• Soil

• Feldspar

• Flux

• Flint

A compound rock, a crypto - crystalline form of silica, which is dens, tough, breaking with a conchoidal fracture.

• Gravel

• Stalactite

• Flint

• Flux

Is the process of using injection wells to bubble air through groundwater.

• Air stripping

• Staged combustion

• Sparging

• Soil washing

A popular term used by utilities to mean upgrading existing plant.

• Replanting

• Repowering

• Recharging

• Reorganizing

A dense, fine grained, light colored igneous rock which is rich in silica.

• Felsite

• Feldspar

• Flint

• Flux

An opening in lava or in volcanic area through which steam and other hot gases are escaping into the air is called:

• Fumarole

• Volcanic leaks

• Seismic outlets

• Seismic leaks

Tidal power is the power generated from:

• Waves of the ocean

• Rise and fall tides

• Thermal energy of ocean water

• Raw sea water

Converts chemical energy directly into electrical energy.

• Fuel cell

• Magnetohydrodynamic generator

• Battery

• Thermoelectric generator

Generates a voltage from incident light, usually light in the visible region.

• Photovoltaic cell

• Solar cell

• Dry cell

• A or B