Geothermal Energy - AP Environmental Science

Minimal land footprint. Small surface area compared to other renewable energy installations.

A water-bearing geological formation used in geothermal systems. Underground rock layer containing heated groundwater for energy extraction.

Geothermal gradient = $\frac{\text{Temperature change}}{\text{Depth}}$. Measures rate of temperature increase with depth, typically 25-30°C per km.

10% to 20%. Lower than fossil fuel plants due to thermodynamic limitations of heat sources.

Reinjection. Cooled water returns underground to maintain reservoir sustainability.

To convert steam back into water. Cooling steam to liquid water completes the thermodynamic cycle.

Volcanoes. Volcanic activity indicates subsurface magma and high geothermal potential.

Provides baseload power. Operates continuously unlike intermittent solar and wind power sources.

Geological conditions. Rock permeability, temperature, and water availability determine project viability.

District heating. Hot water directly heats buildings and communities without electricity conversion.

To reinject the cooled water back into the reservoir. Maintains reservoir pressure and sustainability by returning used water underground.

Release of hydrogen sulfide gas. H₂S creates rotten egg odor and can be toxic at high concentrations.

Limited to regions with suitable geothermal activity. High-quality geothermal resources exist only in specific geological zones.

Geysers. Hot springs that periodically erupt steam and water from underground pressure.

Low carbon emissions. Nearly zero greenhouse gas emissions compared to fossil fuel power plants.

$2,500 to $5,000 per kW. High upfront costs but low operating expenses over plant lifetime.

Induced seismicity. Fluid injection can trigger small earthquakes in fault zones.

Reduced dependence on fossil fuels. Domestic renewable energy reduces imports and price volatility.

Turbine. Steam from geothermal wells spins turbine blades to generate electricity.

To transfer heat between fluids. Enable efficient heat transfer in binary cycle and other geothermal systems.

A technology to extract heat from dry, impermeable rocks. Water injection creates fractures in hot dry rock to enable heat extraction.

Careful site selection and monitoring. Proper location assessment and gradual drilling reduce earthquake risks.

Seismic surveys. Detect underground heat sources through seismic wave analysis.

Reduces heating costs. Stable ground temperatures provide consistent, efficient home heating.

Flash steam power plant. High-pressure hot water flashes to steam when pressure drops in separator.

To extract steam or hot water from the geothermal reservoir. Brings hot fluids to surface for power generation or direct use.

Igneous rock. Formed from cooled magma, often containing high subsurface temperatures.

1 km to 4 km. Deep drilling required to reach high-temperature geothermal resources.

United States. Leads global geothermal capacity with over 3,700 MW installed.