Documentation:

 

Heating and Cooling Efficiency of Geothermal Heat Pumps

https://www.energy.gov/energysaver/choosing-and-installing-geothermal-heat-pump-system

Community Geothermal Heating and Cooling Design and Deployment

https://www.energy.gov/eere/geothermal/community-geothermal-heating-and-cooling-design-and-deployment

Geothermal Basics

https://www.energy.gov/eere/geothermal/geothermal-basics

Geothermal Heat Pump Fact Sheet

https://www.energy.gov/eere/geothermal/articles/geothermal-heat-pump-fact-sheet

GHP Information for Consumers

https://www.energy.gov/eere/geothermal/geothermal-heat-pumps

Low Temperature & Coproduced Resources

https://www.energy.gov/eere/geothermal/low-temperature-coproduced-resources

Geothermal Everywhere

https://www.energy.gov/eere/geothermal/geothermal-everywhere

Ground source heat pump

https://en.wikipedia.org/wiki/Ground_source_heat_pump