Geothermal resources provide energy in the form of direct heat and electricity, totalling an estimated 805 PJ (223 TWh) in 2012.
Geothermal direct use continued to increase globally during 2012. Direct use refers to direct thermal extraction for heating and cooling. A sub-category of direct use is the application of ground-source heat pumps (GHP), which use electricity to extract several units of thermal energy from the ground for every unit of electrical energy spent.
Although there are limited data available on recent growth in direct use of geothermal energy, output is known to have grown by an average of 10% annually from 2005 through 2010; much of that growth was attributed to ground-source heat pumps, which experienced an average annual growth of 20%. Assuming that these growth rates have persisted in the last two years, global geothermal heat capacity reached an estimated 66 GWth in 2012, delivering as much as 548 PJ of heat.
GHP represents the largest and historically fastest-growing seg