The worldwide application of geothermal energy for direct
utilization is reviewed. This paper attempts to update the
previous survey carried out in 2005, presented at the World
Geothermal Congress 2005 (WGC2005) in Turkey and
subsequently updated in Geothermics (vol. 34) (Lund,
Freeston and Boyd, 2005). This update also compares data
from 1995 and 2000 presented at two World Geothermal
Congresses in Italy and Japan (WGC95 and WGC2000).
As in previous reports, an effort is made to quantify
ground-source (geothermal) heat pump data. This report is
based on country update papers prepared for WGC2010 and
other sources of data available to the authors. Final update
papers were received from 70 countries of which 66
reported some direct utilization of geothermal energy.
Twelve additional countries were added to the list based on
other sources of information. The 78 countries having
direct utilization of geothermal energy, is a significant
increase from the 72 reported in 2005, the 58 reported in
2000, and the 28 reported in 1995. An estimate of the
installed thermal power for direct utilization at the end of
2009, for this current reports is 50,583 MWt, almost a 79 %
increased over the 2005 data, growing at a compound rate
of 12.3% annually with a capacity factor of 0.27. The
thermal energy used is 438,071 TJ/year (121,696 GWh/yr),
about a 60% increase over 2005, growing at a compound
rate of 9.9% annually. The distribution of thermal energy
used by category is approximately 49.0% for ground-source
heat pumps, 24.9% for bathing and swimming (including
balneology), 14.4% for space heating (of which 85% is for
district heating), 5.3% for greenhouses and open ground
heating, 2.7% for industrial process heating, 2.6% for
aquaculture pond and raceway heating, 0.4% for
agricultural drying, 0.5% for snow melting and cooling, and
0.2% for other uses. Energy savings amounted to 307.8
million barrels (46.2 million tonnes) of equivalent oil
annually, preventing 46.6 million tonnes of carbon and
148.2 million tonnes of CO2 being release to the
atmosphere which includes savings in geothermal heat
pump cooling (compared to using fuel oil to generate
electricity).