The resources, installed capacity, and its increase in
the last three years for PV, wind, hydro and
geothermal energies are listed in Table 1. Note that
the resources of the four energy types from different
references are very different. According to GEA, the
total geothermal power installed in world was about
11.2 GW until May 2012 (also see Clean Energy, v.6,
p. 72, 2013). According to WEA (2000), geothermal
has the largest resources among the four types of
renewable energies.