World Energy Resources | 2016

MWe
WORLD ENERGY COUNCIL | GEOTHERMAL
The vast majority of conductive geothermal resources have low to intermediate
temperatures. However, deep exploration wells at Habanero (AUS) and Luttlelgeest (NLD)
have encountered temperatures and fluids exceeding 200 o C at 4,000 metres depth. While
these resources are not yet economic, they do illustrate the vast potential of deep
resources.
Over the past 30 years, the geothermal industry has attempted to both improve the
productivity of conventional geothermal fields and exploit new (unconventional) resources
by developing techniques that improve the permeability of hot rocks. For convenience, this
report will refer to such endeavours as engineered geothermal systems (EGS). Although
much of the work to date has focused on recovering heat from impermeable hot rock, the
techniques can be applied to conventional fields as well.
SIZE DISTRIBUTION OF DEVELOPED GEOTHERMAL
RESOURCES
Like many mineral resources, the distribution of convective geothermal resources
resembles a log-normal distribution (Figure 1). The largest 12 fields (10% of the
population) contain 46% of the total installed generation capacity. The presence of large
fields played a pivotal role in stimulating the development of national geothermal industries
in Italy, New Zealand, USA, the Philippines, and now Kenya due to the availability of
economies of scale.
Fault-hosted systems are rarer (25% of all convection systems) and smaller than igneous
systems (mean size of 39 MWe vs 103 MWe). However, these fields may be
geographically clustered (as in the Carson Sink, Basin and Range Province, western USA)
and therefore provide the economies of scale necessary for building a geothermal industry.
FIGURE 1 : CONVECTIVE GEOTHERMAL SYSTEMS - FIELD SIZE
DISTRIBUTION
1000
900
800
700
600
500
400
300
200
100
0
0 20 40 60 80 100 120
Field Rank
5