World Geothermal Energy

L. David Roper
6 April, 2016


This is an attempt to project world geothermal-energy installations into the future.

Three good sources of information about geothermal energy are:

  1. Renewables Global Status Report 2009 Update
  3. (32 TW available geothermal power)
  4. Role of geothermal energy to the mitigation of climate change
  5. Geothermal power technology

I use the data from those sources in this calculation. Here "geothermal energy" includes all kinds of methods to extract heat from the Earth.

Fit to the Data

For the last decade world geothermal-energy growth has been approximately exponential. Of course, at some future time it has to level off. The hyperbolic-tangent function is a good function for fitting physical data that start off exponentially and approach an asymptote exponentially, such as is expected for renewable energy.

The fits given here involve fitting the hyperbolic-tangent function,

by varying its three parameters to the estimated solar-photovoltaic-energy consumed in Terrawatt-hours each year.

Geothermal energy is in such an early stage of exponential growth that fitting the yearly data does not determined the eventual amount to be produced. Using the 32 TW availability given in Ref. 3 above and assuming that about 25% of it can be developed, the asymptote of 70,000 TWh/year is used in the fit given below.

This shows the fit to the geothermal-energy data for an asymptotic value of 70,000 Terrawatt-hours per year.

This shows the projection of the fit into the future and compares the projection to the energy available from fossil fuels. The crossover year is about 2060.


A rough estimate of the future availability of geothermal energy is given.

World Renewable Energy

L. David Roper Interdisplinary Studies