World Solar-Thermal Energy

L. David Roper
6 April, 2016


Solar-photovoltaic-energy installations have been growing at a fast pace. This is an attempt to project world solar-photovoltaic-energy installations into the future.

Two good sources of information about world solar-photovoltaic energy are:

  1. Solar Thermal Power

I use the data from those sources in this calculation.

Fit to the Data

Ref. 1 above predicts that solar-thermal-energy growth will be approximately exponential starting from 777 MW in 2008 to 6400 MW by year 2012. 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-thermal-energy consumed in Terrawatt-hours each year.

Solar-thermal energy is in such an early stage of exponential growth that fitting the yearly data does not determined the eventual amount to be produced. I assume that the asymptote for solar-thermal energy will be the same as used for solar photovoltaics, 110,000 TWh/yr.

This shows the fit to the solar-thermal-energy data for an asymptotic value of 110,000 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 2030.


Earth land area: 1.49x108 km2 (29%). Surface area: 5.10x108 km2. (1 km2=247.1 acres=100 hectares). Arable land: 13.31% of surface (6.8x107 km2); 4.71% (2.4x107 km2) supports permanent crops. 40% is used for cropland and pasture (1.3x107 km2 cropland, 3.4x107 pastureland). Mean height of land above sea level is 840 m.

The aymptote of 1.1x105 TWh/year of the fit to the solar-photovoltaic energy could be generated by using about ~0.7% of the land area of the Earth: 1.1x1017Wh/5x103(Wh/m2)/106(m2/km2)/100/0.2 = 1.1x106 km2, which is 0.74% of the Earth land area.

World Renewable Energy

L. David Roper Interdisplinary Studies