L. David Roper
6 April, 2016
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