L. David Roper
http://www.roperld.com/personal/roperldavid.htm
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:
I use the data from those sources in this calculation.
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: 1.49x10^{8} km^{2} (29%). Surface area: 5.10x10^{8} km^{2}. (1 km^{2}=247.1 acres=100 hectares). Arable land: 13.31% of surface (6.8x10^{7} km^{2}); 4.71% (2.4x10^{7} km^{2}) supports permanent crops. 40% is used for cropland and pasture (1.3x10^{7} km^{2} cropland, 3.4x10^{7} pastureland). Mean height of land above sea level is 840 m.
The aymptote of 1.1x10^{5} 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: 1.1x10^{17}Wh/5x10^{3}(Wh/m^{2})/10^{6}(m^{2}/km^{2})/100/0.2 = 1.1x10^{6} km^{2}, which is 0.74% of the Earth land area.