Low carbon energy and land use
The low carbon energy sources to be considered are solar, wind, geothermal, hydro, bioenergy and nuclear; with the exception of nuclear these are all normally regarded as renewable energy (RE) sources. Comparisons between these energy sources may be made on issues such as greenhouse gas emissions per unit of energy produced, cost and land use, and it is with land use that we will be primarily concerned. Merrill (2021) writes on the land needed for a zero-carbon economy in the U.S. and compares the areas needed to supply 100W for a year by various means. Hydro power needs 296m²; wind with spaced turbines, 37 m²; solar 14 m²; coal, 0.8 m²; nuclear 0.3 m²; and natural gas, 0.1 m². He also provides figures for current land use in the U.S. for its energy sources. Of a total of 81 million acres used for energy production, 51.5 are used to produce biofuels, 8.7 for hydropower, 6.7 for wind farms (the total area, of which the direct footprint is 0.07), 4.8 for power lines, 4.4 for natu