[php function=7]April 9, 2010
Summary
The purpose of this study is to provide a first-pass approximation of world energy needs in 2050, and the ability of alternative energy to meet those needs. We make this approximation according to a specified methodology: We calculate the primary energy consumption per capita of the United States for 2008, and then use that per-capita consumption to project the world energy requirement for 2050. Then, we take that world energy requirement for 2050, and estimate how much of that could be met by alternative energy sources, were the entire world to produce alternative (“renewable”) energy at the same per-square-kilometer level as the United States in 2008.
For energy data, we use the figures published by the Energy Information Administration (EIA) of the U.S. Department of Energy, while for population we use the 2008 estimate and 2050 projections from the U.S. Census.
The Data
The Energy Information Administration of the U.S. Department of Energy publishes an Annual Energy Review which provides figures for total energy consumption in the United States, by a variety of categories. The latest available report contains data for 2008, which shows that the total primary energy consumption in the U.S. was 99.3 quadrillion BTUs for the year, of which 83 quadrillion BTUs came from fossil fuels, 8.5 quadrillion BTUs from nuclear power, and 7.3 quadrillion BTUs came from renewable energy, mainly biomass and hydroelectric power.
Table 1 shows the breakdown of consumption by energy source, and also shows the Joule equivalents.
Notes:
1/ Converted at 1054.35 Joules per BTU
2/ Biomass includes wood, waste, and biofuels
Source: Annual Energy Review Table 1.3, Energy Information Administration, U.S. Dept. of Energy
The U.S. Bureau of the Census estimates that the population of the U.S. was 304 million as of July, 2008, and projects that the world population will be 9.3 billion in 2050.
Dividing U.S. energy consumption by population yields an energy consumption per capita of 344 gigajoules (3.4434 E+11 Joules) for 2008.
We then take that U.S. per capita consumption figure as a baseline standard for human energy consumption, and multiply it by the projected world population for 2050. This yields a projected baseline world energy requirement of 3.2 zettajoules (3.2055 E+21 Joules) for 2050.
Table 3. Energy Consumption Projection
Notes:
1/ Converted at 1054.35 Joules per BTU
Now we turn our attention to renewable energy consumption. Table 4 shows renewable energy consumption in the U.S. in 2008.
Notes:
1/ Converted at 1054.35 Joules per BTU
2/ Biofuels include fuel ethanol and biodiesel
Source: Annual Energy Review Table 10.1, Energy Information Administration, U.S. Dept. of Energy
To generate enough electricity from solar power to meet our projected world energy requirements on 2050, would require large swaths of the planet to be covered with solar panels. Solar power, using your figure of 450 Watts per square meter per hour, six hours a day, would yield 2,700 Watt-hours per day, which at 365 days per year would be 985,000 Watt-hours. Thus is would take 904,127 square kilometers of solar-panel surface-area—some 1.3 times the area of Texas—to produce the desired amount of energy.
However, only about 20% of that potential power, at best, can be turned into electricity. On that basis, each solar panel would produce 540 Watts per day of usable energy, or 197,100 Watt-hours per year. At that rate, it would take 4.5 million square kilometers of solar-panel surface-area to meet our projected 2050 requirements. That is an area equivalent to 47% of the total area of the United States, and 6.5 times the area of Texas.
Some have suggested that the usable power of a solar panel is closer to 12%, a rate at which it would require an area equivalent to 78% of the land area of United States.
Note that these calculations include only the surface-area of the solar panels themselves, and not any associated areas such as access areas between arrays of panels, so the actual area required would be greater.
Table 5. Solar power generation calculations
As a rough first-pass approximation of world renewable potential for renewable energy production in 2050, we take the U.S. total consumption for 2008 and extrapolate it to the land area of the world as a whole (the United States is 6.5% of the world, in terms of land area). Assuming the world as a whole in 2050 produced renewable energy at the same per square kilometer rate as the U.S. did in 2008, the amount of energy produced would be just 3.71% of the requirement (Table 6)
Table 6. Projected World Renewable Energy Capacity, 2050
