179
wind and/or solar electricity making up the “renewables” section of Fig. 9.4 would
have to be expanded to cover the power generated by coal and natural gas (oil is
negligible and can be ignored). Renewables like wind and solar have a low energy
density. This means that unlike energy-dense power plants that use natural gas, coal,
or nuclear and essentially fit into a single building, renewables are spread out over
long distances across the landscape. Anyone who has driven past the wind farms in
Iowa or Texas can attest to their large size.
The math is formidable. The generating capacity of the average onshore wind
turbine is about a million watts (one megawatt, or Mw). One gigawatt (Gw) is a billion watts, or a thousand Mw, requiring a thousand average wind turbines to replace
one Gw of fossil. To replace all 237 Gw of fossil electricity, a total of 273,000 average wind turbines are required. At present, there are about 54,000 wind turbines
operating in 41 states in the U.S. Four times as many would be needed to completely
replace fossil fuel with wind.
Perhaps a larger wind turbine would help. The highest-output onshore wind
turbines in the United States are in Texas, with capacities of around four Mw each.
Using these for the sake of argument, about 68,250 of the four Mw wind turbines
would be needed to generate 273 Gw of electricity. If these wind turbines were
spaced 300 m (1000 ft) apart, their linear extent would be 20,475 km (12,000 mi).
Solar has a similar issue. The largest solar plant in the United States is the $2.2
billion (including a $1.6 billion loan guarantee from DOE) Ivanpah Solar Power
Facility in the California desert, completed in 2014 and capable of generating 392
Mw of electricity (Fig. 9.5). It consists of three tall solar thermal towers heated by
sunlight reflected from some 300,000 mirrors, and covers a land area in Ivanpah Dry
Lake of approximately 3,500 acres, or 14.2 km
2
(source: http://www.brightsourceenergy.com/ivanpah-solar-project accessed 1/20/20). There is also a natural gas
backup to supply additional heat if needed.
To generate the equivalent of 273 Gw of fossil fuel electricity, almost 700 more
solar plants just like Ivanpah would be required. At around $2 billion each, the total
cost would be about $1.4 trillion. If each power plant covered a similar amount of
land area, almost 10,000 square kilometers or about 4000 square miles would be
needed. This is somewhat smaller than the land area of Connecticut. This is not to
say that either of these projects cannot be done, but many people speak glibly about
replacing fossil with wind or solar without understanding the cost or the magnitude
of the undertaking.
Photovoltaics have come down in price and are more efficient at producing
electricity than solar thermal, but a 100 watt solar panel still costs around $150. To
generate 273 Gw, it would require 2.73 billion of these 100 W panels at a cost of
$409.5 billion (although there would probably be a volume discount). Each panel
covers a surface area of 54 x 40 inches or 15 square feet (137 cm × 102 cm or
1.39 m
2
). Laying out 2.73 billion of these panels would occupy a land surface area
of about 1470 square miles, which is slightly larger than the state of Rhode Island.
Another major cost involved is related to the fact that both wind and solar
generate electricity differently than fossil fuel plants. Natural gas and coal-fired
power plants are called “thermoelectric” in that they use heat to boil water to make
9.3 The Future of Fossil Fuel
wind and/or solar electricity making up the “renewables” section of Fig. 9.4 would
have to be expanded to cover the power generated by coal and natural gas (oil is
negligible and can be ignored). Renewables like wind and solar have a low energy
density. This means that unlike energy-dense power plants that use natural gas, coal,
or nuclear and essentially fit into a single building, renewables are spread out over
long distances across the landscape. Anyone who has driven past the wind farms in
Iowa or Texas can attest to their large size.
The math is formidable. The generating capacity of the average onshore wind
turbine is about a million watts (one megawatt, or Mw). One gigawatt (Gw) is a billion watts, or a thousand Mw, requiring a thousand average wind turbines to replace
one Gw of fossil. To replace all 237 Gw of fossil electricity, a total of 273,000 average wind turbines are required. At present, there are about 54,000 wind turbines
operating in 41 states in the U.S. Four times as many would be needed to completely
replace fossil fuel with wind.
Perhaps a larger wind turbine would help. The highest-output onshore wind
turbines in the United States are in Texas, with capacities of around four Mw each.
Using these for the sake of argument, about 68,250 of the four Mw wind turbines
would be needed to generate 273 Gw of electricity. If these wind turbines were
spaced 300 m (1000 ft) apart, their linear extent would be 20,475 km (12,000 mi).
Solar has a similar issue. The largest solar plant in the United States is the $2.2
billion (including a $1.6 billion loan guarantee from DOE) Ivanpah Solar Power
Facility in the California desert, completed in 2014 and capable of generating 392
Mw of electricity (Fig. 9.5). It consists of three tall solar thermal towers heated by
sunlight reflected from some 300,000 mirrors, and covers a land area in Ivanpah Dry
Lake of approximately 3,500 acres, or 14.2 km
2
(source: http://www.brightsourceenergy.com/ivanpah-solar-project accessed 1/20/20). There is also a natural gas
backup to supply additional heat if needed.
To generate the equivalent of 273 Gw of fossil fuel electricity, almost 700 more
solar plants just like Ivanpah would be required. At around $2 billion each, the total
cost would be about $1.4 trillion. If each power plant covered a similar amount of
land area, almost 10,000 square kilometers or about 4000 square miles would be
needed. This is somewhat smaller than the land area of Connecticut. This is not to
say that either of these projects cannot be done, but many people speak glibly about
replacing fossil with wind or solar without understanding the cost or the magnitude
of the undertaking.
Photovoltaics have come down in price and are more efficient at producing
electricity than solar thermal, but a 100 watt solar panel still costs around $150. To
generate 273 Gw, it would require 2.73 billion of these 100 W panels at a cost of
$409.5 billion (although there would probably be a volume discount). Each panel
covers a surface area of 54 x 40 inches or 15 square feet (137 cm × 102 cm or
1.39 m
2
). Laying out 2.73 billion of these panels would occupy a land surface area
of about 1470 square miles, which is slightly larger than the state of Rhode Island.
Another major cost involved is related to the fact that both wind and solar
generate electricity differently than fossil fuel plants. Natural gas and coal-fired
power plants are called “thermoelectric” in that they use heat to boil water to make
9.3 The Future of Fossil Fuel