Utility scale solar power plants require a significant amount of land due to the number of solar panels required. Modern plants require 5 to 15 acres per MW of capacity. Recent Concentrating Solar Power plants (see OWOE:
How do solar thermal power plants generate electricity?) have been between about 10-15 acreas per MW, while Photovoltaic Plants (see OWOE:
How do photovoltaic cells work to generate electricity?have been in the 5-10 acres per MW range. Figure 1 shows the
Crescent Dunes Solar Energy Project, which comes in at about 14.5 acres per MW. Due to the need for land, the need for steady sunlight, and the high cost for transmission lines, the most logical locations for solar plants are deserts in close proximity to major population centers.
Although the land surface required to generate a MW of electricity appears large, on a relative basis it does not appear excessive. In 2009 the Land Art Generator Initiative (LAGI), which uses art to promote clean energy, calculated the amount of land area that would be required to power the entire world with solar energy. Figure 2 shows the map, with the yellow boxes showing area required to meet the estimated power needs (electricity generation and transportation) for 2030. As an example, it would require land equal to several Texas counties to power the entire United States. In 2021 LAGI
updated their calculations to not only account for the land required for solar panels, but the amount of both landscapes and oceanscapes required for ten renewable energy technologies to get to 100% renewable energy worldwide. Their work also addressed the space between solor modules and wind turbines that must also be considered. The resulting map is shown in Figure 3. Their main conclusions were:
- To meet the target of net-zero by 2050 1.4 million square kilometers of renewable energy landscapes and 488 thousand square kilometers of renewable energy oceanscapes must be deployed.
- More than 80% of this area will consist of the grassland between rows of solar panels and the fields or stretches of ocean between wind turbines.
- At least another 8% will consist of rooftop installations that do not take up ground space.
- That leaves 166,000 km2 of land area that will be devoted exclusively to renewable energy technologies.
The 166,000 km2 of land area compares to 800,000 km2 of land that has been paved over or had structures built on it to date. While not insignificant, on a relative basis, the map demonstrates that the earth should have sufficient area to accomplish this target.
One of the positive (and somewhat fortuitous) features of solar power generation at a utility scale is that the places with the greatest amount of sunlight also tend to be the places with the most available land. The National Renewable Energy Laboratory (NREL) map in Figure 4 shows the average annual insolation in kW-h/m2 per day across the US for a fixed solar photovoltaic system that is aimed to the south and tilted toward the sun at the same angle as the lattitude of the location. It can be seen that the land area that receives the greatest amount of solar energy (>6 kW-h/m2 per day) is the desert Southwest, which includes some of the least inhabited land areas in the US.
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