NREL Report Firms Up Land-Use Requirements Of Solar Power Plants

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This post originally published on the NREL website

The Energy Department’s National Renewable Energy Laboratory (NREL) has published a report on the land use requirements of solar power plants based on actual land-use practices from existing solar facilities.

“Having real data from a majority of the solar plants in the United States will help people make proper comparisons and informed decisions,” lead author Sean Ong said. The report, “Land-use Requirements for Solar Power Plants in the United States,”PDF was written with NREL colleagues Clinton Campbell, Robert Margolis, Paul Denholm and Garvin Heath.

Ong gathered data from 72% of the solar power plants installed or under construction in the United States. Among the findings:

  • A large fixed tilt photovoltaic (PV) plant that generates 1 gigawatt-hour per year requires, on average, 2.8 acres for the solar panels. This means that a solar power plant that provides all of the electricity for 1,000 homes would require 32 acres of land.
  • Small single-axis PV systems require on average 2.9 acres per annual gigawatt-hour – or 3.8 acres when considering all unused area that falls inside the project boundary.
  • Concentrating solar power plants require on average 2.7 acres for solar collectors and other equipment per annual gigawatt-hour; 3.5 acres for all land enclosed within the project boundary.

By the third quarter of 2012, the United States had deployed more than 2.1 gigawatts of utility-scale solar generation capacity. Another 4.6 gigawatts was under construction. There has been a long-running debate over the comparative land needs for various forms of energy, old and new. But that’s not the purpose of the new report, Ong and Denholm emphasized.

“The numbers aren’t good news or bad news,” Denholm said. “It’s just that there was not an understanding of actual land-use requirements before this work. However, we were happy to find out that many of the solar land use ranges and estimates used in the literature are very close to actual solar land use requirements that we found.”

These land-use estimates can also be compared with other energy-production land uses. For example, a study by Vasilis Fthenakis and Hung Chul Kim of Columbia University (2009) found that, on a life-cycle electricity-output basis—including direct and indirect land transformation—utility-scale PV in the U.S. Southwest requires less land than the average U.S. power plant using surface-mined coal.

A previous NREL report, “Land-use Requirements and the Per-capita Solar Footprint for Photovoltaic Generation in the United States,” had estimated that if solar energy was to meet 100% of all electricity demand in the United States, it would take up 0.6% of the total area in the United States.

This time, the data come not from estimates or calculations, but from compiling land use numbers from actual solar power plants. Every solar energy site analyzed in the study is listed in a detailed appendix.

“All these land use numbers are being thrown around, but there has been nothing concrete,” Ong said. “Now people will actually have numbers to cite when they conduct analyses and publish reports.”

NREL previously had released a report on land-use needs for wind power. Doing the same other generation resources including coal, natural gas and nuclear — estimating land use via huge sample sizes — would help inform decisions, Denholm said.

The report provides fundamental data that can be used to understand the impacts and benefits of solar. “Modelers and analysts, people looking 10 or 20 years into the future can use this report to evaluate the impacts solar energy may have,” Denholm said.

NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by the Alliance for Sustainable Energy, LLC.

Image Credit: Marika Krakowiak / CleanTechnica / Solar Love

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7 thoughts on “NREL Report Firms Up Land-Use Requirements Of Solar Power Plants

  • In California, 21.93 GWh of solar radiation energy falls on 2.7 acres of land, 30.87 GWh of solar radiation falls on 3.8 acres of land. In other words, on a total enclosed land area basis, the overall efficiency of solar to electric is between 6.5% to 9.1%. If the solar PV nowadays are very efficient, between 15% to 30%, it means that land use is not optimize, IOW, the spacing are poorly designed wasting a lot of land that are not capturing sunlight. We need to be more creative in how to pack the solar PV’s as efficiently as possible, such as those arranged naturally in sunflower’s seed array within the flower.

    But overall, the 6.5% to 9.1% overall efficiency is not that bad, compared to plants, whose energy capture is between 0.5% to 2% before fuel conversion. It means that we could make a lot of improvement by simply using proper geometric layout in the installation of solar PV. Simple math CAD, with simulation and graphics and a little bit of time in the drawing board is all it takes.

    • Or simply put them on rooftops where the effective land use efficiency is infinite because no extra land is used per Kwh generated. There are enough mega warehouses to still have some utility scale plants and surely the lease costs of a warehouse roof is cheaper then a greenfield site. The only good bare land site for solar farms are old industrial sites like old decommissioned chemical or power plants with significant contamination rendering it useless for other purposes. I can see little point occupying greenfield sites until we approach saturation of rooftop systems.

    • Have tilt, want to avoid shading other panels. Thats the biggest source of the area inefficiency. Of course we also have access paths, off sets from fences, etc. etc.
      Give up on the per panel benefits from tilting and tracking, with horizontal panels, and you might be able to do 90% coverage. But then you need more panels. And they are hard to clean. Tilting allows water to run off.

  • 32 acres to produce power for 1000 homes is a steal. Usually 4 houses per acre which is the equivalent of displacing (4×32=128) home sites or for every potential 1000 homes, you could only build 872 of them…that’s if they don’t have solar on the roof. This comes out to 250(1000/4) acres for 872 homes that are solar powered.

    Looking back, I probably messed up on the math;-)

    Maybe better is 282(250+32) acres for 1000 homes.

  • I would have liked to seen a scatter plot of module efficiency against total project land use. It seems like First Solar’s thin film modules would need more acres than SunPower’s high efficiency silicon, or even Trina’s average-efficiency silicon.

  • I’d like to see more encouragement of multiple-use solar farms. In hot, dry climates shade is valuable to plants and animals. There’s no reason why a solar farm should be sterile. A good example from India here. And of course solar-covered car parks are a no-brainer. Here’s one of IKEA’s in Spain.

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