sign in sign up
<<
Home , Land

How much will PV need to supply our electricity?

If photovoltaics were a primary source, what would the world look like? Would PV collectors cover every square inch of available land? Contrary to popular opinion, a world relying on PV would offer a almost indistinguishable Uni-Solar/PIX12961 from the landscape we know today.

The impact of PV on the landscape would be low for three reasons. First, PV systems have siting advantages over other technologies; for example, PV can be put on roofs. Second, even ground-mounted PV collectors are efficient from the perspective of . Third, adequate is ubiqui- tous and present in predictable amounts almost everywhere. As we move away from fossil-fuel energy, PV use will be crucial because of its land-use advantages.

PV’s Low-Impact Siting for -Plate Systems Rooftop PV is practical in urban areas with high land costs. PV graces a rooftop in Brisbane, . In the United States, cities and residences cover about 140 million acres of land. We could supply every kilowatt-hour One way to understand land-use issues for different energy of our nation’s current electricity requirements simply by sources is to realize that the federal government idles applying PV to 7% of this area—on roofs, on parking lots, 30 million acres of farmland every year—or three times along highway walls, on the sides of buildings, and in other the area needed to generate all our electricity from sun- dual-use scenarios. We wouldn’t have to appropriate a single light. We also set aside 23 million acres of land for the acre of new land to make PV our primary energy source! Arctic National Refuge, which is more than twice the acreage needed to generate all our electricity with PV.

PV’s Efficient Ratio of Produced Energy to Land Use Furthermore, we set aside hundreds of millions of acres for Even if it isn’t installed on rooftops, flat-plate PV technology , military bases, airports, and rights-of-way for is the most land-efficient means to produce renewable energy. pipelines, drilling, and reserves every year— As the table to the right shows, PV has a competitive converter PV: The Land-Area Advantage efficiency, a high capacity factor, and can be “packed” Converter Capacity Land per year for: densely in a given area. Technology Efficiency (%) Factor (%) Maximum Packing GW GWh

We still wouldn’t have a land- Flat-Plate PV 10%–20% 20% 25%–75%d 10–50 km2/GW 5000–25,000 m2/GWhk use issue, even if we didn’t Wind Low to 20%a 20%c 2%–5%e 100 km2/GWg 140,000 m2/GWhi use roofs for PV. We would need only 10 million acres Biomass 0.1% totalb High— compete 1000 km2/GWh 500,000 m2/GWhi of land—or only 0.4% of the for sunlight area of the United States—to Solar Thermal 15%–25% 25% 10%–20%f 20–50 km2/GWh,i 10,000–20,000 m2/GWh supply all of our nation’s elec- or PV Concen- 20 km2/GWj tricity using PV. Is 0.4% a lot trators of land? Not for something as awww.windpower.org gHansen 2003 important as producing elec- b0.5% or less light-to-biomass; then 33% to electricity; 0.1% total hHughes 2002 cSite dependent iPimentel 2002 tricity, and not in comparison dTilted arrays at high latitudes versus flat ones at the Equator; jCohen 2003 to some of the other ways we room between for maintenance kAt 15% module efficiency, 12% module-to-system e use land. Pimentel 2002; Dohn Riley et al. operating efficiency losses fTracking arrays need wider separation to avoid shadowing

U.S. Department of Energy Energy Efficiency and Renewable Energy Bringing you a prosperous future where energy is clean, abundant, reliable, and affordable S O L A R E N E R G Y T E C H N O L O G I E S P R O G R A M and most of us barely notice this land use. Thus, enough sunlight to produce economical energy For more information even if we didn’t put PV on a single existing with flat-plate PV. Compare this estimate to on PV, please read the structure, rooftop, or building, we’d still use other technologies: 15% or less for wind, other PV FAQs in this only a tiny fraction of our available land to because wind speeds vary so much, and wind series. You can order produce clean energy from PV. generation relates to the cube of wind speed; hard copies of the 20% for concentrator solar collectors, because FAQs from the A second way to compare energy sources is to they track the sun and use only direct sunlight, National Center for see how much the cost of land contributes to which limits them to less-cloudy ; and Photovoltaics, or overall electricity costs. Which technologies 50% for the best-case biomass scenario, because visit our Web site at produce enough energy so that land cost is crops must be www.nrel.gov/ncpv. not relevant to the total cost of the grown on arable energy produced? For PV, even if land land with good were to cost more than $80,000 per . acre, this cost would contribute less Non-PV sources than one cent per kilowatt-hour to the Shell Solar/PIX12960 may be confined A Strong Energy Portfolio cost of PV energy. Concentrator sys- to locations that for a Strong America tems, or other solar systems that aren’t are far from flat-plate, offer Energy efficiency and markets or even similar land- clean, renewable energy off limits to energy will mean a stronger efficient energy PV installations often development. economy, cleaner production. In do not require land. contrast, wind environment, and greater Uni-Solar/PIX12965 Above, an 84 kW Advantage PV! and biomass installation on a energy independence for are only able to Quonset in North The use of PV America. Working with “afford” land at Wales; left, PV atop affords numerous a wide array of state, less than $5,000 a carport in Santa land-use advan- community, industry, per acre to keep Monica, . tages. PV has flexi- and university partners, the land’s contri- ble siting, with the U.S. Department of bution below one cent per kilowatt-hour. PV rooftops and other urban settings being ideal Energy’s Office of Energy can convert sunlight efficiently into energy, locations for PV collectors. Even ground- Efficiency and Renewable with converters packed together densely. In mounted PV produces the most energy per Energy invests in a cities and affluent suburbs, where land costs unit of land area. And PV uses a natural diverse portfolio of exceed $80,000 per acre, PV can be installed available across the United States energy technologies. on roofs and structures. In other places, where and the world. land costs are lower, PV can be installed almost anywhere. We started by asking: What would our world look like if we used PV to produce significant PV’s Ubiquitous Energy Source amounts of electricity? The answer is that The sun’s intensity doesn’t vary by as instead of our sun’s energy falling on shingles, much as we might think. Looking at the concrete, and under-used land, it would fall extremes, the U.S. Southwest gets only on PV—providing us with clean energy while about 25% more sunlight annually than Kan- leaving our landscape largely untouched. sas City. And Buffalo receives only 25% less sunlight than Kansas City. Because PV energy References output is proportional to sunlight, its cost G. Cohen, Solargenix Energy, Technol- The National Renewable varies proportionally with local sunlight. If ogies Systems Symposium CD. Albuquerque, 2003. Energy Laboratory, a DOE national laboratory, PV is cost effective in a location with average T. Hansen, Chief Engineer. Springerville PV System, produced PV FAQs for: sunlight, such as Kansas City, it will be 25% Tucson Electric Power, 2003. more expensive in the cloudiest place, Buffalo. U.S. Department of Energy E. Hughes, Reduction with Renew- It will be 25% less expensive in the sunniest Office of Energy Efficiency ables. EPRI, TR-113785, 2000. and Renewable Energy place, Arizona. Also consider that conventional 1000 Independence Ave., S.W. energy prices vary by more than this range M. McLaughlin and D. Riley, Alternative Energy Institute, Turning the Corner: Energy Solutions for Washington, D.C. 20585 across the nation because of locally used the 21st Century, 2001. , nuclear, natural gas, coal, or oil. DOE/GO-102004-1835 D. Pimentel et al., Bioscience, Volume 44, #8, Revised February 2004 Sept. 1994. Once PV costs fall to competitive levels in an Printed with a renewable-source average solar location in the United States, , http://www.windpower.org/en/tour/ ink on paper containing at least index.htm. 50% wastepaper, including 10% more than 95% of the nation would have postconsumer waste