Utility-Scale Solar Energy Could Need Land the Size of Connecticut

Combining solar and ecological restoration at Purdue University, Indiana / Great Plains Institute

The U.S. is headed towards a renewable energy future. Over the coming decades, some mix of mostly wind and solar power will spread across the landscape. With the growing cost competitiveness of utility-scale solar power plants, we can expect 583 gigawatts to be in production by 2050. That’s ten times the current amount. At approximately 7 acres per megawatt, that means an area larger than the state of Connecticut could be used for solar energy production.

Through thoughtful planning and design, these future solar power plants can be well-integrated into communities and provide many co-benefits — water quality improvements, ecological restoration, and pollinator habitat, among many others. Renewable energy creates enormous opportunities for landscape architects and planners working in rural, suburban, and urban areas.

At the American Planning Association (APA)’s virtual national conference, Megan Day, a senior energy planner with the National Renewable Energy Laboratory (NREL) in Colorado, said that utility-scale power plants, which are very large-scale solar facilities, are needed to achieve our climate and energy goals.

Utility-scale solar now accounts for 60-70 percent of all solar energy in the U.S. This is because the cost of energy from utility-scale solar is approximately “one third to one-fourth the cost of residential solar.” The market is further heading in the direction of big solar power facilities.

Daly said “these numbers don’t speak fully to value though.” Utility-scale solar creates far fewer green jobs than rooftop solar. 1 megawatt of clean energy could be generated through a single utility-scale power plant or approximately 100 rooftops. While the capital costs of the utility approach would be about $1 million less, there would also be much fewer local green jobs created. “This is because you need a lot more people to install 100 rooftop systems.” (Not to mention utilities offer fewer resilience benefits: Any centralized power plant can go down in a hurricane, storm, or wildfire).

Day said the vast majority of new solar power facilities use tracking systems that rotate photovoltaic (PV) panels to face the sun over the course of each day. While these tracking systems increase the amount of solar energy that can be captured, it also means these power plants require more space so as to avoid over-shadowing other tilting panels. “These panels cast shadows east west, so they need more land.” Combined with ecological site design that avoids existing wetlands, rivers, streams, and forests, these kinds of renewable energy power plants aren’t the most compact. “In fact, compact isn’t the best.”

The trend is for solar power facilities to go bigger and bigger. In 2010, she said, a large solar power plant had a 15 megawatt capacity. Today, there are 75-250 megawatt systems and even larger. “With more land, you can achieve greater economies of scale.”

Showing interactive models NREL can create through its fantastic State and Local Planning for Energy (SLOPE) tool, Day indicated where in the continental U.S. solar energy could be developed. If all land suitable for solar development was used, the country would have 59,000 times more energy than it consumes on an annual basis. “That gives you a sense of the incredible potential.” In contrast, if all suitable roofs in the U.S. were covered with PV panels, they would only meet 45 percent of energy needs.

While California and Texas are currently leaders in renewable power generation because they have invested in transmission capacity, many other states across the country can easily expand their solar energy capacity.

According to Sarah Davis, a planner who founded her own firm, “large-scale solar is coming” to every community. As the U.S. de-carbonizes its energy systems, there an opportunity for “authentic and meaningful community participation” in planning and designing a clean energy future.

Planning new utility-scale solar facilities involves typical development activities — incorporating developments into long-range comprehensive plans, creating enabling regulations, and permitting actual projects. These projects include utilities, developers, landowners, federal and state regulators, residents, and the end-users of the energy generated.

Using NREL’s SLOPE tool, Davis helps communities identify, at a county level, what areas would be ripe for solar development; what areas should be avoided because of existing cultural, scenic, or environmental resources; and where solar developments could provide the most co-benefits.

She outlined a few examples: In Butte county, California, Davis worked with stakeholders to create a vision statement that outlines a set of guiding principles and design and development guidelines. In Stearns, Minnesota, an agricultural community integrated renewable energy into the agricultural section of their comprehensive plan. “PVs need land and can use grazing areas.” But the new policies also required beneficial ground cover amid the solar facilities and enabled laying new transmission cables. And renewable energy planning can even be done in small rural communities. In Gold Hill, Colorado, she worked with an isolated community of 200-300 residents to devise a plan for a micro-grid and distributed household solar systems.

Another theme running through the session was the importance of maximizing the co-benefits of solar energy. Brian Ross, a vice president at the Great Plains Institute in Minnesota, made the case: “if sited and designed appropriately, large-scale solar can provide local benefits to communities. If you can restore watershed functions, diversify agriculture, or protect wildlife habitat and drinking water supplies, does it matter if it’s a solar farm?”

“Solar development is also development, and development means jobs, rents, and tax revenue,” Ross argued. The benefits of utility-scale solar development projects are increased local property tax incomes, increased local power generation, and reduced environmental and climate risks.

Communities should first figure out where to site their large-scale solar power facilities, then determine how the facility should function as a land use. “When planning and designing these projects, it’s important to look for synergies.” If there are valuable natural areas, watersheds, or scenic areas, “don’t put the solar developments in those places.” Instead, use solar farms as a way to fix existing environmental issues.

For example, in one Indiana agricultural community, nitrate run-off from farms was negatively impacting water quality, including groundwater recharge areas and the drinking water supply. The community decided to transform a 33-hectare area of contaminated farmland into land just used for solar power generation.

The new solar facility enabled the farmers to still earn income from the land while also reducing water quality impacts. This is a prime example of the co-benefits of utility-scale solar: “co-locating solar power plants with agriculture is a way to diversify farmers’ incomes and provide buffers for watersheds, including groundwater and surface water,” Ross said.

Solar power plants can not only just serve as buffers that reduce other impacts downstream, they can also be ecologically beneficial themselves. Acres of PV panels can be arranged amid native grassland restoration projects that can yield a three-fold increase in pollinators and a two-third increase in carbon sequestration through the landscape. Furthermore, these native grassland projects can increase sediment retention by 95 percent and water retention by 15 percent.

Engie solar, Vermont / courtesy of Fresh Energy, Rob Davis
Denison University, Ohio / courtesy of Fresh Energy, Rob Davis
Perdue solar headquarters / courtesy of Fresh Energy, Rob Davis

In Indiana, Purdue University’s extension programs worked with conservation, agriculture, and energy stakeholders to create state-wide standards for ground cover in solar power plants. This approach has been included in a model solar ordinance created by Indiana University and codified in an innovative ordinance that requires beneficial ground cover over the lifespan of a solar facility, which is 25 to 30 years. The ordinance ensures that solar energy developers just don’t plant once and then forget to maintain the landscape. Some solar power facilities are even in layering in sheep grazing, vegetable farming, and bee hives. Solar power plants can become multi-functional green infrastructure.

4 thoughts on “Utility-Scale Solar Energy Could Need Land the Size of Connecticut

  1. ronaldsteinptsadvancecom 05/17/2021 / 6:34 pm

    All that land just for intermittent electricity.

  2. George Frantz 05/17/2021 / 6:49 pm

    Existing wetlands, rivers, streams, and forests need to be protected when developing solar arrays, yes. But they are already protected under any number of laws. What is not mentioned by anybody at all in the article is that our high quality agricultural soils are both extremely attractive for solar development and an extremely vulnerable and irreplaceable ecological resource. Solar energy arrays are not at all compatible with agriculture, except for limited grazing use, and with their foundation systems and other underground infrastructure effective destroy the productive capacity of high quality agricultural lands.

    Local governments need to carefully consider not just the “green” in terms of non-carbon energy production, or the “green” in terms of potential new revenues. The need to carefully consider, and enact, effective land use regulations that communicate where large scale solar will be permitted, and not permitted, and put in place effective design standards for design, maintenance and operations, and end-of-life decommissioning/demolition and site restoration.

    • Rob Davis 05/25/2021 / 6:18 pm

      Hi George,
      Energy buyers can express a preference for clean energy paired with agriculture and/or conservation. Communities can adopt ordinances that encourage these practices as well. Well managed perennial vegetation increases soil organic matter. STRIPs research out of Iowa State has 10+ years of research on this.

      Specific to solar, these recent reports show an encouraging opportunity:

      For example, University of Illinois expressed preferences regarding ground cover for its newest 12 MW solar array. https://twitter.com/UofIFS/status/1392861848966516740

      • George Frantz 05/25/2021 / 9:05 pm

        Thanks for the comment, Rob. I have been in the thick of this particular issue as a land use and environmental planner specializing on agricultural land and open space protection, including writing zoning regulations to better guide solar development and protect communities from some the adverse impacts of large scale solar development. As an educator I’ve also worked with Cooperative Extension as well as American Farmland Trust to get the word out to municipal officials, and to farmers, regarding both the opportunities of solar development, and also the pitfalls, and what step they need to take to protect their communities, and farms.

        The sad fact is that not enough communities or farmers are considering that there needs to be planning for not only where solar development should go, but also the decommissioning of solar arrays at the end of their life. With the types of foundation systems required, it is not a temporary use of land. Contrary to what energy company leasing agents may say to close on a lease, solar arrays are not easy nor cheap to remove at the end of life.

        It’s no longer a hypothetical here in New York, where three solar developments ranging between 180 MW and 280 MW, and each to cover 1,000 acres or more, have been proposed in the Genesee Valley south of Rochester. One of them is proposed to cover around 1,000 acres of primarily high quality Genesee River bottomland.

        Up until last year municipal governments had full authority to control solar development through their local zoning regulations, including mandating the preparation of comprehensive environmental impact statements, and also mandating mitigations measures to address environmental impacts. New York state however last year took away local review powers for project 25 MW or larger, instead transferring authority to a new state agency. Moreover, the new agency has the authority to override local zoning regulations, if it determines that they are “overly burdensome.” I suspect that the State will find the zoning in a couple of my client communities “overly burdensome,” because (at the behest of the farm community) they have banned large scale commercial solar development in their agricultural zoning districts to protect the soil resource.

        There is a lot of opportunity and benefits of solar energy development, and also, especially here in New York, plenty of low quality land on which to develop it. But, solar developers, like generations of suburban developers that have preceded them, prefer to build on flat farmland land where construction costs are cheaper.

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