THE DIRT

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.

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.