Maximizing Land Use Benefits From Utility-Scale Solar
Utility-scale solar development has expanded rapidly across the U.S. in recent years, driven by declining costs and improving technology. The most recent Lazard levelized cost of energy (LCOE) analysis shows utility-scale solar now equivalent to or below the cost of conventional generation, with a price range of $36-44 per megawatt-hour (MWh). Thirty-two gigawatts (GW) of utility-scale solar have been installed in the United States to date, and another 50 GW are planned or in development. By 2030, the Department of Energy SunShot program estimates that solar development will encompass between 1 to 3 million acres of land. As the geographic footprint of solar increases beyond the arid southwestern United States, so too has interest in the land use under the panels. In these new geographies, including the Midwest and Northeast, solar is often sited on agricultural land. The ideal tract of land for solar development is flat, dry, unshaded, and close to transmission and load. All of these characteristics are associated with farmland, raising possible tensions between solar and farming as competing land uses. For the most part, solar developers plant shallow-rooted turfgrass or spread gravel under panels, rendering that land unproductive aside from the generation of electricity. However, the co-location of solar projects and innovative vegetation management plans offers the potential to ameliorate this potential land use conflict. Improving the “landscape compatibility” of utility-scale solar has become a topic of great interest in the energy, land use and agricultural research communities. Examples of co-location include growing crops underneath solar trackers; grazing cattle or sheep among elevated solar panels that also provide shade for the livestock; and installing solar in the non-irrigated corners of center-pivot irrigation plots. These approaches can be grouped under the recently coined umbrella term “agrivoltaics.” The researchers developed an Excel-based modelling tool to understand the tradeoffs, costs and benefits between maintaining land as conventional farmland or converting a portion of it to either a conventional solar facility or a pollinator-friendly solar facility. The model accounts for spatial, economic and environmental differences across three counties in South-central Minnesota: Fillmore, Hennepin and Rock. The model is designed as a cash-flow project finance model that incorporates monetized environmental and social costs and benefits. As project finance is the predominant method for financing solar projects in the United States, and a large proportion of a project’s financial return is delivered through preferred tax status and tax credits, they modeled both pre- and post-tax cash flows from the solar projects. Their model also includes a cash-flow operating model for a conventional soy or corn farm. For all land uses, the model incorporates the monetized value of environmental externalities, including carbon emissions, soil erosion and groundwater recharge. Not all externalities and ecosystem services were modeled, due to data limitations and difficulties in quantifying benefits such as habitat creation and biodiversity. We created multiple scenarios within the model to analyze differences in private and social value streams across counties, crop type, and a range of upside and downside inputs. The model outputs are a series of cost-benefit analyses comparing the three main land uses — pollinator-friendly solar, conventional solar, and farming. The financial return of each use varies by crop type, location and upside/downside scenarios. Solar development in Minnesota and across the Midwest is poised to continue on land traditionally devoted to conventional agriculture. Growing interest in low-impact solar development and co-location of solar projects with pollinator-friendly plants represents an opportunity to mitigate energy-versus-food tensions and provide additional benefits to agriculture, ecosystems, and private developers alike. The model presented in this paper takes an important step towards quantifying and monetizing the benefits of pollinator-friendly solar development as a land use option in Minnesota. Understanding the full monetary value of pollinator-friendly solar is necessary to design policies that efficiently and effectively support its development in locations that optimize project value. As the practice continues to gain popularity, there is a pressing need for additional research that clarifies the value of ecosystem services created by this innovative land use. Improved understanding of the diverse social and private benefits of pollinator-friendly solar will allow for strategic deployment of these projects — and will maximize returns for all stakeholders.