ANNAPOLIS, Md. – Yesterday, at a meeting of the St. Mary’s County Solar Task Force, Chesapeake Conservancy’s Conservation Innovation Center (CIC) presented a new report: Optimal Solar Siting for St. Mary’s County, Maryland. Using geospatial analysis, the report identifies optimal solar sites and answers the key question: Are enough optimal sites available to meet St. Mary’s County’s renewable energy goals for solar energy while avoiding impacts to agriculture and the environment?
The analysis results showed St. Mary’s County offers significant optimal opportunities for solar placement in the existing built environment that would minimally impact the natural landscape or prime agricultural land; including on rooftops of commercial and residential buildings, above parking lots as solar canopies, on capped landfills, around the Marlay-Taylor Wastewater Reclamation Facility and on county-owned properties. Other additional preferred solar opportunities were also identified.
Maryland is one of 30 states in the United States with a Renewable Portfolio Standard (RPS), a mandate to increase electricity production from renewable energy sources. Maryland’s mandate requires 50% of electricity sold by utilities to come from renewable sources, with 14.5% from solar. While the Southern Maryland Electric Cooperative (SMECO) that serves St. Mary’s County is excluded from the 14.5% carve-out and is instead required to reach a solar carve-out of 2.5% of retail sales, land in St. Mary’s County could still be used for solar energy installations to meet statewide goals outside SMECO’s service area.
Solar installations range from small rooftop photovoltaic systems and medium-sized distributed generation installations that use energy locally and feed excess energy back to the grid, to large ground-mounted installations that sell energy directly to utilities. The Governor’s Task Force on Renewable Energy & Siting estimates that the land needed to meet the state’s RPS goal will require between 7,750 and 33,000 acres of land across the state. The task force report determined that may impact between 0.4 and 1.7% of available farmland, and between 0.7 and 2.9% of available prime farmland, in Maryland, and wrote, “While small in aggregate, the encroachment of utility solar on prime agricultural and farmland remains a serious concern to rural communities, policymakers and stakeholders.”
St. Mary’s County’s community members have raised concerns surrounding recent applications and requests for utility-scale solar in the county. County Commissioner Morgan suggested that the County Commissioners form a Solar Task Force to gather information about the state and local requirements and make recommendations to the Commissioners.
The Solar Task Force met for the first time in June 2020. The task force is charged with seeking community input, investigating community needs, learning about solar regulations, identifying potential site locations, discussing potential strengths and challenges with solar facilities, and making recommendations to the Commissioners. By August, the task force had approved a contract with Chesapeake Conservancy to study optimal solar citing for the county.
“With the existing and ongoing loss of farmland to residential and commercial development and concerns regarding environmental impacts on land developed for solar energy, it is imperative to maximize the use of degraded lands, rooftops and parking lots for future solar arrays,” said Chesapeake Conservancy’s Conservation Innovation Center Vice President of Technology Susan Minnemeyer.
“Our high-resolution land cover data allowed us to do a very detailed analysis, down to individual parcels, to inform how much area is available in optimal and preferred sites for solar energy development. We also calculated the energy generation potential of these locations,” continued Minnemeyer.
“Based on our analysis of solar energy development opportunities, St. Mary’s County demonstrates the potential to create 4,097 GWh/yr of electricity from solar energy from 4,431 acres of optimal sites such as degraded lands and landfills, rooftops, parking lot canopies, and publicly owned lands,” said Chesapeake Conservancy Senior GIS Analyst Emily Wiggans. “There is an additional 4,026 GWh/yr of potential electrical generation available from 2,614 acres of preferred ground-mounted opportunities less than one mile from electrical transmission lines. These numbers well exceed the 331 GWh/yr estimate for St. Mary’s share of solar compared to the rest of the state.”
The methods set out to identify all potential solar sites — those that meet legal (zoning) and technical criteria for allowing solar energy development. First, county parcels were ranked on a range of environmental, equity, and efficiency criteria to determine optimal siting. Optimal sites were either in the built environment – on rooftops, parking lots, and degraded lands.
The CIC also identified a second tier of locations, preferred ground-mounted sites, that would avoid land use tradeoffs with agriculture or environmentally valuable lands. These sites met the following criteria: had less than 50% total tree canopy in the parcel, had more than 5 acres of ‘Solar Opportunity Area’ (defined as a sum of low vegetation, barren, and herbaceous high-resolution land cover classes), had less than 50% prime agricultural soil, had less than 75% soil of statewide importance, and was not in a designated no-go zone (defined as protected, or legally restricted, areas), or was within a designated Intensely Developed Area of the critical area. Sites that were within a mile of an existing transmission line were defined as ‘preferred’ while sites that met the criteria but were further away were designated as ‘other opportunities.’
The results are displayed in a web app that is open to the public at: https://tinyurl.com/CCStMarysSolarStudy.