Introduction

Power Generation, Transmission, and Use

Markets, Regulation, and Oversight

Impacts of Power Generation and Transmission

Looking Ahead

Appendices

CEIR Report Map

PPRP Home

Maryland Power Plants and the Environment (CEIR-18)

4.4.2 Scenic Quality in Electric Generation and Transmission Assessments

Solar Impact to Agricultural Land Use

Utility-scale solar energy facilities exclude, until decommissioned, most other surface uses of the lands they occupy. This is in contrast to other renewables such as wind which typically maintain a small spatial footprint. As a result, siting guidance for PV systems typically emphasize the utilization of previously developed land such as abandoned industrial sites, fallow agricultural fields or former mining sites. However, because slope is an important consideration in PV facility siting and development costs are lower on previously cleared land, productive agricultural lands have been targeted by project developers in Maryland, particularly on the Eastern Shore. Combined with declining interest in family farming from one generation to another, rising costs and smaller profits for farmers, solar developers have found willing participants within the State’s agricultural community in the conversion of farmlands to utility scale solar energy systems. 

Agricultural lands have also been targeted for solar facilities in other states and countries.  Starting in 2015, for example, the United Kingdom’s Common Agricultural Policy eliminated subsidies for solar farms on agricultural lands through its Basic Payments Scheme even if the land between, under and around the panels are being grazed or is accessible for grazing. Closer to home, a farmland preservation clause was part of a 2012 bill signed into law by New Jersey Governor Christie that was primarily designed to address overbuilding of PV facilities in the state, which caused Solar Renewable Energy Credit (SREC) prices to plummet.  Permits for utility-scale projects on farmland must go through additional review to be eligible to be part of the SREC program. In Maryland, on the basis of recommendations from a Renewable Energy Task Force convened in 2010, Kent County updated its zoning regulations to limit the area of use of utility scale solar facilities to 5 acres on property zoned Agricultural or Resource Conservation, essentially precluding grid connected solar farms from these districts.  The Dorchester County Planning Commission recently considered, but subsequently rejected, a recommendation to amend its Zoning Ordinance to restrict utility scale solar energy systems to commercial and industrial properties within the county.

Loss of productive agricultural lands from solar PV development appears to be less of a concern in United States due to its vast land area. Under the DOE’s SunShot scenario, direct utility-scale PV land requirements for the U.S., much of which would be sited on non-agricultural lands in the Southwest, are projected to range from 667 thousand to 2.1 million acres in 2030, and from 1.4 to 4.4 million acres in 2050. As a point of reference, approximately 2.5 million acres are currently dedicated to golf courses nationwide.  Acreage for other land uses associated with development, such as roads and airports consume even more.

Click to OpenAgriculture and Solar FarmsMaryland’s direct land requirements for an estimated 13.3 GW of installed PV capacity by 2050 in the SunShot scenario amount to 106,400 acres, approximately 1.7% of the State’s total land area. PPRP estimates Maryland’s Renewable Portfolio Standard, which requires that 2% of the State’s energy – about 1,200 MW – come from solar, will displace about 9,600 acres of Maryland’s land area (0.15%) from current uses. Compare this to losses in agricultural and forest lands in Maryland, which averaged 27,630 acres annually between 1973 and 2010, primarily to residential development. Furthermore, not all Maryland’s projected solar capacity will necessarily be located on agricultural land.

The U.S. EPA’s RE-Powering America’s Land Program has identified 279 sites in Maryland totaling 103,000 acres comprising contaminated lands, former mines and landfills that could potentially host renewable energy projects. However, EPA’s list ignores development considerations such as slope, and risk associated with constructing and operating facilities on federally regulated (i.e. RCRA and Superfund) sites. Removing sites with these constraints, up to 30,000 acres of Maryland’s brownfields and closed landfills could be developed if other siting criteria are satisfied, particularly since MDE has a Voluntary Compliance Program for brownfields, which could potentially mitigate liability concerns. SmartDG+, an online screening tool sponsored by MEA and PPRP and designed for distributed generation and renewable energy projects between 1 and 10 MW, focuses on infrastructure proximity, land suitability, and other factors that could help developers and officials identify promising areas from this list.

Among recent solar siting projects reviewed by PPRP, the Great Bay Solar Farm, though expansive at 1,000 acres, would preempt normal agricultural activities from no more than about 1.5% of Somerset County’s total 2012 acreage of land in farms, or about 2.75% of cropland acreage. Projected agricultural land losses to solar farms appear to be small relative to losses from other types of development, and may be reversible if facilities are decommissioned at the end of their useful lives. However, the direct loss of acreage is just one aspect of development pressure that is currently playing out in land use decisions across Maryland and the region. With land requirements in the range of 5 to 10 acres per MW, displacement of agriculture from regional economies, loss of prime farmlands and the security of the nation’s food supply are increasingly seen as issues in utility-scale solar PV systems, a development that has begun to affect siting policy.

Solar Farms and Scenic Quality

Related to the conversion of agricultural lands to solar PV facilities is scenic quality. While an important amenity for residents, it is equally so for the tourism industry, particularly for the attraction of recreational and heritage visitors to a region. Research has shown that degradation of views can affect tourist perceptions of scenic vistas and visitation levels. Therefore, scenic quality can indirectly affect the economic well-being of a region. Because of this, PPRP environmental reviews include assessments of impacts of generation and transmission line projects on the landscape.

Scenic quality is recognized in many of Maryland’s programmatic designations. The Maryland Environmental Trust (MET), for example, accepts offers of conservation easement to protect natural, historic and scenic resources in the state. Maryland’s Rural Legacy Program (RLP) provides “the focus and funding necessary to protect large, contiguous tracts of land rich in natural and cultural resources from sprawl development.” Among its goals are “to establish greenbelts of forests and farms around rural communities in order to preserve their cultural heritage and sense of place.” Administered by DNR, protection is enabled through easements and fee estates and through the program’s support of Rural Legacy sponsors and local governments. The geographic framework for the RLP is the Rural Legacy Area (RLA), a “designated region rich in a multiple of agricultural, natural, forestry or cultural resources.” The Maryland Heritage Areas Program preserves the State’s historical, cultural, archeological, and natural resources for sustainable economic development through heritage tourism. This is accomplished through the local designation and state certification of Heritage Areas, defined by a distinct focus or theme that makes a place or region, including its natural landscapes, different from other areas of the state. SHA’s Scenic Byways Program administers federal highway funds for encouraging the responsible management and preservation of the state’s most scenic, cultural and historic roads and surrounding resources.

The degree to which these programmatic designations protect land from activities associated with electric generation and transmission varies. Generally, land placed in easement is protected from direct effects (i.e., pre-emption or conversion) by the terms of the Deed of Conservation Easement or similar document. The aesthetics of an easement property may be less protected from indirect effects, however. Furthermore, although easements, transferable development rights, and fee estates protect specific land parcels within RLAs, RLA designation, in itself, affords no land use protection. When carrying out activities in a Certified Heritage Area (CHA), a State agency must consult, cooperate, and, to the maximum extent feasible, coordinate their activities with the entity responsible for the management of each CHA; ensure that the activities are consistent with the CHA’s management plan; and ensure that activities will not have an adverse effect on the resources of the Heritage Area unless there is no prudent and feasible alternative. While the SHA funds the development of community-based corridor management plans (CMP) to make scenic byways eligible for additional grants as well as a National Scenic Byway designation, and publishes guidelines for maintaining scenic quality along byways, there are no regulatory protections for scenic byways.

At the federal level, scenic quality is also recognized in the management plans for units of the National Park Service located in Maryland, such as the Appalachian Trail and the Chesapeake and Ohio National Historical Park; the National Register of Historic Places through its designation of historic landscapes and national historic landmarks; the National Heritage Area program; and the Federal Highway Administration’s National Scenic Byway Program, among others. Local governments promote scenery through zoning overlays, such as the Antietam Overlay Zone in Washington County, and in various recreational initiatives, such as bicycle, hiking and water trails.

Federal involvement in scenic protection is in part governed by Section 106 of the National Historic Preservation Act, which requires federal agencies to take into account the effects of their undertakings on historic properties which may include historic landscapes. For National Historic Landmarks affected by undertakings, Section 110(f) of the Act goes further requiring agencies to “minimize harm” to the maximum extent possible. Since an undertaking includes not only projects funded by a federal agency, but also those requiring a federal permit, license or approval, power plants or transmission lines that traverse or otherwise occupy land under federal jurisdiction can be subject to Section 106 review.

In addition to oversight of National Register properties and National Historic Landmarks, the National Park Service (NPS) holds lands in both fee simple and easement, including scenic easements. Scenic easements are designed to limit development and provide a natural view shed to afford visual protection for visitors to national parks and to wild and scenic rivers through protective buffers. In Maryland, NPS currently holds 259 scenic easements in the C&O Canal NHP, most of which are in Washington and Montgomery counties. Outside park boundaries, the NPS acts to protect park resources by working cooperatively with federal, state and local agencies, and with adjacent landowners and other interested parties. National Heritage Area (NHA) and National Scenic Byway management plans carry no regulatory protections of scenic resources, but instead rely on leveraging existing land preservation programs to achieve their goals.

While many federal, state and local land preservation and heritage overlays contain scenic elements, landscapes are not uniform within them. Most views have low scenic value or are compromised by contrasting elements. Because of this, land preservation and heritage overlays are poor proxies for conducting scenic quality assessments. While comprehensive scenic resource assessments have been conducted for some regions of the state, Maryland has not conducted a statewide scenic landscape inventory. As a result, general planning decisions for power plant and transmission line siting, in addition to other growth policy decisions, are constrained by the lack of a scenic landscape data layer based on uniform visual resource assessment guidelines. PPRP visual impact assessments are therefore subjective, based on imperfect scenic resource data and multiple standards among scenic preservation interests for classifying visual resources and county land development regulations.

This is particularly true for solar PV facilities. Sitting no more than 10 feet above ground level, the physical structures associated with solar arrays have a low visual profile. For security and public safety, all facilities are surrounded by a 6-8 foot fence. Views of solar farms are therefore limited by their vertical dimensions.  Still, without mitigation solar farms may be visible from surrounding residential properties or nearby public roads, which can detract from the agricultural landscapes that predominate around most of Maryland’s solar facilities. The toolkit for mitigating visual impacts from solar facilities consists of setbacks and buffering. A setback is the distance from a nearest above-ground structure to a property line or public road right-of-way. In general, visual impact is reduced by a greater setback. A buffer is a visual screen between a viewing location and one or more above-ground structures. Usually, buffers are comprised of trees and shrubs, and may also incorporate a berm. 

Setback and buffer requirements are typically codified in county zoning ordinances, and may apply to specific zoning districts or to specific land uses, such as solar facilities. In Maryland, setback and buffer regulations are not uniform across its counties, nor do all county zoning ordinances recognize utility-scale solar facilities as a specific land use. Such was the case in PPRP’s review of the Great Bay Solar project in Somerset County, which would occupy land zoned AR – Agricultural Residential, I-2 – General Industrial, and R-1 – Low Density Residential. The county’s zoning ordinance does not specifically address wind, solar, and other facilities, and therefore does not specify setback requirements specifically for solar energy systems. It does, however, require landscape or screening buffers for new principal commercial or industrial uses that abut a “primarily residential lot” within the AR, R-1, R-2, R-3 or MRC (Maritime-Residential-Commercial) district. Specific landscaping requirements are set out in §6.12 of the Somerset County Zoning Ordinance.

Drawing on its experience from other solar facility siting cases, PPRP concluded that Somerset County’s setback requirements for new industrial uses were both inadequate for screening solar facilities from adjacent residences, and inconsistent with the region’s goals for preserving and highlighting its natural and historic landscapes. PPRP noted, for example, Queen Anne’s County requires a minimum 25-foot landscaped strip to provide screening from adjacent residential uses and public or private roads. Utility-scale solar energy systems in Dorchester County must be screened from the ground floor of any adjacent residential dwelling unit by a vegetated buffer of at least 50 feet wide, with specific requirements determined as part of the site plan review process. Setback and buffer requirements are similar in Charles County.

To mitigate visual impacts from the facility, PPRP recommended a license condition requiring Great Bay Solar to set back its facilities, defined as facilities within the perimeter fencing, at least 50 feet from any adjacent property line or public road. Where the project abuts a primarily residential property, or a public or private road, Great Bay Solar is required to design a landscape buffer within the setback and outside the fence line that will effectively screen, to a minimum 8 feet above ground level, views of the solar facility. Where it could be demonstrated that the landscaped buffer would serve no purpose, PPRP did permit the landscape screening requirements to be waived by Somerset County. PPRP has since recommended similar license conditions to other solar projects going through CPCN review where county setback and buffer requirements are inadequate.

Glare from Solar Farms

Another visual impact issue is glare. Glare is light that reflects off a surface. It is sometimes referred to as glint when a surface reflects a momentary flash of bright light. For the most part, glint is simply a special case of glare, as both have the same impact upon receptors – a brief loss of vision or “flash blindness.”

Glare is associated with solar PV panels through their interaction with sunlight. While a PV panel is designed to maximize absorption and minimize reflection to increase electricity production efficiency, some sunlight is invariably reflected off its surface. With an anti-reflective (A/R) coating, PV panels reflect as little as 2% of incoming sunlight, depending on the angle of the sun. The reflectivity of solar panels is similar to water, but significantly less than bare soil, vegetation, white concrete or snow. However, reflected light from a solar panel is predominantly specular, which is a more concentrated type of light that occurs when a surface is smooth or polished (Figure 4-29). Still water is another example of a surface that reflects specular light. Diffuse reflection occurs from light reflecting off a rough surface and produces less concentrated light. Many surfaces with higher reflectivity than solar panels produce diffuse reflections. This is important because, except under unusual circumstances, flash blindness can only occur from specular reflections.

Figure 4-29 Specular and Diffuse Reflection

image of specular and diffuse reflection

Source: Technical Guidance for Evaluating Selected Solar Technologies on Airports.  Federal Aviation Administration, Office of Airports, Office of Airport Planning and Programming.  Washington, DC.  November 2010.

Comprised of thousands of panels, a solar PV energy facility has the potential for being a significant source of glare.  However, the potential for glare is related to a number of factors:

The position of the sun in the sky relative to a solar PV facility determines the sun’s angle of reflection off the array, sometimes called the angle of incidence. In general, for southward facing arrays, the angle of reflection is lowest when the sun is shining at its highest point and highest just after sunrise and before sunset. The angle of reflection can be quite large (and glare closest to ground level) at sunrise and sunset for fixed arrays because the sun is more to the sides of the panels at these times. At Maryland latitudes, the sun reaches a maximum solar elevation of 75° at noon of the summer solstice and about 28° at noon on December 21. 

Characteristics of the solar array include the facility’s footprint, angle and direction of tilt of the panels, and whether the panels are fixed or tracking. Footprint relates to the facility’s nameplate capacity. With respect to angle and tilt, many commercial solar arrays are positioned at a horizontal angle to the sun of 25° and azimuth of 180° true north (i.e., due south). Tracking allows solar panels to optimize contact with the sun. Single axis systems track the sun either horizontally, following the sun’s lateral path from sunrise to sunset, or vertically, by changing the panel angle relative to the ground. Dual axis systems move both horizontally and vertically. 

Virtually all light that passes through the front surface of a solar panel is trapped in layers below, so the only source of reflectance is the panel’s front surface. While the specular reflectance of solar glass can be as low as one or two percent at near-normal incident angles, reflectance of solar PV glass can be more than 20 percent at large incidence angles (>60 percent), even with A/R coatings or surface texturing. The degree to which reflected light is specular is related to the texture of the reflecting surface. For solar panels, textured glass and anti-reflective coatings produce more diffuse reflections with lower solar intensities but larger glare sources.

The final factor affecting glare is the location of the viewer relative to the source.  Broadly speaking, the impact of glare declines with increased distance from the source, but increases with the size and orientation of the reflective surface. Finally, one’s light sensitivity can affect the perception of glare.

Potential receptors of glare from solar PV facilities include observers in nearby buildings, motor vehicles, scenic overlooks, and aircraft. Similar to glare from the sun, impacts from ocular discomfort can range from operational, particularly within the realm of motor vehicle and aviation safety, to nuisance, which may affect one’s perception of the working or recreational environment. 

Most regulatory activity addressing utility scale solar projects has been in aviation. However, some communities outside Maryland have begun to specifically address glare in their development standards for either rooftop or freestanding panels, although the language is subjective, typically requiring systems to be designed and sited to avoid glare on adjacent properties or roadways. None require a glare study or specify glare mitigation techniques or technologies. In Maryland some county and municipal zoning ordinances address light trespass onto adjoining properties. However, none explicitly addresses reflected glare from solar PV systems, nor is aesthetic guidance backed by regulation.

PPRP has undertaken glare studies in all recent solar PV licensing cases. It uses the Solar Glare Hazard Analysis Tool (SGHAT) to determine whether a proposed solar energy project would result in a potential glare impact. SGHAT is an interactive web-based tool from DOE’s Sandia National Laboratories. It accepts input on the location and configuration of a proposed solar facility and observer locations, including air traffic control tower and aircraft glide paths. If glare is found, it predicts potential ocular hazards ranging from temporary after-image to retinal burn.  SGHAT is not without its shortcomings. It considers terrain in its calculations, but not landscaping or other vegetative screening. As a result, PPRP considers predictions of glare by the model to be conservative, likely overstating the potential impact upon nearby receptors.

Still, the model has provided useful input into PPRP’s environmental reviews. For the OneEnergy Cambridge Solar project, for example, PPRP’s glare modeling predicted glare significant enough to cause a temporary after-image would be experienced on the Runway 34 glide path into the Cambridge-Dorchester Airport (Figure 4-30). This resulted in a license condition requiring OneEnergy, prior to construction, to file a Notice of Proposed Construction or Alteration to the Federal Aviation Administration (FAA) for a formal determination of the Project’s effect on navigable airspace by aircraft. In many other cases, glare upon nearby residences and public roads has been predicted, but after examining proposed landscape plans and current vegetation around the site, PPRP has concluded the likelihood that reflective glare will trespass onto nearby properties is minimal. To be sure glare is not experienced by a project’s neighbors, PPRP includes a license condition requiring the project developer to document and address complaints related to potential solar reflections.

Figure 4-30 SGHAT Stationary Observation Points and Glide Path at Cambridge Maryland Solar Farm

aerial photo of SGJAT Stationary Observation Points

Visual Impact Analysis for Terrestrial Wind Power Projects

Proposals to develop terrestrial wind energy projects in Maryland have raised concern about visual impacts on the landscape. The placement of wind turbines 400 feet high or more would alter existing views from many perspectives. But the magnitude of visual effects is less certain due to uncertainties in the location of receptors, how they perceive a landscape and a number of other factors.

The visual footprint of a wind energy project can be estimated using a digital elevation model (essentially a digitized terrain relief map), turbine locations and heights, and geographic information system (GIS) analytics. The resulting graphic identifies every point on the ground visible by line of sight from the indicated height of one or more turbines (Figure 4-31). Reversing the perspective identifies locations (i.e., a visibility zone) from which one or more towers of an indicated height (or greater) are visible. Most GIS models are capable of estimating visibility zones. PPRP has utilized a wind farm analysis, design and optimization model in past wind energy licensing projects to compute visibility zones, wire-frame turbine views and 3D visualizations for its environmental reviews.

Figure 4-31 Example of Visibility Zones

Image of visibility zones

Visibility zones computed from digital elevation models overstate the visibility of landscape alterations. In general, the theoretical distance from which an object is visible exceeds the actual distance because of atmospheric scattering of light. Furthermore, terrain is the sole determinant of line of sight computations that generate a visibility zone unless a vegetation layer is incorporated into the digital elevation model, not an easy task. Vegetation, particularly trees, fully or partially obscures views from within much of a visibility zone.

Visual impacts and visibility zones are not the same thing.  Although visual impacts occur within a visibility zone, Bishop and Shang and Bishop, among others, have noted that visual impact thresholds are significantly less than distances from which an object in the landscape can be detected or recognized. Photo simulations, wireframe models, and 3D visualizations of wind turbines from selected locations help stakeholders visualize an alteration to the landscape, but they do not quantify visual impacts. Although their limitations are known, visibility models are useful in visual impact assessments because they identify view sheds, cultural resources, properties and other features that could potentially be adversely affected by landscape alterations. 

 

Minutes – March 4, 2015. Dorchester County Planning Commission. Retrieved from http://docogonet.com/index.php?page=planning_commission on June 19, 2015.
SunShot Vision Study. U.S. Department of Energy. DOE/GO-102012-3037. February 2012. http://www1.eere.energy.gov/solar/pdfs/47927.pdf (Download Adobe Acrobat Reader).
Assuming 8 acres per megawatt (NREL 2013b, p. 10). Maryland’s total land area, excluding inland waters and Chesapeake Bay, is 9,843.62 square miles, or 6,299,916.8 acres. Approximately 32% of Maryland’s total land area was used for farming in 2014. Maryland Manual Online. Maryland State Archives. April 13, 2015. Retrieved from http://msa.maryland.gov/msa/mdmanual/01glance/html/agri.html on June 23, 2015.
A Summary of Land Use Trends in Maryland: The Maryland Department of Planning 2010 Land Use/Land Cover product. Maryland Department of Planning. Retrieved from http://www.mdp.state.md.us/PDF/OurWork/LandUse/MDP2010_LU_Summary.pdf (Download Adobe Acrobat Reader) on April 12 2016.
A House Bill (HB 1241) introduced in the Maryland legislature in 2011 that would prohibit construction of an electric power station or substation (among other non-agricultural uses) in an RLA failed in committee.
County Ordinance No. 11-07. Queen Anne’s County, Maryland. December 13, 2011.
Dorchester County Code. Chapter 155. Zoning. §155-50. Supplementary Use Regulations.
Solar Energy and Wind Energy Systems. Bill No. 2014-02. 2014 Legislative Session. Introduced by Charles County Commissioners. April 1, 2014.
Evaluation of Glare Potential for Photovoltaic Installations. Stephen P. Shea, Chief Engineering Officer, Suniva, Inc. Norcross, GA. 2012
“Relieving a Glaring Problem.” Clifford K. Ho. Solar Today. April, 2013.
Bishop 2002. “Determination of Thresholds of Visual Impact: The Case of Wind Turbines.” Environment and Planning B: Planning and Design Vol. 29: pp. 707-718.
Shang and Bishop 2000. “Visual Thresholds for Detection, Recognition and Visual Impact in Landscape Settings.” Journal of Environmental Psychology, 20, 125-140.
The EPA’s Re-Powering America’s Land Program identified 181 brownfield sites in Maryland, which is approximately 24,000 acres, and 25 closed landfill sites in Maryland, equivalent to 6,000 acres.

Agriculture and Solar Farms

In other parts of the world, agriculture and solar farms coexist reasonably well. Throughout Europe and the United Kingdom (UK), small livestock (sheep, chickens) are grazed on utility-scale, ground-mounted solar farms, and other productive options such as beekeeping have been demonstrated, the latter which could complement PPRP’s promotion of pollinator habitats at CPCN-licensed power projects. Through its “10 Commitments,” which encourages continued agricultural activity and agri-environmental measures that support biodiversity on solar farms, the UK Solar Trade Association enjoys the support of Britain’s National Farmers Union and other organizations concerned with agriculture and land management. Within the United States, loss of agricultural lands to solar farms and potential mitigation strategies have yet to gain visibility within domestic solar trade organizations, such as the Solar Energy Industries Association (SEIA), or from State and federal agricultural agencies, suggesting the adoption of similar coexistence practices is not likely to gain acceptance anytime soon.