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forms of renewable energy, including solar energy, and are discussed in detail in Chapter 1, Section 5 of this report.
5. L
ANDFILL
S
OLAR
R
ESOURCE
A
SSESSMENT AND
S
CREENING
A
NALYSIS
The RESP landfill solar screening analysis synthesizes the siting considerations above and presents them in a Rhode Island-specific context. Like the literature review imparted above,
the purpose of the screening analysis was to help quantify opportunities and constraints relevant to deployment of solar energy on closed landfills in Rhode Island. The first objective of the
RESP analysis was to develop simple and easy-to-use solar energy site screening tools. A secondary objective was to estimate the total amount of photovoltaic power that could be
generated on suitable land at these sites. Lastly, the RESP analysis sought to identify landfills likely suitable for generating at least 1 MW of solar power generally considered to be utility-
scale. The RESP analysis may be used to inform landfill solar decision making processes at
three levels. First, site screening tools can be used to identify which landfills are good candidates for solar development and what are the barriers and opportunities related to deploying solar
energy at various landfill locations. Second, order-of-magnitude solar energy estimates for landfills can help alert municipal officials to solar development opportunities on sites in their
respective towns. Lastly, higher-resolution data characterizing available landfill solar resources and site suitability can help support decision-making at the statewide level for resource
management agencies and policy makers. The following section summarizes the RESP landfill solar screening analysis; the complete study is contained in RESP Volume 2.
To estimate total and site-specific landfill solar resources in Rhode Island, RESP researchers worked with the Rhode Island Department of Environmental Management RIDEM
Landfill Closure Program LCP to identify a complete list of 87 existing landfill sites in the state. All of these sites are closed and no longer accept waste, with the exception of the Central
Landfill and the Tiverton Landfill. Because many of these sites particularly smaller municipal dump and landfill sites have not operated for years, the exact delineation of the waste disposal
area is often unknown, unavailable, or not easily accessible. Because quantification of solar resource and site suitability requires study sites to have defined boundaries, RESP researchers
decided to rely on GIS parcel data to perform the screening analysis. Thus, the study targeted a total of 58 sites comprising 2,787.6 acres for which parcel data was available.
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Ch. 2 Figure 11. Rhode Island Landfill Sites and Solar Measurement Stations.
Landfill Locations
_
National Solar Radiation Points
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Once parcel data was obtained for all 56 landfill sites, RESP researchers used a two- pronged approach to quantify the total area at each site that may be appropriate for solar
development. First, they developed GIS- based “first-cut” site screening criteria to help
characterize the areas in each landfill parcel that appear most compatible with solar development. The main criteria informing this step were slope and land use class. The slope screening criterion
was used to eliminate land areas with steep gradients that likely would pose structural and design challenges for a landfill ground-mounted PV array. RESP researchers used two slope
scenarios —the first, more conservative excluding all areas with a slope greater than 3; the
second, less conservative excluding all areas with a slope greater than 6. The land use class criterion was used to describe the on-the-ground land use at each landfill parcel. For the purposes
of the RESP screening analysis, land use classes considered appropriate for solar PV development included waste disposal, vacantbarren, brushland, and agricultural use.
Having isolated areas in each landfill parcel exhibiting appropriate slopes and land use characteristics, RESP researchers calculated the amount of PV capacity in megawatts that
could be produced on these areas. Because the capacity of a PV array is directly related to the number and design features of panels in that array, researchers made a series of assumptions
regarding panel type, tilt, and packing factor a parameter describing the space requirements around PV panels to account for maintenance, accommodate equipment, and mitigate shading
effects. Under the set of relatively conservative assumptions used in the RESP screening analysis, Rhode Island landfills need approximately 6.6 acres of area to generate 1 MW of
photovoltaic power. Using this figure as an indicator of the relationship between acreage and solar energy production potential, RESP researchers were able to generate estimates for site-
specific and total landfill solar resources on flat areas with appropriate land uses for solar development.
The results of the RESP screening analysis demonstrated that a potentially significant amount of solar power could be generated on Rhode Island landfills. Gently-sloped areas on all
landfill parcels could support a grand total of 391 MW of estimated potential power. Restricting this area to only “appropriate” land use classes reduces the total amount of estimated potential
power to 110 MW. The RESP analysis, however, found that solar resources are distributed
unevenly across the different land use classes: for example, forested areas account over half of the area in landfill parcels; such areas could support PV arrays only if this growth was cut down.
In total, 37 sites were found to have the potential for at least 1 MW of photovoltaic solar generating capacity.
The first-cut screening analysis performed by the RESP helped establish a first-order estimate of acreage on Rhode Island lands that could support solar. Despite high solar potential,
however, a landfill may not be immediately suitable for solar development. For example, even if a landfill parcel contains a large amount of vacant area on a gently sloping southern exposure,
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this area, may have been developed into athletic fields, or the landfill may be unreasonably far from a connection point to the electrical distribution grid. Another situation to consider is that a
waste disposal site may not be currently capped according to RIDEM standards, and could possibly require some form of remediation before development.
Therefore, study sites were further classified by several additional site suitability characteristics identified in partnership with RIDEM. These measures of site suitability help
gauge the ease of bringing high- potential sites to “shovel-ready” status for solar development.
The RESP research team compiled a comprehensive spreadsheet detailing the status of each site in terms of: presencetype of landfill cap, current use, interconnection feasibility, and site
control. The results can be found in the appendices in the Volume 2 Technical Report.
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