5. Data Documentation for Mapping and Screening Criteria for Renewable Energy Generation Potential on EPA- And State-Tracked Sites

5.1 Overview

The U.S. Environmental Protection Agency (EPA) Office of Land and Emergency Management (OLEM), Office of Partnerships, Communication and Analysis (OCPA) created the RE-Powering America’s Land Initiative to demonstrate the enormous potential that contaminated lands, landfills and mine sites provide for developing renewable energy in the United States. To that end, the Initiative developed the RE-Powering Mapper tool. The tool is a publicly available spatial database of more than 190,000 sites that have been evaluated for renewable energy potential. This section details the screening process and data underlying the Mapper.

EPA developed national-level site screening criteria in partnership with the U.S. Department of Energy (DOE) National Renewable Energy Laboratory (NREL). The most recent screening occurred in August 2021. Described in this document, the screening criteria demonstrate the potential to reuse contaminated land for solar, wind, biomass and geothermal energy production based on resource availability, acreage and distance to transmission lines and roads. Although these sites have been preliminarily screened for renewable energy potential based on several technical considerations, many other factors should be considered to determine a project’s ultimate feasibility. Renewable energy developers and/or relevant stakeholders usually conduct rigorous site-specific analyses to verify both technical and economic feasibility.

For the purposes of this screening, the Mapper does not consider site status in terms of clean-up or potential contamination status. Sites may or may not have been assessed and/or remediated. The Mapper database includes a link for each site to a source with more information about the site’s environmental conditions.

The federal- and state-tracked sites included in this screening represent a subset of nationwide contaminated lands, landfills and mine sites. The inventory includes sites that are tracked at the national level through EPA remediation and grant programs, as well as datasets provided from 22 state partners. Many additional sites are tracked at the state and local level but EPA did not screen them in the Mapper. Information regarding state brownfields and response programs can be found on the State and Tribal Response Program page.

5.2 Data, Criteria and Methodology

EPA developed an inventory of contaminated lands, landfills and mine sites from various sources, as listed here. Next, EPA screened this subset of EPA- and state-tracked sites for renewable energy resource potential, as described in the Screening Criteria.

5.2.1 Site Information Datasets

While EPA and state databases are refreshed regularly with new sites and updated acreage, the data in the Mapper represent a snapshot in time. The tables in this section provide sources and timing of data extraction and screening. Users should understand that the site-specific information provided herein may change over time.

EPA does not maintain or manage state datasets. Snapshots of the following states’ data are included in this update of the Mapper: California, Colorado, Connecticut, Florida, Hawai’i, Illinois, Iowa, Maine, Maryland, Massachusetts, Minnesota, Missouri, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Texas, Virginia, West Virginia, and Wisconsin.

5.2.2 EPA Datasets

5.2.3 State Agencies

The following table contains contact information for state agencies that provided information and data for the state-tracked sites included in the RE-Powering Mapper.

5.2.4 State-Tracked Abandoned Mine Lands Datasets

EPA included two types of AMLs in this analysis. The first are coal mining sites that were operated prior to August 3, 1977. The federal Surface Mining Control and Reclamation Act (SMCRA) of 1977 created a fund to eliminate (reclaim) health and safety hazards associated with coal mining operations that were abandoned before the statute was enacted. As a result of SMCRA, Pennsylvania, Virginia and West Virginia developed these datasets as inventories of AML sites eligible for reclamation. The second type of AMLs in the Mapper includes hard rock and other mineral mine sites.

5.2.5 State-Tracked Contaminated Site Datasets

Most states track and remediate contaminated sites; the level of detail and types of information tracked and reported varies from state to state. EPA aims to standardize the reported data gathered in this study to capture the most important information consistently across a wide range of states. In addition, EPA eliminated duplicates between state and federal datasets (to the extent possible) and verified locations. These data represent a snapshot in time.

5.3 Screening Criteria

EPA and NREL developed the following screening criteria to evaluate renewable energy potential. Planners should consider other critical factors for siting renewable energy facilities (e.g., slope) on a site-by-site basis.

Solar Photovoltaic (Columns 1 and 2) and Global Horizontal Irradiance in kWh/m2/day)

Renewable Energy Type and Scale	Estimated Renewable Energy Project Capacity Range*	Renewable Energy Resource Availability	Acreage (Acres)	Distance to Transmission** (Miles)	Distance to Graded Roads (Miles)
Utility scale PV	≥ 5 MW	N/A	≥ 35	≤ 10	≤ 10
Distributed scale PV	< 5 MW	N/A	< 35	N/A	N/A
Off-grid PV***	N/A	N/A	N/A	N/A	N/A
Unknown acreage PV****	N/A	N/A	N/A	N/A	N/A

Wind and Wind Speed (m/s)****

Renewable Energy Type and Scale	Estimated Renewable Energy Project Capacity Range	Renewable Energy Resource Availability	Acreage (Acres)	Distance to Transmission** (Miles)	Distance to Graded Roads (Miles)
Utility scale wind	≥ 15 MW	5.5 m/s at 80 m	≥ 1,200	≤ 5	≤ 10
Community scale wind	1.5 MW - 15 MW	5.5 m/s at 80 m	40 - 1,200	N/A	≤ 1
Facility scale wind	<1.5 MW	5.0 m/s at 40 m	0.5 - 40	N/A	N/A
Unknown acreage wind****	N/A	5.5 m/s at 80 m	N/A	N/A	N/A

Biomass and Biomass potential within 50 miles (metric tons/year)

Renewable Energy Type and Scale	Estimated Renewable Energy Project Capacity Range	Renewable Energy Resource Availability	Acreage (Acres)	Distance to Transmission** (Miles)	Distance to Graded Roads (Miles)
Biopower	> 10 MW	≥ 150,000 (woody)	≥ 6	≤ 10	≤ 3 road; ≤ 8 rail
Biorefinery	> 20 MMgal/year*	≥ 286,000 (herbaceous)	≥ 132	N/A	≤ 3 road; ≤ 8 rail

Geothermal and Permafrost Presence

Renewable Energy Type and Scale	Estimated Renewable Energy Project Capacity Range	Renewable Energy Resource Availability	Acreage (Acres)	Distance to Transmission** (Miles)	Distance to Graded Roads (Miles)
Heat pump	Not Applicable	Absence of glacier or continuous permafrost	Acreage and distance variables are not included in the prescreening.

The screening categories for wind and solar (other than off-grid) are based on a review of past and current projects. These guidelines can be used generally to screen sites, but more in-depth analysis should be used prior to making investment decisions. The main consideration for distinguishing between project potential is the relationship between size (based on acreage value) and relative distance to transmission lines. Transmission lines are typically defined as power lines with voltages greater than or equal to 69kV. Large capacity (>15 MW) projects require these high-voltage transmission lines to move large amounts of power. The larger a project, the greater the ability to absorb the cost of a long- distance connection to existing transmission and higher cost substations. Distributed generation projects (0–15 MW for wind and 0–2 MW for solar) are typically connected to power lines with distribution voltages less than 69 kilovolts (kV ); as such, for the purposes of this screening the criteria do not fac tor a distance to transmission for these projects. For example, smaller projects may be quite far from transmission lines, assuming there is distribution voltage infrastructure available. However, the distance to the nearest substation can be critical depending on project size. Existing generation on the feeder, which connects the consumer/load end with the substation, is also an important consideration. Coordination with the local utility is highly recommended when assessing the potential of a distributed generation project. ^{[2], [3], [4]}

Acreage is not a screening criterion for off-grid solar because such systems are typically used to power a single property or local area and are typically small enough that limited acreage is not a constraint. For example, a property owner could install PV panels to supplement the electricity provided to the site from traditional sources. In some cases, an off-grid system may power a given load (e.g., a small-scale pump and treat system).

Approximately 108,000 sites in EPA’s inventory do not include acreage values. These Acreage Unknown sites cannot be screened, but EPA does include sites that may potentially meet the resource criteria for wind and solar. Further investigation of these sites is required.

The total acreage required for a given wind project varies widely depending on total project capacity (MW), turbine type, resource strength, geographic region, power market and the cost of leasing land. Land requirements for single turbine projects are frequently driven by the requirement that the distance from the turbine to the property boundary be greater than the turbine tip height, which can go up to 500 feet for a utility scale turbine. Based on this criterion, minimum parcel sizes range from roughly an acre for a 100-kilowatt (kW) turbine (tip height 52 m) to roughly 7-8 acres for a utility scale turbine (tip height 150 m). These data illustrate the wide range of capacity densities that are found among wind installations in the United States. ^[5]

The main biomass feedstocks for power are paper mill residue, lumber mill scrap and municipal waste. For biomass fuels, the most common feedstocks are corn grain (for ethanol) and soybeans (for biodiesel).^[6] See additional sources on biopower screening criteria. ^{[7], [8]}

Acreage is not a screening criterion for geothermal heat pumps because they have a small, primarily subterranean footprint. Typically, any site with existing or planned buildings or that has other heating or cooling needs (e.g., office buildings, warehouses or greenhouses) could be considered for geothermal heat pumps. Near surface temperatures of 10° C (50° F) to 24° C (75° F) are most suitable for geothermal heat pumps but were not considered for prescreening criteria. Additionally, geothermal heat pumps should not be cited on permafrost locations, which only impacts sites in Alaska. For general information about geothermal heat pumps see additional sources. ^{[9], [10]}

5.4 State Policies

The economic viability of renewable energy projects is closely tied to the policy context of the jurisdiction in which the projects are sited. States have adopted numerous policies to support greater investment in renewable technologies. The RE-Powering Mapper includes a layer with common types of policies that support or can be conducive to renewable energy at the state level. These policies are described in more detail below, and the Mapper values for each policy are listed in the table at the end of this section. ^[11]

Renewable Portfolio Standard (RPS): An RPS establishes the minimum percentage of electricity supplied within the state each year that comes from eligible renewable sources, such as wind, solar, geothermal and certain types of biomass, biogas and hydropower. The list of eligible resources varies from state to state. An RPS can be mandatory or voluntary. Voluntary RPS are also called RPS goals, as opposed to requirements. In states with mandatory RPS, electricity suppliers must include at least the required level of renewable sources in their supply mix each year or be faced with making alternative compliance payments for their shortfalls.

Thirty states, the District of Columbia, Puerto Rico and the U.S. Virgin Islands have adopted a mandatory RPS, and additional states have voluntary RPS policies ^[12].Several states have also included sub-requirements (or “carve-outs”) within their RPS for specific technologies such as solar PV. According to NREL, RPS policies have been one of the primary policy drivers for the growth of renewable energy over the last two decades in the United States, alongside federal tax credits like the investment tax credit and production tax credit. ^[13]

Clean Energy Standard (CES): A CES is like an RPS but “may include low-carbon or otherwise low-polluting, non-renewable electricity sources.”^[14] Five states have a mandatory CES, while additional states have CES goals.^[15]

Deregulated Retail Electricity Market: A deregulated retail electricity market, also called a competitive generation and transmission (G&T) market, is one in which electricity end-users can choose a supplier of G&T for their home, business or government agency. End-users will still have the delivery or distribution part of their electricity service provided by the local electric utility. A total of 17 states and the District of Columbia offer at least some degree of a deregulated retail electricity market.^[16] Deregulated markets can be beneficial to renewable energy development because they may offer additional options for including renewable electricity in customers’ supply.

Markets that are not deregulated generally follow the traditional “vertically-integrated utility” structure, with the local utility providing bundled electricity service including generation, transmission and distribution. However, vertically integrated utilities increasingly offer more renewable options, through “green tariffs” or other mechanisms.^[17]

Community Choice Aggregation (CCA) Market: CCA allows local governments to procure electricity on behalf of residents, businesses and governmental end-users, which still receive power delivery from the local electric utility. A CCA market is similar to a deregulated retail electricity market in some ways, but with a local government-established entity serving as the supplier in place of a competitive supplier. Ten states have CCA legislation.^[18] Depending on local government priorities, a CCA market may emphasize renewable energy procurement to a greater degree than the prior market structure or the state RPS or CES.

Traditional Net Metering: Net metering, or net energy metering, policies “are established at the state or local utility level and define both (1) what size and other characteristics of generation projects interconnected with household or business customer meters are eligible for compensation from the utility for excess production (above what is consumed on-site), and (2) what compensation they receive for such excess production.”^[19] To the extent that net metering policies provide ready means and/or high levels of compensation for excess production, they can be supportive of renewable energy development.^[20] Thirty-nine states, the District of Columbia, Puerto Rico and the U.S. Virgin Islands presently have some form of mandatory net metering rules. Eight states have or are in transition to compensation rules other than traditional net metering.^[21]

Distributed Generation (DG) Compensation Rules other than Net Metering: Increasingly, states are starting to phase out traditional net metering programs and are adopting a range of successor policy designs. These changes are driven by concerns about the overall cost of traditional net metering to utility ratepayers, cost allocation between net metering participants (e.g., with on-site solar projects) and non-participants, a desire to better tailor compensation based on project location, and other factors.^[22] Five states have DG compensation rules other than traditional net metering, and another five states are transitioning to such policies.^[23]

Community Solar: “Community solar, also known as shared solar or solar gardens, allows customers to buy or lease part of a larger, off-site shared solar PV system and receive benefits of their participation.”^[24] By doing so, community solar policies can greatly increase customer access to solar for electricity users beyond those that are candidates for on-site projects. Community solar projects tend to be 5 MW or less in capacity and, therefore, are similar to the typical scale of RE-Powering projects.^[25] “Twenty states (and the District of Columbia) have passed some form of legislation enabling community solar, either through statewide programs or the authorization of a limited number of pilot projects.”^[26]

RE-Powering State Policy: Certain states have adopted policies or regulations specifically targeted at reuse of contaminated lands, landfills and/or mine sites for renewable energy. These are labeled as “RE-Powering State Policies” and cover the following types of policies: financial incentives, procurement preferences or requirements and streamlined permitting or environmental reviews. States with such policies tend to have the highest levels of deployment of RE-Powering projects. The annual tracking matrix published by the RE-Powering Office contains additional information on these policies.^[27]

Completed Renewable Energy Projects on RE-Powering Sites: The RE-Powering Office publishes an annual tracking matrix of known projects that have been completed on contaminated lands, landfills and mine sites. The number of renewable energy projects completed in each state reflects, in part, the state policies in effect to encourage development on these types of sites. There are currently over 600 and counting installations in multiple states and territories, and over 4 gigawatts (GW) of capacity.^[28]

The following information is included in the Mapper as a state policies layer:

State Policy Name	Policy Short Definition	Mapper Values	Source	Date Accessed
Renewable Portfolio Standard (RPS)	States with a mandatory or voluntary RPS indicating the percentage of electricity supply from renewable sources	“Yes” if mandatory RPS is in state, “Goal” for voluntary RPS, and “No” for no RPS	NCCETC, DSIRE®, Renewable & Clean Energy Standards	6/2021
Clean Energy Standard (CES)	States with a mandatory or voluntary CES indicating the percentage of electricity supply from clean sources	“Yes” if mandatory CES is in state, “Goal” for voluntary CES, and “No” for no CES	NCCETC, DSIRE®, Renewable & Clean Energy Standards	6/2021
Deregulated Retail Electricity Market	State electricity markets that are deregulated (i.e., competitive markets for generation and transmission for retail customers)	Yes/No – “Yes” if state has a deregulated retail electricity market	EPA, Understanding Electricity Market Frameworks & Policies	6/2021
Community Choice Aggregation (CCA) Market	States with legislation that specifically allows CCA statewide or in specific markets	Yes/No – “Yes” if state allows CCA	LEAN, CCA by State	6/2021
Traditional Net Metering	States have traditional net metering compensation mechanisms, in at least some utilities, for renewable electricity projects at retail customer sites	Yes/No – “Yes” if state has traditional net metering rules	NCCETC, DSIRE®, Renewable & Clean Energy Standards	9/2021
Distributed Generation (DG) Compensation Rules other than Net Metering	States with DG compensation rules other than traditional net metering in place or that are in the process of transitioning to such rules	Yes/No – “Yes” if state has DG compensation rules other than traditional net metering in place or is transitioning to them	NCCETC, DSIRE®, Renewable & Clean Energy Standards	9/2021
Community Solar	State has legislation enabling statewide community solar programs or pilot projects	Yes/No – “Yes” if state has community solar legislation	NREL, Community Solar 101, p. 28 (pdf)	6/2021
State RE-Powering Policy	States that encourage, through specific policies or regulations, renewable energy on contaminated lands, landfills and/or mine sites	Yes/No – “Yes” if state has RE-Powering policy	EPA, RE-Powering Tracking Matrix	6/2021
Completed Renewable Energy Projects on RE-Powering Sites	The total number of completed renewable energy projects on contaminated lands, landfills and mine sites (collectively “RE-Powering sites”) in the state known to and recorded by the RE-Powering Office as of its most recent Tracking Matrix	Number of known renewable energy projects on REPowering sites in the state	EPA, RE-Powering Tracking Matrix	10/2021

5.5 Screening Methodology and Constraints

EPA screened all sites by comparing the site location with renewable energy resources. Specific renewable energy technology type, site size and proximity to infrastructure criteria are applied to give the Mapper user a high-level indication of sites with likely renewable energy potential. These criteria are described in the Screening Criteria section of this document.

As noted in the Overview section of this site, this analysis represents an initial screening, and planners should investigate sites further for both technical and economic feasibility. For example, although slope is a critical factor for siting some types of renewable energy, it was not considered in the analysis due to limitations in the availability of high-resolution slope data for sites dispersed across the United States. Site-specific slope analysis should be performed for any site being considered for renewable energy development.

EPA validated sites by identifying and eliminating those with potentially incorrect spatial reference data. If mapped locations did not match state data as recorded, they were excluded from the analysis.

EPA removed sites that appeared to be residential sites from consideration in the dataset.

EPA also considered duplication in developing the full dataset. In instances where a state-tracked site was also in an EPA database, that site was removed from the state dataset. Additionally, if a property was listed in a state-tracked database multiple times (e.g., multiple responses at a single property), it was revised to only be included once per property. One exception is EPA Superfund and RCRA sites; if a site is designated as both, it is included twice in the data. It is likely that some unidentified duplicates still exist in the dataset.

For the LUST program, 50 sites are being piloted in the RE-Powering Mapper and are a very small subset of the entire LUST universe. These 50 LUST sites are considered active releases located at inactive facilities The national universe of UST and LUST sites can be found in EPA’s UST Finder.

EPA performed all screening on site polygons, i.e., sites with area over which a renewable resource can be assessed. Polygon site boundary files are not consistently available, so EPA collected data in both point and polygon ESRI shapefile format. Some site boundary polygons for Superfund (National Priorities List) sites were available and used for screening. State-tracked sites were provided as polygons in these state programs: Colorado Institutional Control, Colorado Uranium Mill Tailings Radiation Control Act, Florida Brownfield, Florida Institutional Control Registry, Missouri Abandoned Mine Land, Missouri Industrial Minerals Unit, Missouri Metallic Minerals Unit, New Jersey Solid & Hazardous Waste, New York Environmental Site Remediation Program, North Carolina Brownfield Projects, Oregon DEQ Environmental Cleanup Program, Pennsylvania Abandoned Coal Mine Lands, Virginia Abandoned Coal Mine Areas, Virginia Orphan Land Program and West Virginia Abandoned Coal Mine Areas.

Those polygons were used as is, and the remaining site boundaries were estimated. To approximate the site size/boundary and estimate the potential for renewable energy generation across an entire site, EPA mapped the site latitude and longitude point and drew a circular buffer corresponding to the area reported around that latitude/longitude point. The maximum renewable energy resource values were recorded for these areas. Sites are typically not circular, and latitude and longitude are not always recorded at the geographic center of the site. Despite these limitations, the method employed allows for a more accurate snapshot of the energy potential available at the site versus a single data point.

For sites that did not have acreage size reported, a minimal acreage buffer was generated using a radius of 0.01 meters (approximately 0.03 feet); the buffer was approximately 0.00000007 acres. This allowed for consistent geoprocessing across the datasets and gave each property a small footprint.

Except for Puerto Rico and the Virgin Islands, U.S. territories were not evaluated or included in this analysis because renewable energy resource and transmission data were not readily available for these territories. Other limitations to the datasets are as follows. Biomass, geothermal near surface temperature and rail data were not readily available for Puerto Rico and the Virgin Islands. Geothermal near surface temperature data are limited for Alaska and Hawai’i. A similar wind dataset was not readily available for Alaska, Puerto Rico or the Virgin Islands. Transmission line and substation data was not readily available for the Virgin Islands.

Acreage values for each site might not represent available land or the total contaminated area. For example, some sites are listed “fence to fence,” which encompasses the entire facility, rather than only the contaminated portions of the facility. As such, the potentially or formerly contaminated areas may represent only a portion of the total acreage of these sites. In addition, acreage values do not consider the physical characteristics at the site (e.g., buildings, topography, tree cover) and, thus, may not represent the true usable acreage of the site.

For the biomass analysis, note that the resources are evaluated within a 50- mile radius of the site. Therefore, EPA drew a 50-mile buffer around the actual or modeled site boundary and recorded the sum of the biomass resource within 50 miles of the site.

Distances were calculated using GIS software to determine the proximity of the site boundary to specific infrastructure. In instances where distances to transmission lines, highways or rails are zero, the transmission line, highway or rail intersects the site buffer, meaning that the infrastructure is present within the site boundary. Because these distances were calculated using GIS software, they may not reflect real-world conditions or distances due to inaccurate or incomplete geospatial datasets and topography.

5.6 Screening Datasets

EPA compiled and used the following geospatial data to perform the screening.

5.6.1 National Renewable Energy Laboratory (NREL) Data

Solar, wind and biomass resource data was obtained from NREL.

Resource Name	Description of Dataset Used in Analysis	Date of Access
Global Horizontal Irradiance Re-source 1998 to 2019	Provides annual average of the daily total solar resource using 1998-2019 data covering 0.038-degree latitude by 0.038-degree longitude. Source: Sengupta, Manajit, Yu Xie, Anthony Lopez, Aron Habte, Galen Maclaurin, and James Shelby. “The National Solar Radiation Data Base (NSRDB).” Renewable and Sustainable Energy Reviews 89 (2018): 51–60. For more information visit: The National Solar Radiation Data Base (NSRDB).	7/2021
Solid Biomass	Contains information about the biomass resources generated by county in the United States. Includes the following feedstock categories: crop residues, forest residues, primary mill residues, secondary mill residues and urban wood waste. Used to determine potential for biorefinery and biopower facility siting. Data available for all jurisdictions except for Puerto Rico and Virgin Islands. Source: NREL Biomass Data.	7/2021
NREL WIND Toolkit	The WIND Toolkit includes meteorological conditions and turbine power for sites in the continental United States for the years 2007–2013. Source: Draxl, Caroline, Andrew Clifton, Bri-Mathias Hodge, and Jim McCaa. “The Wind Integration National Dataset (WIND) Toolkit.” Applied Energy 151 (2015): 355–66.	7/2021
Hawai’i Wind	Wind speed resource data at heights of 40 and 80 meters, the data encompasses annual average wind speeds for 2000-2019 inclusive. Source: Optis, Michael, Rybchuk, Oleksa, Bodini, Nicola, Ros-sol, Michael, and Musial, Walter. “2020 Offshore Wind Resource Assessment for the California Pacific Outer Continental Shelf (pdf)”. United States.	7/2021

5.6.2 Census Data

Distances to rails and roads were obtained from U.S. Census Bureau.

Resource Name	Description of Dataset Used in Analysis	Date of Access
Rails	Includes main lines such as spur lines, rail yards, mass transit rail lines (such as carlines), streetcar track, monorail or other mass transit rail and special purpose rail lines such as cog rail lines, incline rail lines and trams. Extracted from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). Source: Census TIGER Files.	7/2021
Primary and Secondary Roads - Puerto Rico	Includes primary and secondary roads extracted from the U.S. Census Bureau's MAF/TIGER MTDB. Primary roads are generally divided, limited-access highways within the Interstate Highway System or under state management, and are distinguished by the presence of interchanges. Secondary roads are main arteries, usually in the U.S. Highway, State Highway and/or County Highway system. These roads have one or more lanes of traffic in each direction, may or may not be divided, and usually have at-grade intersections with many other roads and driveways. Source: Census TIGER Files.	7/2021
Primary and Secondary Roads - Virgin Islands	Includes primary and secondary roads extracted from the U.S. Census Bureau's MAF/TIGER MTDB. Primary roads are generally divided, limited-access highways within the Interstate Highway System or under state management, and are distinguished by the presence of interchanges. Secondary roads are main arteries, usually in the U.S. Highway, State Highway, and/or County Highway system. These roads have one or more lanes of traffic in each direction, may or may not be divided, and usually have at-grade intersections with many other roads and driveways. Source: Census TIGER Files.	7/2021

5.6.3 Homeland Infrastructure Foundation Level Data (HIFLD) Open Data

Distances to transmission lines and substations were obtained from HIFLD Open Data. HIFLD Open Data provides national foundation-level geospatial data within the open public domain.

Resource Name	Description of Dataset Used in Analysis	Date of Access
Electric Power Transmission Lines	This feature class/shapefile represents electric power transmission lines. Transmission lines are the system of structures, wires, insulators and associated hardware that carry electric energy from one point to another in an electric power system. Lines are operated at relatively high volt-ages varying from 69 kV up to 765 kV and are capable of transmitting large quantities of electricity over long distances. Underground transmission lines are included where sources were available. The following updates have been made since the previous release: 6,457 features added. Source: HILFD Open Data.	7/2021
Electric Substations	This feature class/shapefile is for HIFLD as well as the Energy modelling and simulation community. This feature class/shapefile represents electric power substations primarily associated with electric power transmission. In this layer, substations are considered facilities and equipment that switch, transform or regulate electric power at voltages equal to, or greater than, 69 kilovolts. Substations with a maximum operating voltage less than 69 kilovolts may be included, depending on the availability of authoritative sources, but coverage of these features should not be considered complete. Source: HILFD Open Data.	7/2021

5.6.4 Southern Methodist University (SMU) Data

Surface temperature data for geothermal heat pumps were obtained from SMU.

Resource Name	Description of Dataset Used in Analysis	Date of Access
Surface Temperature	Grid depth information was obtained from SMU on June 27, 2009. Source: Dr. David Black-well, Maria Richards and Petru Negraru, 2006, SMU Geothermal Laboratory Temperature Maps.	7/2021

5.6.5 ESRI Data

Distances to roads were obtained from Esri Data and Maps 2021.

Resource Name	Description of Dataset Used in Analysis	Date of Access
U.S. Highways	U.S. Highways represents the major and minor highways of the United States. These include interstates, U.S. highways, state highways, major roads and minor roads. This dataset is from the Census 2000 TIGER/Line files. Source: Esri.	7/2021

5.6.6 University of Alaska

EPA obtained permafrost data from the University of Alaska.

Resource Name	Description of Dataset Used in Analysis	Date of Access
Permafrost Characteristics of Alaska	Identifies glacier and permafrost locations across Alaska. Source: Torre Jorgenson et al.2008. “Permafrost Characteristics of Alaska” Institute of Northern Engineering, University of Alaska Fairbanks. 2008.	7/2021

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Footnotes

² Source: Bank, J. et al. High Penetration Photovoltaic Case Study Report. No. NREL/TP-5500-54742. NREL, Golden, CO (United States), 2013 (pdf).

³ Source for PV Cost: 2017 Cost Benchmark (pdf).

⁴ Source: Interconnection Plugging RE-Powering Sites Into the Electric Grid, EPA, 2019.

⁵ Source: Denholm, Paul, et al. Land use requirements of modern wind power plants in the United States. No. NREL/TP-6A2-45834. National Renewable Energy Lab.(NREL), Golden, CO (United States), 2009 (pdf).

⁶ Source: NREL Biomass Energy Basics.

⁷ Source: Humbird, D.; Davis, R.; Tao, L.; Kinchin, C.; Hsu, D.; Aden, A.; Schoen, P.; Lukas, J.; Olthof, B.; Worley, M.; Sexton, D.; Dudgeon, D. (2011). Process Design and Economics for Biochemical Conversion of Lignocellulosic Biomass to Ethanol: Dilute-Acid Pretreatment and Enzymatic Hydrolysis of Corn Stover. 147 pp.; NREL Report No. TP-5100-47764 (pdf)..

⁸ Biofuels criteria furnished by Gregg Tomberlin, Senior Engineer, NREL.

⁹ Source: DOE Geothermal Heat Pumps.

¹⁰ Source: DOE (2009). Ground‐Source Heat Pumps: Overview of Market Status, Barriers to Adoption, and Options for Overcoming Barriers. Navigant Consulting, Inc (pdf).

¹¹ For information on a broader range of state policies for renewable energy, the NC Clean Energy Technology Center (NCCETC) maintains the Database of State Incentives for Renewables & Efficiency® (DSIRE®). Readers interested in learning about state policies specific to contaminated lands, landfills and mine sites can contact EPA’s RE-Powering office.

¹² Lawrence Berkeley National Laboratory (LBNL), U.S. Renewables Portfolio Standards 2021 Status Update: Early Release, p. 9 (pdf); and NCCETC, DSIRE®, Renewable & Clean Energy Standards (pdf).

¹³ LBNL, U.S. Renewables Portfolio Standards 2021 Status Update: Early Release, p. 16 (pdf).

¹⁴ U.S. Department of Agriculture (USDA), Renewable Energy Trends, Options, and Potentials for Agriculture, Forestry, and Rural America, p. 28 (pdf).

¹⁵ NCCETC, DSIRE®, Renewable & Clean Energy Standards (pdf).

¹⁶ U.S. Environmental Protection Agency (EPA), Understanding Electricity Market Frameworks & Policies.

¹⁷ See, for example, EPA, Green Power Partnership: Utility Green Tariffs.

¹⁸ Local Energy Aggregation Network (LEAN), CCA by State.

¹⁹ USDA, Renewable Energy Trends, Options, and Potentials for Agriculture, Forestry, and Rural America, p. 58 (pdf).

²⁰ “There also are ‘virtual net metering’ (or ‘meter aggregation’) arrangements in some cases that allow customers with multiple electricity meters with a utility to transfer excess solar production between the meters for billing purposes.” USDA, Renewable Energy Trends, Options, and Potentials for Agriculture, Forestry, and Rural America, p. 90 (pdf). Virtual net metering policies also vary by state and utility and can be conducive to renewable energy development by separating the site of electricity production from the site of electricity consumption.

²¹ NCCETC, DSIRE®, Net Metering (pdf).

²² For more information on this topic, see National Regulatory Research Institute, Review of State Net Energy Metering and Successor Rate Designs (pdf).

²³ NCCETC, DSIRE®, Net Metering (pdf).

²⁴ NREL, Community Solar 101, p. 3 (pdf).

²⁵ For more information on community solar policies as they relate to RE-Powering sites, see EPA, Community Solar: An Opportunity to Enhance Sustainable Development on Landfills and Other Contaminated Sites.

²⁶ NREL, Community Solar 101, p. 28 (pdf).

²⁷ EPA, RE-Powering Tracking Matrix.

²⁸ EPA, RE-Powering Tracking Matrix.