REMPD Overview

REMPD Background

Renewable energy is providing a growing share of electricity generation in the United States, with utility-scale wind and solar increasing by 12% and 29%, respectively, in 2021. Approximately 9% of U.S. electricity generation in 2021 was from wind and 4% from solar (Energy Information Administration 2021). Installing new renewable energy facilities requires material inputs that range from common construction materials to specialized, high-performance materials that may have limited availability.

The Energy Act of 2020 directs the DOE's Office of Energy Efficiency and Renewable Energy (EERE's) Wind Energy Technologies Office (WETO) and Solar Energy Technologies Office (SETO) to deliver a “comprehensive physical property database of materials for use in [wind and solar] energy technologies, which shall identify the type, quantity, country of origin, source, significant uses, projected availability, and physical properties of materials used in [wind and solar] energy technologies” by no later than September 1, 2022. Here we summarize the capabilities and open-source outputs from a new database, the Renewable Energy Materials Properties Database (REMPD), which documents materials used in domestic wind and solar installations.

In August 2022, Congress passed the Inflation Reduction Act (IRA), which has several provisions that incentivize wind and solar energy deployment. Estimates of future material quantities for wind energy (available in the Wind Quantity section), are based on annual capacity additions that incorporate anticipated effects of IRA incentives; however, full details on how the IRA will be implemented were not available when this analysis was completed and, thus, the wind-related material quantity projections that are presented here cannot fully anticipate all of the market reactions to the IRA.

The focus of the REMPD is on quantifying the raw and processed materials used in renewable energy technologies. The database contains information on the amount of each material that goes into wind and solar power plants, descriptions of the relevant material properties, and the primary countries of origin for each material. Some materials go through several stages of processing and/or are incorporated into subcomponents that make up the completed electricity-generation facilities. This project does not analyze supply chains for producing renewable energy plant components. However, the DOE conducted related analysis in response to Executive Order 14017, which directed production of “America's Supply Chains” reports for wind and solar. The supply chain reports can be found at https://www.energy.gov/policy/securing-americas-clean-energy-supply-chain; links to individual reports are provided below:

• Wind
• Solar

Additional reports in this series that are relevant to wind, solar, and hybrid plants include:

• Grid energy storage
• Rare earth permanent magnets.

Coordination and Collaboration

The REMPD was developed by the Department of Energy's (DOE's) Office of Energy Efficiency and Renewable Energy (ERRE) Wind Energy Technologies Office (WETO) and DOE's EERE Solar Energy Technologies Office (SETO) to comply with Congressional guidance outlined under sections 3003(b)(5) and 3004(b)(5) of the Energy Act of 2020 (42 U.S.C. 16237(b)(5) and 16238(b)(5)).

The National Renewable Energy Laboratory (NREL) led the research and developed the database in collaboration with:

• Oak Ridge National Laboratory
• Sandia National Laboratories
• Lawrence Berkeley National Laboratory
• Arizona State University
• Industry partners (e.g., GE, Vestas, Siemens).

Please refer to the Resources section for more details on the REMPD team.

Technical Description of the REMPD

The REMPD is a relational database developed using the open-source database server PostgreSQL. Relational databases define relations (tables) comprising unique rows of data. The REMPD information was collected by combining proprietary and nonproprietary information from wind and solar manufacturers and suppliers, along with peer-reviewed publications. The publicly accessible database information protects the proprietary inputs by aggregating data into material types and providing ranges that are indicative of the most common wind and solar installations. In the future, the REMPD could be expanded to include additional information such as externalities (e.g., emissions from transportation, material requirements for transmission, impacts on local communities) or additional energy categories, such as other generation and energy system types; for example, geothermal plants, marine and hydrokinetic plants, hydrogen electrolyzers, or battery energy storage systems.

An open-source version of the database is available to download on the Resources page.

Data Taxonomy

The REMPD uses a six-tiered approach to collect and organize data, which is shown in Figure 1. This taxonomy was developed for use across a wide range of energy technologies. Examples are provided in Figure 1 for wind and solar energy.

The top tier comprises all components and materials required to construct facilities in the selected category (e.g., all solar photovoltaic [PV] plants in the United States). The next level captures individual system components, such as the wind turbine, PV module, substation, and electrical cables. Each component is associated with subassemblies and subcomponents; materials data are provided whenever they are available to populate these levels (e.g., the pitch drive in a wind turbine is a subcomponent of the hub subassembly). The next tier includes the finished materials, or primary processed materials, such as steel, that are required to manufacture the component, subassembly, or subcomponent. The lowest tier provides the raw materials, which also include some secondary processed materials (e.g., glass) that are required to manufacture the finished materials. This taxonomy allows the database to capture all material requirements for energy technologies and breakdown the material requirements by component.

In some cases, because of data constraints and the desire to focus primarily on material quantities, the REMPD does not necessarily have all data at the subassembly or subcomponent levels. In addition, to protect proprietary information, data in the publicly released version of the database are aggregated at the subassembly level. For example, substation data are broken down only by material type and are not subdivided at the subassembly or subcomponent levels, and wind turbine and PV module data are reported at the subassembly level. In all cases, the REMPD includes data for the raw and finished materials associated with each component.

Definitions

As requested in the Energy Act of 2020, the REMPD provides the following information regarding the materials used in wind and solar plants (see Table 1):

• Country of origin
• Source
• Significant uses
• Projected availability
• Physical properties
• Type
• Quantity

Table 1. Definition of Terms Used in the REMPD

Term	Definition
Country of origin	The country where the material is produced, focusing on the earliest production stage for the material (i.e., mining when applicable).
Critical mineral	Any mineral on the list of critical minerals published by the U.S. Department of the Interior United States Geological Survey (USGS) (refer to Table 4 for the 2022 USGS list of critical minerals).
Current production	The quantity of material that is currently available, as measured using global production in 2020.
Source	The geographic country of origin of the material.
Significant uses	End uses (other than for renewable energy technologies) of the material that comprise more than 10% of the market share for that material.
Projected availability	The quantity of material that could be available globally in the future, as measured using total known reserves.
Physical properties	The key physical properties of the material that are relevant to its function in wind and solar energy technologies.
Type	The category within which the material belongs.
Quantity	The amount of material needed to manufacture, operate, and decommission a selected set of renewable energy technologies at a given time under a given scenario of deployment and technology innovation.
Solar energy material	Any nonfuel mineral, element, substance, or material used in the production, use, or disposal of solar energy technologies.
Wind energy material	Any nonfuel mineral, element, substance, or material used in the production, use, or disposal of wind energy technologies.
Vulnerable material	Any nonfuel mineral, element, substance, or material that the DOE Office of Energy Efficiency and Renewable Energy determines has a high risk of a supply chain disruption and serves an essential function in one or more energy technologies, including technologies that produce, transmit, store, and conserve energy or a critical mineral.

Metrics

In addition to the attributes listed in Table 1, the REMPD can calculate a variety of metrics for analysis. Table 2 provides a selected list of such metrics, including material intensity, annual material quantity, and percentage of projected availability.

Table 2. Selected List of Metrics That Can be Computed by the REMPD

Metric	Units	Description	Levels of Aggregation
Material intensity	kilogram (kg)/ megawatt(MW)	Estimated mass of material required per rated capacity	By material type, material class, or material category at the facility, component, or subassembly* levels
Annual material quantity	kg/year (yr)	Estimated mass of material needed to meet specified annual deployment level	By material type, material class, or material category at the facility, component, or subassembly* levels
Percentage of current production	%	Relative amount of material needed for a selected set of U.S. renewable energy technologies compared to current global production (as measured using 2020 global production)	By material type
Percentage of projected availability	%	Relative amount of material needed for a selected set of U.S. renewable energy technologies compared to projected global availability (as measured using global reserves)	By material type

* Not all components in the database have data at the subassembly level. This tier is populated based on available data (i.e., whether the materials needed for each component can be disaggregated to the subassembly level, or if they are instead reported at a higher level, such as the component level). Ability to aggregate or disaggregate at the subassembly level data depends on data availability.