Abstract
In response to language set forth in The Energy Act of 2020, the U.S. Department of Energy’s (DOE’s) Wind Energy Technologies Office (WETO), working with the National Renewable Energy Laboratory (NREL), explored the potential for, and technical viability of, airborne wind energy (AWE) technologies, which convert wind energy into electricity using tethered flying devices. As part of its inquiry, WETO drew on findings and insights gained from a synthesis of existing literature, NREL internal analysis, and outreach through interviews of AWE industry leaders. Supported by WETO, NREL hosted a technical workshop on U.S. Airborne Wind Energy in March 2021, attended by more than 100 experts and interested parties.
Based on these activities, WETO completed an assessment of the potential for, and technical viability of, airborne wind energy systems as means to provide a significant source of energy in the United States. Its conclusions are summarized below:
- The technical resource potential1 of wind energy available to AWE systems is uncertain, but likely similar in magnitude to that available to traditional wind energy systems. The extent to which AWE represents an additional wind energy resource is not clear, and it will depend on the energy harvesting characteristics of commercial designs. Even if there is no additionality, the resource (along with that of traditional wind energy) remains significant compared to national electricity use.
- If AWE could be captured economically, it could provide a significant source of energy. In general, however, AWE remains an immature and unproven technology that requires significant further development before it could be deployed at meaningful scales at the national level.
- AWE technologies are fundamentally new. They are different from traditional wind turbines in their design, manufacture, supply chain, logistics, installation, operations, and maintenance. Challenges and opportunities arise from these differences and are not within the scope of traditional wind energy research and development (R&D).
- AWE system designs to date are diverse and largely experimental. There is little convergence, so far, as to a preferred technology or approach, and no megawatt-scale AWE systems have been commercially deployed. Several AWE designs under development show promise. The overall design space has not yet been fully explored.
- Like high-performance aircraft, AWE systems can be technically complex and must sustain flight through demanding atmospheric conditions. However, AWE systems also must operate autonomously and are tethered to the ground, presenting additional challenges.
- Federal programs have intermittently supported U.S. AWE R&D in the past (~$13M since 2009). However, AWE is actively supported by research programs in the European Union (EU) (~$58M since 2008), where most AWE advancements occur.
With these factors in mind, the report’s authors identified research, development, demonstration, and commercialization (RDD&C) activities needed to advance and validate the technical and economic viability of airborne wind energy systems. These plans span a notional 10-year period and, if pursued, could occur within a phased-gate approach that communicates expectations for progress at each stage-gate, before commencing the next stage of investment.
A conceptual RDD&C plan could include the following elements and activities:
- Characterize the quantity, quality, and complementary nature of the wind resource above traditional wind turbines, higher than 200 meters (m).
- Carry out national and regional cost and feasibility studies to evaluate key cost drivers, market potential (including offshore), and economic benefits of AWE technology.
- Broaden and deepen the physical understanding of various AWE concepts through modeling and simulation with a focus on power density, robust controls, and scaling potential.
- Establish test facilities and research capacities to enable AWE system developers to prove system and sub-system reliability and performance, and study grid/micro-grid integration.
- Encourage industry R&D, including with cooperative research and development agreements or other mechanisms that enable access to research and engineering talent at the National Laboratories.
- Participate in standards-setting organizations and contribute to the establishment of international standards for AWE design, testing, and certification.
- Assess the social acceptance and environmental implications of AWE technology. Explore and, to the extent possible, quantify the environmental and human impacts of AWE.
- Attract and develop a pool of talent for the AWE industry through research fellowships, centers of excellence, prize competitions, and other training mechanisms.
- Explore options for cost-effective policies and technical assistance mechanisms for the development and commercialization of AWE technology.
The above elements and activities are integral parts of a whole concept. All are important, but their relative priority and timing over a 10-year period would be determined by the desired commercial timeline, availability of funding from various sources, and the targeted AWE market.