Elastic energy storage proof of concept and scalability

Team: David Camarillo, Steve Collins, Ovijit Chaudhuri, Gordon Avery
Planning (Scoping)

Solar panels and wind turbines generating renewable energy for green and sustainable future. (*Image credit: Getty Images*)

The goals of this project were to build a prototype of an elastic energy storage system and to demonstrate that it could be a cost-effective grid-scale technology. Low-cost energy storage would mitigate the intermittency problem that has limited the adoption of renewable energy. It would thereby help to establish solar energy and wind energy as viable, cost-effective alternatives to fossil fuel combustion. Theoretical estimates indicate that the levelized cost of elastic energy storage could be as low as $20 per megawatt hour. The team tested three premises: The emerging field of mechanical energy storage shows technical and economic promise; elastic materials can store energy at lower cost than current technologies; and it may be feasible to incorporate elastic materials into established systems. Surveys of materials databases identified elastomers, e-glass, and fiberglass as candidate materials. Mechanical testing protocols followed to measure energy storage density, efficiency, stress relaxation, and fatigue. Tests of elastomers such as natural rubber, polyurethane, silicone, Buna - N rubber, and EPDM. Medium-stiffness polyurethane showed the best combination of high-density energy storage and high efficiency during loading and unloading cycles. This project identified long elastic cables under tension as the optimal loading modality (i.e., better than compression, torsion, or bending), and this analysis indicated the importance of orienting the cables parallel to the ground. This financial model indicated that grid-scale elastic energy storage is generally viable and competitive with other energy storage technologies. However, performance of elastomers must improve in order to maximize long-term energy storage and minimize losses during loading and loading. The team is preparing a manuscript on its studies for submission for publication and seeking additional funding to support these studies.