Session: 01-01: Decarbonizing Industrial Processes

Paper Number: 155348

155348 - Scalable, Transportable Thermochemical Energy Storage for Decarbonization of Industrial Process Heat 

Abstract: 

Energy storage based on reversible chemical reactions, termed thermochemical energy storage (TCES), has been proposed since the 1970s. TCES based on calcium oxide and hydroxide, where dehydration of Ca(OH)₂ to CaO (lime) stores energy and the hydration of CaO to Ca(OH)₂ releases the energy, is especially promising. The material is cheap at $100/ton, has high energy density at ~ 500 (W·h)/kg, the reaction is highly reversible, and the reaction temperatures of > 550 ^oC can serve ~ 75% U.S industrial process heat demand. Additionally, the temperatures are high enough to drive efficient heat-to-power conversion cycles for electricity generation. However, commercialization of TCES has been hindered due to several material level challenges. One of the major challenges is the high volumetric change of > 150% during charge/discharge process. This leads to lime pulverizing into fine powder which agglomerates and causes mass transfer limitations leading to capacity decay with cycling. The other major challenge is the requirement of a large heat exchanger surface which makes the technology expensive and non scalable. Cache Energy's developed a long duration storage technology overcoming these challenges through major innovations in the reactor technology as well as lime pellet optimization using a binder. Cache's storage system can charge and discharge energy over thousand cycles with a round trip efficiency of 95%. Once charged with waste heat or renewable electricity, the pellets store energy at ambient temperature and can be easily transported to other sites where energy is needed. This highly scalable energy storage system can dispatch energy continuously for > 100 hours while storing energy at ambient conditions for up-to > 6 months making industries energy resilient and flexible. The optimized pellets can cycle without any major loss in chemical reactivity or mechnaical strength over many cycles. The storage system is also cost competitive when compared to other storage technologies with a capital cost of ~ $5-10/kWh and a storage material cost of ~ 0.2 $/kWh. Cache Energy did a pilot demonstration of a 100kW in Alaska with the objective of catering to inter-seasonal storage by storing excess renewable energy during summer and providing resisential heating during winter. Cache’s technology’s ability to provide ultra-long-duration energy storage under ambient conditions at low cost makes it transformative and disruptive, positioning it as a superior alternative to any other thermal energy storage technologies and potentially even chemical energy storage processes such as the use of hydrogen for temperatures up to ~550 ^oC.

Presenting Author: Lakshmi Amulya Nimmagadda Cache Energy

Presenting Author Biography: Lakshmi Amulya Nimmagadda is the director of R&D at Cache Energy. Cache Energy has developed a long duration energy storage technology using thermochemical energy storage. She works on material development and reactor scaling to develop robust storage technology in an effort to accelerate industrial decarbonization. She received her PhD from the University of Illinois at Urbana Champaign. Cache Energy is the recipient of Department of Energy's Energy Storage Innovations prize and has won the pitch competition conducted by EPIC Prize Collaboration Event at the White House.