Ultra-high-efficiency Carnot battery with waste heat integration

Low power-to-power efficiency remains a primary challenge for Carnot batteries. Unfortunately, enhancing this efficiency through internal system modifications or adjustments to cycle parameters, including the coexistence of heat and cold storage and the adoption of various energy storage methods, has encountered limited progress. Capitalizing on the inherent thermal coupling advantage of Carnot batteries, this work aims to improve the power-to-power efficiency by integrating external waste heat sources. An ultra-high-efficiency Carnot battery system assisted by waste heat resources is presented, and the equipment of two 7.7 m 3 pressurized heat storage tanks enables the operation for 6 hours. An optimized power-to-power efficiency of 0.85 is attainable for a 4-hour charging and discharging period. This is predicated on the quantification of operating losses and the elucidation of operational characteristics under a range of waste heat and heat storage conditions. Furthermore, this study innovatively proposes the operation strategy of extending discharge time for efficiency improvement by exploiting the waste heat utilization potential, and the maximum power-to-power efficiency can attain as high as 1.06, which is significantly higher than the highest level of 0.80 reported in the current public.