Flexible HPWH with Embedded Energy Storage

Designs using heat pumps to heat water have been proven to achieve the energy savings goal for water heating. Current electric HPWH products are rigid in operation since the capacity is not flexible and it cannot accommodate any load fluctuations. Regardless, these are considered as a distributed energy storage system (hot water storage tank). ORNL will work with A.O. Smith to redesign an electric HPWH and achieve a highly flexible operation by embedded energy storage system. The objective of the proposed project is to develop next-generation HPWHs that can actively participate in load shifting while achieving increased capacity for comparable footprints at minimal increased in cost. The project aims to develop HPWHs that can achieve at least 20% higher capacity due to embedded storage solution. At the same time, the design should lead to substantial reduction in refrigerant charge because of the compactness of the components (such as the condenser and evaporator). In addition to improved performance, the aim is to determine the feasibility of recently emerging refrigerants, particularly HFOs and blends, to substitute for existing refrigerants.

Project Impact

This project will deliver enhanced performance, with a 20% increase in capacity within the same footprint, significant carbon emission reductions (~60% compared to electric resistance and 10% compared to hybrid HPWH), and a minimum 30% cost reduction compared to existing leading technology. Furthermore, it will offer a minimum four-hour load-shifting capacity for medium to high usage scenarios, integrate energy storage without external vendor involvement, and present a compact design that reduces maintenance requirements. Its applications will span across residential air cooling, heating, refrigeration, and process water heating.