Leveraging existing water and wastewater infrastructure to develop distributed pumped storage hydropower in California

To accomplish California's aggressive 100% clean energy by 2045, new sources of flexibility should be integrated into the system to ensure stable and reliable operation of the grid. Economical and scalable energy storage technologies are key to deliver such flexibility services. Pumped storage hydropower (PSH) is an economical and mature energy storage technology; however, apparent barriers, such as lack of new sites, prevent the development of new projects. This study aims to evaluate the technical feasibility of leveraging existing water and wastewater infrastructure to develop distributed pumped storage hydropower. We analyze the possibility of installing secondary tanks at a higher/lower elevation near the existing water storage tanks, to enable exploitation of elevation difference for storage of energy. The base plant and the additional tank must have adequate elevation difference and be close enough, so that they can be reasonably linked. A case study is conducted for the state of California, where over 200 exiting water and wastewater treatment facilities are assessed and 65 sites are identified as potential candidates, which satisfy minimum design requirements. The qualified facilities are then ranked and classified into three categories, in terms of their potential to deliver high value, low cost, energy storage capabilities. The results show that the theoretical potential energy storage capacity of the suitable plants is significant as it reaches over 280 MWh. This study concludes that the water and wastewater treatment facilities in the state of California can be leveraged for the future PSH project developments. Due to the heavy reliance on the existing infrastructure, the new projects are expected to be cost effective.

Automated summary

This study evaluates the technical feasibility of leveraging existing water and wastewater infrastructure to develop distributed pumped storage hydropower for future project developments in California. By installing secondary tanks at higher/lower elevation near existing water storage tanks, the study aims to exploit elevation difference for energy storage. Over 200 facilities are assessed, with 65 identified as potential candidates, showing significant potential energy storage capacity of over 280 MWh.