Low-Cost Utility Scale Offshore Energy Storage

Abstract

In order to curb anthropogenic climate change, deep decarbonization of the electric grid is essential. Although the economical front of technologies like wind and solar power has improved, the fundamental intermittency of these sources of energy remains a challenge. Cheap, reliable and scalable storage solutions are urgently required. Most energy storage technologies are either expensive (Lithium Ion) or geographically constrained (Pumped Hydro). Low cost bulk energy storage could be a vital catalyst in decarbonizing our current grid infrastructure and would increase the competitiveness of offshore renewables considerably. This paper explores the feasibility of a large scale offshore floating Osmotic Energy Storage (OES) system. OES stores electrical energy by desalinating a clean, mixed solution to create a chemical potential between NaCl brine and freshwater in a closed loop system. It recovers this energy in a controlled membrane based mixing process called Pressure Retarded Osmosis (PRO). An offshore digitally operated Reverse Osmosis-Pressure Retarded Osmosis based OES system could be scaled up to upwards of 6 MWh to function as storage for coastal utilities or offshore communities. The core value proposition is in its economical, modular and environmentally benign design that could increase access to large scale energy storage integration to the grid globally.