Patent ID: 8197974

Claim:
A closed loop energy storage system comprising: a fuel cell system configured to react a gaseous fuel with a gaseous oxidizer using a proton exchange membrane to produce a liquid product and electrical power, the fuel cell system being further configured to separate the liquid product into a humid fuel including the gaseous fuel and product humidity, and a humid oxidizer including the gaseous oxidizer and product humidity, wherein the humid fuel produced by the fuel cell system is intermixed with liquid product, and wherein the humid oxidizer produced by the fuel cell system is intermixed with liquid product; a first phase separator configured to separate the liquid product from the humid fuel; a second phase separator configured to separate the liquid product from the humid oxidizer; a fuel tank configured to store the gaseous fuel for subsequent reaction in the fuel cell system; an oxidizer tank configured to store the gaseous oxidizer for subsequent reaction in the fuel cell system; and a heat exchanger configured to preheat the gaseous fuel from the fuel tank and the gaseous oxidizer from the oxidizer tank prior to the gaseous fuel and the gaseous oxidizer being reacted in the fuel cell system; wherein the fuel cell system is configured to receive the gaseous fuel from the fuel tank and the gaseous oxidizer from the oxidizer tank; and wherein the heat exchanger is configured to receive heat from the fuel cell system, and is further configured to use that heat to concurrently preheat the gaseous fuel and the gaseous oxidizer.