A discrete regenerative fuel cell mediated by ammonia for renewable energy conversion and storage

The sustainable nature of renewable energy, with its vast resource potential and reduced costs, has triggered a rapid increase in its direct utilization in a solar/wind-electricity manner. As the installed capacity increases, cost-effective and efficient technologies for renewable energy storage and utilization will be critically important to mitigate the intermittency of the solar and wind resources and maintain the stability of electrical grid. In this work, we demonstrate a discrete regenerative fuel cell, mediated by ammonia, capable of converting and storing intermittent power in an electricity-fuel-electricity approach. During energy storage (electricity to fuel), charging an electrolysis flow cell for ammonia production from nitrogen and water results in a Faradaic efficiency of 2.18% and a rate performance of 15.03 × 10^-10 mol s⁻¹ cm⁻² at 23 ^oC, which is one order of magnitude higher than those reported in the open literature. During energy utilization (fuel to electricity), energizing a flow cell with ammonia results in a peak power density of 8.86 mW cm⁻² at 80 °C. Hence, a discrete regenerative fuel cell mediated by ammonia for renewable energy storage and utilization is demonstrated, which represents a promising alternative choice for the regenerative fuel cell mediated by hydrogen in terms of storage, transportation, distribution, and dispensation costs, as well as safety issues.