From hydrogen storage to fuel cells: hydrogen discharge as the next bottleneck

Abstract

Advances in engineering have enabled a wide range of technologies for hydrogen generation and storage. Although hydrogen storage remains challenging in many cases, the controlled discharge of stored hydrogen to conditions suitable for fuel cell operation has emerged as the next system-level bottleneck. Here, the main challenge lies in the hydrogen storage conditions (temperature, pressure, and physical state), which differ partially from the operating requirements of fuel cells. In particular, hydrogen needs to be supplied to fuel cells in the gas phase at near-ambient pressure (∼0.5 MPa) and temperature (∼353 K). These conditions are not fully aligned with any of the existing storage forms, including compressed gas, cryogenic liquid, liquid hydrogen carriers, or solid-state storage systems. Such mismatches lead to heat losses, increased capital investment, flow rate fluctuations, system-level inefficiencies, and safety concerns. Thus, the next key question in advancing hydrogen energy is how to enable stable and controlled hydrogen release from various storage forms into fuel cells for desired electricity generation. This study presents a perspective on directions in this area for future research and development.