Materials challenges in the hydrogen cycle

[...]there are many challenges to be met to make fuel cells energy- and cost-efficient: reducing the amount of expensive platinum catalyst, finding suitable nanoporous solid adsorbents or metal hydrides to make hydrogen storage practical, and discovering the best way to assemble the five-layer fuel-cell sandwich (membrane in the middle, electrodes on either side of the membrane, and gas diffusion media outside the electrodes) at large scale. According to E4Tech’s Fuel Cell Industry Review 2017, 72,600 fuel-cell units were shipped in 2017, broken down geographically by 56,800 units in Asia, 9900 in North America, 5100 in Europe, and 800 in the rest of the world. In this area, automotive manufacturers currently use carbon fiber-reinforced composite tanks filled with hydrogen gas pressurized to 700 bar (>10,00 psi), which has a system gravimetric capacity of 4.2 wt% H2, a system volumetric capacity of 24 g H2/liter, and a cost of USD$15/kWh. With each innovation, the question of scalability returns. Because platinum can account for up to a third of the cost of the catalyst, finding alternatives to platinum group metals would go a long way toward reducing the cost.