Producing drinking water from hydrogen fuel cells

In a future hydrogen economy, harvesting water from H₂ fuel cells and other devices should be considered as a by-product of their operation. We hypothesize that the water quality produced by modern fuel cells is higher than typical tap waters and complies with US Environmental Protection Agency (USEPA) regulations. Water samples were collected from six different fuel cells (FCs) operated at research centers across the US, and their constituents were measured. The water quality parameters were below the maximum contaminant levels except for zinc, lead and antimony, which may be related to plumbing or FC material leaching. To investigate the yield of water from FCs, water to energy production ratios were modeled. With 85% capture of exhaust water, an FC operating to meet daily energy consumption needs of a typical US household would produce ∼16 L of water. This is nearly the volume of internal human consumption of water, but far less than the ∼410 L/capita/d of total potable water demand which accounts for all uses of water. In a nationwide hydrogen economy, where all energy consumed comes from hydrogen, over 4.9 billion m³ of high quality water per year would be produced as by-products of hydrogen usage.