Carbon-free fuels could have a dark side

As climate-friendly fuels, hydrogen (H 2 ) and ammonia (NH 3 ) are enticing. Because they lack carbon, they can be burned to produce nothing but environmentally benign water and nitrogen (N 2 ). But if producers do not take care to prevent leaks or incomplete combustion, researchers are now warning, the fuels could generate pollutants that could harm human health and shrink or reverse the climate benefits. For example, one analysis finds that, under a worst case scenario, using ammonia as a fuel could have a greenhouse gas footprint as bad as burning an equivalent amount of coal. “We can’t just be hoping these things work,” says Amilcare Porporato, an environmental engineer at Princeton University and a co-author of the study, which was published last week in the Proceedings of the National Academy of Sciences . “We need to do due diligence.” These potential side effects are too often overlooked, says Paul Wolfram, a researcher at the Joint Global Change Research Institute. “The focus is almost solely on [carbon dioxide] emissions,” he says. Today, hydrogen and ammonia mainly come from energy-intensive, polluting processes. But they can also be made cleanly, with renewable electricity, resulting in a green fuel. Green hydrogen got a boost last month, when the U.S. Department of Energy announced $7 billion in funding to support several hubs to make it. Ammonia has an additional advantag...
Source: ScienceNOW - Category: Science Source Type: news