WOULDN鈥橳 it be wonderful to have a way to cut the smogs that plague our cities and halt global warming at a stroke 鈥� all without changing our way of life and at no great cost. That is the promise of replacing carbon-based fuels with hydrogen to keep our cars running and the lights burning. Many governments have started to embrace the idea. But now a spate of studies is telling us what we should already know: there is no such thing as a panacea.
Those papers have pointed out that hydrogen itself increases global warming and could even harm the ozone layer (see 鈥淩eality bites for the dream of a hydrogen economy鈥�). These suggestions have been fiercely contested by the green-tinted proponents of the hydrogen economy. But the arguments on both sides have revealed how much we have to learn about a hydrogen-fuelled future.
Beyond global warming and ozone, predicting what will happen to the atmosphere during the long transition as the world turns away from carbon is a particularly thorny problem. And we know nothing about the way soil microbes, which absorb most of the hydrogen from the atmosphere, will respond to a warmer, hydrogen-rich world.
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Astonishingly, we do not have direct measurements of how much hydrogen we emit today, so perhaps it is not surprising that arguements rage over how much might leak from fuel tanks and pipelines in future.
Before we commit to hydrogen fuel, we must know more. To continue as we are would breach the precautionary principle so dear to many of hydrogen鈥檚 advocates. Our future should be governed by the best scientific information, not the most persuasive rhetoric. Yet there are disturbing signs that the debate is polarising. Hydrogen advocates are greeting critical results with thinly veiled sarcasm, and it can only be a matter of time before the vested interests of the oil, gas and coal industries mount a counter-attack.
The UN, through its Intergovernmental Panel on Climate Change, has done a superb job of building a scientific consensus over global warming. It is time to do the same for hydrogen, if not through the IPCC itself then through a new body. We have the rare chance to be certain of the benefits of a massive technological change before it begins. Let鈥檚 not waste that opportunity.