December 4, 2013
ECONOMIST: The Dirty Secrets of Clean Cars.
Then there is the question of where the hydrogen comes from. At present, industrial hydrogen (which is used as a feedstock for refining oil, as well as for making chemicals, electronics and foodstuffs) is produced by reforming natural gas with steam. This is not a particularly clean process. According to the National Renewable Energy Laboratory, a federal facility in Colorado, producing a kilogram of hydrogen by steam reformation generates 11.9 kilograms of carbon dioxide. As the Honda Clarity could travel 68 miles (109km) on a kilogram of hydrogen, it would cause 175 grams of carbon dioxide to be dumped into the atmosphere for every mile it was driven.
By way of comparison, Volkswagen’s small diesel cars produce 145 grams per mile. On that reckoning, even petrol-electric hybrids like the Toyota Prius, which produces 167 grams per mile, are cleaner than the fuel-celled Clarity. Admittedly, fossil fuels also produce carbon emissions while being dug out of the ground, refined and transported to the pump. But burning hydrocarbons in internal-combustion engines is becoming cleaner all the time. When measured on a well-to-wheels basis, the steadily declining emission levels of conventional vehicles is putting the squeeze on so-called ZEVs.
Until you can electrolyze hydrogen with power from orbital solar plants, it probably isn’t going to be all that clean.