TOKYO -- Masaki Tajima is trying to pave a greener path to hydrogen for Japan. And the road starts at a simmering sewage field on the southwestern island of Kyushu.
Tajima's work is aimed at resolving a central challenge in fighting carbon emissions with hydrogen-fueled cars: The cars themselves are carbon-free, but getting the hydrogen in the first place isn't. Most of today's hydrogen is a carbon-intensive byproduct of oil and gas refining or the chemical industry.
Japan's plan is to harvest untapped sources of byproduct hydrogen and then shift to carbon-neutral sources.
That can be done by sequestering the carbon dioxide emissions underground or eventually switching to renewable sources that electrolyze hydrogen from water. Japan wants a zero-carbon-emissions network of manufacturing, transporting and storing hydrogen after 2040.
But there are two big caveats: Japan has no carbon capture and storage facility yet, and using such a sequestering system doubles the cost of creating hydrogen, says Tajima, a scientist at Kyushu University's International Research Center for Hydrogen Energy.
The sewage field in Kyushu offers an interim solution. The decomposition of human waste at that facility generates methane, which in turn can be used to manufacture hydrogen.
This process emits carbon dioxide, but it is considered carbon-neutral because it returns to the atmosphere carbon that was stored in plant matter through photosynthesis. Releasing it simply completes the carbon cycle.
Tajima has been running a hydrogen refueling station off the sewage field for two years.
It makes enough hydrogen each day to refill 65 fuel cell vehicles -- though the pump itself is open only one day a week and gets just two or three customers.
Japan has about 300 sewage facilities that could be harnessed in this way, he estimates.
"In the case of Japan, we have hydrogen fuel cell technology that is very advanced," Tajimas said, "and we want to make further advances in that technology."