But after a $12 million investment from Japan's government, plus research, engineering, design and building work by Mitsubishi, Toyota and Kyushu University, Yuji is no longer laughing. Starting late last year, drivers of vehicles like the Toyota Mirai and Honda Clarity have been able to drive up to the sewage plant and power up their hydrogen fuel cell cars.
The station is working only 12 hours a day but is making enough hydrogen to fill 65 cars daily. That could increase to 600 if all the biogas at the plant is used.
After years of fits and starts, Japan is in the midst of a major push to move hydrogen-powered cars off the drawing board. The government this year doubled its funding for fuel cell vehicle subsidies, construction of filling stations and hydrogen energy farms to about $US280 million, up from $US120 million last year. Meanwhile, carmakers are preparing to make more zero-emission vehicles.
After years of debate globally about which should come first, the cars or the stations to support them, the numbers of both are mushrooming. Japan now has about 80 stations, Germany has 50, and California has 20.
In the US, most hydrogen is produced from natural gas. But a 2014 study by the US Department of Energy's National Renewable Energy Laboratory found that biogas from waste water treatment plants, landfills, manure and industrial facilities could be used as a major source of hydrogen - enough to support 11 million fuel cell vehicles a year.
"Sewage sludge is completely untapped today as a fuel source," chief engineer of the Toyota Mirai, Yoshikazu Tanaka said. "We believe it's very promising and would bring ultimate self-sustainability to communities."
Toyota started offering the Mirai last fall and has sold about 1000 in Japan and 200 in California, Mr Tanaka said. The company has already received more than 2,000 orders in the U.S., and Americans who reserve vehicles now will have to wait until 2017 to get them. There's an even bigger backlog in Japan. Honda and South Korean automaker Hyundai are also selling fuel cell vehicles in California.
"We hope to be able to take our advanced technology and sell it to Europe and the U.S.," said Seiichi Hirashita, manager of the Kyushu branch of Mitsubishi Chemical Engineering, which installed the Fukuoka station and has planned and built about a third of Japan's hydrogen stations.
Customers are charged about $US11 for a kilogram (2.2 pounds) of hydrogen, and a fill-up requires about five kilograms, making the cost comparable to driving a gasoline car. But producing a kilogram of hydrogen at the sewage plant costs about $US100, Mr Tachibana said, and the number of fuel cell vehicles in the city is still so low - 30 to 40 - that the station is open only one day a week. The Mirai has a range of about 310 miles, and in the US, the purchase price includes three years of fuel.
Takeo Kikkawa, a professor at Tokyo University of Science's Graduate School of Innovation Studies, said that even with government subsidies worth thousands of dollars to each buyer, hydrogen fuel cell cars remain out of reach of middle-class consumers. In the US the suggested retail price of the Mirai is $US57,000, but buyers are eligible for about $US20,000 worth of incentives, rebates and tax credits.
Japan is the most advanced country in terms of developing fuel-cell technology, Mr Kikkawa said, but "we are lagging on infrastructure because we don't yet have a mass market."
California, he said, has done a better job of promoting other fuel-cell powered vehicles, including buses and forklifts used in warehouses, ports and airports.
But he said Japan has an opportunity to catch up by focusing on the 2020 Olympics in Tokyo. On July 1, the city announced it would open a Hydrogen Museum to educate residents and visitors about the technology.
The city and national governments have also pledged to have 100 hydrogen-powered buses on the city's streets in time for the Summer Games. Those will require four high-capacity hydrogen stations, Mr Kikkawa said. "This is a major development," he said.
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