The cell is two to three times more efficient than burning gas to produce power, they said.
The group led by Yusuke Shiratori, a Kyushu University associate professor specializing in electrochemistry, is a joint project with a Vietnamese university and several Japanese companies.
The team began the experiment in January 2018 and achieved power generation efficiency of 62.5 percent in July this year, a record high.
The researchers credited improvements they made along the way, including reducing hydrogen sulfide and soot, which hinder power generation, for helping them top their 53-percent goal.
The efficiency of methane gas combustion engine generators typically ranges from only 20 to 30 percent.
The researchers intend to develop large-scale power-generating facilities that use household garbage as fuel in urban areas to make use of organic waste as a power source in Vietnam, where the electrical supply is unstable.
“Our goal is to significantly improve the power systems in developing countries with biomass resources,” said Shiratori.
The breakthrough occurred in Vietnam at a pilot plant built for a demo experiment being conducted by the group.
The researchers have been developing the plant to produce electricity from methane gas generated from sludge from ponds for shrimp cultivation and other waste, including coconut pomace.
Shrimp is big business in Vietnam's Mekong Delta, but ponds used to cultivate them become useless when sludge accumulates, prompting operators to fell forests to secure space for new ones, Shiratori said.
The new system offers a way to extend their longevity. By supplying oxygen to the ponds using electricity generated by it, volumes of sludge can be reduced.
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