I n J a p a n
Breakthroughs in cheaper hydrogen extraction from natural gas
Two recent reports in the Nihon Keizai Shimbun describe developments in producing hydrogen from natural (city) gas.
Nagoya-based NGK Insulators has developed a filter to efficiently separate hydrogen from fuels like natural gas. The hydrogen filter can be used in fueling stations for fuel cell vehicles. NGK claims that, compared with refining hydrogen using catalysis, the hydrogen filter can reduce the equipment size by 80%.
The filter comprises a three-layer ceramic cylinder -3 cm in diameter and 30 cm longplated with a thin palladium alloy film, through which only hydrogen can pass. NGK claims that when gas comprising just 50% hydrogen is passed through the filter, the hydrogen concentration can be raised to 99.5%. These ceramics with homogenous microscopic holes that can be plated with a palladium alloy film as thin as 2 ยตm, offer a significant reduction in the amount of expensive palladium used.
Meanwhile, technology developed by Ishikawajima-Shibaura Machinery Company in Nagano and Professor Hideo Kameyama of the Tokyo University of Agriculture & Technology is expected to reduce the cost of extracting hydrogen from natural gas supplied to households to less than one-fifth of that using conventional technology. The industry/ academic collaboration will apply the technology to residential fuel cells in field trials next year, hoping to produce cost-effective systems by 2005 in cooperation with gas suppliers.
The process uses a chemical reaction on the surface of an 80 ยตm thick stainless-steel sheet covered with a 40 ยตm layer of aluminum oxide containing nickel catalysts. The researchers raised the temperature of the reaction on the sheet surface to more than 600ยฐC from the standard 500ยฐC, while using a material that can withstand higher temperatures. The team also modified the catalyst surface from flat to 'spongy', increasing the active area. The amount of catalyst is reduced by 90%, for substantial cost reductions. The new material is also highly conductive and needs less than 1 min to power up a fuel cell, compared with the more than 10 min normally required.