No. 311: Green hydrogen made of water from water vapor electrolysis (September 17, 2011)

Green hydrogen does not emit carbon dioxide. It can open up the road to use hydrogen as fuel of the fuel cell and as a medium to store power. Toshiba developed an elementary element, which is 16 mm in diameter, to produce hydrogen without fossil fuel by dissolving vapor in the high-temperature gas furnace. The company plans to put the system into practical use toward 2020. Currently, it is widespread to produce hydrogen through the thermochemical reaction using natural gas and naphtha, but Toshiba’s system is to produce hydrogen through the electrochemical reaction using water. It adopted the water vapor electrolysis method that can produce hydrogen with 80% efficiency, two times higher efficiency of the existing methods.

The elementary element, or the electrolysis cell, for the system is a three-layer ceramic element that sandwiches the zirconia electrolyte film by two electrodes. That is, the system has almost the same structure as the power generation cell of the solid-oxide fuel cell to be utilized for household fuel cells shortly, and uses the electrolytic reaction that is the opposite direction of power generation. The company created tiny air holes in the materials to improve the electrode material and successfully achieved the world’s highest production capacity of hydrogen, 7% higher than the highest electrolytic property at present. It already verified the durability performance of the new elementary element by a continuous operation of longer than 6,000 hours. The system is scheduled to be presented in the fall convention of Japan Chemical Industry Association.