Chiho Matsuda, Nikkei Monozukuri, techon.nikkeibp.co.jp – Mar 16, 2009
Tokyo Gas Co announced March 12, 2009, that it succeeded in halving CO2 emissions in a verification test of CO2 separation/collection in a hydrogen production process while maintaining its production efficiency.
Tokyo Gas has been developing and verifying hydrogen production equipment intended for fuel cell vehicles at its JHFC Senju Hydrogen Station (in Arakawa Ward, Tokyo). In November 2008, the company attached a CO2 separation/collection device to the equipment and started the test.
Analysis of the obtained data showed that the energy loss due to CO2 separation/collection was about 3%.
At the station, hydrogen is produced from city gas by using a hydrogen separation type reformer that produces hydrogen and CO2 by the steam-reforming reaction between city gas (methane) and steam. The generated hydrogen is extracted during the production process by installing a film that transmits only hydrogen in the reformer where the reaction occurs.
The hydrogen production efficiency is 81.4%, which is “the world’s highest” for a process of producing hydrogen from fossil fuel, according to Tokyo Gas.
The reformer carries out the reforming reaction and hydrogen separation in one process, contributing to downsizing of equipment. In addition, CO2 concentration in the reforming offgas (the gas left behind after extraction of hydrogen), which is generated during the hydrogen production process, is 70 to 90%; therefore, it is easy to separate and collect CO2.
The hydrogen separation/collection device compresses the reforming offgas exhausted from the reformer to 7MPa and cools it down to -20°C so as to liquidize CO2 in the reforming offgas for separation and collection. Combined gases containing methane and hydrogen are used as a fuel for heating the reformer.
Tokyo Gas is planning to form the “Local Hydrogen Network,” which evolves around hydrogen stations equipped with a distributed CCTS (carbon dioxide capture, transportation and storage) function for CO2 separation, transportation and processing.
With the network, hydrogen will be supplied to fuel cell vehicles, as well as to houses, offices and plants near the station through pipelines. The company intends to further reduce CO2 by using fuel cells with higher efficiency. Also, it plans to utilize the results of the verification tests for creating this network.
The reformer used for the experiment was developed jointly by Tokyo Gas and Mitsubishi Heavy Industries Ltd as part of the “Basic Technology Development Program for Safe Use of Hydrogen,” a program for the period from fiscal 2005 to 2007, implemented by the New Energy and Industrial Technology Development Organization (NEDO).