Researchers from Imperial College London have designed a system which uses coal to generate hydrogen.
The technology combines several different systems. First, the coal is brought into contact with hydrogen at 70 bar and 700 degrees C using hydrogasification, which converts the carbon in the coal into methane. Steam is then pumped into the reactor, absorbing some of the heat given off by hydrogasification, and providing the reaction mixture for the second phase.
Here, gases pass into another reactor containing calcium oxide (lime) and a catalyst which promotes the ‘water-shift’ reaction, converting the methane and steam into carbon dioxide and hydrogen. The lime reacts with the CO2 to form calcium carbonate (limestone), leaving near-pure hydrogen.
Next, the limestone is passed into a third reactor called a calciner, where it is heated, reversing the first reaction and releasing a pure steam of CO2. This, say the researchers, can be captured and sequestered.
The hydrogen produced by phase two of the reactor splits into two streams. One is recycled to form the hydrogen feed for the hydrogasifier; the other is ‘polished’ — purified to a high degree — and fed into a solid oxide fuel cell to generate electricity.
According to Kandiyoti the technology should help the
‘Therefore, the concept of generating power from coal, with zero or near-zero emissions of CO2, is receiving serious consideration in both Europe and the
The concept of ZECA technology was developed at Los Alamos National Laboratory and
Kandiyoti’s team is currently studying a novel type of hydrogasification reactor, where the gases pass through a heated wire mesh, which can perform the reaction at the required conditions.
In the next phase of the research, they hope to optimise the conditions inside both the hydrogasifier and the second-phase reactor, while another team at
‘The data obtained will be used to test the concept and progress the design on a novel zero-emission power plant,’ said Kandiyoti.