Expert Insight

The Claverton Energy Group investigates........
(Producing Hydrogen from Coal using gasification)

The Claverton Group has been following the work at The European Commission's JRC-Institute for Energy (IE) in the Netherlands, because this apparently represents a serious attempt to investigate the issues in producing hydrogen from coal using a gasification process.

Hydrogen is generally considered to be one option for a future energy scenario, and the gasification process for producing hydrogen facilitates the capture of CO2 at high pressure. The concept is that the hydrogen can be used as a fuel gas in gas turbines, or after in-depth purification, piped to consumers. The captured CO2 is intended to be sent to disused oil fields in the North Sea for indefinite storage, so this concept is of "clean fossil" type.

The IE has published several papers over the last 12 months on an Integrated Coal Gasification Combined Cycle (IGCC) design which is intended to produce hydrogen as well as electricity. Some of the IE work relates the Dynamis Hypogen programme, which is being part funded by the European Commission. The programme is due to end in 2009, with possible construction starting after 2012. Hypogen is analogous to the USA FutureGen initiative.

There are only a small number of IGCC plants operating, and none of these is of the carbon capture type. These processes produce a gas containing a substantial amount of carbon monoxide as well as hydrogen. After removal of H2S this gas is burnt in a combined cycle gas turbine plant to produce power. But the combustion of carbon monoxide results in CO2 emissions.

The IE/Dynamis work has been to investigate the design issues when raw gas from the gasifier is reacted with steam to produce more hydrogen and to convert the carbon monoxide to CO2. The CO2 will be removed using liquid solvents. It will then be compressed to 120 bar for transmission to the storage site, somewhere in the North Sea. Major changes to conventional IGCC practice include changes to the type of solvent, and a two stage system for removal for producing a reasonably pure stream of CO2.

However IGCC type plants suffer from poor efficiency at part loads, and the IE have realised that this will be a serious issue when, in the future, much of the electricity will be coming from wind generation. Hence for significant periods of time fossil fuel power plants, of all types, will be either off-line or operating at low load. The IE work has shown that an IGCC-Hypogen can be modified. so that at times when there is no demand for electricity, hydrogen can be produced instead. Since this is a gas which can be stored in pipelines, gasholders or salt cavities, the IGCC-Hypogen plant can be kept operating at full output and efficiency.

In principle conventional power generating plants could use their unwanted electricity to produce hydrogen by electrolysis. However there is a serious loss of efficiency and substantial addition to plant capital costs when this is done and it would make the price of the hydrogen uneconomic. This is not a problem with the IE IGCC-Hypogen approach. Many in the Claverton group warmly welcomes this initiative and looks forward to further developments, despite the refusal of the UK Government to support such concepts.

For more info about the Claverton Group visit: http://energydiscussiongroup.wikispaces.com/

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