Institution of Mechanical Engineers IMechE

The Future of Coal: Pre-combustion Extraction of Carbon

03 October 2013

Coal has always been the biggest single contributor of raw energy for fossil fuel power generation stations, and there is a commercial desire to maintain this status quo – but only if its CO2 contribution is reduced by at least 50%. How can this be addressed cost-effectively?

Previous attempts to mitigate carbon emissions have been based around fitting a CO2 exhaust 'filter' to existing plants, as used successfully for removing sulphur. For carbon extraction, however, this method fails, as electricity production is reduced by a third and a continuous subsidy is required.

Partial oxidation or gasification of coal produces a pressurised synthesis gas containing all the carbon in the coal in the form of carbon oxides. Optionally, by using steam in a catalytic reactor, this gas can be converted into a mixture of carbon dioxide and hydrogen, thus producing an optional export of hydrogen plus a low-carbon fuel suitable for gas turbine firing.

Such technologies have been commercially employed for more than 25 years in Integrated Gasification Combined Cycle (IGCC) power stations. But the higher cost of removing CO2 as well as sulphur has hindered further investment.

This lecture introduces a fresh approach - replacing complex pressurised liquid washing systems for removing undesirable gases with a dry molecular sieve separation system, based on pressure swing absorption. Results so far indicate a commercially viable process, without the need for a continuous subsidy.


The Future of coal: Pre-combustion Extraction of Carbon

: Presented by John Griffiths CEng FIChemE FEI, Gasification Matters

John has over 50 years’ chemical engineering experience, in process engineering, commissioning and consultancy. His main expertise is in the production, treatment and use of synthesis gas (syngas) for fuel gas, chemical and power production.

For the first ten years of his career, John was involved in design and commissioning of syngas units in the refinery, fertiliser and power industries. He then led the conceptual design teams for the 521 MW ISAB and 575 MW Saras IGCC plants in Italy, and was an original member of the design team which developed the first IGCC plant with carbon capture in the UK. He holds several patents and is a regular contributor to the Leeds University chemical plant commissioning course.

Duration: 1 hour 25