Introduction

IEA GHG has undertaken several studies on power plants with CCS which include assessment of operation at steady state full load. An important aspect which has not been considered in detail is operability, which includes the ability to change the power output in response to changes in power demand, to be able to accommodate changes in ambient conditions, fuel compositions etc., to be easily started-up and shut-down and to be able to accommodate equipment failures in a safe manner.

Operability of fossil fuel power plants is likely to become more important in future as more renewable power systems with variable outputs and more nuclear plants, which are relatively inflexible, are built to reduce CO2 emissions. The operability of power plants with CCS could have a major impact on the extent to which CCS will be used in future and it could also be a significant factor in the choice of the optimum CO2 capture technology. However, little information on the operability of power plants with CCS is currently available. IEA GHG has employed the University of Waterloo in Canada to undertake an initial scoping study on CCS plant operability which provides the following:

• A review of operability drivers and issues within electricity systems

• A review of literature on operability of power plants with CCS

• Discussion of techniques for the detailed assessment of the operability of power plants with CCS

• Discussion of the trade-off between operability and cost

• A proposed scope of a detailed study, including an estimate of the amount of effort required.

Major Conclusions and Recommendations

Operability is an important consideration for power plants operators and it is likely to become even more so in future due to the increased use of renewable energy sources with low-CO2 emissions. It could be a significant factor in the choice of the optimum CO2 capture technology and it may also affect the extent to which CCS will be used in future. There is currently little published work on operability of power plants with CCS.

The amount of effort required for detailed analysis of the operability of power plants with CCS would be substantially greater than that of IEA GHG’s other technical studies. For such a study to go ahead addition funding would be needed, for example from any IEA GHG Members and Sponsors that are especially interested in this subject.

IEAGHG will organise a workshop to discuss CCS plant operability. This will involve researchers working on modelling and design of CCS plants and modelling of future electricity systems. This may lead to IEA GHG setting up a network of researchers on this subject and organising technical studies.