Introduction

This report was commissioned as an internal study of the issues and potential for integrating renewable energy technologies with carbon capture and storage. A prime purpose was to identify possible areas for further study by the IEAGHG R&D programme. Both CCS and renewable energy sources will be integrated into the overall energy system by virtue of their being connected to the same electrical distribution system. The subject of this report, however, is possibility for deeper and closer integration at the level of individual power plants with a view to enhancing overall performance.

The report gives insights into some of the issues which closer integration would need to address and highlights a number of reasons why such integration may not be particularly effective or efficient. The conclusions of this first scoping study are thus not encouraging but this should not be taken as being in any way a criticism of the individual technologies. The study documents a number of possible types of integration but the list should not be considered as exhaustive.

Conclusions

Of the high temperature CSP applications only the central tower raising steam as working fluid seems worthwhile as a partner to a CCS plant utilising hydrogen produced from coal or natural gas with CO2 capture. Even this option makes rather less efficient use of hydrogen than a stand alone pre-combustion CCS plant. The cost would be significantly higher than that of using natural gas as backup fuel because of the cost of the conversion equipment and the energy losses during conversion. The scheme would work best if coupled with a hydrogen store. Because of the high cost the support to the solar systems should be limited to the minimum needed to prevent undesirably fast thermal cycling and for provision of essential power requirements during hours of darkness. Longer periods of support may be better provided by thermal storage systems. Given that direct use of the fossil fuel without capture would be cheaper any decision to use hydrogen derived in a Gasification/CCS process in this way would depend on the importance attached to minimising greenhouse gas emissions.