Introduction

This report is largely based on a conference held by the GFZ in Potsdam on Geothermal Energy and CO2 Storage: Synergy or Competition, which was attended by Millie Basava-Reddi, IEAGHG. The aim of the report is to establish what the possible conflicts and synergies are between the geological storage of carbon dioxide and geothermal energy, and what further steps could be taken by IEAGHG. It should be noted that the conference was largely focussed on European issues and did not cover an overall global perspective. The major focus was also mostly on geothermal use for power generation, though some low enthalpy (heat generation) activities were also considered.

Conclusions

There are many similarities between CO2 storage and geothermal energy, especially in the way that exploration of the area takes place and the design process of the projects. Both technologies require detailed information of the subsurface and site exploration would be a similar process and so there are many opportunities for sharing of information.

Geothermal and storage activities will usually take place at different depths, but there will be the occasional conflict of pore space, which will need to be addressed at the time of site selection and characterisation.

For the two activities to work in synergy together appears to be possible, but has not yet taken place on a large scale and further study is required. Therefore knowledge of whether a site can be used for geothermal projects at a deeper level, especially in regards to EGS, after storage of CO2 has taken place, becomes very important.

There is likely, only to be a relatively small amount of real-life data regarding the possible synergies of geothermal and CO2 storage activities and any IEAGHG study would probably mostly focus on modelling. The only current projects or proposed projects are on a small scale and in only a few areas where it is possible for the technologies to work in conjunction with each other.

Induced seismicity has been experienced in some geothermal projects and the possible impact of CO2 injection on seismicity could be an area for future research.

Regarding public perception, CO2 storage may be seen in a more positive light if used in conjunction with geothermal energy.

Recommendations

More research is needed on the possible synergies and conflicts of geothermal activities and CO2 storage, especially in regards to using formations at different depths for different activities.

It is necessary to find out if there will only be niche opportunities for synergy or if it can be used more widely and be possible on a larger scale. It may be useful to carry out an IEAGHG study at some point in the future to explore this as there is currently much uncertainty and controversy in this area, however the lack of much real-life data would make this particularly challenging. Any study should also look how any joint projects could encounter issues such as induced seismicity and the public perception towards joint projects could be considered.

Also noted is that the conference attended gave an overall European perspective and so it could be useful to carry out further research to get a more worldwide perspective into the issue.

Overall it is felt that IEAGHG should continue to monitor the results from the Delft project in the Netrherlands and any other such projects members could make IEAGHG aware of. Then the need for a study in this area could be reconsidered at an appropriate time in the future.