Professor Barry McMullin:

Battery storage has a role but it is for the short term - maybe for less than one day. To eliminate the need for natural gas as a backup to electricity generation we need to be able to shift from weeks to months. There are three orders of magnitude and the scale required is a factor of 1,000. The role for batteries is not the same as the role for long-term storage. The only plausible routes are synthesising chemical fuels from electricity. This means we generate renewable electricity from wind and solar when the wind is blowing and the sun is shining and we overbuild the capacity relative to instantaneous demand so that we can put the surplus into storage for when the wind does not blow etc.

I do not know if I am optimistic or aggressive but given the challenge and the urgency, we have to press ahead. The natural gas route, including fracked gas, is too short so we have to proceed with all possible speed. The basic technologies for producing hydrogen from electricity are well proven, well known and well established but the technologies for storing hydrogen at progressively larger scales, while the basic research is well developed, require pilot deployments before full-scale deployments. Medium-scale to large-scale hydrogen synthesis facilities are already being built in northern Germany. This could be rolled out in the next decade but it requires a policy imperative and we need to say it is a national priority. It will involve projects of common interest and critical national importance and we should look in particular at chemical storage, particularly if we continue to say "No" to nuclear deployment. Carbon capture and storage, CCS, makes sense if we are willing to blinker ourselves to the upstream emissions on the basis that they are the responsibility of some other country, although it is expensive. We are all living on the same planet, however, so there is no such thing as somewhere else - the upstream emissions go into our atmosphere. CCS for fossil fuel mitigation is not a good story, in my view, though we will need it, largely because we are going so fast in the wrong direction and we will end up having to suck carbon dioxide back out of the atmosphere. CCS is a key enabling technology for that purpose although for continuing to burn fossil fuels it is not so positive.