To summarize: the plan is to build up to 26 GW of new gas capacity between now and 2030. This will result in a total gas capacity of 37 GW in 2030, 5 GW more than current capacity. The previous estimate of total new gas capacity needed was 10-20 GW, and DECC justify the new upper estimate by saying that projected population will be higher than expected (i.e. higher electricity demand) and the number of plant retirements also. DECC’s estimate of 21 GW of plant retirements appears to be about double earlier estimates. (this is from memory of DECC’s estimates. Certainly independent modelling suggested about half. See figure 8).
Is up to 26 GW of new capacity consistent with the UK decarbonising electricity by 2030? There is no straightforward answer to this, because it is very dependent on the amount of nuclear power on the grid and electricity demand. However, let’s consider a report published this week, commissioned by Greenpeace and WWF. This was principally looking at the economics of a high wind scenario versus a high gas scenario. To provide back up to renewables they estimated that the UK needed 36 GW of gas in 2030, 1 GW less than DECC’s projection. (see page 10 of the report.) I would view this as possibly a low estimate, because the reports authors assume 15.4 GW of interconnectors to help balance wind power. In reality this amount is not likely to be built and more gas is likely needed.
So, we can conclude that 26 GW of new gas is probably consistent with the level of renewables the main Green NGOs support (The report’s scenario appears to be 66% renewables, from a quick reading). A missing element however is nuclear power. This requires much lower levels of gas back up than renewables. The government does not plan for 66% renewables, but more likely around 40% renewables, 40% nuclear. This will push the needed levels of gas down. For example modelling by Poyrys for the CCC indicated that 8 GW of nuclear meant the amount of gas capacity needed would be reduced by 5 or 6 GW. (see figure 5) So, it looks as if 26 GW is probably only consistent with 2030 decarbonisation if Greens get their way and no new nuclear is built.
The other rather more alarming suggestion in the Gas Strategy is that the UK could build up to 37 GW of new gas capacity. And this is almost certainly inconsistent with 2030 decarbonisation, no matter what level of renewables you imagine.