The Committee on Climate Change, under the chairmanship of Lord Deben, recently released its report entitled Power sector scenarios for the fifth carbon budget. As summarized in this Bloomberg article the report’s basic conclusions are:
- The U.K. can cut three quarters of the carbon emissions it’s producing from making electricity without driving up bills too much by deploying more clean-energy technologies.
- Investments that are planned in the power industry in the next five years already are sufficient to reduce the so-called carbon intensity of electricity to 200-250 grams of carbon dioxide per kilowatt-hour, from 450 grams today.
- Emissions below 100 grams are “an appropriate aim for 2030”.
The CCC report provides three scenarios under which this ~75% reduction in electricity sector emissions can be achieved by 2030 plus four other “alternative” scenarios that either exceed it or fall short. It’s impossible to review these scenarios in detail (the CCC report is 111 pages long and comes accompanied by another 68-page report entitled The Scientific and International Context for the Fifth Carbon Budget) so here I adopt a simplified approach that hopefully sheds some light on what these scenarios actually boil down to.
The key to electricity sector CO2 emissions reductions is of course the generation mix, and Figure 3 of the CCC report shows the 2030 mixes for CCC’s three “base” scenarios – high nuclear, high renewables and high CCS – all of which lower emissions slightly below the 100 gCO2 =/kWh target:
Figure 1: The Climate Change Committee’s three base scenarios for 2030
Because there is little difference between them I’ve picked just the first one – “high nuclear”, although it isn’t what I would call high – to play games with. Figure 2 shows three bar-chart versions of this scenario:
Figure 2: CCC’s “high nuclear” scenario segregated into “load following”, “intermittent renewables” and “baseload” categories
“A” shows the chart as it appears in the CCC report but with the bars labeled so one doesn’t get eyestrain trying to match the colors to generation types.
“B” reshuffles the bars into three generation categories – Load following (gas and hydro), intermittent renewables (solar, tidal and wind) and baseload (biomass, CCS and nuclear).
“C” merges the individual bars into load following, intermittent renewables and baseload categories – hydro remains as a separate category for comparison purposes – and changes the colors for reasons that will also become apparent in the next Figure.
Back in July I published Decarbonizing UK Electricity Generation – Five Options That Will Work. These five options used nuclear to provide constant baseload capacity and gas as load-following capacity to balance increasing amounts of intermittent wind power against UK demand for February 2013, which I used as a proxy for February demand in unspecified future year 20XX. Figure 3 plots Figure 2C alongside my Option 3, which like the CCC scenario also achieves a ~75% reduction in CO2 emissions:
Figure 3: CCC’s 2030 generation mix versus my generation mix in February 20XX
By virtue of diligent analysis or sheer coincidence the CCC and I have independently come up with substantially the same generation mix, and having claimed that my generation mix will work it seems that I must now acknowledge that the CCC’s will too.
But I won’t, because it won’t.
Why not? Because my mix uses only proven generation technologies (I give wind the benefit of the doubt here) while the CCC mix includes a lot of what David Cameron could legitimately have called “green crap”.
What is the green crap? Once again I exclude wind, which although it arguably qualifies is the only viable option if the UK continues to insist on targeting high levels of renewables generation. But CCC’s scenario shows 20% of 2030 total generation (75TWh of 380TWh) coming from a combination of biomass, solar, tidal power and thermal plants equipped with carbon capture and storage. It’s generally accepted that a mix of different generation sources improves energy security, but what are the chances that by 2030 the UK will be generating 30TWh from CCS, which doesn’t yet exist as a commercially-viable technology and the way it’s going probably never will? And of what use is 20TWh of solar generation when almost all of it arrives in daytime in the summer when it’s not needed and none of it at night in the winter when it is? And why should 25TWh of biomass generation, which emits about as much CO2 as coal, be preferred over 25TWh of coal generation, particularly when burning coal consumes long-dead forests rather than living ones? And why should the UK spend £1 billion to generate 500GWh of wildly erratic tide power from Swansea Bay when it can generate maybe five times as much dispatchable power from a couple of new CCGT plants for the same money?
What we are seeing here is green pipe dreams trumping common sense. Replace these pipe dreams with nuclear and maybe a little gas and I could give qualified approval to the CCC’s 2030 generation mix and the UK’s fifth carbon budget. I say “qualified” because it would still look a lot better with a good deal less wind.