The end of March is the year-end in a number of contexts, and as it supposedly marks the end of the winter period here in the UK (ignoring the brief flurry of snow we had this week) April is a good time to review the UK’s generation market.
It started with much excitement last April when National Grid announced we’d had the first coal free day since 1882. In fact a year later there has now been 3 such days and the average generation from coal across the year was 2 GW, equivalent to just one power station. For a system with a demand which ranges from 20-50GW, once dominated by coal which produced more than 70% of the power, this would seem an amazing achievement for the environment.
So coal is pretty much dead, right? Can’t be long before it’s gone completely, certainly before government deadline of 2025? Well let’s check that out by looking what it provided to the grid
Although there were 3 days with no coal generation, there were 5 days when it averaged more than 10GW. Given that there is only 13.5GW available that’s an average load factor of 75%. Crucially those 5 days were consecutive, making it extremely challenging to deal with. Let’s consider the options:
Demand Reduction. This should always be the first port of call. However finding 10+GW of energy efficiency or demand side response is very unlikely. It’s true that better home insulation should help, but only 9% of homes use electricity as their primary means of heat. More industrial energy management would help, but asking a factory to shut one of (or all of) its processes for 5 consecutive days with only a couple of day’s notice is likely to fail.
New Gas plant: The reason coal was running so hard those 5 days was that there was a shortage of gas. The UK was being blasted by unusually cold Siberian winds which had been nick-named the Beast from the East. All available gas was going to domestic boilers which were struggling to satisfy the demands of most residential thermostats set at 25 degrees above ambient. In the midst of this National Grid issued a “Gas Deficit Warning” – a plea to the market place to find more gas. The next line of defence would be to cut off supplies to large industrial consumers, starting with power stations. Therefore to suggest that some new gas power stations could fill the gap left by coal is foolhardy without first addressing the need to find more gas supplies. These could come from new LNG supply routes, new pipelines or new indigenous supplies (e.g. from Fracking), but all will need time to develop and will meet significant opposition (probably from the same people wanting to shut coal early).
New Oil or Diesel plant: The capacity mechanism has encouraged some new plant to come forward based on diesel “farms”. These consist of a collection of 19.9 MW diesel gensets (sized to avoid more onerous responsibilities associated with 20+MW plant) or gas turbines burning kerosene. The CO2 emissions from these are much worse than gas and only slightly better than coal, and other emissions like particulates and NOx are much higher and emitted much closer to the ground than a coal power station. These then are not a step forward but an expensive way to move sideways, or backwards from a clean air perspective.
New nuclear, marine renewables or Carbon Capture and Storage: By 2025? Really?
Biomass conversion: Drax has done great job of converting 2GW of coal plant to biomass, but they’ve had to build up their own supply chain from pelleting plants in the US, to complex transport arrangements involving river barges, trains, and trucks in the US, transatlantic ships and bespoke trains in the UK. Costly and time consuming to assemble, and if we were to convert the remaining coal to biomass that’s another 6 x what’s been done already. Is there enough biomass resource to cover that without utilising sources of increasingly questionable sustainability?
Interconnection: Although still importing the interconnectors dropped their supply by 500MW over the 5 days in question. Continental Europe was also in the grip of the Beast so was unable to supply more. The only interconnector which may help here is still under construction to Norway. It is however only 1 GW.
PV: Useful in the summer but not much help in these months.
Wind + Storage: The high density, cold easterlies were good news for our wind farmers which would suggest that a combination of wind and storage would be a good replacement for coal. Indeed a simple analysis of generation shows that wind plant was actually operating around 8GW during that period which is twice its average output. If we just consider energy production, the coal plant, averaging 10½ GW, could be replaced by adding 130% of our current wind capacity. Coal was no doubt using its headroom to provide some reserve and response services but adding 3 GW of storage (doubling our current pumped storage) would see to that.
There, sorted! We’ve designed a system that can cope with the Beast from the East and not overstretch the gas system. Well at least it would’ve coped with this last year.
Unfortunately that’s not the whole picture. The Beast was an unusual weather condition caused by the Arctic misplacing its polar vortex, which settled over Europe dragging in air from Siberia. If we look back to the year before we see another weather condition entirely, one that seems to happen once or twice a year (but not last year), and one that is no friend to windfarmers. This is the classic anticyclone, a cold still weather system with clear frosty nights that can sit over Europe for a week of more. The chart shows wind and coal output in January 2017. The 8 day dip in wind output (averaging 1 GW) is clear, meanwhile coal is running at 7-8GW, slightly lower at the weekend. It does not seem sensible to build 7 x current wind capacity just to get through one or two weeks a year, knowing that when it’s windy much of the energy will go to waste.
So isn’t this where storage saves the day? Well if it were just a day, then perhaps, but what we’re looking for here is an average of 7GW output for 8 days. That’s 1,300 GWh fully charged and ready to go. To put that in context we currently have 30 GWh of pump storage. Tesla have just installed the largest battery in the world in Australia. It can store 0.13 GWh, so we’d need 10,000 of those. So no, electricity storage is not the answer to this issue. The problem is that we’re trying to replace ½ million tonnes of coal, which is nothing in terms of coal stock but an awful lot of batteries.
So what is the answer? Well probably it will come down to a combination of some of the options above. A diverse solution: more biomass, a new interconnector, some demand reduction, a bit more wind and PV, a little storage, some diesel, fracking, more LNG, perhaps even a stay of execution for some of the coal? I can’t imagine anyone will be happy with that but at least the lights will stay on.
Fundamentally though we won’t have solved our long-term search for a low carbon firm supply of electricity. The quest for that continues.