By Paul Homewood
Bishop Hill had a post the other day, about a presentation on climate change given to the cabinet by Chief Scientist, Sir Mark Walport, seen at right.
One of the slides shown was this one on various scenarios for electricity generation in the UK in the brave new world. (Sorry for the quality, the original is no better!)
So I thought I would have a closer look at one of the options, “Higher Renewables”, to see whether they made any sense. Let me first say that the presentation does not state when this is all targeted for, so I cannot make any comment about the likelihood of technology for CCS and marine (tidal) becoming available in time.
Total Demand For Electricity
Last year, UK electricity supply amounted to 354 TWh. Walport is projecting forward on a total of 530 TWh, an increase of 50%. This increase reflects the greater demand as domestic heating and transport are decarbonised.
The table below compares projected capacities with current, to give an idea of the scale of change envisaged.
1) Current solar capacity works out at about 0.2GW, so to get to 14GW would be an enormous increase.
2) I have not included Hydro, as this is not in the Walport list, but currently capacity is 4GW, and unlikely to change much. Also, Bio is missing, and this currently has a capacity of 3GW.
3) Nuclear – of the current nine sites, only Sizewell B is scheduled to still be operating after 2030, and this has a capacity of 1.2GW.
My understanding is that the proposed new nuclear at Hinkley Point will be 3.2GW, so to get to 16GW, we would need another four of that size.
4) Wind capacity would have to be increased tenfold.
5) The current capacity of gas is probably a little bit misleading, as much of it is old and mothballed. To get a better idea of the amount needed for back up capacity, gas power stations provided 27% of last year’s electricity supply. To supply this amount would require 13GW of capacity, assuming the plants were running at 85% utilisation.
Put another way, the projected gas back up capacity would be capable of supplying about half the UK’s total power, in other words quite a lot!
Let’s now look at the power we need to keep the grid running. Currently, power demand fluctuates between 30GW and 60GW. (See for instance here.) There have been odd occasions when hourly demand spikes at near 70GW, but let’s assume 60GW as a realistic requirement. If total demand increases by 50%, as mentioned above, we would be looking at a need for 90GW, and, with a safety margin, at least 100GW.
It is worth noting here that, while electric cars would normally be recharged overnight when demand is lower, domestic heating would normally be at its peak at the very times when electricity demand already peaks – i.e.winter mornings and evenings. This could mean that peak demand for electricity increases by more than the average of 50%.
So how does Walport’s mix of capacity stack up against this? The guaranteed capacity, excluding intermittent wind and solar, and for the sake of argument assuming hydro and marine * are continuous, would be:
|Balance needed from back up||51|
* The argument with tidal is that, although not continuous, it is predictable and therefore manageable
In other words, the 24GW of back up gas capacity, pencilled in by Walport, is less than half that is needed. The capacity of 51GW, that is actually required, would in fact be enough to produce about 380TWh a year, about 70% of the total UK supply!
This alone makes a nonsense of his calculations. But it gets worse!
What Happens When The Wind Blows?
Walport projects 82GW of wind power, but, as we have already seen, power demand will probably fluctuate between 45GW and 90GW. So, when the wind is blowing, wind may be able to provide most, if not all, of the power needed.
In which case, what happens to all of the other kit? Will nuclear operators be happy having their plant sat around doing nothing half the time? Of course not. Neither will any of the others.
The most likely scenario is the one we have now, whereby wind operators are paid to turn off supply. This would, of course, be horrendously expensive, but would also call into question why all this wind capacity had to be built in the first place. It would make much more sense scrapping all wind farms, and using gas to top up the other low carbon sources. I also suspect this solution would give a pretty low CO2 figure as well.
Quite simply, Walport’s numbers just don’t stack up.
How often might wind run at near capacity? Research has suggested that wind works at over 50% capacity for about 20% of the time. This figure would probably rise as more offshore wind comes on stream.
So, there will be plenty of days when wind will be able to supply most or all of the power needed.
(The same research suggests that wind runs at less than 29% capacity for half the time, and below 10% for an eighth of the time).
1) Discussing tidal power, the Committee for Climate Change say, “Even at a social discount rate (e.g. 3.5% and declining over time as in HM Treasury’s Green Book), tidal range is expensive relative to wind and nuclear generation”
2) Imports/Exports can provide a certain amount of flexibility, always assuming we can find someone who wants all our surplus power, or has plenty for us when we need it!
However, net imports are a relatively low figure as far as the Grid is concerned. For instance, the French ICT typically imports about 1GW.
Let us assume that it is logistically and technologically possible to build the capacity that Walport wants. Even then, on a number of counts, his numbers simply do not stack up.
I may be missing something, and maybe he has all the answers up his sleeve. But there is certainly no evidence of that in his presentation.
Which all rather raises the questions:
1) How does the government’s Chief Scientist manage to come up with such an obviously flawed piece of work? He may be no expert on electricity supply, but there again neither am I, and it did not take me long to spot the obvious flaws.
2) Was there not one Minister sat around the Cabinet table, who had the gumption to ask some of these questions? What about Ed Davey, who is supposed to be Secretary of State for Energy & Climate Change?
It has often been said that we only have a Secretary of State for Climate Change now. I guess this whole charade rather proves that this is true.