The Government intends to rely on renewable electricity to meet the largest part of its renewable-energy targets, and for wind and other intermittent generators to supply most of that renewable electricity. To be precise, they have produced the following graph (p.44) indicating what they think the capacity of the various renewable-generation technologies will be in 2020 compared to last year:
Of this, output from the wind (onshore and offshore), some of the wave and tidal, and most of the small-scale projects will be inconsistent and unpredictable at more than short timescales. That makes up around 32 GW of the capacity envisaged for 2020.
Here is a graph of how our demand for power has varied over the past week, from National Grid's realtime data-display facility:
The vertical scale is in megawatts (MW, of which there are 1000 to a gigawatt, GW). As you can see, the peak demand last Sunday was around 34 GW, and demand at night-time is under 30 GW. So, even if we hypothetically switch everything else off (the nuclear, gas and coal-fired power stations, and the more reliable renewables like bioenergy and hydro), on a windy summer night we may be producing more power than the total demand in the country. And this is only a hypothetical, because much of that alternative capacity cannot just be run up or down to suit the weather patterns.
Conversely, under an anti-cyclonic system in winter, we may have minimal wind output (5% of capacity across the country) and demand of 58 GW or more. The unavailability of around 30 GW from intermittent renewables will not be helpful. The other technologies will want and need to charge very high prices at this time, as they will have to recover their capital and fixed operating costs over fewer periods when they can export, as they will be displaced by wind (etc) for a fair amount of the time.
But this is not good enough for the Government. It is altogether too unambitious. From p.41 of the Renewable Energy Strategy:
"In particular, in the case of offshore wind, our ambitions are for much greater levels of deployment than shown in Chart 2.3. Discussions with the offshore wind industry suggest that far higher levels may indeed be possible. Estimates of what is achievable are nearer to 20 GW and the Strategic Environmental Assessment recently undertaken for offshore energy indicates that a further 25 GW is feasible by 2020, in addition to that already deployed. In all cases, the estimated contributions for each technology in this lead scenario are in no sense an upper limit on our ambitions."
Note 30: "The figure of 25 GW relates to new capacity (on top of existing plans for 8 GW from previous leasing Rounds) in the UK Renewable Energy Zone and the territorial waters of England and Wales, in water depths of up to 60m. The Scottish Executive is in the process of assessing the potential for an additional 6.4 GW in Scottish territorial waters, which is subject to a separate SEA."
So that's 8 GW from previous rounds, plus 25 GW of new capacity around England and Wales, plus 6.4 GW around Scotland, plus the 14 GW of onshore wind already assumed and around 5 GW of other intermittent projects. That's 58.4 GW - coincidentally almost exactly the same as the highest level of demand achieved in any half-hour period so far this year. So 99.9% of the time, on a windy day under an "ambitious" scenario for the Government where all this capacity is developed, we would be producing more power than we could use, even if we shut down all other technologies. And for a good part of the year, there would be a risk of producing more than twice as much as we could use.
But that's just a detail. Governments can't let details get in the way of their ambitions.
AFTERTHOUGHT: What would this cost, if we were unlucky enough that they achieved this amount of capacity and found a way to absorb all the power produced? I'll come on to the question of the Government's assumed load factors in another post, but let's go with 30 per cent as an average across onshore, offshore and the other intermittent technologies. If so, they would produce 153.5 TWh (around 40 per cent of our total annual production), costing consumers around £6 billion a year, above the cost of generating electricity by other means. If those costs were divided evenly amongst the sectors in proportion to their share of electricity consumption, domestic consumers would pay around one-third of that, i.e. £2 billion, or £80 per household per year. Not too bad, but (a) that's just for the intermittent part of the electricity part of renewable energy, and (b) this does not take account of the effect that this amount of intermittent electricity would have on wholesale electricity prices. By forcing all other generators to ramp up and down to suit the intermittent generators, their production costs per unit would be increased dramatically. Unfortunately, it is not possible to calculate what the precise effect would be, but the Government's advisory Climate Change Committee have estimated that prices could vary from minus £30/MWh to plus £8000/MWh under much more benign circumstances than these (wholesale prices currently average around £50/MWh). And they have also calculated that we will have to expect some blackouts under those more benign circumstances of much lower wind penetration. The choice with this amount of wind on the system will be to have electricity prices an order of magnitude higher than at present if we want to pay for the standby power to prevent regular blackouts, or somewhat lower prices than that (but still much higher than we have been used to) and accept that the electricity won't be there all the time. Quite apart from the direct costs of higher bills, the costs to the economy of unreliable and expensive electricity will be massive.
Sometimes you wonder if Gordon Brown's answer to the inequality between rich and poor countries is to reduce Britain to the living standards of a third-world nation.