MOST OF THE UK has seen ten days of ideal summer weather, with a settled anticyclone producing little rain and daytime temperatures consistently in the range 20-25C. It may be the holiday season, but industry and commerce continue to function. Peak electricity demand is about one third less than the winter maximum, but is still 36 to 37,000 MW.
This stable weather has little effect on most power plants but it has revealed the weakness of an energy policy that is evermore reliant on renewable power. Unfortunately, the risks to electricity supplies posed by our support for renewable energy are not recognised by most media commentators and are effectively hidden from the public.
Our society is accustomed to electricity supply security of at least 99.9 per cent, i.e. a power loss of only about one hour per annum. An infrastructure that is dependent upon electronic information, robotics and electrical power for ever more transport is totally incompatible with an unreliable electrical generation network that depends upon the vagaries of the weather. It is the weather that controls the quantity of renewable energy and it has recently revealed its drawbacks in no uncertain terms. Since the end of May, wind power – our primary renewable power source – has revealed its “famine or feast” nature.
Starting on Wednesday 30th May, wind turbine output has been in the doldrums and the episode, now nine days, will probably extend to two weeks. Apart from Monday night and Tuesday morning, aggregate wind output has hovered in the hundreds of MW – even declining below 50MW for a time on 3rd June – less than 0.2% of electricity demand. During this period, when the ten thousand wind turbines were almost all stationary, we were reliant on imports of almost 2,000 MW continuously from the French nuclear stations to prevent power cuts.
When conditions were favourable earlier in the year, the wind contribution reached 30 per cent and the PR forces were proclaiming its success in newspapers and the BBC. Why is it excused scrutiny when its performance is so abysmal? What other sector would receive such favourable treatment… not the railways, nor the banks, not the water supply or gas? Since its true failings are not exposed, green activists and politicians of all parties continue to maintain the illusion that its further expansion is desirable and inevitable to achieve CO2 reductions.
Our present policy of encouraging more wind turbine construction is courting disaster. After Brexit, our access to French electricity may be curtailed. Some backup to wind is still provided by the remaining coal plants, but the UK has agreed to phase out these coal plants by 2025. We still operate 8,000 MW of nuclear plants but the oldest will be retired in 2023, then all but Sizewell B progressively. Since some backup mechanism for renewables will be as essential in the next decade as it is now, more Combined Cycle Gas turbine (CCGT) plants will be needed.
Unfortunately, the operating privileges allowed to wind farms reduces the number of hours that the gas-fired plants can operate and earn income to cover their investment costs. As a consequence, very few new plants are being constructed. The most secure way to reduce carbon emissions from electricity generation and backup wind failings would be to replace and expand the nuclear fleet. The long planning and construction times involved discourage such investments, although Hinkley Point C and Wylfa are positive signs.
This collapse of wind-generated electricity occurs relatively frequently.
Analysis of nine years of wind turbine performance by Dr Capell Aris of the Scientific Alliance in 2015, revealed the following statistics, showing that the collapse of wind power is a regular event.
· Power is below 20 per cent of nominal rating for 20 weeks of the year (more than a third)
· Power is below 10 per cent of nominal rating for 9 weeks of the year.
· There are also many days in the year when output falls to less than 3 per cent of nominal output – including most of the last eight days.
Unlike water or natural gas, electricity cannot be stored on a large scale. The decline of wind power to one or two percent of its potential output for a period of a week represents a threat that effectively means its secure contribution is zero. Such a failure can be countermanded only by having backup of the same capacity of thermal plants. For all future wind turbine installations, it will be necessary to construct a parallel set of gas or nuclear stations to fall back on when the wind contribution is zero… or risk days of power cuts. This will double the cost of the investment for a very modest reduction in CO2 emissions.
Despite this evidence, the Climate Change Committee continue to recommend to the government not only that more renewable generation should be supported but that the transport sector should decarbonise its operations as quickly as possible by converting to electric vehicles.
Predicting the mixture of vehicles in the transport fleet twenty years ahead is very uncertain. It is necessary to make some broad assumptions but looking at an extreme case provides a boundary condition. If there were 30 million vehicles, with similar levels of performance to the present fleet, a significant increase in electricity generation would be needed - about 70 TWhr - almost 25 per cent of UK annual electricity consumption of 285 TWh. This is almost certainly an underestimate since most new electrical vehicle designs fall in the ‘high-performance’ bracket with larger motors and electricity demand than the vehicles they replace.
This energy would have to be generated in additionto the present output, but a repeat of the current weather conditions with low air speeds, would then expose transport to energy failure.
There are also proposals for electricity to be progressively introduced to replace natural gas in home and commercial heating. The energy consumed as natural gas outside of electricity generation is about 540 TWh. In this scenario, together with the transport component our electricity generation would have to increase at least threefold compared with 2018. Remembering also that every renewable scheme would have to be backed up by firm generation to prevent power cuts. National Grid in its modelling of Future Energy Scenarios has drawn similar conclusions.
The waste and futility becomes even more indefensible when the wider picture is examined. It will require the gas-fired boilers used in 85 per cent of homes to replaced by electrical heating – and subsequent rewiring to cope with the extra power use. At the same time, all the HV transmission and local distribution networks would have to be upgraded to handle three times the existing peak demand.
Last but not least, part way through the transition to a scenario with more wind power, all the older turbines will reach the end of their lives and have to be upgraded or replaced with no clear disposal route for all the scrapped turbine blades.
Environmentally friendly and efficient they are not.