ONE DOES NOT have to work in electricity supply to recognise how electricity supports almost every aspect of our lives. There would be no modern financial services, no food storage, no instant power and light, no innovative surgery, no rapid communications or entertainment etc, etc. Electricity has to be available twenty-four hours per day, throughout the year. Starting in the 1880’s, for the first one hundred years, coal was the dominant fuel for generating electricity, later supported by hydro, nuclear power, oil and natural gas. All these systems are amenable to control by the generating companies. Their outputs are adjusted to suit our changing needs through the year.
Some twenty-five years ago, a major innovation began. As part of the policy to reduce greenhouse gas emissions, renewable power generation equipment was added – mainly wind turbines, but latterly also solar panels. There are now more than ten thousand wind turbines on the uplands and around the coast and on favourable days they can produce 6000 MW – 30 per cent of our electricity if demand is low. Unfortunately, on unfavourable days, their output can decline to very low levels. Their output can vary over a range of 100 over two days i.e. from 5000 MW down to 50 MW.
There have been three periods already this summer – two separate weeks in June and now the first week in July, when anticyclones have brought very low wind speeds and hence very little renewable electricity generation. For the past week (starting Wednesday 4th July), wind power has been providing on average only about 2 per cent of our electricity. The argument is sometimes put forwards by its proponents that “the wind is always blowing somewhere so we can generate and store the energy in batteries from days of high output and release it on the calm days”. That can be true in unsettled weather, but high pressure anticyclones can affect all of the UK and in some cases almost all of Northern Europe. More importantly, if there are several periods of calm weather with typical levels of demand and no large low pressure periods in between, there is no surplus energy being generated to store in batteries.
A typical household may use 4000 or 5000 kWh per year. Usage varies, but it can be easily 15 kWh per day in the winter. The largest battery in a Tesla car is rated at 90 kWh. It could provide power therefore for a typical family for only six days. As recent experience shows, one week is a valid period of time over which wind power output is very low for several times per year. The cost of batteries have fallen by 50 per cent in recent years, but the Li-Ion assemblies of Tesla cars are still in the range £5,000 to £10,000. Even if surplus power could be guaranteed to be generated at the most opportune times throughout the year, the cost would not be affordable for most people.
The government has announced its plans to phase out pure petrol/diesel private vehicles by the year 2040. The replacement electric vehicles will require electricity in place of liquid fuel, necessitating increased electricity generation. This could be a thirty percent increase depending upon the size of replacement vehicles. It has also proposed the progressive replacement of domestic gas central heating systems by electrical heating. Such a change could easily double the quantity of electrical energy needed every year.
Our society faces a similar challenge of storage to maintain water supplies. We have little choice however other than to build reservoirs and hope that the rain arrives in sufficient quantity in the winter to provide for our needs in the dry summer. We cannot produce water. Electricity is different however, we do not have to increase our dependence and invest billions of pounds on an unreliable electricity generating system – renewables that have to be backed up by some form of controllable power plant. We can increase our generation from nuclear power and continue to build gas-fired power stations with ever improving thermal efficiency.
The drought this summer is revealing our vulnerabilities in many aspects of modern life. We must not let the evidence about the failure of renewable electricity go unheeded. It would be particularly useful if the BBC relaxed its obsequious attitude to the renewables industry and reported on the failure of wind power to meet its expectations for the third time in less than two months.
Paul Spare CEng FEI FIMechE