the climate brief Accurate Reporting of Climate Science

Christopher Booker proves that wind energy is intermittent

• 15 Aug 2012, 13:35
• Robin Webster

Wind power is a variable energy source and we need to be able to get power all the time. So how much will it cost us increase the amount of power we get from wind in the UK, and will our energy system be able to cope?

This week, Christopher Booker argues that our national energy policy is "a shambles" because it is "wholly focused" on the prospect of getting power from wind. He says:

"At one point last week, Britain's 3,500 turbines were contributing 12 megawatts (MW) to the 38,000MW of electricity we were using. (The Neta website, which carries official electricity statistics, registered this as '0.0 per cent')."

Wind power varies - some days are windier than others. This is Booker's point. Sometimes, when it isn't windy, the amount of power produced from wind turbines can be very low.

This means, he argues, that wind power is much, much more expensive than other electricity-generating technologies. As well as building wind turbines, he says:

"...we would have to build dozens of gas-fired power stations just to provide back-up for all the times when the wind is not blowing at the right speed."

Balancing intermittent power production from power sources like wind does require energy from a range of other sources, and that costs money. But does it require as much expensive gas plant as Booker suggests?

Gas turbines - open cycle and closed cycle

At the moment, the data shows that the UK gets electricity from two kinds of gas turbine, coal plants and nuclear plants, and a certain amount of power that is shunted back and forth along interconnectors to the Netherlands, France and Ireland.

As the amount of wind on the grid increases, it becomes more challenging to back up.

In order to support his argument that gas backup will be very expensive, Booker uses the conclusions of a report published by climate skeptic think tank the Global Warming Policy Foundation in March. We discussed the work, written by Professor Gordon Hughes, last week.

Hughes projected costs for wind an " order of magnitude" higher than he did for his alternative scenario, in which gas is used to produce electricity. Why?

One reason is that he doesn't include the costs of the fuel (gas) in his gas scenario, arguing that they are not particularly significant. Hughes also argues that wind power will have to be backed up by less efficient gas plant known as Open Cycle Gas Turbine (OCGT) plant, instead of the more modern and efficient Closed Cycle Gas Turbine (CCGT) plant, because OCGT are more flexible and responsive, and designed to start and stop generating electricity quickly.

In oral evidence to the Energy and Climate Change Committee, Rob Gross of Imperial College disagreed with this interpretation. We asked the National Grid, which is responsible for ensuring the grid copes with changes to the energy system over the next few years, whether this was a reasonable contention. It replied:

"When we call on generation for balancing we are obliged to do this in the most cost effective way. It would be highly unlikely to be OCGT which is relatively expensive and small scale."

In contrast, renewables trade body RenewableUK estimates that large-scale wind rollout would allow CCGT to be used. This is because single windfarms' output is more variable, so OCGT backup would be necessary. It says, however, that once you get into using large amounts of wind across the system, CCGT backup is possible as output is more balanced.

So unless Professor Hughes knows something that everyone else doesn't, this probably means the GWPF report overstates the cost of providing backup to wind power.

According to Imperial College, the 'intermittent' nature of wind has been "comprehensively studied by academics, utilities and consultancies from around the world". Imperial concludes that the cost to households from intermittency in 2020 is likely to be around £6-£8 per year, far less than Hughes's estimate. Imperial bases its conclusion on an assessment of all the data it collected in 2006.

The energy consultancy Poyry undertook a study in 2011 for the government's decarbonisation advisers, the Committee on Climate Change, which also concluded that the electricity system would be able to accommodate high levels of renewable generation up to 2050.

Genuinely worried?

Intermittency aside, Booker's worries about the UK's shambolic energy policy's ability to deliver enough power sound more reasonable.

Estimates from - among others - the National Grid, the Committee on Climate Change and the energy regulator Ofgem - suggest that the UK could meet its renewable energy and climate change targets without jeopardising the country's reliable electricity supply - it's technically possible.

But experts have recently raised concerns about the government's progress. UK energy policy has often been characterised by delay and dithering - and if this continues, then Booker's worries about the lights going out might be on more solid ground.

Energy geek out
           
For those of you still reading, this is a good opportunity to do a serious energy geek-out and introduce you to a really interesting source of energy statistics referenced in the Sunday Telegraph article.

The Neta website, which Booker cites, provides half-hourly information on how much power is produced by all the different power sources in the UK. This chart, for example, shows the amount of power generated from wind for the past 24 hours or so:

Source:  Neta website, screenshot taken 10:12, 14/08/12. Each bar refers to one half hour period. Yellow bars are the initial prediction for the amount of electricity the wind will produce; green is the most recent prediction; the red line is the actual reading.

At the time of writing, Neta says that wind power generated 28023 megawatt hours of power over the last 24 hours, or 3.4 per cent of the UK's total output.

It looks as though it hasn't been that windy over the last day or so. According to official statistics from the Department for Energy and Climate Change (DECC), wind power generated 15.75 TWh of electricity in 2011 - 4.3 per cent of the total output in the UK (see p.135).

Source:Neta website (screenshot taken 10:14, 14/08/12) Table shows wind power generated 28023 megawatt hours of power over the last 24 hours. NB. Image has been adjusted so that figures are aligned in the table.

The Neta website also gives the raw data for production of energy all the way back to 2008 (login required). The data is released quarterly - last week's isn't available yet, but we looked at the most recent data covering May to June.

During this period, the data shows that wind power is indeed an intermittent power source. Over the three months, the amount of power generated by wind per half-hour varied from almost nothing up to around 3500 megawatt-hours - producing an average of 1041.9 megawatt-hours per half hour period over the three months.