Germany’s large amount of wind and solar power gives us a clue of what will eventually happen to UK energy markets. With over 60 gigawatts of capacity from wind and sun renewables can provide a large fraction of German electricity needs across the year. A windy week cuts average power prices nearly in half.

The chart below shows how the average day-ahead power price in Germany fluctuated during the thirteen weeks of January, February and March. The weekly cost of wholesale electricity has been as high as €45 a MWh and as low as €25. (These figures are well below the equivalent UK figures, which averaged about €60 during the period).

The variation in wholesale price has been driven by changes in the average percentage of electricity provided by wind and solar during the week. This has swung between 8 and 27% of  electricity supply over the three month period.  Peak wind weeks have been associated with average power prices well under €30.

A CCGT power station needs to spend €30 just on fuel to generate a megawatt hour. The downward price pressure imposed by wind is making gas generation particularly unprofitable.The first three months of 2014 have shown just how destructive wind and solar can be to the finances of traditional power sources. Even nuclear power stations, which cost no more than €10 a MWh to operate, have been affected.

German power prices Weeks 1-13 2014

(Original data from the wonderful people at

During the first quarter of the year power prices went close to zero at some point during almost all Sundays, when power demand is at its lowest. On two days, Sunday 16th February and Sunday 16th March, prices fell to minus €50 for several hours. These negative prices arose because of forecasting errors of 2 and 3 GW. In the context of available wind generation capacity of more than 30 GW, these numbers are not large: errors of more than 1 GW are not uncommon in the UK which has about a quarter as much wind power as Germany. Power prices in countries with large amounts of variable renewable capacity are becoming hugely sensitive to unexpected small changes in electricity production.

staffs sunny schoolsThe government’s new plan for solar wants the south facing roofs of public buildings covered with PV panels as quickly as possible. The 22,000 schools in England and Wales are a particular target.

Two communities are currently raising money for schools in their area. Staffordshire Sunny Schools  is raising about £1m to put an average of 40 kW of panels on 25 primary schools. Plymouth Energy Community is looking for £0.5m to match a loan from the local council that will see PV installed on about the same number of schools.  The two schemes are both proposing investor returns of about 5-6%, as well as discounted electricity for the schools and large amounts of cash devoted to local energy efficiency schemes. Both these companies will happily accept investors from outside their area.

Staffordshire and Plymouth will benefit from EIS eligibility, meaning that taxpaying investors will get 30% back in reduced income tax bills. EIS also avoids inheritance tax, which may be a worthwhile additional benefit for investments that will deliver value for the 20 year period of feed-in tariffs. Read the rest of this entry »

The Renewable Energy Foundation, an anti-wind body, has complained again about payments made to wind farms when the National Grid is facing an inability to ensure that all wind electricity can be used.

In March 2014, the Grid made payments of about £8.7m to wind operators. REF portrays this as part of a ‘steadily increasing trend’.

It may be useful to throw some extra facts into the ring.

a)      During March 2014, wind supplied about 2 TWh of the UK’s total need for electricity. The percentage of total wind output that was not used was about 5%. This was a high figure for the UK: for the first quarter of 2014 as a whole, the figure is about 1.2%. January and February saw constraint payments for wind output of approximately 0.5% of the electricity generated.

b)      There is no ‘steadily increasing trend’ over time. March was relatively high, February very low. (And February’s wind power output was one of the highest ever monthly figures). In the four most recent six month periods recorded by the National Grid, the percentages have been 1.4%, 2.1%,0.9% and 0.3%. (These figures are from April 2011 to March 2013).

c)       REF complains about industry behaviour, saying it charges too much money for agreeing to curtail output. The average charge was about £80 per MWh in March, well down on typical figures for previous years. And REF may not be aware that National Grid payments for curtailment are usually the outcome of auctions. The price isn’t set by the wind farm operators.

d)      Lastly, REF ignores the real problem, which isn’t the wickedness of farm operators or the fickleness of the wind. It’s the lack of reinforcement on the pylon lines from NW Scotland. But by late 2015 the improved line from Beauly to Denny will remove much of the constraint on wind farm output in northern Scotland. In the meantime, probably including last month, the continuing construction work on the line (which already carries electricity), means that more curtailment than usual needs to take place.

As always, the UK is coping well with the variable nature of wind power and curtailment costs add very little to the average bill. My estimate is that wind curtailment has cost a domestic customer about 25p a year.

Ofgem has asked the Competition and Markets Authority (CMA) to review the workings of the UK energy market. As a result, we’re now in for three to six years of investigations, draft decisions and endless appeals. The energy firms will spend £10m a year on City lawyers contesting every single paragraph that the CMA produces and little will eventually change. Regulatory processes in the UK stink.

Let’s look on the bright side. The document setting out the reasons for Ofgem decision is really clear, well-written and comprehensive. But it’s 120 pages long. So here are some of the most striking factoids that back up Ofgem’s conclusion that the Big Six aren’t competing effectively in supplying domestic customers. Read the rest of this entry »


Cool Planet's core technologies

Cool Planet’s core technologies

Nature had a recent article on the poor health of advanced biofuels companies in the US. Entitled ‘Cellulosic  ethanol fights for life’, the author took particular aim at the new Abengoa refinery in Kansas that uses enzymes to break up the complex cellulose molecule into sugars that can then be fermented into ethanol.

The Abengoa plant was expensive to build, is one mile square in size and probably produces ethanol from cellulose at a cost that makes it uncompetitive with first generation corn ethanol plants. Nature may have been right to be gloomy about its prospects.

But this doesn’t mean that all the companies intending to make fuels from cellulose – the most abundant organic molecule in the world – suffer from similar problems. Actually, 2014 may see greater advances in the production of low-carbon biofuels than ever before. After nearly a decade of failure, it looks increasingly likely that cellulose will eventually become a useful source of transport fuels around the world. Although Abengoa may have built a refinery that embodies a technological dead-end, others such as the extraordinary Cool Planet, may show that low-value plant matter is capable of being turned into fuel that can compete on price with fossil fuels. And Cool Planet is also turning out large volumes of biochar as a by-product. I think this is one of the most interesting companies in the world. Read the rest of this entry »


George Monbiot points his critical attention to the increasing use of food crops in the UK’s anaerobic digesters (AD). These huge green cylinders, usually on farms, take organic matter, expose it to bugs that have excrete enzymes that eat cellulose and starch in the absence of air. The bugs produce a mixture of methane and carbon dioxide as an output. This ‘biogas’ that comes out of AD plants is burnt in an engine to produce electricity.

Many digesters use the human waste from water treatment plants or from animal slurry while others take waste from food factories or from doorstep collections. But increasing number of AD plants are using maize and other food crops because the simple starches in these ingredients break down very well, creating more cubic metres of  valuable methane gas than, for example, the more complex molecules in cow manure. Many UK AD plants – built to digest municipal waste, for example – are now boosting their yields by mixing in maize that would otherwise have been used as food for animals or people.

Does it make sense in energy terms to grow maize (or even wheat) as a feedstock for a digester? No. The energy value of the methane that is produced in an AD plant, converted into electricity via a gas engine, is about 0.4 megawatt hours per tonne. This is approximately a tenth as much as the calorific value of maize to a human being.

This isn’t the whole story, since the digestate left behind after the energy has been extracted in an AD plant does have some value as a replacement fertiliser when it is reapplied to the fields. Nevertheless, putting maize into an AD plant to make energy involves a huge loss of calorific value. And the climate change implications also need considering: as well as the energy used in the Haber Bosch process the high levels of nitrogen fertiliser used on maize land produce large amounts of nitrous oxide, a powerful warming gas.

Monbiot has also recently shown the other cost of growing maize for AD: land used for maize has low water retention capacity in winter. The recent floods on the Somerset  Levels were exacerbated by the large areas of adjacent land given over to maize. If, instead, these hectares had been planted with short rotation coppice, such as hazel or willow, more water would have been stored in the soil. And, second, the energy value of the harvested wood, converted into pellets for use in domestic wood burners would have been about twice as great as the energy captured from the same area given over to maize for anaerobic digestion.

There are no good arguments for using productive food land for maize that is then pumped into an AD plant. (AD plants may get more effective at conversion of cellulose in the future and this might affect the universality of this assertion). Read the rest of this entry »

energy houseThe Salford Energy House is a remarkable laboratory. A reconstructed 1919 end-of-terrace dwelling, it sits within a completely insulated warehouse on the university campus . External temperatures can be precisely adjusted. Simulated rain falls from the ceiling onto the roof of the house. Wind is mimicked by giant fans. 400 measurements can be taken every minute.

Researchers are able to make large and small changes to the house (such as opening or closing the curtains) and measure accurately what the impact is on energy consumption and internal temperatures. This is the only place in the world, I was told when I visited a couple of weeks ago, where the real impact of energy-saving measures can be exactly calculated.

Commercial companies can use the house for experiments. The building products company St Gobain recently released some details of the work it has carried out on the Salford house. Although the published data is very sketchy, the headlines suggest that external wall insulation can be much more effective than some other estimates would suggest. When St Gobain put insulation on the outside of the end of the house and the back wall and also added internal insulation on the front wall, it reduced heat loss by almost 50%, saving over £250 a year. This is about three times what the latest government data suggests. The reasons will include the care with which the St Gobain staff installed the insulation and the quality of the product. Read the rest of this entry »


Today’s provisional energy consumption figures from DECC suggest a striking improvement in energy efficiency in 2013. The key ratio of primary energy use to UK GDP improved by about 4%. Expressed another way, energy consumption in 2013 fell by 2% as the economy grew by about 1.9%. This ratio has improved an average of 2.8% a year since 2000, suggesting that the rate of efficiency improvement may be increasing.

Whatever else the UK is doing wrong in energy policy, there’s little doubt that overall energy use is tending to fall quite sharply. Much of this improvement may be driven by rising energy prices. In recent years, the rise in wind power production has also helped; a turbine’s usable power is nearly as much the primary energy it produces but it takes about two units of input energy to make one unit of electricity from fossil fuel. This effect alone represented one percentage point of the decrease in total (‘primary’) energy use. Nevertheless if the UK returns to the average growth rates of pre-2007 of around 2-2.5% a year, total energy use seems likely to continue to fall.

Primary Energy production

Tesla snapTesla isn’t just a car company producing the world’s best regarded electric vehicles. It’s also driving forward a network of very fast chargers (20 minutes or so) across the US and its other important markets such as Norway. And, lastly but most significantly, it is changing the economics of battery storage.

Nobody quite knows how far Tesla has pushed down the price of batteries but some commentators suggest that the business is already paying less than $250 a kWh for its lithium ion rechargeable packs. At this price, it might almost makes sense to use Tesla batteries to store domestic solar power. And, tagged on to the end of the annual letter to shareholders written last week, the company confirms that its ambition is indeed to provide electricity storage for solar PV installations as well for its cars. Read the rest of this entry »

All machines get less efficient as they grow older. Wind turbines are no exception to the rule. A new study shows that a turbine has an average ‘capacity factor’ of 28.5% when new and this falls to about 21% in the nineteenth year of its life. (1) This finding implies shows that the average wind farm loses just less than 1.6% of its expected output for each year that passes. Over a twenty year working life, a turbine will therefore produce about 12% less electricity than predicted by the manufacturers. Some of this decline is due to the turbine being out of action and awaiting maintenance more frequently later in its life. Another reason is simple wear and tear.

These results are very different to those obtained by Gordon Hughes and published in late 2012. Hughes said that the rate of decline was very much faster, calculating that typical output of a wind farm halved by the fifteenth year, implying a rate of decline three times the speed of the new study. Hughes didn’t use estimates of actual wind speeds and experts such as DECC Chief Scientist Professor David MacKay have strongly criticised the statistical techniques he employed. Read the rest of this entry »

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