Matt Ridley wrote an article in The Times (London) on 24th October, suggesting that using batteries for long-term energy storage is both expensive and impractical. Several people wrote to me about this, asking about its accuracy. The Times never publishes factual corrections so I thought I would quickly write down some of the mistakes in the piece.

a) Batteries don’t currently cost $410 per kilowatt hour. When GM announced its Chevy Bolt electric car in autumn of 2015 it said that the battery cells it would employ were costing $145 a kilowatt hour. This is about a third of the number Matt Ridley used, although the GM figures excludes the cost of combining the cells into full battery packs. However the cost of batteries is continuing to fall sharply and the largest suppliers are suggesting that a figure of $100 a kilowatt hour is within sight, perhaps within a couple of years. Mr Ridley is several years out of date.

b) Matt Ridley says that batteries are more expensive than 'pumped storage' for storing electricity. (He also writes that 'piles of coal' would be better). The most developed proposed new scheme in the UK is at Glyn Rhonwy in Snowdonia. The latest costing for this 500 MWh site is £160m, or about £310 a kilowatt hour. This is about twice the price of electric vehicle batteries today. Matt Ridley also writes that pumped storage ‘wastes’ less than batteries. I presume he means that the energy losses are smaller when charging and discharging. But Glyn Rhonwy will have a net energy conversion of ‘more than 75%’.[1] The batteries in a Tesla Powerwall have 92.5% efficiency. Mr Ridley is therefore wrong.[2]

c) Matt Ridley refers to Professor David MacKay’s estimates of the UK’s need for storage to cope with wind variability. He suggests that the country would need to spend £130 billion to cope with the erratic power produced by turbines. What MacKay said was actually ‘There is thus a beautiful match between wind power and electric vehicles. If we ramp up electric vehicles at the same time as ramping up windpower, roughly 3000 new vehicles for every 3 MW wind turbine, and if we ensure that the charging systems for the vehicles are smart, this synergy would go a long way to solving the problem of wind fluctuations’.[3] The key point is that a large number of electric vehicles will help us stabilize the grid without any need for dedicated batteries. (And even if we did need batteries, the cost would be far lower than Ridley says because the cost has come down so much in recent months and years).

d) Energy return on energy invested. Ridley makes the point that renewable electricity sources such as wind turbines and solar panels require energy to make. If this energy cost is greater than the energy they generate, there is no point in building them. We are all agreed on this. But he then goes on to assert that solar panels never pay back the energy used in manufacture. This particular story resurfaces depressingly often and is complete nonsense. The typical solar panel, even if it spends its 35 year life in dull old UK, creates far more electricity than is used to make it. Energy payback times for PV are falling all the time but even conservative estimates suggest a 10 times payback.[4] As silicon gets thinner and more efficient this number is rising rapidly.

e) Elon Musk’s Gigafactory. Matt Ridley mentions Musk’s new battery factory in Nevada. This will make more batteries in 2020 in a single location than were made in the entire world in 2013. Ridley’s figure for the output of the factory is wrong by a factor of 3. By 2020, the Gigafactory will be producing 150 gigawatt hours a year of batteries for cars and for energy storage, not the 50 gigawatt hours he claims. I won’t comment on his suggestion that Elon Musk is operating some sort of pyramid scheme to draw subsidy out of the US government. If the world had more entrepreneurs like Musk the problems of climate change would be a lot more manageable.

f) Ridley says that the cost of electric cars is ‘huge’, although he agrees they are quiet and non-polluting. The current price of EVs is indeed higher than equivalent petrol cars, but the difference is far less than the annual difference in fuel costs over the typical 15 year life of a vehicle. The BMW i3 offers nearly 200 miles of range for less than £28,000. Compared to petrol models, this price cannot be called ‘huge’.

g) He also slams electric cars for taking a long time to charge. However the BMW referred to in f) will fill from empty to full in less than 40 minutes at a fast charging point in the UK.

h) And, lastly, he tries to suggest that an electric car is likely to set itself on fire if it charges quickly. (He uses the recent history of new Samsung phones as justification for this assertion about electric cars). While it is true that a small number of Tesla vehicles have had fires, the chance is almost certainly less than for petrol cars. Yes, batteries can malfunction but petrol is a far more dangerous fuel than electricity.

As far as I know, no-one other than Mr Ridley has ever actually suggested that batteries will be used to meet the need for long-term storage in high latitude countries such as the UK. The role of batteries here will be to help match supply and demand in the electricity system and to provide some overnight electricity. Britain will manage seasonal storage need in different ways, such as converting surplus electricity into methane in summer and at times of high winds.

Addendum 27th October. In another slighting remark about Elon Musk, Matt Ridley states that some analysts believe Tesla is 'burning through $1bn a quarter'. The company has today released its latest quarterly report. In q3 2016, showing a net positive free cash flow of $176m. Only about $1.2bn out Mr Ridley..

(This article was corrected at 11am on 26.10.16. I changed kilowatt to kilowatt hour when describing the cost of the Bolt's batteries).

(Further correction, 12 noon on 26.06.16. I changed 'smaller than' to 'greater than' in describing the energy return on energy invested calculation.)

[1] http://www.quarrybatterycompany.com/docs/QB_FACTSHEETS_ENGLISH.pdf

[2] https://www.tesla.com/powerwall

[3] Page 195 of the online edition of Sustainability – Without the Hot Air

[4] http://rameznaam.com/2015/06/04/whats-the-eroi-of-solar/