Return to Website

Number Watch Web Forum

This forum is about wrong numbers in science, politics and the media. It respects good science and good English.

Number Watch Web Forum
Start a New Topic 
Energy storage for wind and solar power

Having followed the renewable energy malarkey for about the last 10 or 15 years, one thing that has always struck me is the lack of urgency and the lack of discussion about the important issue of storing energy from wind and solar power. The eventual Green dream is to have the entire world running largely on wind and solar power, and you might have thought they would have done a lot more by now in making moves to store the energy from it rather than just continue to produce electricity intermittently and 'piggy-back' on fossil fuel.

An important paper by Weißbach (Weissbach is I think the anglicised equivalent) was published last year which investigates the potential implications of a world run on wind and solar power. A blog post from the "Brave New Climate" (BNC) blog called "The Catch-22 of Energy Storage" gives a pretty good discussion of the paper, and includes a link to a free-to-view copy of the paper:


Weissbach looks at a parameter called EROEI, or energy returned on energy invested, the ratio of useful energy produced by a power plant over its lifetime to the energy expended in building and maintaining it. Normally this EROEI parameter only tends to be considered in the work of Green-leaning researchers, and previous research has tended to ignore the effect of including energy storage in the EROEI value. If you include energy storage in the EROEI for wind and solar power, it drops below a value of 7 that Weissbach identifies as being necessary to support a modern industrial society. (I believe Green-leaning researchers are satisfied with a value of just over 1, as that is all you need to do to be 'sustainable'). Solar power can't meet the factor of 7 even if energy storage is excluded, at least in the case of not particularly sunny countries like Germany. All the forms of electricity generation that are not favoured by the Greenies, including the traditional version of renewable energy, large scale hydroelectric power, exceed the factor of 7 by some margin. Out of the modern Green-favoured versions of renewable energy, only concentrated solar power plants located in deserts can meet the factor of 7 with energy storage included.

Figures in the BNC blog post also suggest the minimum EROEI of 7 may be a bit on the low side for people that are enthusiastic about high levels of public spending. It quotes EROEI factors of 9 being needed for education and 12 for healthcare (presumably this is free at the point of use education and healthcare). So one of the ironies of lefties backing the wind and solar power horse is that it looks like it will eventually lead to a society that cannot afford the level of spending on public services that make up a major part of their politics. If you want public services, you need fossil fuel.

Re: Energy storage for wind and solar power

One thing that intrigued me about the Weissbach paper is that it quotes an EROEI value of 75 for nuclear power, which is the highest value I've seen, more than twice the value being quoted in the same paper for natural gas (CCGT) and coal. I had previously picked up the impression from somewhere that nuclear power had a lower EROEI than fossil fuel.

I think I've found the answer to this puzzle after checking out the Wikipedia page on EROEI:


The EROEI values for nuclear power depend heavily on the technology used for uranium enrichment. If the old-fashioned gaseous diffusion technology is used, the value is given as 10, and the value is given as 50 to 75 (according to Wikipedia) for the more modern centrifuge process. So the lower EROEI values I've seen in the past for nuclear power must be due to Green-biased researchers (who are the main people who would publish work that uses this EROEI parameter) tending to select the lower and less favourable value.

The Wikipedia article mainly features EROEI values given by Murphy and Hall in 2010. They quote the lower value of 10 even though hardly anybody would actually be using diffusion for uranium enrichment in 2010, and the world's last diffusion plant was shut down not long after in 2013. In the UK we stopped using diffusion for uranium enrichment back in 1982, and we have been using the much more efficient centrifuge process since 1976.

I suspect that all the Murphy and Hall figures in the Wikipedia article could be a bit dodgy in view of the way they've treated nuclear power - they're probably knocking down the EROEI values for oil and gas, and their solar PV value of 6.8 looks a bit high. (The Wikipedia article mentions an EROEI for solar power in Spain of 2.45, suggesting the Weissbach figure of 3.9 for Germany is a bit generous). Murphy and Hall of course don't consider the important issue of the effect of energy storage on EROEI.

A good question might be that if the EROEI value for nuclear, 75, is so much better than natural gas-fired plant, 28, then why is nuclear power so expensive in comparison with gas? The answer to that is probably the cost of borrowing money to build something with a comparatively long construction time, and all the red tape associated with nuclear. It involves large numbers of people sitting at desks writing reports and shuffling paper, who may not be expending much in the way of energy but are still racking up costs.

Re: Energy storage for wind and solar power

Probably the major engineering cost advantage of natural gas systems come from being able to simply buy a complete plant off a production line. All the major engineering is already done and improvements incorporated as technology is proven. Maybe a little customisation involved but nothing compared to the start from scratch pretty much every time effort involved with nuclear. There may be a basic overarching concept with the essential design parameters and basic layout sitting on the contractors shelf but most of it has to be individually designed.

Then, as noted, there are the chair warmers and 'crats multiplying like blowflies that have to be paid for.

As for energy storage surely the simple answer is liquid hydrocarbons. We have an established technology for handling the stuff. People are used to it and understand the relatively simple safety precautions involved. Energy per unit mass and volume beats the pants off anything else whatever the battery or hydrogen gas proponents may claim. Energy transfer rates when re-fueling are colossal too. Which is nice. Pull the carbon out of atmospheric carbon dioxide, hydrogen out of water and the whole cycle is just as green, actually greener, than any of the other renewables. Surely efficient catalysts or reaction cycles for carbon and hydrogen extraction could be developed given a bit of effort. Plants it do very well after all.

Of course the daft thing about all the carbon dioxide causes global warming nonsense is that the whole concept is thermodynamically impossible. Anyone who goes outside on a regular basis will know that earth temperatures are stabilised by water vapour (clouds). Here and now around half the incoming solar energy is reflected by clouds. Both ways which is why clear cold nights mean ice in the morning but cloud usually reflects enough heat keep the roads safe. Any increase in surface temperatures due to carbon dioxide reducing heat loss will increase the amount of water vapour in the air reducing incoming solar radiation pro rata so the actual temperature increase is very small.
Its all fairly easy to calculate from black body radiation laws.


Re: Energy storage for wind and solar power

Yes Clive. Negative feedback dominates everything in the natural world (with the exception of nuclear fusion). Yet the loonie greenies believe that the climate is dominated by positive feedback.

Re: Energy storage for wind and solar power

In reply to Clive, that's an interesting point you raise about the "start from scratch pretty much every time effort involved with nuclear". Quite a few people might be puzzled by that claim as it's not consistent with the idea that nuclear power is a "mature technology", which it might reasonably be expected to be as it's been around for sixty years.

An example of something like the starting from scratch syndrome is this new Hinkley C nuclear power station proposed for the UK. People might assume that as the French are now in control of Britain's nuclear industry, we might get the advantage of the well-established French tendency to build lots of plants of the same design, which has been one of the major factors in France being able to build up to having 80% of its electricity generated by nuclear power. But Hinkley C is a significantly new design, an enhanced safety Generation III reactor known as the EPR or "European Pressurized Reactor", as described in this Wikipedia article:

What the motivation is for embarking on the EPR I don't know - it could be that to be perceived as leaders in the international nuclear industry your reactors need to be regarded as the safest, it may be a change pushed for by Western nuclear regulators to improve safety, or it could be that Western politicians are putting pressure on their nuclear regulators to reduce the likelihood of major nuclear accidents even further. You might have thought that there would have been a push to keep on building the cheaper Generation II reactors in response to the AGW malarkey and in recognition of the death rate in major nuclear accidents being extremely low.

Four of these EPRs are currently under construction. One in Finland started in 2005 and is expected to be completed in 2018 at a cost of 8 billion Euros. One in France started in 2007 and is expected to be completed in 2017 at a cost of 8.5 billion Euros. Two in China started in 2009 and 2010, with the first of these expected to be completed in 2015, at a cost of 8 billion Euros for the pair. I would guess that the lower costs in China, about half what they are in Europe, might be attributable to it being likely there is less 'red tape' in China.

In the case of the UK's Hinkley C station, which is a pair of EPRs, there is an additional cost element coming from having the Lib Dems in charge of the arrangements. The UK's electricity consumers are going to pay a guaranteed price of £92.50 per MWh for Hinkley C's electricity, which is apparently based on the pair of stations possibly costing £24 billion (33.5 billion euros) to build, presumably based on the project going very badly indeed, even worse than in Finland. I suspect that in Finland, France and China the electricity consumers are just going to pay a price based on what it actually did cost to build the EPR.

One thing I didn't mention in my earlier posts in this thread is that the EROEI figures quoted by Weissbach don't give too much confidence in the cost of wind and solar power coming down, as is often claimed by the proponents of wind and solar power. The EROEI values are a bit low in comparison with fossil fuel, and that's after forty years of development effort. The flying wind turbines idea might improve the EROEI relative to fossil fuel, if they ever got that concept to work. However when you eventually bring in the issue of energy storage it looks, from the EROEI figures, like the price of wind is going to quadruple and the price of solar is going to double, unless this future Green utopian world is going to put up with the blackouts.

Re: Energy storage for wind and solar power

Ah? Should I buy a truck that lets me get my garbage to the dump, haul dirt to my house, carry away the green downfall after storms, and still get me to the store when I need to? Or do I buy a economy car that lets me drive to the store and then rent when i need a truck?

Time Value of Money lets me put numbers to it, but then you have to take in the convenience factor.

How much is that convenience factor worth?

I have seen discussion of "Cradle to Grave" that try to encompass the entire problem. They leave me a little cold, because they too have a convenience factor involved.

R > E. Always R > E..