Don't believe in miracles

The above was one of the closing points in an excellent talk I saw earlier today by Dr Jef Ongena, the chairman of the Energy group at the European Physical Society. Based on the email announcement for the talk I was expecting to hear mostly about current progress in nuclear fusion research, but what we got was partly a thought-provoking and fiercely critical overview of the European approach towards renewable energy, and partly a call for better public awareness and consideration of wider context. It really deserved a larger audience than it had so I thought I’d write a bit about it!

“Europe alone cannot save the world” was the first key message, giving examples such as Germany: around 1 trillion Euros has been committed to the Energiewende, and has so far brought about very little meaningful reduction in Germany’s CO2 emissions, which themselves contribute only ~2.5% of the world’s emissions (interestingly enough, the decade following the collapse of the GDR saw German CO2 emissions drop by a quarter, simply because of the loss or modernisation of East German industry). Globally, this reduction is insignificant, because emissions from countries such as India and China have increased to a greater extent. More than this, as a result of this policy, German energy prices are among the highest in the world.

Dr Ongena was also keen to point out that at least a portion of the EU’s reduced emissions are effectively an accounting trick – we import more goods from China rather than produce them here, meaning the associated emissions appear as Chinese emissions and not European. It’s worth reading the EPS Energy Group’s position paper on this topic.

What was most interesting for me was the stark look at what the consequences of an energy system based 100% on renewable energy would be. At this point I am reminded of this excellent post on the situation in Scotland, since this is exactly what the Scottish government is aiming for in the short-term (the blog at which that post resides, Energy Matters, is excellent in general by the way). The biggest issue with renewable energy such as solar and wind is the intermittency; wind is unpredictable, and the demand for solar is typically out of phase with the consumption, so some energy storage is essential. But how much?

It’s also one thing to cope with diurnal (day/night variation) in production/consumption, but if you plan for a future in which solar is a large or the major part of the energy production mix, then the huge seasonal variation in energy production becomes a big problem.

Dr Ongena gave an example of a study looking at German energy production as it would look in 2050 based on current plans. Unfortunately, I didn’t note down the reference, but the short version is that coping with the seasonal variation in energy production and consumption would require of the order of 33 TWh of storage capacity for Germany alone! To put this into context, if this energy was to be stored using batteries, 27 cubic kilometers(!!) of space would be needed to store the batteries themselves. How much space is that? Well, I calculated that myself, and it would take an aircraft hangar tall enough to fit an Airbus A380, this big:

What 900 km<sup>2</sup> looks like

Or, about 2,000 buildings the size of the Boeing Everett Factory, the largest building in the world by volume. I won’t even try to estimate the impossible cost of such a solution.

This idea of “knowing your numbers” was I think the main scientific point in the talk, which pleased me greatly: this is something I think is really important, and is something I try to prioritise in any teaching that I do. Dr Ongena gave a few interesting factoids – for example, that the energy consumed by satellite TV boxes in Belgium is something like 17 times more than the energy consumed lighting all the country’s roads – but the main point was about the power density of energy production.

Power density, as in power per unit area, tells you about the land area needed to produce energy, and in this respect all renewable energies are considerably more “dilute” than conventional (fossil fuel, nuclear) technologies. I’ve since found some good references for this, notably this one, so I won’t write anything else on this except to say that it is often and easily forgotten that wind power, for example, requires 400-500 times the land area to provide the same power as nuclear (and optimistically about 50 times for solar). It’s long been a mystery to me as to why some types of environmental destruction (e.g., large scale pumped hydro or vast fields of massive on-shore wind turbines) are apparently preferable to others (e.g., storing relatively small amounts of nuclear waste, or fracking).

Although it was a talk with relatively few crumbs of comfort for the future energy landscape (fusion power was not even discussed), it was still rather refreshing to get such a brutal reality check and plenty of food for thought. Unfortunately, my suspicion is that politics and emotions will always trump science in any decision-making process, but I would be happy to be proved wrong on that.

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