Heat management and the cost of phasing out nuclear power

It has been very hot in Europe for the past two months, with a significant impact on human activities and public health. For some, “it’s always been hot in summer”; for others, “the apocalypse is coming”. Then the torrential autumn rains will once again fuel the debate between sceptics and doomsayers. Setting aside the chatter on social media (which used to take place in pubs), it must be said that global climate models are highly complex, so much so that probabilistic formulas are often used – even in IPCC reports. However, this ‘caution’ on the part of climate science does not affect two certain facts, from which we can learn a lesson.

Firstly, the concentration of CO₂ in the atmosphere is now measured directly; for the past, it is derived from air bubbles trapped in Antarctic ice, which can be dated based on their depth. We thus know that, over the last 800,000 years, the concentration has fluctuated several times between 200 and 280 parts per million (ppm), causing cyclical cooling (low concentration) and warming (high concentration) of the Earth. Since the appearance of Homo sapiens, there has been a warm-cold-warm cycle, and up until 150–200 years ago, the concentration stood at 280 ppm. Then, from the Industrial Revolution onwards, due to the massive use of fossil fuels, the concentration has risen to its current level of 430 ppm – more than 50 per cent higher than the previous peak. Climate scientists attribute climate change to this abnormal increase in atmospheric CO₂ concentration.

Secondly, CO₂ has a residence time in the atmosphere of the order of hundreds of years. Thus, if – purely hypothetically – we were able to reduce global anthropogenic emissions to zero tomorrow morning (all of them, not just the 6–7 per cent from the European Union or the 0.8 per cent from Italy), around 70 per cent of the excess CO₂ would be reabsorbed within 150–200 years; the remaining 30 per cent would take around a thousand years to be reabsorbed.

The immediate consequence is that measures to adapt our territory, our water and energy systems, our crops, etc., to climate change – which will in any case persist for a couple of centuries – are both unavoidable and urgent. And this requires substantial investment, albeit less than the money needed to repair the damage caused by extreme weather events.

‘So reducing emissions is pointless,’ some might say. But no, because allowing them to rise out of all proportion would exacerbate those extreme events, rendering adaptation measures insufficient, in an endless vicious circle. It is true, however, that the need to invest in all the engineering works required for adaptation makes it imperative to reduce emissions as efficiently as possible.

And this is where climate scientists should hand over to their colleagues specialising in energy technology, energy economics and energy scenarios.

Reducing emissions in Italy by drastically increasing the production of “renewable energy” is not the most efficient approach. This is because, in Italy, it would mean increasing solar power generation – which is characterised by significant daily and seasonal variability – whilst only marginally increasing wind power generation, due to low wind speeds. And converting the intermittent energy produced by photovoltaic systems and, to a lesser extent, wind power into continuous energy entails high additional costs (due to summer overproduction, storage systems and the grid), which can be calculated using accurate simulations.

It has been found that continuous electricity generated in Lombardy using a mix of 85 per cent solar power, 15 per cent hydroelectric power and the necessary battery storage, net of grid costs, would cost €380/MWh. With a nuclear reactor, it would cost between €70 and €100/MWh (depending on the remuneration and financing arrangements, to be decided by the implementing decrees of the enabling act) during the reactor’s first 30 years of operation and around €45/MWh over the following 50 years, once depreciation has been taken into account. Decarbonisation without nuclear power is merely a board game in which everyone loses.