Newly-elected president Emmanuel Macron has pledged to to cut the amount of nuclear electricity in France’s generation mix from 75% to 50% by 2025 while doubling wind and solar capacity and closing all of France’s coal-fired power stations by 2022. Will France still be able to generate enough electricity to fill demand if it does this? This post concludes that the answer is no, not even if France’s electricity demand decreases in accordance with the most optimistic projections. With 25% of its nuclear generation shut down France would likely face unmanageable power deficits.

First a quick refresher on the French electrical system: The table below summarizes France’s installed capacity and electricity generation in 2015. The data are from the French grid operator Réseau de transport d’életricité (RTE), with wind capacity from the European Wind Energy Association and solar capacity from PV Tech (RTE’s totals do not include installations smaller than 1 MW and therefore underestimate wind and solar capacity). Hydro generation allows for pumped hydro losses and includes both run-of-river and reservoir hydro. Oil capacity is believed to consist largely of diesel peaking plants that are activated only during peak demand hours. A small amount of tidal, biomass and “other” capacity for which complete data are not available are included as “Other”:

According to these numbers France obtained over 93% of its electricity from low-carbon sources (nuclear, hydro, wind, solar, biomass etc.) in 2015, which is about as good as it gets for a country with limited hydro resources. The question of why France should now want to change things is not discussed here.

Figure 1 shows France’s average daily generation by source (data from Leo Smith’s Gridwatch France site) for the 20 months from November 21, 2014, when the Gridwatch data begin, through July 20, 2016. Later data are distorted by the progressive shutdown of nuclear plants for inspection during the French “nuclear crisis” and are therefore not used. (Note that the data shown are daily averages, so daily variations in generation – which commonly approach 20GW – will not be visible. Peak demand on any given day could therefore be as much as 10GW higher than shown):

Figure 1: France’s average daily generation by source, November 21, 2014 through July 20, 2016

Figure 2 compares total generation with demand. Over the period considered France generated 900TWh of electricity but consumed only 799TWh. The 101TWh surplus, representing 11.2% of France’s total generation, was exported.

Figure 2: France’s average daily electricity supply/demand balance, November 21, 2014 through July 20, 2016

Now we turn to France’s plan to double wind & solar, eliminate coal and cut nuclear supply from 75% to 50% by 2025. How might this affect the supply/demand balance? I analogued this generation mix over the October 2014 to July 2016 period as follows:

Reduce nuclear generation by two-thirds across-the-board.

Double wind and solar generation (for good measure I doubled biomass generation too).

Cut coal generation to zero (which makes little difference. France has less than 3GW of coal-fired capacity left).

Leave hydro, gas and oil generation unchanged.

Applying these adjustments shows what the situation would have been over the November 2014 – July 2016 period if this generation mix had been in place then. It does not necessarily tell us what will happen in 2025 because there is no exact way of predicting what demand will be at that time.

Figure 3 replots Figure 1 with the new generation mix in place:

Figure 3: France’s average daily generation by source with new generation mix, November 21, 2014 through July 20, 2016

And Figure 4 shows the resulting supply/demand balance. France’s total generation has fallen from 900TWh to 710TWh and its 101TWh surplus has become an 89TWh deficit, meaning that France would have had to import 12.5% more power than it generated to meet electricity demand over this period:

Figure 4: France’s average daily electricity supply/demand balance with new generation mix, November 21, 2014 through July 20, 2016

There are of course ways in which the situation might be improved. Lowering France’s nuclear generation from 75% to 50% would presumably involve some nuclear plant shutdowns, but if enough of France’s nuclear fleet remains operational it might be possible to increase nuclear production in the winter, when the largest deficits occur. France’s 6.7GW of oil capacity could also be more heavily utilized, although this would be counterproductive from the emissions standpoint. But with only 50% nuclear generation there would still be a large overall deficit, and unless France’s neighbors have large generation surpluses available for export, which they almost certainly won’t, the country would at some point find itself freezing in the dark.

The only factor that might save the situation would be a reduction in electricity demand, and a reduction is indeed projected by RTE in its 2016 Generation Adequacy Report. In this report RTE reverses its 2015 projections and shows future demand decreasing rather than increasing in its baseline case (Figure 5). For the first time, says RTE, electricity demand forecasts assume a contraction over the medium term.

Figure 5: Annual domestic electricity demand in mainland France, reproduced from RTE 2016 Generation Adequacy Report.

It’s probably not a coincidence that RTE should forecast a reduction rather than an increase in future electricity demand just after France, after several years of debate, formally committed to cut its energy use (France’s Energy Transition and Green Growth Law, which calls for national energy usage to be cut by at least 50% by 2050, was passed in August 2015.) But RTE’s forecast reduction would make little difference even if it turned out to be correct. Figure 6 shows my eyeball projection of RTE’s baseline case out to 2025 (orange line). It shows total annual demand falling to around 460TWh in 2025:

Figure 7: Author’s projection of RTE baseline case to 2025

And the problem here is that with 50% nuclear generation, and using the 2015 French grid data as the base for calculation, France would generate only 415TWh in 2025, leaving a deficit of 45TWh relative to RTE’s projected 460TWh of demand. Even RTE’s “Low variant” case, which looks implausible to say the least, would not result in a supply/demand balance.

So whither France? Emmanuel Macron had pledged a surge in nuclear decommissioning activity in the event he won the election, but there are now doubts that this will happen :

Macron has set out bullish renewable energy objectives and pledged to retain laws introduced in 2015 which aim to cut the share of nuclear power from 75% to 50% by 2025. However, Macron has not set out a firm position on this nuclear target and market analysts have highlighted the challenge of shutting down an estimated 25 GW of nuclear power capacity over such a short time frame while maintaining grid stability.“The lack of a firm position on this issue may be because Mr Macron is well aware that the 2025 target is highly ambitious,” Jefferies analysts Ahmed Farman and Oliver Salvesen said in a research note April 24.

My prediction? France’s generation mix in 2025 will include a little more wind and solar but nuclear will still account for close to 75% of total generation. France really has no alternative if it wants to keep the lights on.

Postscript: One can in fact demonstrate that France’s plan to reduce nuclear output won’t work without referring to the grid data at all. In Major Electricity Trends for the Month RTE provides the following generation numbers (in GWh) for January 2017:

Nuclear generation 40,499; wind+solar generation 2,332; other generation 14,333. Total generation 57,164; consumption 57,325; deficit 161 (effectively in balance)

Now we apply the new generation mix, cutting nuclear generation by a third and doubling wind and solar. Ignoring the loss of a small amount of coal generation here’s what we get:

Nuclear generation 26,999; wind+solar generation 4,664; other generation unchanged at 14,333. Total generation 45,996; consumption 57,325; deficit 11,329.

The numbers speak for themselves.