Over the Easter break, French daily Le Monde reported that an official study for a conference to be held last week was being held back. The energy experts investigated a 100 percent renewable supply of electricity by 2050. Craig Morris got hold of a copy, which still lacks an executive summary. So he wrote one.

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Last week, a conference was held in France to investigate, as the title puts it (website in French), whether France is ready for 40 percent renewable electricity by 2030. But as Le Monde pointed out at the beginning of the month (report in French), French energy agency Ademe announced at the beginning of the year (press release, PDF in French) that the centerpiece was to be “the presentation of an unpublished study showing the path towards 100 percent renewable electricity.” Ademe itself commissioned the study, which was conducted under conditions that French think tank negaWatt calls “extraordinary” (in French).

According to Le Monde, Ademe says the presentation of the study has been taken off the agenda because the subject is “very sensitive.” The paper goes one step further calling it “explosive.” At the beginning of the year, French Energy Minister Ségolène Royal threw her weight behind the construction of a “new generation of reactors” (report in French), potentially calling into question the government’s official goal of reducing the share of nuclear in the power sector from around 75 percent to 50 percent.

The word now is that the study – which reportedly already cost nearly 300,000 euros – is to be published later this year. In the meantime, the experts are to “verify” a number of the findings.

What are the findings? The leaked PDF has two blank pages where the executive summary should be. So I wrote my own.

Executive Summary

The French power sector faces fundamental challenges over the next two decades. Nuclear power currently covers around three quarters of demand, but the average nuclear plant is around 30 years old. The government aims to reduce its dependence on nuclear, partly by switching to renewables.

France has not only been a leader in science for centuries, but is also proud of its long democratic tradition. The combination of democracy and research makes a broad investigation into possible options obviously desirable. This study is designed as a scientific investigation within a democratic debate.

Previous studies have investigated (nearly) 100 percent renewables in Japan (Energy Rich Japan), Germany (Kombikraftwerk, Geschäftsmodell Energiewende, and SRU), the UK (Zero-carbon Britain), Australia, the US (90% renewable electricity in Renewable Electricity Futures), California (PDF), and indeed for the European Union as a whole (RE-thinking 2050). Ecofys has conducted a 100 percent renewable scenario for the entire world, and Greenpeace regularly updates its Energy [R]evolution studies, which are also global. PriceWaterhouseCoopers has also produced a roadmap for 100 percent renewable electricity in Europe and North Africa (PDF). This list is not exhaustive; we refer readers to the World Future Council’s (WFC) list of such studies and reports, which can be searched by region. The WFC has also produced this overview. Furthermore, Denmark and the Netherlands already have an official target of 100 percent renewable energy by 2050.

The present study is intended to help fill that gap for France. It is hoped that the findings will contribute to an open discussion about the French energy future, including with the informed public. The main previous study for France was produced by négaWatt, which investigated more than 90 percent renewable energy (not just electricity) in 2011.

In line with these other publications, the study found that a 100 percent supply of renewable electricity would be possible and affordable but not trivial. To account for efficiency and conservation, two basic scenarios are investigated, one with 406 TWh of annual consumption, the other with 487 TWh (2014: 465 TWh). The study also investigates the effect of temperatures on power demand – an aspect not generally covered in other such studies, but useful here because France is so reliant on electricity for space heating. Note here that Denmark aims to use excess renewable electricity to produce heat (power-to-heat). In other words, France’s current dependence on electric heat, which is currently seen as a problem, can be helpful in a transition towards renewables.

One question is how much of each type of energy source – solar, wind, biomass (excluding methanization), geothermal, hydropower, and ocean energy – would need to be installed. The study answers this question in great detail for each of the country’s 21 regions.

In the reference case, wind and solar would be the main sources of electricity. France would need nearly 96 GW of wind power onshore along with 10 GW offshore. A total of around 63 GW of solar would be installed as well, around 2/5 of which would be on roofs, with the other 3/5 on the ground. Social considerations (public resistance) may result in a lower share of ground-mounted PV, for instance, which is also modeled. The 96 GW of onshore wind is also assumed to require the construction of 50,000 turbines, compared to 4,000 today, a situation that could also lead to public resistance. However, those numbers produce an average turbine size of just under 2 MW, which is already modest; the average turbine size installed in Germany last year was 2.6 MW. As turbines become more powerful, fewer will be needed to produce the same installed capacity. Note that public concern about grid upgrades is not expected to be an obstacle.

Cost is another major issue. Assumptions are made about what each technology will cost in the future, but overall system costs are arguably more relevant. In the reference case, the cost of renewable generators alone makes up 65 percent of the total annual investments needed, which amounts to 50.1 billion euros. The average kilowatt-hour would then cost 11.9 cents (including generation, the grid, demand management and storage, but excluding taxes). The cost does not, however, drop considerably at lower levels of renewable energy. For instance, it is 11.7 cents at a 40 percent share. The current cost of electricity defined in this manner is 9.1 cents in France.

The study divides up the cost analysis of storage into short-term and seasonal storage for a fuller investigation. The proper mixture of fluctuating renewable power sources is crucial to limiting the need for power storage, as is their geographical placement. Demand management – including electric vehicles, residential hot water, and household appliances – is also included in this analysis as a cost-effective instrument. The mixture of power storage and demand management will ensure that only three percent of total power production is curtailed. However, the study found that the amount of surplus renewable electricity skyrockets between 80 percent and 100 percent.

The entire investigation also places France within its European neighbors, which are assumed to be 80 percent renewable by 2050 (in accordance with the European Commission’s Roadmap 2050). The power trading situation is therefore also studied. The goal will therefore be greater energy independence without complete autonomy.

Finally – and here I simply translate a passage from page 6 – “Ademe is fully aware that this study is only a first step down a path we will have to travel in the years to come. The findings raise new questions, which future studies will have to address.”

Craig Morris (@PPchef) is the lead author of German Energy Transition. He directs Petite Planète and writes every workday for Renewables International. For this report, he would also like to express his thanks to the swarm (you know who you are), who helped him put together the list of studies into 100 percent renewables.