Valentin Russeil was studying in Paris in 2018 when protests against the rising cost of living and 24% unemployment broke out on the island of Réunion. The island is an overseas department of France, located east of Madagascar. Russeil, who is from Réunion, followed the news closely and spoke to his family back home every day. He was disturbed to learn that the island’s docks had been blocked by protesters, preventing the import of food and fuel. “Things started to disappear very, very quickly,” he says. “My family had to start doing everything with bicycles, not gas.”

The most intense protests stopped after a couple of weeks, and an emergency was avoided. Life on Réunion soon returned to normal. For Russeil, however, the events left a lasting impression: it had demonstrated to him just how vulnerable Réunion is to even minor disruptions, let alone major disasters. “I was worried about the future of the island,” he says.

Part of this concern stemmed from Réunion’s over-reliance on imports, including for energy, says Russeil, who is now at the French National Research Institute for Agriculture, Food and Environment in Paris. Russeil and a number of his colleagues have begun looking for a way to guard against scarcity problems in the future and to strengthen Réunion’s autonomy. The best way to do this, Russeil says, is for the island to increase its energy independence.

“If there’s climate-change problems, or war, or any political conflict in the world, Réunion wouldn’t be the first region where people would think to send food or energy,” says Jean Philippe Praene, who studies renewable energy at the University of La Réunion in Saint Denis. “So we have to be as self-sufficient as possible.”

Energy transition

In 2022, 86% of the island’s energy supply came from abroad, mainly in the form of liquid fossil fuels and coal. Most of this was used for transportation, with electricity generation accounting for about one-quarter of total fuel consumption. The island’s main electricity plants are aiming to finalize a switch from coal to wood pellets and from oil to biofuel by the end of 2023. The government’s aim is to produce almost all of Réunion’s electricity from renewable sources by the end of 2023.

Although laudable, switching to renewables will not solve the self-sufficiency problem. The renewable sources Réunion uses to generate electricity will still be mainly imported from abroad. “Forests will be cut in Canada to put in our furnaces in Réunion island,” says Mathieu David, who studies mechanics and energy at the University of La Réunion. “This is clearly not autonomy, and it’s not carbon-free.”

Scientists such as Praene and Russeil say that there are a number of reasons why Réunion has the ability to produce much of its own energy. Fewer than one million people live on the 2,500-square-kilometre island, meaning there is a relatively small demand. It also receives heavy subsidies from mainland France and the European Union, and the island’s research infrastructure means detailed scientific information is available that could be used to make informed, data-based decisions. “In some ways, we have all the tools we need to make a sustainable transition,” Russeil says.

Numerous obstacles, however, reduce the likelihood of this happening in the immediate future — from powerful industry interests to high rates of poverty.

Russeil sees two possible paths for the future: Réunion could become a proof-of-concept model for energy self-sufficiency and an inspiration for other small islands around the world who want to do the same. Or it could remain a case study on how difficult it is to transform a place’s potential into a reality. “We’re small, have a lot of money and a lot of research, and yet it’s still so hard,” Russeil says. “If a territory such as Réunion doesn’t make it, I don’t know if any other territory can.”

A volcano in the sea

In the early 2000s, Réunion emerged as a forward-thinking leader with regards to energy when Paul Vergès, then-president of the regional council, revealed plans for the island “to be a sort of example, a laboratory to experiment with renewable-energy technology”, Praene says. Self-sufficiency was an integral part of the plan, including through solar, wind and wave energy. As Vergès told The New York Times in 2008, “We have more energy than we need for our development.”

When Vergès made this comment, about 36% of the island’s electricity came from renewable sources. In 2022, however, that figure was almost the same. But the stagnant rate of renewable contributions isn’t due to a lack of commitment on paper. For years, Région Réunion, the territory’s public authority, has been encouraging a “massive injection of renewable energies” into the island’s power supply, says Michel Benne, an engineer at the University of La Réunion.

Région Réunion also aims to fully decarbonize the territory’s electricity production and become self-sufficient by 2030. The transportation sector, however, has been intentionally left out of that goal because of people’s reliance on cars and because Réunion’s location means the most practical option for reaching it is to take an aeroplane. Given these realities, most research on self-sufficiency focuses only on electricity generation, excluding the two-thirds of energy consumption that’s accounted for by the transportation sector.

So far, only very small islands such as El Hierro in the Canary Islands have achieved complete energy self-sufficiency, says Dominique Grondin, who studies energy engineering at the University of La Réunion. The challenge is greater for bigger islands, especially those with significant industrial activity, high standards of living and large numbers of people. Another of France’s island departments, Corsica, has similar energy self-sufficiency to Réunion, about 13%. The two islands share the same electricity grid operators. “Researchers in Réunion and Corsica are collaborating mainly on the integration of photovoltaic solar energy into the electricity grid — a major resource from both regions,” Grondin says.

Differences between the two islands, however, mean that replication of solutions will probably be limited. Corsica is more than three times larger than Réunion but has a smaller population and lower levels of energy consumption. It’s also connected to the Italian power grid, whereas Réunion is “totally isolated”, Grondin says.

Of France’s other island departments, New Caledonia is bottom of the energy-independence list, at just 3%. But once again, New Caledonia has its own set of characteristics that make a direct comparison with other islands difficult. It has a strong mining sector, creating higher demand for energy than in places such as Réunion.

Every island has its own socio-economic and environmental context, but Réunion’s dynamic economic and academic sectors make it an ideal testing ground for solutions that could be replicated elsewhere, David says. “Other French overseas departments such as Guadeloupe, Martinique and Mayotte are watching closely to see if they can replicate La Réunion’s hopefully successful footsteps.”

Pathways to self-sufficiency

Motivated by the 2018 protests, Russeil begun to look at routes that Réunion could take to become more food and energy self-sufficient. While Russeil was a doctoral candidate at the University of La Réunion, where Praene served as one of his advisers, he set about building a detailed computer model of Réunion that would allow him to predict how different land-use decisions would affect food and electricity production. He generated five scenarios spanning a range of possible futures, shaped by data he collected from stakeholders and specialists.

As Russeil, Praene and their colleagues reported this year1, Réunion’s lack of available land area is the biggest limiting factor to becoming fully self-sufficient. The models did reveal, however, that a number of changes could help to increase Réunion’s share of locally produced food and energy. This includes replacing sugar cane with different food crops; restricting urbanization; increasing the capacity for producing energy from waste; significantly scaling up photovoltaics that convert sunlight directly into energy; and convincing Réunion islanders to make certain lifestyle changes. For example, if rice- and wheat-based staples were replaced with starchy roots such as sweet potatoes, “it would have a tremendous effect on self-sufficiency prospects”, Russeil says. But, he adds, “there is a social limitation, which is that people want bread, pasta and rice”.

In the most ambitious of scenarios, he and his colleagues found that Réunion would be able to produce around 50% of its own food and nearly 75% of its electricity. These prospects will probably improve, too, as technologies evolve. So, although “it’s a bit of an impossible equation from a total self-sufficiency perspective”, he says, this doesn’t mean that the island shouldn’t try to make gains where it can.

The biggest priority, Russeil says, should be to “stabilize or even decrease energy consumption per person”. In 2019, the average energy consumption per person was 1.7 tonnes of oil equivalent. In Russeil’s most ambitious scenario1, individual consumption drops to about 0.41 tonnes of oil equivalent per person per year by 2040. One way for this to happen would be to invest in collective transportation methods, such as a tramway project that has been on the table for several years. Encouraging people to switch to electric vehicles could also help. In 2022, the island was home to 20,664 electric and hybrid cars and motorcycles, says Grondin, and numbers are only set to grow. Réunion’s relatively small size makes it “very attractive” for making the switch to electric transport, David says. “With just one full battery, you can go everywhere.”

Benne agrees that changes to the transport sector should be at the top of the list for increasing energy self-sufficiency. He also sees a number of other strategies that could be taken, including investing in technologies that convert waste into energy; examining the possibility of installing more small hydropower projects; funding research programmes to develop technologies to capture Réunion’s offshore wind, ocean-thermal and wave energy; and looking into the potential for geothermal energy projects outside the island’s wildlife conservation zones.

Reality check

Although electricity self-sufficiency on Réunion is theoretically possible, there are still a number of constraints imposed by factors such as nature, technology and economics. The island’s remote location and geographical features are serious challenges for starters. Other islands tend to be connected to continental mainlands through submarine cables, but “we’re a volcano in the middle of the sea”, says David. “We can’t rely on our neighbours, so everything must be done locally.”

There are also social limitations. Sugar cane, for example, is Réunion’s biggest industry, and it receives millions of euros in annual subsidies, much more than other agricultural sectors. Many people on the island are opposed to changing out this crop in the interest of energy goals, Russeil says, “because they get so much money”. In private presentations, he adds, some people in the sugar-cane industry even cherry-picked his results to argue that sugar cane is essential for the island’s energy system.

For now, no single technology is suitable for generating enough electricity to power the entire island. For example, offshore wind turbines might seem to be an obvious choice for Réunion, David says, but the island is surrounded by very deep sea, making installation difficult. Other ocean-based solutions also seem plausible, such as thermal-energy conversion — a technology that exploits the temperature difference between deep and surface water. But according to David, engineers still haven’t worked out how to securely install the huge pipes needed to implement this solution. Wave energy is another option, but leading technologies from Australia and the United Kingdom are not suited for the sea conditions and industrial support found at Réunion. Bespoke solutions will be needed to tailor these kinds of technology for the island.

Solar and land-based wind power are affordable options, David continues, but the intermittent availability of sun and wind is not ideal. Usually, the wind dies down as soon as the Sun sets, creating an energy deficit just as islanders are using electricity at home — a phenomenon known as the rice-cooker peak, David says. “Every family has their own rice cooker, and everybody switches on their rice cooker between 7 and 9.”

Energy-storage systems could get around this, he adds, but this would be “very expensive to install and the electricity price would increase”.

Technical, economic, environmental and social reasons, mean it might make the most sense for Réunion not to strive for 100% self-sufficiency, Grondin says. The island could instead try to reach, for instance, 95% self-sufficiency — which is likely to be a more affordable and feasible goal, he says. And there are other sustainable options that Réunion could pursue that don’t require complete self-sufficiency, such as purchasing a small amount of renewable fuel from abroad — for example, green hydrogen from Australia. Far from a failing, Grondin says, this would just be a smart way to strategize. In today’s interconnected world, after all, “no country is really self-sufficient”.