The ocean could be the next frontier for the world’s rapidly expanding solar energy industry. That’s the finding of a study showing a floating solar farm off the coast of Taiwan produces more electricity and more profit than a nearby solar farm on land.

Taiwan is roughly the same size as the Netherlands, but it is mostly mountainous and has 5 million more people, meaning open space is scarce. As a potential solution, built a 181-megawatt offshore floating photovoltaic (OFPV) project – sometimes called a “floatovoltaic” – on 1.8 square kilometres of water in the protected bay of an industrial park in western Taiwan in 2020-21.

The year before, the Taiwan Power Company had constructed a 100-megawatt land-based photovoltaic (LPV) project on 1.4 square kilometres near the bay, providing an ideal comparison once researchers excluded the additional 81 megawatts of capacity at the floating solar installation.

Pound-for-pound, the floating solar produces 12 per cent more electricity than the land-based solar, they found. Even though it has slightly higher operations and maintenance costs, it generates 11 per cent net profit, as opposed to 8 per cent for the land-based solar.

“Installing the PV system on the sea, on water, is more difficult than installing the PV system on the ground,” says team member Ching-Feng Chen at the National Taipei University of Technology. But “for the carbon reduction, emissions reduction, OFPV is much better than LPV”.

More than 1100 floating solar systems have been on lakes and reservoirs, mostly in China and other densely populated Asian countries.

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While the main attraction is that they don’t take land away from farming or development, they can also up to 20 per cent more electricity than land-based systems, although that number varies widely from site to site. The improved performance comes from the fact that solar panel efficiency declines as temperatures rise, and because conditions are typically 2-3°C cooler over water than over land. The stronger winds experienced over large bodies of water also contribute to this cooling effect.

“The principal enemy is the heat,” says Chen.

Floating solar on the ocean, where temperatures are even lower than on lakes and reservoirs, can more electricity still. But it’s also more challenging to build, and only a handful of projects have been deployed. The largest is in China, a 1-gigawatt system in shallow waters off the coast of Shandong province.

A framework of solar panels is attached to buoys and anchored to the ocean bottom. The floating solar in Taiwan rests directly on the seabed when the tide is out.

Installation costs in general are expected to be about 30 per cent higher on sea than on land because the systems have to resist humidity, rust, salt and waves, says Chen.

Salt and bird droppings also build up. Employees of the Taiwan project have to the panels from walkways and for driftwood and debris on jet skis. But the higher electricity output will more than compensate for these costs over a project’s lifetime.

Chen’s study did not consider the long-term wear and tear of waves and storms. That could become a bigger factor as offshore wind farms consider using floating solar to generate power when the wind isn’t blowing. Combined wind and solar covering 1 per cent of suitable ocean surface could provide almost 30 per cent of global electricity demand in 2050, a published last year found.

German and Dutch companies have been two solar projects about 12 kilometres off the coast of the Netherlands, one of which has waves of up to 10 metres since 2019. But last year, Shell and Eneco another floating solar system off the Netherlands’s coast – this one installed at the Hollandse Kust Noord offshore wind farm – after a defective electrical connector led to overheating.

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Another concern is that floating PV shadows the water column and reduces wind mixing, which can oxygen and light available for aquatic life like phytoplankton and seaweed.

“If you do it further offshore, then maybe the waves and weather conditions and so on will become more problematic, but the closer to the shore the less favourable for biodiversity,” says at HZ University of Applied Sciences in the Netherlands.

Given that it impacts human activities less than land-based solar, however, “there’s definitely potential for this technology”, he says.

Because offshore PV is technically challenging, Chen thinks it will expand mainly in sunny islands that don’t have much offshore wind power, like Taiwan, Japan, Indonesia and Caribbean nations.

“Location is very important,” he says.

A record surge of solar panels flowing from China to countries in Africa over the past year is a sign the continent is seeing a rapid build-out of renewable energy. That could help expand access to cheap, clean electricity and reduce reliance on imported fossil fuels.

“This isn’t a massive explosion yet in itself,” says at Ember, an energy think tank in the UK. “It’s the start of the takeoff.”

Jones and his colleagues analysed on Chinese solar panel exports since 2017. There is some solar panel manufacturing capacity in Africa – but as with most of the world, Chinese imports make up nearly all of the continent’s supply.

Between June 2024 and 2025, the researchers found exports to Africa surged 60 per cent compared to the previous year, amounting to just over 15 gigawatts of power capacity imported over that period.

Unlike an earlier surge in 2022 and 2023 that was driven mostly by imports to South Africa, this upward trend was spread across the continent – with 20 countries seeing import records and 25 countries importing more than 100 megawatts worth of panels. “It’s not being led by one or two countries,” says Jones. “To me, that’s the most incredible part of the story.”

South Africa was still the leader, importing about a quarter of the total. But other countries also imported a raft of panels: Nigeria was second with 1721 megawatts, followed by Algeria with 1199 megawatts, about a tenth of the total. Over the past two years, solar panel imports from China to countries in Africa – excluding South Africa –have more than tripled.

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Assuming all the panels imported over the past year were installed, the researchers estimate 16 countries imported enough to supply at least 5 per cent of current electricity generation; Sierra Leone could generate more than 60 per cent of its current electricity with the panels it imported alone. These solar imports could begin to offset far more expensive fossil fuel imports.

“Africa’s just energy transition is no longer a future aspiration. It is unfolding now,” says at Greenpeace Africa, an environmental advocacy group. “This transition has a huge potential of reshaping how we build resilience to the climate chaos and drive development.”

The surge comes partly from large solar installations under construction, but that isn’t the whole story. Jones says a lot of the imports appear to be going to small, distributed installations on rooftops or farms, as people seek cheaper, more reliable sources than national grids. A similar trend is playing out in Pakistan, which saw explosive growth in rooftop solar over the past few years driven by the falling cost of panels.

This is a hopeful trend, given about in Africa – nearly half of the continent’s population – lack access to reliable electricity. However, solar development on the continent still lags behind the rest of the world. African countries have struggled to attract investment in renewable energy, receiving just of the global total in recent decades, according to the International Energy Agency. Over the past year, Pakistan alone saw more solar panel imports than all of Africa, despite having one-sixth the population.

“The real challenge before us is to turn this momentum into lasting gains by aligning financing, policy and local industries to ensure clean energy is not only available, but also reliable, affordable and inclusive for all Africans,” says Wemanya.

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The leftover ore discarded by US mines is packed with key minerals – enough to provide virtually all of the raw material needed to build clean energy technologies. Recovering just a fraction of these minerals could meet the country’s growing demand for green energy without requiring imports or environmentally-damaging new mines – but getting them is easier said than done.

“We have to get better at using the material that we mine,” says at the Colorado School of Mines.

Currently, most individual mines focus on extracting just a few types of minerals, such as copper or gold. That involves digging up ore, crushing it and then separating out the main product using various metallurgical processes. Everything left over is then disposed of as tailings. “Most of what we are mining is waste,” says Holley.

These leftovers often contain other useful materials, including dozens of critical minerals the US government has identified as essential to military and energy technologies, such as solar panels, wind turbines and batteries. But the supply chains for some of these minerals are controlled by China, sparking urgent concern among the US and its allies they could be wielded for geopolitical leverage. That has spurred a search for alternative mineral sources, including mining byproducts and tailings.

However, most mines don’t know exactly what they are tossing out. “Many of the elements we currently consider critical were not in much use in the past, so no one was analysing for them,” says Holley.

Holley and her colleagues looked at thousands of ore samples and production data representative of mines around the US. They used this information to estimate the volume of other minerals that could be extracted from 54 active hard rock metal mines if new refining steps were added.

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For some minerals, they found extracting just 1 per cent of what is contained in mining byproducts could replace all current US imports. Other minerals required higher recovery rates, ranging from 10 to 90 per cent, to replace imports. And a few metals, including gold, platinum and palladium, would still have to be imported even if 100 per cent could be recovered from byproducts.

These numbers suggest the US could meet most of its rising demand for critical minerals without building new mines, says Holley. That would help secure supply chains, as well as reduce the environmental impacts of mining. “It would be better to get more out of what we already mine,” she says.

at the University of British Columbia in Canada says this shows the “opportunity is vast” – but much more research is needed to translate estimates of the total quantity of minerals that are out there into actual recovery. “Hopefully it energizes people in government as well as industry to take a closer look at what we’re mining,” he says.

Just knowing where these minerals exist is hardly the only barrier. Current refining technology isn’t well-suited for these small, complicated waste streams, and deploying the necessary tech is too expensive for most US mines, says at Nth Cycle, a start-up focused on extracting critical minerals from unconventional sources.

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Mines can also be hesitant to invest money in extracting new types of minerals when future demand is so uncertain, says McNulty. Whether it is electric vehicle batteries or solar panels, “the change in technology is happening exponentially faster than how we mine”, he says.

Despite its hostility towards renewable energy, the Trump Administration has made boosting US critical mineral production a key part of its agenda. Last week, the Department of Energy (DOE) nearly a billion dollars in funding for unconventional mining efforts, including $250 million focused on recovering minerals from mining byproducts.

A spokesperson for the DOE says these mine tailings are “an important domestic opportunity” and could help the US diversify its sources of critical minerals and materials.

However, this doesn’t preclude support for new mines, said the agency’s undersecretary during a workshop about the DOE’s strategy on 20 August. “We should never apologize for our modern way of life or our abundance of natural resources,” he said.