Floating solar power frees up land for other use, while efficiency is gained by cooler panels. Photo Dreamstime.
Can the energy transition occur quickly enough to avoid the worst of global warming? The technology is there, or nearly so, but where is the political will, the focus? There is room for both anxiety and hope, as the renewables sector (sun, wind, tidal/wave and geothermal, along with storage) is bristling with invention and creativity.
By James Chater
Introduction
How much longer have we got? About half a billion years, according to the scientists, after which the sun’s swelling will start to make human life on earth unsustainable. A matter of decades, if current trends in energy production and consumption continue.
Good and bad news
The news is not all bad. Clean energy production has reached record levels, and the increase in renewable capacity is beating fossil fuels hands down. In 2024 alone, wind and solar energy grew by 16%, with China accounting for 57% of the added capacity. China not only dominates solar and wind technology and rare earths production, but it also has, in BYD, the world’s largest electric vehicle (EV) manufacturer. Moreover, it looks as though China’s GHG emissions may have peaked1.
Growth in the share of renewables has been fastest in the Asia Pacific, followed by Europe. Former laggards, such as Australia, are catching up: since June 2005 emissions have fallen by 28.2%. In Europe, thanks to generous government help, renewables have surged ahead. Denmark, which sourced 88.4% of its electricity from renewables in 2024, is now a wind superpower. Portugal, Spain, Hungary, Germany and the UK are not far behind. In November, Italy’s Enel Group announced investments of 43 billion euros in grid stability, wind and storage.
Africa has seen notable advances. Kenya is making large investments in renewables, with wind, solar and geothermal playing a role. In 2024, it generated 90% of its energy from renewables. Morocco and Namibia are advancing quickly. Morocco’s Ouarzazate (or Noor) is the world’s largest concentrated solar power (CSP) plant.
Despite this real progress, however, the G20 are still not on track to meet the goal set out in the Paris Agreement of limiting global warming to “well below” 2°C by the end of the century2. GHG emissions continue to mount overall. With any luck, increased energy efficiency and renewables capacity have staved off the worst. However, if current trends continue, the Earth is heading for 2.7°C of warming, with dire consequences for humanity. This could be reduced to about 2.3°C if decarbonisation efforts are intensified; anything below 2° is looking very difficult, though not entirely out of reach. Although demand for electricity is increasing both in absolute terms and compared with other energy forms, this demand is not being met by renewables alone: in 2024, consumption of all energy sources increased. There are other difficulties. With the increase of geopolitical tensions, wars and dictatorships, security of supply is of greater concern than before, making policy makers more conservative. Several oil and gas companies have reduced their investment in renewables after the war in Ukraine caused a rise in oil and gas prices. In 2024, fossil fuels still accounted for 87% of the energy mix. And now the USA has re-elected a climate sceptic as president. The United States has withdrawn from the Paris Agreement for a second time, and legislation that has just passed will undermine renewables. In the near future, the US’s main contribution to decarbonisation is likely to come not from renewables but from nuclear power (especially small modular reactors, or SMRs), hydrogen, and carbon sequestration.
Energy types
Of all the variable (or intermittent) energy types, hydropower still holds the largest share, although by 2030 it will have been overtaken by solar PV and will be neck-and-neck with wind3.
Solar is probably the sector in which innovation is advancing the fastest. Researchers at Ulsan National Institute of Science and Technology have developed a transparent, all-back-contact (ABC) configuration, which places all electrical contacts on the rear side, creating a glass-like transparent crystalline silicon cell. Space Based Solar Power would harness the sun’s power in space and transmit it wirelessly (via microwaves or lasers) to earth. The energy harvested would avoid the intermittency problem of terrestrial solar power and would result in enormous gains of efficiency. Until recently, because of the uncertainties and expense, this has been just an idea, but Europe, Japan and other countries are actively pursuing it. China is working on a station that would be a kilometre wide.
Other types of innovation concern installation and location. Floating solar power frees up land for other use, while efficiency is gained by cooler panels. Among the world’s largest floating solar power plants are the Dezhou Dingzhuang project in China and India’s Omkareshwar project. The world’s largest such floating farm is at Huainan, Anhui Province, China, with a capacity of 1GW. It was created by the China Three Gorges Corporation, which also built the world’s largest hydroelectric dam. Another way of saving space is to mount solar panels above crops (agrivoltaics). The shade can also protect crops from excessive heat from the sun. Among the countries pioneering this approach are Germany and Japan. In other experiments, solar panels have been laid on railway tracks (Switzerland), bicycle lanes and on the roofs of public buildings. Dual-use solar + desalination is also increasing. A CSP plant in the Atacama Desert in Chile also makes water by using solar power to extract moisture from the air.
Regarding wind power, China has set yet another record with the world’s tallest and highest-capacity offshore wind turbine, the 26-MW turbine from Dongfang. According to the manufacturer, the new turbine, which is currently under construction, features higher corrosion resistance and can better withstand typhoons. If China dominates production, several countries are busy with installations, including Kenya (the Lake Turkana project) and the Philippines, where German companies are helping to construct offshore wind farms by supplying expertise in grid systems, energy storage, and clean energy generation.
Geothermal, unlike sun and wind, offers the chance to supply non-intermittent energy. Up to now, it has been available only in areas where hot rocks are relatively near the surface: Iceland, Italy, parts of the USA, Kenya and other countries. Can the industry grow if it were to drill deeper, tapping even hotter rock lower down? Quaise Energy is attempting to do this with a new technology called Millimeter Wave Drilling, developed for use in nuclear fusion. This uses electromagnetic waves to vaporise ultrahard rock, using repurposed fossil fuel infrastructure. This method is in the demonstrated phase, and Quaise hopes to have a geothermal power plant, repurposed from fossil fuels, up and running by 2028. Geothermal power plant pipes.
Wave and tidal is another non-intermittent form of energy with great promise. One of the world’s leading countries is the UK, and the O2 tidal turbine from Orbital Marine Power, anchored off the Orkney Islands, is the most powerful in the world. In 2024 the UK government earmarked GBP 15m for tidal stream project auctions. Wales is setting up a research centre to improve the efficiency of tidal energy blades. Wales has also approved four new tidal stream zones. An English company, Proteus Marine Renewables, has designed the AR1100, first deployed off the coast of Scotland in 2017 and recently installed in Japan’s Nafru Strait. Also in Japan, Shimizu Corporation is planning Ocean Spiral, a self-contained underwater city that harnesses deep-sea thermal energy and generates power by exploiting temperature differences between the warm surface and the cold deep.
Storage
Two weak links in the energy transition are grid systems and storage. Many of the grid systems currently operating were not designed to handle a combination of baseload and intermittent sources and will need to be upgraded to avoid blackouts. Moreover, the intermittent nature of solar and wind will require better and more efficient storage. Battery storage has relied heavily on lithium up to now, but this material comes with drawbacks: limited resources, flammability, and a high carbon footprint during the extraction process. EVs makers are now transitioning to sodium-ion batteries, and China has even built a train powered by sodium-ion batteries.
Other types of storage being developed depend on hydrogen, are gravity-based, or use molten salt. This last is an essential component in CSP solar plants. A small Danish company, Hyme, has built a molten salt battery that can store one GW-hour of energy – enough to power 100,000 homes for 10 hours – with up to 90% efficiency. Electricity is stored by heating molten hydroxide salt to 600°C, which is then used to generate steam for heat or electricity. The system uses pumps and a heat exchanger.
Did you know?
- AI data processing centres are major consumers of electricity. Will AI end up consuming more energy than it can save? Probably not, as AI is dynamic and adaptive, capable of learning as it goes along. It can therefore be used to create predictive models and is already being harnessed to reduce energy waste in commercial buildings.
- King Charles III is a major investor in offshore wind through the Crown Estate. Wind farm leases are the estate’s largest source of revenue.
- Global warming has changed the equation for water-based reactors. Hot summers are forcing the closure of water-based nuclear reactors in Europe. Excessive warming of the released water can cause harm to fauna and flora. It can also happen that the water is too hot to cool the reactors sufficiently. We can expect more closures as temperatures rise.
- Singapore has developed a technology for transforming rain into electricity. Ultra-thin panels embedded with triboelectric nanogenerators receive raindrops, which generate an electric charge through friction. The devices can be installed on buildings.
Materials
The energy transition is increasing demand for critical minerals, not only lithium and cobalt, but also rare earth metals, in which China still dominates. Nickel is currently in oversupply, but demand is likely to remain high due to its role in batteries and its use as an ingredient in many nickel alloys and grades of stainless steel. Stainless steel is used in the construction of hydropower facilities and in the frames and fasteners of solar panels. Nickel alloys are used in the pipes that carry molten salt in CPS solar power plants. When added to stainless steel, nickel enhances the corrosion resistance and mechanical stress resistance required in offshore wind farms. For decades, stainless steel has been applied to the turbine blades of tidal power stations, though composites and carbon steel are also used. A martensitic grade was used in a tidal power station at Rance, northern France, in 1966. The National Renewable Energy Laboratory (NREL) is exploring the 3D-printing of a structural spar for an axial-flow tidal turbine blade. Type 316L stainless steel was selected for its strength, corrosion resistance and compatibility with the Meltio 3D printing process. Stainless steel, especially superduplex grades, titanium alloys and nickel alloys (for example 625), are indispensable in geothermal power, where high temperatures, pressure fluctuations and acidic fluids combine to create very harsh conditions.
Conclusion
As I write, Europe is overheating, and the world is suffering from fires and floods. Ideas of how to tackle global warming are not lacking, but they are not being implemented fast enough. The obstacles are more human and political than technical. The achievements of one administration can all too easily be undone by the following one.
References
- https://www.carbonbrief.org/analysis-clean-energy-just-put-chinas-co2-emissions-into-reverse-for-first-time/
- Global Climate and Energy Outlook, IEA, 2024 (https://www.iea.org/reports/world-energy-outlook-2024); Statistical Review of World Energy, Energy Institute, 2025 (https://www.energyinst.org/statistical-review).
- https://www.iea.org/energy-system/renewables/solar-pv.
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