Enthusiasm for lower carbon emissions is fuelling record investment in energy technologies. In 2024, global energy investment exceeded US$3 trillion for the first time, two-thirds of which went towards clean-energy technologies and infrastructure. This trend, detailed in the World Energy Investment 2024 report by the International Energy Agency (IEA), is mirrored by a surge in research on affordable and clean energy. In the Nature Index, which tracks output in selected natural- and health-science journals, such research accounted for just 3.7% of all papers in 2015. By 2023, that figure had grown to 8.3%. While these are positive steps in the transition away from fossil fuels, a deeper look at the data reveals challenges that must be addressed for clean energy to be scaled up globally.
Nature Index 2025 Energy
“There is a ramping up of clean-energy investment against a backdrop of plateauing fossil-fuel spending,” says IEA investment and finance analyst, Tanguy De Bienassis. But, he adds, it’s probably premature to say that the halcyon days of oil and gas are finished, because that plateauing could simply mean that fossil fuels don’t need as much investment as they once did to remain competitive.
The fact that renewables don’t meet demand in key areas emphasizes the work that needs to be done to reduce reliance on fossil fuels. According to the IEA report, global demand for heat energy — used to warm buildings and power industrial processes — is outstripping the rate at which renewables can be deployed to meet the need. The subsequent use of fossil fuels for heat is predicted to drive a 5% increase in annual carbon dioxide emissions from the energy sector between 2024 and 2030.
At the same time, the way that clean-energy investment is shared between countries is highly uneven (see ‘Stark imbalance’). China, for instance, is responsible for roughly one-third of global spending on renewables (and a similar share of global carbon emissions). In 2023, it spent an estimated $890 billion in clean-energy sectors, up by 40% on 2022, according to an analysis by the Centre for Research on Energy and Clean Air in Helsinki. This is just shy of the total global investments in the fossil-fuel supply in 2023, at $950 billion, as reported by the IEA.
Source: World Energy Investment 2024, IEA (2024)
A big part of China’s efforts in clean energy is building renewable power facilities. The country invested $359 billion in this area in 2024, compared with $85 billion from the United States and the European Union’s $106 billion. Emerging and developing economies, including Brazil, India and South Africa, account for just 15% of global renewables investment, and risk missing out on the benefits of clean-energy technologies, including energy independence.
Solar stronghold
Among renewables, solar energy dominates research and investment. In 2023, solar outperformed investments in every other energy type combined for the first time. This happened again in 2024, and the gap widened (see ‘Solar supremacy’). “We’re always underestimating how much solar is going to come online,” says De Bienassis. “It shows that the technology is rich and reaching its maturity. It’s very easy to install and that’s what makes it a success.”
China boasts the world’s most advanced manufacturing base for solar-energy generation. The Tongwei Company, for example, which is headquartered in Chengdu, produced enough solar panels in 2023 to meet 10% of global demand that year. But the vast solar-panel plants that China specializes in have their weaknesses. De Bienassis notes that if one of them underwent an industrial accident, “it would completely disrupt the supply chain”. For now, however, China remains the leading force in solar-energy technology and facilities.
Source: World Energy Investment 2024, IEA (2024)
China’s dominance also extends to nuclear power. Over the past five years, China has added 11 gigawatts to its nuclear power capacity, according to the IEA report, far outstripping any other country. It was one of only two countries (the other being Egypt) that started construction on a new nuclear power plant in 2023, and of the estimated $80 billion spent on nuclear power globally last year, China contributed the lion’s share. “They’re the country that builds the most nuclear plants, the most solar and the most wind,” says De Bienassis. “We call them the powerhouse of the clean-energy transition.”
The United States, meanwhile, is likely to continue decoupling its trade and supply chains from China. President Donald Trump has signalled that he favours fossil fuels over renewables and pledged to withdraw the United States from the Paris climate accord earlier this year.
