Why solar energy is the only viable energy source in the long term

Just 0.3% of the world's land area would need to be covered with solar panels to meet all energy needs (VCG via Getty Images)

Solar power has been on the rise for years, and for good reason. It has become one of the cheapest ways to generate energy in most places, and one of the best options for fighting climate change.

But there are naysayers. US energy secretary Chris Wright has argued that solar power cannot provide all the energy the world needs. This is completely wrong and shameful, as many have pointed out. In fact, in the long run, solar power—including wind, which captures energy from the Sun in a different way—is the only energy source that can meet growing demand without overheating the Earth.

On September 2, Wright posted on social media platform X: ' Even if you covered the entire planet with solar panels, you would only be generating 20% ​​of global energy. One of the biggest mistakes politicians can make is equating ELECTRICITY with ENERGY! '

Starting from the basics, electricity is measured in terms of the energy it provides, so in practical terms, yes you can think of electricity as energy.

As climatologist Gavin Schmidt at NASA Goddard Institute for Space Studies pointed out on Bluesky, the total pre-expenditure energy of all fuels used in the world in 2024 is 186,000 terawatt-hours. He says Earth receives 6,000 times that amount of energy each year.

Furthermore, Schmidt says, if one takes into account the fact that 60% of fossil fuel energy is lost when converted into useful power, the Earth receives 18,000 times more energy from the Sun than it currently consumes.

Of course, current solar panels only capture about 20% of the Sun's energy, and you can't put them everywhere. But a 2021 report from Carbon Tracker estimated that 0.3% of global land—yes, just land—would be needed to meet current energy needs with solar alone, which is smaller than the current footprint of fossil fuel infrastructure. Solar and wind could, in principle, provide more than 100 times the current global energy needs, the report said.

Since meeting current energy needs with fossil fuels has caused catastrophic global warming, fortunately there are not enough fossil fuels on the planet to provide 100 times that amount of energy. But what about nuclear fusion? Would it be a better option than solar power if it became viable?

The answer is no. Eric Chaisson at Harvard University estimates that even assuming a moderate increase in global energy demand, waste heat alone could be enough to warm the planet by 3°C over the next three centuries. We're talking about the waste heat that's generated when energy is used, when you boil a kettle, or use a computer, for example.

With solar energy — and wind and wave energy, which are actually forms of solar energy — waste heat isn't a problem because that energy ends up as waste heat anyway, whether we use it or not. With other energy sources like nuclear fission, waste heat is extra heat that wasn't there before.

' Sagan used to teach me, and I now teach my students, that any intelligent civilization on any planet would eventually have to use the energy of its parent star, exclusively ,' Chaisson told New Scientist in 2012.

While three centuries is a long time, waste heat has had a significant impact at the regional level. Researchers estimate that maximum summer temperatures in Europe are 0.4°C higher due to waste heat. By 2100, average annual temperatures in some industrial regions could be nearly 1°C higher due to waste heat—an effect not currently included in climate models.

The conclusion is that not only can solar and wind provide all the energy we need for centuries to come, but they are the only technologies that can do so without causing catastrophic warming. Wright was completely wrong.