Explained: High-tech climate solutions

Traditional clean energy sources like solar and wind power are expected to play a leading role in helping countries reach near-term emissions reduction goals,

But it’s the higher-tech solutions, like fusion and advanced nuclear plants, that could play a crucial role in longer-term energy plans.

Here are some of the technologies drawing the most attention.

1/FUSION

Fusion is the process that fires the sun.

It works when the nuclei of two atoms are subjected to extreme heat.

That leads them to fuse into a new larger atom, giving off enormous amounts of energy in the process.

However, no facility has yet performed a fusion reaction that releases more energy than it requires – the usual fuel hydrogen must be heated to 150 million degrees Celsius.

2/ADVANCED NUCLEAR

Advanced nuclear plants would be smaller than today's massive nuclear reactors.

They could theoretically be used in remote locations, complement wind and solar power, and some versions could use nuclear waste as fuel. But advanced reactors are a challenge to build.

Critics also say they will create more concentrated waste and would run on enriched uranium, which could make some advanced reactors and their supply chains attractive to bad actors.

In the U.S., Bill Gates wants to build a Natrium reactor in Wyoming for about $1 billion and have many of the plants providing power to the grid in the 2030s.

3/CARBON CAPTURE AND STORAGE

Last month in Iceland, Climeworks AB partnered with carbon storage company Carbfix to open the world’s largest plant to suck carbon dioxide out of the air and pump it underground where it becomes rock.

It is one of 15 direct air capture plants in the world that together suck about 9,000 tonnes of CO2 a year out of the sky.

Sounds impressive, but that is only about the amount that comes out of the tailpipes of 2,000 cars.

Proponents say the high costs will fall as the technology improves.

4/HYDROGEN

Long used in rocket fuel, hydrogen can be mixed with natural gas to make a cleaner-burning fuel, or used in a fuel cell vehicle, releasing water vapor as exhaust.

The holy grail is so-called clean hydrogen produced with wind, solar or nuclear power – today’s “grey hydrogen” is made with fossil fuels.

But that costs about four times as much.

Saudi Arabia, the world's largest oil exporter, is planning a $5 billion plant at its futuristic city NEOM to produce clean hydrogen.

5/GEOTHERMAL POWER PLANTS

Geothermal power plants tap heat up to 700 degrees Fahrenheit far below the Earth’s surface.

This creates steam that powers electricity-generating turbines.

But the technology needs to ramp up greatly to play a significant role in providing an alternative to fossil fuels.

And high upfront costs hold back investments.