By Sam Thompson
At last year’s UN General Assembly, President Xi Jinping announced to the world via video link that China plans to reach carbon neutrality by 2060. This was a bold statement from the planet’s largest contributor to increasing CO2 levels and was welcomed across the international community.
Speculations abound about whether this is a plausible and serious target, but first impressions would suggest that the government’s leading role in the economy may be able to accelerate the decarbonisation of the country quicker than a lot of western decentralised states. One way this can be accomplished is through greater investment in green science endeavours.
This opens routes to lower emissions whilst also establishing China as the primary player in green technologies and will help close the gap to the United States as both superpowers grapple for global dominance.
Within this context, the reasons for China’s latest scientific enterprise are obvious. In July, government scientists announced that they were investing heavily in new nuclear technologies: thorium-based molten-salt nuclear power plants, with the first experimental tests on a prototype reactor beginning in September. Strictly speaking, these are not a new concept.
The Molten Salt Reactor Experiment (MSRE) at the Oak Ridge National Laboratory, located in the eponymous city in Tennessee, ran on thorium fuel rather than uranium for four years in the 1960s. More recently, private companies have revived this space-age relic. However, this announcement is the first serious backing from a major government.
Thorium is an element two protons smaller than uranium and both are members of the actinides, a group in the periodic table. Interest in thorium has been maintained by a small vocal minority within the scientific community with advocates promising a multitude of benefits over uranium.
Despite its reputation of sustainability, nuclear energy is not renewable. Uranium is a limited resource found in the ground and will eventually run out. Thorium does not eliminate this problem but is three times more abundant in the Earth’s crust. This can increase the transition window between fossil fuel-based energy and fully renewable technologies allowing further refinement of solar cells and wind generators.
The ore, monazite, contains only a single useful isotope of thorium, Th- 232, whereas uranium ores contain only around 0.7% of the fissile isotope U-235. Monazite is also easier to mine in open pits, where there is a reduced threat of radiation poisoning from the high radon gas levels found in underground uranium mines.
Thorium is melted into a liquid fluoride salt matrix which eliminates the need for water as a heat transfer agent, increasing the efficiency due to higher temperatures and allowing usage in dry desert countries. This molten salt solidifies quickly on contact with air, effectively self-sealing any leaks and drastically reducing the risk of explosive meltdowns relative to uranium water-based reactors.
One of the largest concerns related to nuclear power is the radioactive by-products that are produced in the reactors. The Chinese scientists claim that their thorium reactor will produce a thousand times less waste which will return to safe levels a thousand times quicker than conventional nuclear waste.
All of this raises the question: why was uranium chosen over thorium in the first place when it is clearly inferior? Thorium is cleaner, safer, and more abundant. It has one major ‘downside’, however, in that the nuclear waste produced by thorium reactors is much harder to develop into nuclear weapons. In the middle of 20th century, around the time that MSRE at Oak Ridge was shut down, the US and Russia were embroiled in the Cold War, which sounded the death knell of thorium.
As both countries hastened to bolster their nuclear arsenals, uranium research intensified, and massive strides were made in reactor technologies setting the world down the bad path of nuclear energy. In the succeeding decades, any country looking to build nuclear powerplants would have no choice but to choose uranium due to the massive investment required for thorium research to catch up with uranium. China’s is the first government that appears willing to delve back into this area.
Questions remain on the logistics of transitioning to thorium. Can pre-existing uranium reactors be converted to thorium in a sustainable way, if at all? How unfeasible is it to make weapons from thorium byproducts? Will the scale-up from prototype reactors to commercial reactors be financially viable and will they be developed in time to help China reach its carbon neutrality target by 2060?
But this announcement is a good first step. There is no one fix for limiting man-made climate change; it requires a concerted multi-pronged approach guided by scientifically informed governments. Hopefully, China’s actions can inspire all governments that they can and should do more. Market-based economies like our own are efficient at what they’re designed to do but they contain little incentives for collective action that has no financial benefits like combating climate change.
The announcement of AUKUS this month may be seen as the opening act of the arms race with China as the West prepares for a new Cold War.
This was heavily contrasted with China’s thorium announcement in the same month, a technology that has little military usage and may let the US allow nuclear power in semi-developed countries like Iran without the fear of nefarious side projects (as these would be rendered near impossible). With China willing to share their findings not only will they be able to power themselves more cleanly but, like thorium’s Norse god namesake, help electrify the rest of the world.
Image: jplenio, Pixabay