The tropical beaches of India probably bring to mind sun-dappled palms, fiery fish curries and dreadlocked backpackers, but they also hold a surprising secret. Their sands are rich in thorium – often hailed as a cleaner, safer alternative to conventional nuclear fuels.
The country has long been eager to exploit its estimated 300,000 to 850,000 tonnes of thorium – quite probably the world’s largest reserves – but progress has been slow. Their effort is coming back into focus amid renewed interest in the technology. Last year Dutch scientists fired up the first new experimental thorium reactor in decades, start-ups are promoting the technology in the West and last year China pledged to spend $3.3bn to develop reactors that could eventually run on thorium.
Proponents say it promises carbon-free power with less dangerous waste, lower risk of meltdowns and a much harder route to weaponisation than conventional nuclear. But rapid advances in renewables, a costly development path and question marks over how safe and clean future plants would really be mean its journey to commercialisation looks uncertain.
India’s pursuit of thorium is driven by unique historical and geographic conditions, which have given it considerable staying power. Some see a quixotic quest unlikely to live up to its promise, but the country’s nuclear scientists see a long-term strategy for carbon-free energy security in a country whose population could peak at 1.7 billion in 2060.
“We are a power hungry nation,” says Srikumar Banerjee, secretary of India’s Department of Atomic Energy (DAE) until 2012. “Eventually we need to rely on indigenous raw materials for the long-term sustainability of a country which is going to support one fifth of humanity.”
Today all commercial nuclear plants run on uranium, a fact at least partly down to geopolitics. The West’s development of nuclear energy was inextricably linked to the development of atomic bombs and uranium’s by-products are much easier to weaponise. “In a different era maybe a different choice would be made and we’d have headed down the thorium route in the 1950s instead, but we are we are where we are,” says Geoff Parks, a nuclear engineer at Cambridge University.
Thorium doesn’t spontaneously undergo fission – when an atom’s nucleus splits and releases energy that can generate electricity. Left to its own devices it decays very slowly, giving off alpha radiation that can’t even penetrate human skin, so holidaymakers don’t need to worry about sunbathing on thorium-rich beaches.
To turn it into nuclear fuel, it needs to be combined with a fissile material like plutonium, which releases neutrons as it undergoes fission. These are captured by thorium atoms, converting them into a fissile isotope of uranium called U233. An isotype is a variant of an element with a different number of neutrons.
India isn’t putting all its eggs in one basket though. Besides its continuing work on wind and solar energy, the government approved construction for 12 new heavy-water reactors to add to the 22 in operation and 9 under construction. It’s also exploring deals for foreign-designed reactors with Russia, France and the US. But given its progress so far, Parks thinks thorium makes sense as a long-term hedge for India. “They should be commended for having had a plan and stuck to it,” he adds. “I wish the UK could be accused of the same.”
Even India’s nuclear scientists doubt thorium’s prospects in developed countries though. With little headroom in energy consumption and established uranium-based technology, they’ve little incentive to risk switching tracks, says Kakodkar. The opportunity is booming energy consumption in the developing world where he sees thorium’s abundance and proliferation-resistance making it a promising carbon-free baseload provider.
“If you really want to move toward carbon-free energy for the world, I don’t see how it can happen without nuclear and I don’t see how nuclear can grow without thorium,” he adds. “So somebody has to take the lead.”
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