Green transition set to put pressure on sulphur supply

Published by University College London in The Geographical Journal, the work outlines how global demand for sulphuric acid is set to rise from 246 to 400 million tonnes by 2040. This increase is expected to be fuelled by the expansion of agriculture - where sulphuric acid is used in the manufacture of phosphorous fertilisers - and of mineral processing, where it is vital for extracting metals such as cobalt and nickel that are central to Li-ion batteries.  

Currently, more than 80 per cent of the world’s sulphur supply comes from the oil and gas industry, where it is essentially a waste product. Removing sulphur from these fossil fuels helps minimise sulphur dioxide emissions, which cause acid rain. Decarbonisation should correlate to a shrinking of the oil and gas sector and therefore a reduction in the amount of sulphur produced via this channel. The researchers predict an annual shortfall of between 100 and 320 million tonnes, depending on how quickly decarbonisation takes place.

“Sulphur shortages have occurred before, but what makes this different is that the source of the element is shifting away from being a waste product of the fossil fuel industry,” said lead author Professor Mark Maslin, from UCL’s Department of Geography. “What we’re predicting is that as supplies of this cheap, plentiful, and easily accessible form of sulphur dry up, demand may be met by a massive increase in direct mining of elemental sulphur. This, by contrast, will be dirty, toxic, destructive, and expensive.

“Research is urgently needed to develop low-cost, low environmental impact methods of extracting large quantities of elemental sulphur from the abundant deposits of sulphate minerals in the Earth’s crust. The international community should consider supporting and regulating sulphur mining to minimise the impacts of the transition and also to avoid cheap unethical production from distorting the market.”

In the study, the UCL team estimated three sulphuric acid demand scenarios from 2021 to 2040, based on historic and forecast demand, with annual growth rates ranging from 1.8 per cent to 2.4 per cent. The researchers also explored several ways that demand for sulphur could be reduced as part of the green transition, including recycling phosphorus in wastewater for the fertiliser industry, by expanding Li-ion battery recycling, or by using lower energy capacity/weight ratio batteries that require less sulphur for their production.

With demand for sulphur set to rise in both the food and technology sectors, one possible worrying scenario could see the limited supply fought over by multiple industries, with the developing world likely to bear the brunt.

“Our concern is that the dwindling supply could lead to a transition period when green tech outbids the fertiliser industry for the limited more expensive sulphur supply, creating an issue with food production particularly in developing countries,” said study co-author Dr Simon Day, from UCL’s Institute for Risk & Disaster Reduction.

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