The question is, can this baking soda process save the planet from runaway climate change? Jones, himself a chemist, is realistic. “Skymine by itself cannot save the world, because the sodium-based product market by itself could only support 200-250 plants worldwide,” he said. But a second design, code named Skycycle, that will manufacture calcium-based products like chalks and limestones, might be able to.
“In this county alone there are more than a pentillion tons of limestone, that contain more CO2 than has or could be generated by all fossil fuels for all time,” Jones said. “Disposing of CO2 as solids has already been proven to work over very long, geological periods of time.”
Despite the straightforward chemistry, it’s the first attempt at mineralizing carbon in a way that is commercially viable and carbon negative. The method seen as more mainstream is to capture the CO2, transport and inject it in gaseous form into subterranean geological formations. The UK has a great number of these, Michelle Bentham, senior geoscientist at the British Geological Survey. “We have lots of suitable formations offshore, and lots of oil and gas fields, in which the gas and oil collects in the same way the CO2 would.”
The so-called reservoir rocks such as sandstone are filled with tiny holes known as pore spaces which are microns in size, into which the CO2 is forced, eventually bonding to the rock. While the technology required at each stage – scrub, capture, transport and inject – are well-established, commercial schemes have been held up by economic, not technical questions.
“There are still unanswered questions until we actually do it, but I have no doubt that carbon dioxide can be stored in that fashion,” said Bentham. A Norwegian drilling firm has been carrying out a similar process since the 1990s – stripping CO2 from oil and gas as it is extracted and then injecting millions of tons of it every year back under the North Sea.
Judith Shapiro, policy and communications manager for the Carbon Capture and Storage Association, a trade association, said the Skyonic project was promising, and demonstrated that there were different ways to going about capturing carbon. “But I’d say that scale and challenge of climate change is such that it’s unlikely the mineralization process would be sufficient,” she said.
For comparison, the US alone produced 5.5m tons of CO2 in 2008, compared to the estimated 83,000 tons Skymine would remove. “In terms of the time we have and volume we’re producing, it’s just not possible be able to mineralize that amount of carbon dioxide.”