Christopher Barton began his career in the aerospace industry, but now sees an opportunity to use carbon dioxide to create useful materials like silica, in a way that is cheaper and with a lower carbon footprint than current methods.
“The logic was that CO2 is the most abundant, low cost potential feedstock in the world, and the business model should be profitable without relying on a carbon tax,” Barton says.
He set up Barton Blakeley at Rothamsted Research’s site in Harpenden, UK, where an anaerobic digester nearby provides a good source of CO2, and Rothamsted could provide analytical support and other agricultural waste materials as potential feedstocks. The CO2 is blended into a fuel mixture, which is fed into the company’s Hyper Xi process reactor.
There are multiple reactions occurring in the reactor simultaneously, he explains. “That gives us the ability to break up the carbon dioxide.” The oxygen from the CO2 combines with a metal to form various metal oxide powders, depending on the other fuels that are fed into the reactor. “The majority of the mass from the CO2 – the oxygen – is stored within the powder product.”
The carbon can be used to functionalise the end product, distributed into other reaction products, or can be recycled to regenerate more of the fuel mixture, he says.
Initially, the company has focused on silica as a cost-effective product with high demand. By tuning the reactor conditions, a variety of different grades and forms of silica can be achieved. That includes a hydrophobic fumed silica covered in methyl or short alkyl groups – derived in part from the carbon from the CO2 in the fuel mixture. This kind of hydrophobic silica has a well-established market, but it is expensive and energy-intensive to make. “We skip out quite a few of the energy-intensive and siloxane-based steps,” Barton says. The overall carbon footprint of silica from the Hyper Xi process is significantly lower than current commercial production methods used by the global silicones industry.
“Fumed silica has a pretty huge carbon footprint – it’s about 30kg of CO2 equivalent per kilogram of material produced,” says Barton. “If we buy in the fuel materials for our process – which is completely different and involves very different chemistry – you can quite comfortable halve that.” Barton believes that accounting for recycling of the fuels and sourcing some of the inputs from waste materials like rice husk ash, or fabrication waste from the aerospace industry, could eventually bring that figure closer to a 90% reduction in carbon footprint.
The company has now built a larger, pilot-scale plant, with an aim to refine the process and prove its business model works. “It’s capable of consuming about 6 tonnes-worth of CO2 per year, and we’re expecting that to make about 3–4 tonnes of silica powder,” explains Barton. “We have the capability to have a kilotonne scale plant either in construction or completed within the next five years. Our plans are to go as high scale as quickly as possible. Mostly because, while a kilotonne plant is great, until it’s on a megatonne scale, it’s not really doing anything to help fix the planet.”