Carbon capture and sequestration (CCS) is a approach to climate change mitigation that we used to hear more about. There were government incentives and pilot schemes, all aimed at capturing CO2 as it was emitted by industry and locking it away in long term storage underground. Progress is ongoing, but there are a number of reasons why things are quieter on that front, including the falling use of coal in many developed countries, and the lack of places to store captured CO2. Perhaps the most important is simply that nobody wants to pay for it.
Fortunately, the falling mentions of CCS and the ‘clean coal’ that it might enable have been replaced by something more interesting – carbon capture and utilization. If there’s a use for the captured CO2, then it has an economic value and the whole business case looks completely different. It makes carbon capture into a potential revenue stream, rather than a business expense.
So what can we do with captured CO2? So far the most common use is ‘enhanced oil recovery’, which perversely pumps the CO2 into oil fields to push more oil to the surface. I wrote about that here, but since it doesn’t lock the CO2 away, I’m not going to include it in the list. Here are five other uses:
Building materials – a couple of different companies have recently developed industrial processes that mimic the natural formation of limestone, and accelerate it dramatically. Carbon8 is a British firm that reacts waste products with captured CO2 and makes an aggregate for construction. An Australian company called Mineral Carbonation International has just opened a pilot plant that will use CO2 to make materials for plasterboard, cement and bricks.
Fertilizer – earlier this year the world’s first commercial air capture plant opened in Switzerland. It draws CO2 from the air, and pumps it across a field to a farm where it is used in their greenhouses. There’s another way to make it into fertilizer though, without the greenhouse. Oxford based CCM Research have been developing a way to combine CO2 with waste straw and methane from a landfill site, creating a crumbly soil enriching fertilizer.
Plastic – I’ve mentioned Newlight before, who make plastics out of methane. You can do the same thing with CO2, it transpires. Econic Technologies is a company that uses CO2 as a feedstock for plastic. There’s a double benefit here. First, it replaces half of the oil normally used as a feedstock, and second, it locks up that CO2 in a durable plastic item. Another company, Covestro, makes a plastic foam with a mixture that is 20% CO2. Both of those are commercial operations already, and researchers are developing new techniques that could make plastics by combining CO2 with agricultural wastes.
Gas – Archaea are single-celled organisms and one of the most ancient forms of life on the planet. Methanogenic archaea consume CO2 and produce methane as waste, and a company called Electrochaea uses them to turn carbon emissions into natural gas. I’ll come back to Electrochaea another time, because they use the same technique to turn surplus renewable energy into gas, a useful form of energy storage and potential source of renewable heat.
Baking soda – two Indian chemistry graduates have pioneered a process that takes waste carbon and turns it into baking soda. It has been installed on a coal-powered industrial boiler at the port of Tuticorin, India, possibly making it the first non-subsidised industrial CCS plant.