Khosla shuns CCS in favour of coal-to-cement

A new breed of carbon capture technologies capable of turning CO2 emissions into cement could soon provide a cost effective alternative to high profile, but as yet unproven, carbon capture and storage (CCS) systems, according to one of the world's leading clean tech venture capitalist.

Speaking at the World Future Energy Summit in Abu Dhabi today, Vinod Khosla, a leading silicon valley venture capitalist who in recent years has become a major investor in clean technologies, said that CCS technologies were simply too expensive to acheive mainstream adoption and as such more cost effective alternatives are required.

"I believe CCS is too expensive and so we are looking at a technology that turns CO2 into cement building materials," he said, adding that he had invested an undisclosed sum in California-based Calera, a company that pioneers CO2-to-cement technology.

Calera has been in stealth mode for a number of years, its website stating only that it is "dedicated to reversing global warming and ocean acidification by trapping the greenhouse gas, carbon dioxide, in the built environment".

However, the company has now provided fresh details of its plan to pull carbon dioxide out of the atmosphere and sequester it in cement that can be used as a building material.

The process works by converting CO2 into carbonic acid and then turning it into a carbonate, in a process similar to that used naturally by coral to form shells and reefs.

The process can also be used to desalinate seawater, usually an expensive process, though the water would have to be treated before use.

The company said the technology could also be fitted to power plants in the same way that advocates of more established forms of CCS hope to do.

Cement production itself is a huge emitter of CO2 – responsible for some 2.5 billion tonnes a year. Calera believes these emissions would also be reduced if the technology is successfully deployed globally.

Calera is just one of a number of firms currently investigating converting CO2 into useful materials.

California-based firm Carbon Sciences has proposed a pilot plant to turn waste CO2 into precipitated calcium carbonate, a chemical compound that could be used in everything from drywall and fertiliser, through to yoghurt and toothpaste.

UK start up Carbon 8 Systems is similarly investigating technologies capable of turning CO2 into useful carbonates, while a Norwegian research team including energy giant StatoilHydro is undertaking a project to use captured CO2 to treat mine tailings.

Advocates of these approaches argue that not only are they more cost effective than large CCS systems, but they also create a marketable product and ensure that the CO2 is sequestered more stably than if it is pumped underground.