What is Carbon Capture and where is it heading?

Carbon Capture is a term that's been around for quite a while. It's the umbrella category for Carbon Capture and Storage (CCS) and its cousin Carbon Capture and Utilisation (CCU).

Carbon Capture projects were once all the talk in UK policy circles, before major public funding was axed and industry players withdrew. But now it's back up the agenda. The British Government has recently introduced legislation to reach net-zero emissions by 2050, and its independent advisers - the Committee on Climate Change - said in its May 2019 report (p182) that CCS "was on the critical path" for achieving this. It suggested that a whopping 75-175 million tonnes (megatonnes, Mt) per annum of CO₂ storage would be needed by that time.

But let's go back a little and briefly define some terms.

Carbon Capture and Storage (CCS) means capturing carbon dioxide (CO₂ herein) from an industrial process - like making energy or a tangible substance - and burying it permanently in something like an oil and or gas field. Sometimes the S stands for Sequestration, but we're talking the same principle.

Carbon Capture and Utilisation (CCU) still involves the capturing part. Though instead of burying it, the idea is to use the CO₂ and make use of it in a manufactured product (like beer or the holes in crumpets), rather than using energy to manufacture CO₂ from scratch for that purpose.

Together, these are Carbon Capture. Actually, the umbrella term CCUS, where the U can stand for usage or utilisation, is increasingly being used. Because, heaven knows, we need more and longer acronyms, right? Seriously, this post will refer to CCS and CCU when talking specifically, and Carbon Capture when referring to the umbrella category.

Policy talk aside, then, are there any contemporary projects that demonstrate a renewed interest by industry? Yes.

• Canadian firm CarbonCure holds a patent for mineralising captured CO₂ into concrete. The usual process for making concrete involves mixing water with sand, gravel and cement. That last  ingredient is the killer, as cement is made by heating calcium carbonate - limestone to you and me - to around 825 °C for for several hours. Not only does that require huge energy inputs, but the process itself emits huge amounts of CO₂. By mineralising CO₂ into the concrete mix, it becomes stronger, and that means less you can use less concrete and therefore less cement. And that CO₂ is effectively stored, as concrete structures can stand for hundreds of years. CarbonCure concrete is being used in the 725 Ponce complex in Atlanta, opening in 2019. Spookily enough, I've spent time in that neighbourhood, including the Ponce City Market.

• Tata announced in June 2019 a £16m project to capture CO₂ from its onsite gas turbine, and utilise that in its production of sodium bicarbonate, used in baking powder and pharmaceuticals. The economics of capturing gas from a gas turbine are typically challenging, as the CO₂ is far more dilute in the flue gas than in a coal power station, but then again they are utilising it on-site rather than transporting it by pipeline. It also helps that the British Government is stumping up £4.2m. Aiming to capture 40,000 tCO₂ a year by 2021, it would be the largest Carbon Capture project in the UK.

• In the same funding round, Drax Group plc and partners secured £5m of government funding to expand its Carbon Capture project at the Drax Power Plant in Yorkshire. This will boost its capture to a potential 16 MtCO₂ per annum by mid-2020s, up from the current figure of 365 t.  (Full disclosure: I have financial ties with Drax, but opinions are my own). The Drax project already achieved a world first back in February 2019 (paywall), being the first to harness Bioenergy Carbon Capture and Storage (BECCS) technology. This combines Carbon Capture with biomass combustion, which has the potential to be carbon negative, given that the biomass absorbed CO₂ during the growth (i.e. tree!) stage. Though note that the carbon isn't yet being stored underground or utilised, as it's still a trial.

• One future user of Drax's captured CO₂ is the British startup Deep Branch, who have designed a process to feed microbes with hydrogen and CO2 to produce fishmeal, used to feed fishfarms. There's a good diagram at the bottom of the article that explains how it works.