Science – Carbon capture and its problems

In the current climate impacts assessment from the NZ Government, it proposes to establish carbon capture (CO2) installations. What is carbon capture and is it important in the long journey ahead to zero carbon (ZC)?

The basic process involves capturing the primary greenhouse gas, carbon dioxide, directly from the atmosphere or from other gases in industrial waste streams. CO2 gas is at the heart of atmospheric warming and is the root cause of the increasingly devastating climate change impacts that are reported daily on TV news.

There are two types of carbon capture in global discussions at present. One involves the progressive removal of excessive historical CO2 formed from burning firstly coal, and later natural gas (methane), since the start of the coal-powered industrial revolution, which started about 1850. The carbon emissions are currently 37 billion tonnes a year and the only successful commercial carbon dioxide trapping process is the Climeworks facility in Switzerland, which traps 1000 tonnes of CO2 per year. This would mean we would need 37,000 such facilities worldwide to return our atmosphere to its pre-1850 state!

The oil and gas industries in the USA have had several attempts to build a large scaled-up version of the small Swiss facility. These carbon capture facilities are referred to in that context as Direct Air Capture (DAC) plants. Their latest failure is the largest DAC plant ever built, which is the Occidental Petroleum DAC facility in Wyoming. Occidental Petroleum were hoping to have a USA government off-set agreement to enable them to continue operating but it has recently quietly abandoned this massive investment.

The second type of carbon capture, which is the one referred to by MBIE in its climate impacts assessment, is a much smaller type of plant usually attached to an industrial waste stream. It removes the CO2 gas from other gases emitted into the atmosphere and so enables the NZ industries involved to continue operating in a CO2 neutral mode. The only problem is that there are about 30 such plants in the world and only a couple of these are working. Recently, the EU as part of its climate strategy proposed installing such plants. However, according to the respected Nature News (2024), the EU was advised by both its own scientific advisors and by independent advisors that this type of carbon capture technology was not yet developed to a practical level. The NZ government would be well advised to abandon this attempt to permit CO2 emitting industries to continue operating and so contributing to climate warming.

In conclusion, industries that generate significant CO2 emissions must avoid or eliminate those emissions. Invoking the deployment of carbon capture technologies that are well known not to have been developed yet will certainly be recognised as an evasion of responsibility both in NZ and among our leading trading companies.