According to this week’s report by the Intergovernmental Panel on Climate Change (IPCC), large-scale implementation of carbon dioxide removal (CDR) measures is now “inevitable” if the world is to reach net-zero greenhouse gas emissions. It is done.
The report, released on Monday, found that in addition to a rapid and profound reduction in greenhouse emissions, CO2 removal is “an essential element of the current scenario that limits warming to 1.5 °C or 2 °C by 2100”. strengthens the possibility of being below.
The CDR points to a set of activities that reduce the concentration of CO2 in the atmosphere. This is done by removing CO2 molecules and storing the carbon in plants, trees, soil, geological reservoirs, marine reservoirs, or products derived from CO2. As the IPCC points out, each mechanism is complex, and has advantages and disadvantages. Much work needs to be done to ensure that CDR projects are undertaken responsibly. CDR is distinct from “carbon capture”, which involves capturing CO2 at a source, such as a coal-fired power plant or steel mill, before it reaches the atmosphere.
What are the methods of removing CO2 from the air?
There are several ways to remove CO2 from the air. They include terrestrial solutions, such as planting trees and adopting regenerative soil practices, such as little or no cultivation and cover crops, which limit soil disturbances that can oxidize soil carbon and release CO2. .
Geochemical approaches that store CO2 as a solid mineral carbonate in rocks. In this process, known as “enhanced mineral weathering”, rocks such as limestone and olivine can be finely ground to increase their surface area and to enhance the naturally occurring process that produces calcium and magnesium. Rich in minerals react with CO to form a stable mineral carbonate. Chemical solutions such as Direct Air Capture which use engineered filters to remove CO2 molecules from the air. The CO2 retained in this way can be dumped into deep underground brackish aquifers and basaltic rock formations for long-term storage. Ocean based solutions, such as increased alkalinity. This involves adding alkaline substances directly to the environment, or electrochemically processing seawater. But more research is needed before these methods can be applied.
Where is it being used now?
So far, US-based company Charm Industrial has delivered 5,000 tonnes of CDR, the largest ever volume. This is equivalent to the emissions produced by about 1,000 cars in a year. There are also plans for large-scale direct-air stop facilities. In September 2021, Climeworks established a project with 4,000 tonnes per year capacity for CO2 removal in Iceland, and in the US, the Biden administration has allocated US$3.5 billion to build four separate direct air capture hubs , each of which has the potential to remove at least one million tonnes of CO2 per year. However, a previous IPCC report estimated that in order to limit global warming to 1.5 °C, 100 billion to one trillion tons of CO2 must be removed from the atmosphere this century. These projects work on a large scale, yet they are a drop in the ocean compared to what is needed. In Australia, Southern Green Gas and Corporate Carbon is developing one of the country’s first direct air capture projects. This is being done in collaboration with researchers from the University of Sydney, including us. In this system fans push atmospheric air over finely tuned filters made of molecular adsorbents, which can remove CO2 molecules from the air. The CO2 collected in this way can be injected deep underground, where it can remain for thousands of years.
What are its options?
It is important to emphasize that CDR is not a substitute for emission reduction. However, it may complement these efforts. The IPCC has suggested three ways to do this. In the short term, CDR can help reduce net CO2 emissions. This is important if we want to limit warming below the critical temperature threshold. In the medium term, this could help balance emissions from sectors such as agriculture, aviation, shipping and industrial manufacturing, where direct zero-emissions options do not exist. In the long term, CDR could potentially remove large amounts of historical emissions, stabilize atmospheric CO2 and eventually bring it back to pre-industrial levels. The latest IPCC report estimates technical readiness levels, costs, scale-up efficiencies, risks and effects, co-benefits and trade-offs for 12 different forms of CDR. It provides an updated perspective on the many forms of CDR that have received little attention in previous reports. It estimates that each ton of CO collected via direct air capture will cost US$84–386, and has the potential to remove between 5 billion and 40 billion tons annually.
concerns and challenges
Each CDR method is complex and unique, and no solution is perfect. As their use increases, many concerns have to be addressed. First, the IPCC believes that increasing the CDR should not detract from efforts to dramatically reduce emissions. According to it, “CDR cannot serve as a substitute for deep emissions reduction, but may well serve a number of complementary roles.” CDR deployment should involve communities, policy makers, scientists and entrepreneurs to ensure that it is done in an environmentally, ethically and socially responsible manner.