Briefing Note 6 – How Can We Recapture the Already Emitted?
What Are Greenhouse Gas Removal Technologies?
Greenhouse gas removal (GGR) technologies aim to actively remove greenhouse gases (e.g. CO2) from the atmosphere. The gases that have been removed require to be reliably stored for at least 1,000 years, preferably 10,000 years.
Several techniques, such as biochar, bioenergy with carbon capture and storage (BECCS), or soil carbon sequestration, use photosynthesis to achieve removal.
Removal can also be engineered directly with chemical reactions: for example, Direct Air Carbon Capture and Storage (DACCS) use chemical sorbents, and enhanced weathering would grind silicate rocks, increasing the surface area and enhancing the natural rate of CO2 absorption.
These technologies are considered distinct from Nature Based Solutions with net negative greenhouse gas emissions such as afforestation and reforestation, land-management of soil carbon, and agroforestry.
Permanent storage of CO2 can be achieved through geological sequestration of greenhouse gases in subsurface rock formations. Alternatively, CO2 can be chemically converted into stable materials for building or other purposes. This is referred to as carbon capture, utilisation, and storage (CCUS).
What Role Can Greenhouse Gas Removal Technologies Play in Achieving Net Zero and the Goals of the Paris Agreement?
GGR technologies presently cost more than many forms of mitigation, such as enhanced energy efficiency, electrification, and renewable power.
However, GGR is deployed in 87% of the cost-effective mitigation scenarios considered by the IPCC as consistent with the Paris limit of 2°C of warming.
GGR technologies are most useful for hard-to-decarbonise sectors of the economy, such as transport, agriculture, steel, aviation, cement, and chemical production. This would allow for some flexibility in mitigation, and, if available at scale, the maximum price of reducing net emissions by a tonne of CO2 is set by the cost of removing that tonne from the atmosphere.
Some argue that managing sector-specific issues, stalled technologies, or policy failure will become exceedingly difficult without GGR technologies. The amount of GGR required depends on key factors including near-term emissions reductions and final energy demand.
What Is the Current State of Research, Development and Deployment of GGR Technologies?
Carbon capture and transportation has been used by the oil and gas industry for decades. In total, there are as many as 18 large-scale carbon capture storage (CCS) projects currently in operation, 5 under construction, and 20 further planned projects. CCS can be applied to GGR, cleaner industry, heat, or power.
Some GGR such forestry or biochar are ready to use. Other GGR technologies are mostly in the pilot project phase, such as BECCS at Drax, Enhanced Weathering at CarbFix, Iceland, and Direct Air Capture plants such as Climeworks in Switzerland.
These pilot projects have demonstrated that GGR can be achieved with existing technology, but these pilot projects have demonstrated that GGR can be achieved with existing technology. Continuing research, development and deployment will increase size, improve efficiency and reduce costs.
The level of development and deployment for GGR technologies is well below the amount used in many scenarios. The 2°C scenario of the United Nations requires 100Mt per year of CO2 storage in Europe by 2030, compared to a mere 1.8 Mt CO2 per year in Europe during 2019.
What Are the Barriers to the Acceleration of GGR Development and Deployment and How Might They Be Addressed?
One major barrier to accelerated development and deployment of GGR technologies is a lack of incentive. Previous CCS projects have stalled due to cost overruns and uncertainty surrounding their future. Private investment is also limited by the lack of a clear business models to deploy GGR technologies without government subsidies to reduce costs.
This incentive issue could be addressed by a carbon price and a robust certification of storage and trading scheme, or by a targeted carbon price. Procurement rules, with supply side measures and regulations create markets to motivate industry.
What Are the Concerns Surrounding the Deployment of GGR Technologies?
GGR technologies use resources: direct air capture and enhanced weathering requires energy, while high levels of BECCS can put strain on the land area and freshwater required to grow the necessary feedstocks. Durability and reliability of storage is short in forestry, but long and secure in geology.
Other concerns are fairness, sustainability, and equity. These issues play out on intergenerational, international, and intrasectoral scales. Some argue that GGR poses a moral hazard, allowing polluting industries and nations to shift the burden onto future generations. Plans that assume GGRs will be available at scale by the end of the century will fail if the technology is not scaled up.
What Does Achieving Net Zero Conclude and Recommend?
Engage youth with government action against climate change
Recommend common practice for reporting GGR sustainability
Support reduction of fossil fuel use, and a just transition
Devise a consistent and universal approach to UN-NDC accounting for us by all states including markets for verified storage by geology or in land