To reverse the climate crisis, hundreds of gigatons of CO2 must be removed from the atmosphere annually, over the next three generations3. What if we could recycle CO2 now, by capturing emissions and storing them safely or use the emissions as ingredients for other products?
The Earth is warming at an unprecedented rate due to anthropogenic CO2 emissions. The 2015 Paris Climate Agreement (COP21) resulted in a commitment to keep the temperature increase, relative to pre-industrial levels in global average temperature, to well below 2°C, and to pursue efforts to limit warming to 1.5°C.
To reach internationally agreed climate goals, it is essential that we act along two lines simultaneously. We need to reduce and prevent CO2 emissions to the extent possible, and we need to remove CO2 from the atmosphere and store it safely.Negative emissions technologies
Negative emissions technologies are used to remove CO2 from the atmosphere via enhanced land-use sinks and advanced storage technologies. These technologies contribute to a net removal of CO2 and. are needed to handle the overshoot of atmospheric CO2, in order to avoid escalating climate catastrophes caused by global warming1,2.
Negative emissions technologies can be divided into natural technologies based on forestry and agriculture, technology associated with energy and industry, and a combination of both. Natural solutions are in general less costly and closer to deployment than technological solutions, but at the same time also more vulnerable to release of captured CO23.
A promising negative emissions technology that combines technology and nature is permanent geological storage of CO2 from sustainable biomass, also called bioenergy with carbon capture and storage (often referred to as BIO–CCS or BECCS)4. BIO-CCS includes capture of CO2 from energy production, waste incineration and other industries where biomass is used in production. In addition to capturing CO2 from existing point sources, we need to capture and store CO2 from new sustainable biomass. Despite being immature both as a concept and from an environmental footprint perspective, there is interesting potential for utilising the ocean space as a source of biomass to capture CO2.
One example of natural technologies is the reintroduction of some of the CO2 lost from the soil in conventional farming. This can be done by changing tilling practices and growing deep-rooted perennials rather than shallow rooted annual crop species. Every farmer that adopts a climate positive approach helps, but for this to have a significant positive climate impact we need a global revolution in the way farming is conducted. Harnessing the carbon removal potential of other land-based ecosystems such as forests, wetlands and soils is another interesting option. The important additional benefits of such approaches include the opportunity to meet other global sustainability goals such as ecosystem restoration, biodiversity preservation, and improved water quality.
In addition to using biomass to reduce CO2 from the atmosphere, it is also possible to capture CO2 directly from the air (direct air capture) and store it in geological formations. This is a costly process. First, capturing CO2 from the atmosphere is an energy-intensive activity, and hence a viable option only if there is a surplus of renewable energy available. Second, there are costs associated with transportation and storage of the captured CO2.
An interesting possibility is that CO2 can be recycled and put to industrial use as ingredients in products, also called carbon capture and use (CCU). CO2 has successfully been used for the production of chemicals, plastic and carbon fibre. Technologies are emerging based on enzyme activities or amino acids salts that capture CO2 in the form of glucose and bicarbonates in highly effective processes5. There is reason to believe that CO2 required for such purposes is too limited to contribute an appreciable reduction of atmospheric CO2. Potentially more promising applications for the reuse of CO2 are found in carbonate mineralization, bauxite residue carbonation, enhanced coal bed methane, renewable methanol, and CO2 carbon curing6. Carbon curing in cement production is an interesting option, as in addition to sequestering the CO2 in buildings, walls, bridges and other concrete structures, carbon curing also increases the water resistance and strength of concrete. The manufacture of cement in itself accounts for about 8% of global carbon dioxide emissions, so a net atmospheric CO2 reduction can only be achieved if CCS is applied to capturing CO2 from the production process.Opportunities and market impacts
The focus on negative emissions technologies will increase in the future, for several reasons. The public is increasingly aware that we are on a catastrophic climate trajectory, and that progressive measures must be taken in order to save the planet’s ecosystems. This also gives politicians licence to implement tighter regulations on emissions and to incentivize costly solutions. An early example of a climate-positive policy is California’s Low-Carbon Fuel Standard7. One element of this institution is to provide credits to fuel producers who capture and store CO2 in the production process. Such incentives will spur innovation in finding more efficient and cheaper ways to extract and deposit atmospheric CO2 that hopefully will have implications far outside of California’s borders. Given that economic incentives for carbon storage are provided, an obvious market opportunity for oil producing countries would be to move from an oil economy to a carbon sequestering economy. CO2 shares similar properties with oil. It can be stored in the same places, and the technology, people and jobs are to a large extent the same. Except for in California, negative emissions technologies will likely not achieve significant market penetration in the next decade, but some technologies may move beyond the experimental phase.Risks and uncertainties
There are several important risks and uncertainties related to the uptake of negative emissions technologies for CO2. First and foremost, weak price indications for CO2 in most of the world, hinder investments, innovation and research in the technologies, rendering them immature8. The lack of experience with full-scale implementation leads to uncertainty regarding both the true cost of operation, and conflicts of interest regarding the extensive land use for production of biomass or energy. The supply chain for technological solutions combined with underground storage of CO2 (BIO-CCS, DAC) is currently lacking, as is a functioning infrastructure from existing emissions points to storage sites. International agreements covering CO2 storage.
Except for in California, negative emissions technologies will likely not have a significant market penetration in the next decade, but some technologies will move beyond the experimental phase. By 2030, however, there will be ambitious plans, political action and capital rising starting to happen for climate positive solutions for CO2.
Governments play a key role in realizing the potential of negative emissions technologies by providing funding and incentives for large-scale investments in research and development. Governmental policies are also important for handling and assessing potential negative side effects associated with large-scale operations employing such technologies. Read more: Carbon Capture and Storage
- WMO 2018. WMO Statement on the State of the Global Climate in 2018.
- IPCC, 2018 Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty.
- UNEP (2017) The Emissions Gap Report 2017. United Nations Environment Programme (UNEP)
- Global CCA Institute 2019. Bioenergy and Carbon Capture and Storage
- Global CCS Institute 2011.Accelerating the uptake of CCS. Industrial use of carbon dioxide capture