Carbon dioxide removal is required alongside reducing emissions to help reach net zero. Once removed from the atmosphere, CO2 can be stored in numerous ways, such as trees and ecosystems, ocean reservoirs, and underground geological storage.
Reforestation and mineralization
Nature-based approaches are established ways to remove CO2 from the atmosphere, although they have recently seen increasing competition from engineered approaches. While afforestation and reforestation effects could last up to 100 years, these are not long-lasting or durable enough and have the potential to be reversed. Unlike engineered solutions however, there is no need for large capital investments – instead, startup companies can simply use drones to plant seeds over large areas. Although planting trees can be done at large scales and may be cheaper than other methods, the captured carbon can be hard to measure, making it difficult to set and record targets.
A longer-lasting method of carbon removal is mineralization. In this naturally occurring process, atmospheric carbon dioxide reacts with certain rocks to produce carbonate minerals, preventing excess CO2 from reaching the earth's atmosphere. However, it is clear that more engineered carbon dioxide removal approaches are needed to reach net zero targets.
Bioenergy with carbon capture and storage (BECCS)
BECCS (bioenergy with carbon capture and storage), also referred to as Bio-CCS, refers to any setting where biogenic gaseous CO2 emissions can be captured and permanently sequestered. This includes generation of heat and power from biomass in various contexts, but also industrial facilities such as pulp and paper mills or ethanol plants. As of 2023, 1.7Mtpa of biogenic CO2 was captured and stored, making it the largest scale engineered approach of carbon removal.
IDTechEx predicts that BECCS could help remove over 204 Mt CO2 per year by 2044. The maturity of carbon capture technologies and existing biogenic CO2 industrial processes represent a clear pathway for scale-up. However, the 1 megatonne per annum scale is yet to be successfully operated for BECCS and the necessary CO2 transportation and storage infrastructure does not yet exist. Above a certain scale, crops for BECCS will compete with agricultural land, potentially limiting further growth.
Ocean-based capture
Ocean-based approaches have the potential to play a larger role in carbon dioxide removal. Ocean alkalinity enhancement or direct ocean capture could enhance natural carbon sinks and have good potential to become a successful means of CO2 removal. Although they are not yet mature methods, IDTechEx reports that it only took around 3 years to reach 1000 tons per annum, proving these methods have good prospects in the industry.
More help required
Players using various CO2 storage methods such as mineralization, geological storage, and enhanced oil recovery will need to come together to help make CO2 removal even more successful. Reducing emissions will be the main approach going forward, but CO2 removal is needed to reach net zero.
