What Are CCUS, BECCS, and DAC?

1. What is Carbon Capture, Utilization, and Storage (CCUS)?

Carbon capture, utilization, and storage is an emerging negative carbon technology that can play an important and diverse role in achieving energy and climate goals. CCUS involves capturing carbon dioxide from large point sources (such as power plants or industrial facilities that use fossil fuels or biomass as fuel) or directly from the atmosphere. If not utilized on-site, the captured CO2 will be compressed and transported via pipelines, ships, railways, or trucks for subsequent applications; or injected into deep geological formations (including depleted oil and gas reservoirs or saline formations) for permanent storage. Major capture technologies include chemical absorption, physical separation, oxygen-fuel separation, membrane separation, calcium looping, chemical looping, direct separation, and supercritical carbon dioxide power cycles; the main uses of CO2 include the production of fertilizers, generation of hydrocarbon fuels, and the manufacture of chemicals and building materials.

2. What is Bioenergy with Carbon Capture and Storage (BECCS)?

Bioenergy with carbon capture and storage is a carbon removal technology that relies on two processes: biomass (organic material) is converted into heat, electricity, or liquid or gas fuels (the “bioenergy” step), and the carbon emissions generated from this bioenergy conversion are captured and stored in geological formations, or embedded in durable products (the “carbon capture and storage” step). Since biomass absorbs carbon from the atmosphere during its growth, if implemented properly, BECCS can become a negative emission technology—meaning that BECCS can be used to reduce carbon dioxide in the atmosphere. This is contingent on the emissions produced during the growth, harvesting, transportation, and processing of the biomass not exceeding the captured carbon, and the storage of the captured carbon being reliable over a long period.

3. What is Direct Air Capture (DAC)?

Direct air capture refers to the technology that extracts CO2 directly from the atmosphere. CO2 can be permanently stored in deep geological formations (thus achieving negative emissions or carbon removal) or used in food processing or combined with hydrogen to produce synthetic fuels. Currently, there are two technological methods for capturing carbon dioxide from the air: liquid and solid DAC.

Liquid DAC passes air through a chemical solution (such as hydroxide solution) to remove carbon dioxide. The system recovers chemicals by applying high temperatures while returning the remaining air back to the atmosphere.

Solid DAC uses solids that can chemically bond with carbon dioxide as absorbents; when heated under vacuum, they release concentrated CO2 that can be collected for subsequent storage or use. Its advantages include lower environmental impact and the ability to utilize it on-site, avoiding long-distance transport; however, its drawbacks include higher costs.