How do carbon sequestration technologies such as direct air capture and bioenergy with carbon capture and storage (BECCS) work?

Carbon sequestration technologies, such as direct air capture (DAC) and bioenergy with carbon capture and storage (BECCS), aim to reduce greenhouse gas emissions by capturing carbon dioxide from the atmosphere or during energy generation processes and storing it in long-term reservoirs. DAC involves using specifically designed devices to capture CO2 directly from ambient air, while BECCS combines the use of biomass energy production with carbon capture and storage. These methods help counteract climate change by reducing the concentration of CO2 in the atmosphere.

Long answer

1. Direct Air Capture (DAC): DAC is a carbon sequestration method that involves removing carbon dioxide directly from ambient air using specially designed technologies. It typically employs large-scale machines containing sorbents that selectively bind to CO2 molecules, allowing separation from other gases present in the air. After capturing the CO2, several techniques can be used for its storage or utilization. One option is geological storage, where the captured CO2 is injected into deep underground formations like depleted oil and gas fields or saline aquifers. Alternatively, the captured CO2 can be utilized for enhanced oil recovery (EOR), where it is injected into oil reservoirs to enhance oil extraction while simultaneously being stored underground.

2. Bioenergy with Carbon Capture and Storage (BECCS): BECCS relies on combining bioenergy production with carbon capture and storage technologies. The process begins by growing dedicated crops or utilizing organic waste materials, which then undergo combustion or fermentation to produce energy in forms such as heat or electricity. While this generates CO2 emissions similar to conventional fossil fuel-based energy generation, BECCS incorporates carbon capture during these processes. The produced CO2 is captured either directly from flue gases emitted during biomass combustion or through separating it from other waste stream gases generated during fermentation.

Once captured, the CO2 can be transported and stored through various methods mentioned in DAC, such as geological storage or utilization. Additionally, the captured CO2 from BECCS could potentially be used for other purposes such as product manufacturing or in combination with enhanced oil recovery techniques.

Both DAC and BECCS offer opportunities to remove CO2 from the atmosphere and reduce its concentration, thereby combating climate change. These technologies are still being developed, and their large-scale implementation faces challenges related to cost, scalability, energy requirements, and sustainability. However, ongoing development efforts aim to increase their efficiency and optimize their feasibility in significantly contributing to global carbon dioxide removal goals.