Daily Hot Topic
Topic : World’s Largest Facility to Remove CO2 from Atmosphere
GS-3 Mains : Science & Technology
Revision Notes
Location: Iceland (dormant volcano, near active volcano)
Name: Mammoth (2nd commercial DAC facility in Iceland)
Function: Removes CO2 from atmosphere and stores it underground
Capacity: Aims to remove 36,000 tons of CO2 annually (equivalent to taking 7,800 cars off the road)
Technology: Direct Air Capture (DAC)
- Extracts CO2 directly from the air, unlike capture at emission sources (e.g., factories)
- Captured CO2 can be permanently stored underground or reused for various applications
Current Status of DAC:
- 27 operational DAC plants worldwide (Europe, North America, Japan, Middle East)
- Total capture: almost 0.01 million tons CO2 per year
Concerns about DAC:
- High Energy Consumption: Requires significant energy to operate, potentially increasing emissions if not powered by renewables.
- Cost: Expensive to build and operate, especially at large scale.
- Scalability: Uncertain whether DAC can be scaled effectively for substantial impact on global CO2 levels.
- Focus Shift: May divert resources from natural climate solutions like reforestation.
Carbon Capture Technologies
Carbon capture technologies can be broadly categorized into three main types: pre-combustion capture, post-combustion capture, and oxy-fuel combustion.
Pre-Combustion Capture:
- Gasification: Involves converting carbon-containing feedstock like coal or biomass into a synthesis gas (syngas) primarily composed of carbon monoxide (CO) and hydrogen (H2). The CO2 can then be separated from the syngas before combustion.
- Chemical Looping Gasification: Utilizes metal oxide particles to indirectly convert carbon-containing fuel into syngas. The metal oxide captures carbon from the fuel, and then the CO2 can be separated from the metal oxide.
- Integrated Gasification Combined Cycle (IGCC): Integrates gasification technology with a combined cycle power plant, allowing for efficient power generation while capturing CO2 before combustion.
Post-Combustion Capture:
- Amine Scrubbing: Involves passing the flue gas from combustion through a liquid solvent, typically an amine solution, which absorbs CO2. The CO2-rich solvent is then heated to release the captured CO2 for storage or utilization.
- Membrane Separation: Uses selective membranes to separate CO2 from other gases in the flue gas based on differences in permeability.
- Adsorption: Utilizes solid materials, like activated carbon or zeolites, to adsorb CO2 from the flue gas. The adsorbent is then regenerated by desorbing the CO2, allowing for multiple cycles of capture and release.
Oxy-Fuel Combustion:
- Involves burning fossil fuels in oxygen instead of air to produce a flue gas consisting mainly of CO2 and water vapor.
- The CO2 can then be easily separated from the water vapor and other impurities, resulting in a concentrated stream of CO2 for storage or utilization.
Emerging DAC Technologies:
- Electro swing adsorption (ESA)-DAC is based on an electrochemical cell where a solid electrode absorbs CO2 when negatively charged and releases it when a positive charge is applied. It’s currently under development in the US and UK.
- Zeolites are being increasingly adopted for DAC due to their porous structure suitable for CO2 adsorption. The first operational DAC plant using zeolites was commissioned in Norway in 2022, with plans to scale up the technology to 2,000 tCO2/year by 2025.
- Passive DAC relies on accelerating the natural process that transforms calcium hydroxide and atmospheric CO2 into limestone. This process is being engineered in the US by a company using renewably powered kilns to separate CO2 from limestone.
The Road Ahead
- Current global carbon removal efforts can only handle about 0.01 million metric tons per year, far short of the 70 million tons per year needed by 2030 to meet climate targets.
- With larger DAC plants under construction and more ambitious plans for future facilities, there’s hope for significant progress in combating climate change.
- Innovation in CO2 use opportunities, including synthetic fuels, could drive down costs and provide a market for DAC.
- Early commercial efforts to develop synthetic aviation fuels using air-captured CO2 and hydrogen have already begun, reflecting the potential role these fuels could play in the aviation sector.
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