Carbon is one of the most abundant elements on Earth. The rise of carbon emissions, especially in the form of carbon dioxide, has been significant. It has also become an environmental concern with respect to climate change. Emissions have increased the CO2 concentration in the atmosphere due to human activities since the industrial period. Let’s try to understand the carbon cycle, emissions, and how they are captured and stored across countries.
The Carbon Cycle
It is a natural process that regulates the flow of carbon among land, soil, atoms, the ocean, and living organisms. It has been happening for thousands of years between the above reservoirs. This helps maintain the equilibrium state on Earth.
Atmosphere: in the form of CO2
Land: living and dead biomass like plants, animals, and soils
Oceans: CO2 dissolved in the ocean, stored under coral reefs, and more.
Rocks: Fossil fuels (decomposed organic matter)
The carbon cycle can be divided into two main components.
Fast carbon cycle: The plants absorb CO2 for the process called photosynthesis. It is converted into glucose and oxygen. This is utilized by organisms like us that require oxygen for survival. This is the rapid conversion of carbon to oxygen in the atmosphere.
Slow carbon cycle. This is a long-term process of storing carbon in rocks, fossil fuels, and deep oceans. It takes millions of years to happen.
Increase in CO2 concentration
Burning fossil fuels, deforestation, industries, aviation, agriculture, and many human activities have disrupted the carbon cycle. Before the industrial age, atmospheric CO2 levels were around 280 parts per million. The levels have been rising and reached around 420 ppm (0.042%).
With the levels of CO2 rising, actions need to be taken to remove the excess CO2 from the atmosphere. Otherwise, it might affect the global temperature, ocean acidity, and changes in weather patterns around the world.
Major source of emissions
Energy Production: Most of the power plants use fossil fuels (including coal, oil, and natural gas). It makes up the largest source of CO2 emissions.
Transportation: Automobiles, airplanes, ships, and trains that run on fossil fuels also contribute to emissions.
Industrial Process: Manufacturing processes such as steel, cement, and certain chemicals release an amount of CO2.
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Carbon Capture Technologies
There are a lot of technological approaches that have been developed to capture CO2 emissions before they are released into the air. Certain approaches remove CO2 directly from the air. They are called Carbon Capture and Storage (CCS) or Carbon Dioxide Removal (CDR). It aims to capture and store it in a way that prevents it from escaping into the atmosphere. It is done in two ways.
Point source capture
Here, the CO2 emissions are directly captured from large point sources like power plants and industries. There are three major ways.
Pre combustion capture: CO2 is removed from the fuel before combustion.
Post combustion capture: CO2 is removed from the gases after combustion.
Oxyfuel combustion: Fuel is burned in pure oxygen to produce a CO2 stream.
Then it is compressed and transported through a pipeline for storage. It is usually injected underground between the rocks for permanent storage. SaskPower’s Boundary Dam project can capture around 1 million tons of CO2 per year from the coal power plant. Carbon Clean Solutions has developed carbon capture solvents (amine-promoted buffer salts) that reduce costs and increase the efficiency of CO2 capture.
Direct Air Capture (DAC)
Another technique that is gaining traction these days is direct air capture. It removes CO2 directly from the air around us. It focuses on the emissions from transportation and others.
A leading Swiss company called Climeworks uses filter material to capture CO2 from the air. The machines work on geothermal energy, which is abundant in Iceland. It has two facilities called Orca and Mammoth. The captured CO2 is then stored underground. Global Thermostat is developing direct air capture to produce carbon-negative hydrogen fuel as well as capture it for storage and utilization.
Carbon Storage Technologies
Once the carbon is captured from the point or direct air, the CO2 must be transported and stored permanently. The most widespread storage approach is injecting it into the deep underground. It is sent into the depleted oil and gas reserves, where it can be stored for years.
Carbfix, a Swiss based company that works in conjunction with Climeworks, injects into the underground. Then the CO2 is mixed with water and reacts with basalt to form the stable carbonate minerals. It has been said that nearly 90% of the injected CO2 is mineralized within 2 years.
Other CCS Technologies
Enhanced Weathering
It involves spreading the minerals that react with CO2 over a larger surface. These minerals capture CO2 and convert it into stable forms. Heirloom does the same by grinding the minerals into a fine powder and spreading them over a large surface. It reacts and forms stable carbonates.
Bioenergy with CCS
Using biomass like wood pellets or residues from agriculture to produce biogas.
Biochar
Burning the biomass with limited oxygen to produce biochar, which can be used to store carbon.
Challenges
However, scaling up these CCS will require high costs, land, technologies, and policies, not relying on fossil fuels to run the machines. It has significant challenges to overcome and a meaningful impact on CO2 levels.
Energy Requirements
Each of these techniques and approaches has the potential. One of the important challenges is the energy required to operate them. DAC is energy intensive, as it involves large volumes of filters to absorb the CO2. In case of Climeworks, Carbfix, Iceland has lot of geothermal, so the emissions from it are very less. It would be a difficult for countries based on fossil as power source. If they are used, then the benefits of Co2 capture will be negated by the emission from the energy production. In that case, solar energy can be used. It is sustainable, abundant and cost effective making it as an attractive option. However, weather conditions, land use and initial investments are the challenges that needs to be addressed.
Scaling up and Regulation
The cost of building and scaling up carbon capture infrastructure is rising, involving financial investment, infrastructure development, and regulatory frameworks. Effective policies and incentives are crucial to drive investment in these technologies. International cooperation and agreements are necessary to standardize and regulate carbon capture practices.
The technologies are evolving to capture and store the carbon but the hurdles remain to scaling up and implementing them across. Often, this requires a multifaceted approach. While reducing emissions through cleaner energy sources and improved efficiencies is critical. This is don’t mean to keep using fossil fuel and involving increase the carbon footprint, but as a necessary complement to reduce emissions. However, challenges related to energy requirements, economic viability, and scalability need to be addressed through innovation, investment, and supportive policies.
Cheers!
PS: Some make Ink out of Carbon emissions.
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