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A Darjeeling-based company, Alt Carbon is turning mining dust into a climate-friendly solution by utilising a process called enhanced rock weathering to address the issue of atmospheric carbon dioxide (CO2).
It is the natural carbon removal technology that permanently removes CO2 by spreading finely ground silicate rock, such as basalt, onto surfaces which speeds up chemical reactions between rocks, water, and air.
The speeding reaction removes carbon dioxide from the atmosphere.
This technique enhance weathering reactions by three ways:
Rock Weathering is a geological process that has happened naturally for millions of years.
All rocks naturally break down into minerals over thousands of years.
This happens because the rocks are exposed to rain and heat, and as a consequence of this the atmospheric carbon reacts with these minerals which includes the calcium and magnesium and becomes bicarbonates.
Enhanced Rock Weathering (ERW) we simply speed up the process of rock weathering.
As per the sixth assessment report of the IPCC, the world will probably see a 3-4°C (worst case) rise in temperatures due to global warming and climate change. Use of ERW to artificially remove CO2 from the atmosphere ensures removal of CO2 in a more useful timescales.
ALt Carbon experiment shows that It takes about 3-4 tonnes of basalt dust to sequester 1 tonne of atmospheric carbon within 2-4 years, compared to the natural process that would take about 1,000 years.
Mineral resources, especially different kinds of rocks, such as granite, limestone, basalt, and others; can be found in a wide range of places across the world.
Crushed basalt can be applied to increase soil fertility, which will increase crop yields.
By adding natural minerals from basalt to soil nutrients, chemical fertilizers may not be as necessary.
By improving soil structure, ground stones can help retain more moisture and require less irrigation.
A sustainable method of removing carbon can be achieved by repurposing leftover rocks as the minerals such as granite, limestone, basalt, etc are useful in other industries such as cement and granite manufacturing.
Making use of these by-products lowers waste and encourages a circular economy, where items are reused rather than thrown away.
However there are many challenges in the ERW process.
Carbon mineralizationIt is a carbon removal process that also involves the natural reactions between carbon and rock. It is also called mineral trapping. Mineral trapping is paired with carbon capture, in which machines take pure CO2 out of industrial waste streams or the air itself. The captured CO2 is typically stored underground as a fluid, similar to oil, in carbon capture plants. However, in mineral entrapment, the CO2 is injected into deep-seated basalt after being dissolved in water. Here, CO2 and rock react more quickly due to naturally high pressures and temperatures, which causes the carbon to swiftly become a part of the stone. |
Making ERW a practical climate solution is difficult because the processes of mining, grinding, transporting and processing rocks requires significant energy, which is primarily derived from fossil fuels. This in turn could negate the benefits of CO2 removal by the ERW process.
It requires large areas of land for establishing the processing centre.
The process of ERW requires a large capital investment and the investment in this area is still inadequate in India.
There is a need for more investment in the development of new technology to increase the efficiency and scalability of currently available ERW technologies.
There is a need to promote Enhanced Rock Weathering research in India by collaborating with global as well as Indian partners. With recent advancements in grinding technology, researchers can now create much finer particles than before, which should enhance the weathering process. However there is a need to do more.
The use of artificial intelligence and machine learning could optimise the distribution and application of rock dust. This could reduce waste and improve crop yields.
Example: Researchers at Columbia University for instance have developed a system that uses machine learning to predict the optimal amount of rock dust to apply on croplands, thereby increasing carbon sequestration and reducing alkalinity levels.
Collection of Basalt: Alt Carbon collects crushed basalt from the Rajmahal mines, known for their rich basaltic rock.
Crushing to increase the Surface Area: The collected basalt is finely crushed to enhance its surface area, which accelerates chemical reactions necessary for carbon sequestration.
Transportation: The crushed basalt is transported approximately 200 kilometers to Darjeeling, where it will be applied.
Application as Soil Amendment by sprinkling it on Tea Estates: The basalt dust is spread across tea estates in Darjeeling and serves as an organic fertilizer for improved soil health.
The basaltic dust enriches the soil and simultaneously facilitates the capture of atmospheric CO2 by sequestering carbon.
Carbon Credit Generation: Each tonne of sequestered carbon counts as a carbon credit, which Alt Carbon sells to companies looking to offset emissions.
Partnerships and Agreements for Carbon Credits: Alt Carbon has secured contracts with organizations like Frontier and NextGen to sell carbon credits.
Research and Validation: Alt Carbon is working on developing standardized measurement protocols, such as FELUDA, to ensure accurate tracking of carbon sequestration efforts.
Rock WeatheringIt is the deterioration of rocks, soils and minerals including wood and artificial materials through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs in situ (on-site, with little or no movement), and so is distinct from erosion, which involves the transport of rocks and minerals by agents such as water, ice, snow, wind, waves and gravity. Types of weathering: Mechanical, Chemical and Biological weathering are main types. Mechanical weathering, or physical weathering, is the process in which the rocks crumble without altering their chemical composition. Mechanism of mechanical weathering: Microfracturing (Frost Weathering) Water seeps into rock cracks; when it freezes, it expands, whicha act as a wedge. The freeze-thaw cycle then widens cracks, causing rocks to split. When ice melts, liquid water erodes and carries away fragments.
Exfoliation due to Thermal StressRepeated temperature changes cause rocks to expand and contract.This process weakens rock structure. This results in crumbling, especially in desert landscapes and in turn the outer layers flake off in thin sheets.Exfoliation due to Pressure Release (Unloading): it involves the removal of overlying materials allowing underlying rocks to expand. This expansion increases vulnerability to fracturing.
Haloclasty: In this process, the Saltwater infiltrates rock cracks and the evaporation leaves salt crystals behind. Growing crystals exert pressure and break the rock apart.
Chemical weathering It occurs when chemicals in the environment, like rainwater, react with the minerals in a rock. Rainwater is slightly acidic due to dissolved carbon dioxide from the air. This process can also involve hydrolysis, hydration, oxidation, and reduction. The end products of chemical weathering include silica, hydrated oxides, and inorganic salts Biological weathering: It occurs when plants, animals, or microorganisms like lichens and mosses cause rocks to erode. Examples: A rabbit burrows into a rock crack, A plant grows in a crack and widens it, Lichens live on rocks and produce acids that corrode the rock and lead to soil formation. |
Important articles for refrence
Sources:
https://un-do.com/enhanced-weathering/
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PRACTICE QUESTION Q.How could the Enhanced Rock Weathering (ERW) prove to be a potential climate change mitigation strategy? Critically analyse by discussing the benefits it offers. (250 words) |
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