The company uses mining dust to increase carbon capture

Alt Carbon collects crushed basalt from the Rajmahal mine and has people sprinkled on tea estates. Photo: Special Arrangements

The last thing you expect is that dust from mining will be climate friendly. But the right kind of dust that is moved to the right place is the core business of the Darjeeling-based company Alt Carbon, and it has received an investment of $ 5,00,000 for the carbon credit company. At the heart of the company’s approach is a geo-chemical process called rock weathering.

All rocks naturally break down into minerals over thousands of years. This happens mainly due to exposure to rain and heat, and the result of this process is that atmospheric carbon reacts with these minerals (calcium and magnesium in general) and becomes bicarbonate.

Eventually through aquifers, or underground streams and rivers, they enter the ocean where the carbon is locked up for years.

The ocean, therefore, is a major carbon sink and captures about 30% of CO2 from human activities. Left to nature, this process takes aeons. However, with the increasing level of carbon dioxide in the air and the consensus by the Intergovernmental Panel on Climate Change that some of the carbon dioxide already in the air must be removed by 2050, so that the temperature does not exceed 2 degrees Celsius. at the end of the century, the government and business are experimenting and investing in plans to accelerate the process of natural carbon removal. This is where the ‘enhanced’ rock weather comes in.

Basaltic rock, a type of volcanic rock, is rich in minerals such as calcium and magnesium. Many parts of Maharashtra and Gujarat, where the Deccan Trap is volcanic, are rich in basaltic rocks as are parts of Jharkhand and West Bengal where the Rajmahal Trap is located. The latter is regularly mined for construction.

“Once the basaltic rock is crushed into a fine powder, the effective surface area is greatly increased. This accelerates the formation of bicarbonate by anywhere from ten to a hundred and can be flushed into the sea – depending on the soil, temperature and river – within a month,” said Dr. Sambuddha Misra, associate professor and chemical oceanographer. , at the Indian Institute of Science, Bengaluru. He is also the lead scientist at Alt Carbon.

The company, which has roots in the family-owned tea plantation industry, collects tons of crushed basalt from the Rajmahal mine, transports it about 200 kilometers to Darjeeling and sprinkles it on tea plantations in the area.

As an organic fertilizer, basaltic dust enriches the soil and also accelerates carbon absorption. So far, the company has used about 500 tons of dust. Although it’s still early years, it would take about 3-4 tons of basalt dust to absorb, or trap, a ton of atmospheric carbon over two to four years. “It usually takes 1,000 years for natural basaltic rock to capture that much carbon,” said Shrey Agrawal, CEO and co-founder, Alt Carbon.

Each ton of carbon sequestered in this way counts as one carbon credit. This September, the company signed an agreement with Frontier, a consortium of McKinsey Sustainability, Alphabet, Meta, Shopify and Stripe, to buy a tranche of carbon sequestered in this way for $5,00,000. Last week, the company signed another agreement with NextGen, a company that collects these carbon captures from projects around the world, to buy the credits in the amount of $200 per ton of locked carbon. Carbon credits generated in this way are purchased by companies and can be used to offset carbon emissions, which is required by national legislation. Currently, these purchases are largely voluntary.

While the basic principles of enhanced rock weathering are well established, the question remains whether the processes used by different companies accurately measure the claimed sequestered carbon. An analysis by the research group Carbon Plan, which synthesized the published literature on the results of the weather experiments, said that the variation between the 116 studies included “four orders of magnitude” meaning that some projects claimed 100 tons and others 10,00,000 tons trapped. carbon for the same experiment. Factors such as rock, type of agriculture, climate affected by weather. There are also differences from year to year with faster weather in the early stages and slower ones later. There is also variation in how projects measure sequestration rates.

“We hope to capture about 50,000 tons in the next few years. The laboratory facilities provided by Dr. Misra are precisely to measure these aspects of the weather. We have a protocol called FELUDA that can be used by other companies that want to use our approach, said Mr. Agrawal.