Company uses mining dust to enhance carbon capture

Sub: Env

SEC: Climate Change

Context:

Alt Carbon, a Darjeeling-based company, is pioneering a surprising climate-friendly solution using dust from mining and has already secured $500,000 in investments from carbon-credit companies. The company’s approach is based on the geo-chemical process called rock weathering, which accelerates natural carbon sequestration.

Details:

Over thousands of years, rocks break down into minerals due to exposure to rain and heat. Atmospheric carbon reacts with minerals like calcium and magnesium, forming bicarbonates. These bicarbonates are carried by underground streams into the oceans, where carbon is stored for millennia.
Oceans act as major carbon sinks, capturing about 30% of CO2 from human activities.
As carbon dioxide levels rise, natural rock weathering is too slow to mitigate climate change.
Governments and businesses are experimenting with ways to accelerate carbon removal, including enhanced rock weathering.

What is Enhanced Rock Weathering (ERW)?

Enhanced rock weathering (ERW) is a nature-based process that accelerates the natural weathering of rocks to remove carbon dioxide from the atmosphere and help address climate change:
How it works?
ERW involves spreading finely ground silicate rocks, like basalt, on land. This increases the surface area of the rock, which speeds up the chemical reactions between the rocks, water, and air.
Benefits:
- Carbon sequestration: ERW can help remove carbon dioxide from the atmosphere.
- Improved soil: ERW can improve soil pH, nutrient uptake, and fertility.
- Reduced ocean acidification: ERW can help mitigate ocean acidification.
Challenges
- High energy requirements
- Elevated levels of heavy metals
- Limited availability of suitable rocks
- Logistics of transportation
- Cost of rock crushing

How Alt Carbon Accelerates Carbon Capture?

Rich in minerals like calcium and magnesium, basaltic rock is abundant in areas such as Maharashtra, Gujarat, Jharkhand, and West Bengal.
When basaltic rock is crushed into fine powder, its surface area increases significantly, speeding up the conversion of carbon into bicarbonates.
Operational Process:
- Alt Carbon collects tonnes of crushed basalt from the Rajmahal mines.
- The dust is transported 200 km to Darjeeling and spread on tea estates, enriching the soil while sequestering carbon.
- The basalt dust acts as an organic fertiliser and helps capture carbon 10 to 100 times faster than natural weathering.

Results and Carbon Credits:

Carbon Sequestration Efficiency:
- It takes 3-4 tonnes of basalt dust to sequester 1 tonne of carbon over 2-4 years, compared to 1,000 years for natural basalt.
- So far, Alt Carbon has used 500 tonnes of basalt dust.
Carbon Credit Agreements:
- Each tonne of carbon sequestered counts as one carbon credit.
- In September, Alt Carbon entered an agreement with Frontier (consisting of McKinsey, Alphabet, Meta, Shopify, and Stripe) for $500,000 to buy carbon credits in advance.
- Another agreement was signed with NextGen, which buys carbon credits at $200 per tonne.

Challenges and Future Plans:

While enhanced rock weathering is promising, there are concerns about the accuracy of measuring sequestered carbon across different projects.
Studies show variations in sequestration, with some projects claiming 100 tonnes and others up to 1,000,000 tonnes for similar efforts.
The company aims to sequester 50,000 tonnes of carbon in the next few years.
To address measurement challenges, Dr Sambuddha Misra (Chief Scientist at Alt Carbon) has set up lab facilities and developed a protocol called FELUDA to standardize measurements, which can be used by other companies.