Carbon Capture, Utilisation, and Storage (CCUS)

The Capture stage involves separating CO2 from other gases in industrial emissions or directly from the air. This can be done using various technologies, including absorption, adsorption, and membrane separation. For example, power plants can install equipment to capture CO2 from their flue gas before it's released into the atmosphere.

The Utilisation stage focuses on converting captured CO2 into valuable products. This can include using CO2 to produce chemicals like urea and methanol, creating synthetic fuels, or manufacturing building materials like concrete. For instance, captured CO2 can be reacted with minerals to create stable carbonates for use in green concrete.

The Storage stage involves injecting captured CO2 deep underground into geological formations, such as depleted oil and gas reservoirs or saline aquifers. The CO2 is stored permanently to prevent it from re-entering the atmosphere. This requires careful site selection and monitoring to ensure the CO2 remains safely stored.

Direct Air Capture (DAC) is a technology that removes CO2 directly from the ambient air, rather than from industrial sources. While still in early stages, DAC is gaining attention as a way to address historical emissions and achieve net-zero targets. Climeworks, a Swiss company, captures CO2 directly from the air and either stores it via mineralisation or supplies it to partners producing carbonated concrete and synthetic fuels.

The economic viability of CCUS projects is a major challenge. Capturing, purifying, and converting CO2 is energy-intensive and expensive. Without policy incentives or carbon pricing, CCUS-derived products may struggle to compete with cheaper fossil-based alternatives. The Indian government's ₹20,000 crore outlay aims to address this by supporting research and development and incentivizing CCUS projects.

Infrastructure gaps pose another significant hurdle to scaling up CCUS in India. Effective CCUS deployment requires co-located industrial clusters, CO2 transport systems (e.g., pipelines), and integration with downstream industries that can utilise the captured CO2. Such infrastructure remains unevenly developed across the country.

Regulatory and market uncertainty can also hinder CCUS deployment. The lack of clear standards, certification systems, and stable market signals creates uncertainty for investors and limits demand for CO2-based products. Clear and supportive regulations are needed to encourage investment and create a market for captured CO2.

Enhanced Oil Recovery (EOR) is one of the early applications of captured CO2. CO2 is injected into oil reservoirs to increase oil production. While this can generate revenue, it also raises concerns about the continued use of fossil fuels. The focus is shifting towards using CO2 for other applications that don't involve fossil fuel extraction.

Biological CO2 capture uses algae or bacteria to consume CO2 and produce biomass, biofuels, or animal feed. This approach offers a potentially sustainable way to utilise captured CO2. For example, Carbelim, an IIT Madras-incubated startup, is developing algae-powered air capture systems that convert CO2 into biomass, vegan Omega-3 oils, spirulina protein, and oxygen.

Mineralisation involves reacting CO2 with minerals like magnesium or calcium to create stable solid carbonates for building materials like bricks and green concrete. This permanently locks carbon into durable products and reduces dependence on natural resources. Researchers at the Indian Institute of Science (IISc), Bengaluru, are turning captured CO2 into a resource for construction materials.

A key challenge is ensuring Measurement, Reporting, and Verification (MRV) of CCUS projects. Rigorous MRV is essential to ensure that CO2 is actually being captured and stored or utilised effectively, and that the claimed emission reductions are real. This is important for building trust in CCUS and for carbon credit frameworks.

The 2070 net-zero target for India relies heavily on the successful deployment of CCUS technologies. Even with substantial growth in renewable energy, fossil fuels will continue to play a role in India's energy mix for some time. CCUS can help to mitigate emissions from these fossil fuel sources and achieve the net-zero target.