Carbon Capture Begins at India’s Largest Coal Power Plant

India's largest coal-fired power plant, NTPC's 4.8-GW Vindhyachal Super Thermal Power Station, has begun capturing carbon dioxide (CO₂) from plant flue gas as part of a foundational project to explore the conversion of CO₂ to methanol.

The carbon capture plant, built by UK-based carbon capture solutions provider Carbon Clean and Green Power International, an engineering, procurement, and construction (EPC) firm, is designed to capture 20 tonnes per day (TPD) of CO₂ from a 500-MW unit's flue gas using a modified tertiary amine.

The pilot project, built for NTPC Energy Technology Research Alliance (NETRA), is part of an initiative NTPC unveiled in 2020 to build a CO₂-to-methanol plant at a coal-fired power plant. NTPC envisions that the project will comprise three parts: a carbon capture unit; a hydrogen generation unit that will use high-temperature steam electrolysis (HTSE) to generate 2 TPD of hydrogen; and a methanol production unit that will convert the CO₂ to methanol through a catalytic hydrogenation process.

A Carbon Dioxide to Methanol Pilot

NTPC's Vindhyachal Super Thermal Power Station in Vindhyanagar in Singrauli district of Madhya Pradesh, is a massive 13-unit facility that comprises six 210-MW units, first built in 1987, and four 500-MW units. A pithead power plant, it sources coal from the nearby Nigahi Mines. The plant supplies power to the states of Madhya Pradesh, Gujarat, Maharashtra, Chhattisgarh, Goa, Daman, and Diu, as well as Dadra and Nagar Haveli. According to the Central Electricity Authority of India (CEA), the plant had a load factor of 85% in 2019, against the national average of 60.85% for coal-fired power plants in the nation.

Bharat Heavy Electricals Ltd. (BHEL) in August 2015 commissioned the 500-MW Unit 13 of the Vindhyachal Super Thermal Power Station in Vindhyanagar in Singrauli district of Madhya Pradesh. This is the seventh 500-MW unit commissioned by BHEL at the plant. Vindhyachal is a 4.7-GW pithead power plant. Courtesy: NTPC

Carbon Clean said the carbon capture pilot harvests flue gas from the 500-MW Unit 13, the plant's newest unit, which came online in August 2015. Carbon Clean's CDRMax carbon capture technology can be used with point source gases that contain CO₂ concentrations between 3% and 25% by volume and produces CO₂ with purities greater than 99%, which can then be sold, reused, or sequestered," the company explained. The CDRMax process uses the company's proprietary solvent, process equipment design, and advanced heat integration to significantly reduce both capital and operating costs, it said.

Setting up of this 20 TPD demonstration plant is the first step towards decarbonizing the power plant," Carbon Clean told POWER on Sept. 29. The objectives of the project are to review the economics, design optimization, and waste heat utilization, in order to further reduce the overall cost of [carbon capture utilization]," it said. Evidence suggests that it will be both feasible and cost-effective by using our carbon capture technology-CDRMax."

A Sustainability Pathway for NTPC

For New Dehli-based NTPC, India's largest energy conglomerate, the carbon capture demonstration serves as an integral pathway to explore sustainable, stable, and low-carbon thermal power development. The company, which is 51.1% owned by the Indian government, holds a 70-GW fleet, including 25 coal-fired power plants with a combined capacity of 50.5 GW.

The company is exploring several pathways to enable more efficient and cost-effective coal power. Vindhyachal, the largest plant in NTPC's massive fleet, has recently served as the site of a flexible operation study, which was spearheaded by the CEA and the Japan Coal Frontier Organization. Vindhyachal Unit 13, notably, in 2018 also pioneered India's first wet flue gas desulfurization unit suitable for 100% gas flow continuous operation.

NTPC is committed to sustainability, however, and it is currently also working to deploy 60 GW of renewable capacity by 2032. As part of its Brighter Plan 2032" goals, it has also set out to explore commercial-scale carbon capture, hydrogen generation, and conversion to methanol.

Methanol, in particular, is seen as a feasible pathway for carbon capture utilization because the chemical (CH₃OH) is an important industrial raw material. Methanol is currently widely used as a starting substrate for the synthesis of various other chemical compounds like acids, anhydrides, and esters, used in adhesives, foams, paints, and polymers. However, experts say it can also be used as a low-carbon alternative fuel for many sectors, mainly because it has the highest hydrogen-to-carbon ratio of any liquid fuel.

Methanol production from captured carbon could ensure that we generate a clean fuel as well as sequester carbon from the environment," as well as add great economic value," NTPC said in its most recent sustainability filing.

In July 2022, the company signed a memorandum of understanding with Gujarat Alkalies and Chemicals Ltd. to mutually explore opportunities to supply 100 MW round the clock" power and synthesize 75 TPD of green methanol and 35 TPD of green ammonia for captive use at GACL. If the project comes to fruition, it would be the first commercial-scale green ammonia and green methanol project in the country," NTPC said.

The carbon capture project at Vindhyachal is being watched carefully, given the Indian government's ambitions to leverage carbon capture utilization and storage (CCUS) for its energy security and emission abatement aspirations. The country, which is currently heavily reliant on coal power, is acting with urgency. Last year it set out to achieve net-zero greenhouse gas emissions by 2070.

In a June 2022-issued draft roadmap, India's Ministry of Petroleum and Natural Gas proposed several measures to achieve quick deployment of CCUS/CCS technologies, including financial support for early movers and funding programs for up to 10 demonstration projects.

-Sonal Patelis a POWER senior associate editor (@sonalcpatel,@POWERmagazine).

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