Oceans of Opportunity: Carbon Capture for Net-Zero India

Climate change, driven by the emission of greenhouse gases (GHGs) such as carbon dioxide (CO₂), nitrous oxide (N₂O), and methane, has caused severe environmental impacts. With 2.6 gigatonnes of CO₂ emissions per annum, India is the world’s third-largest emitter after the United States (US) and China. Since the Industrial Revolution, CO₂ concentrations have increased by 32 percent, from 280 to 400 parts per million (ppm). The 2018 IPCC Report warns that unabated global warming could exceed 1.5°C by 2040, triggering sea-level rise and biodiversity loss. Preventing this requires a 45-percent emission reduction by 2030 and net-zero emissions by 2050. Rising CO₂ levels have also caused ocean acidification, harming marine ecosystems. India has committed to halving its CO₂ emissions by 2050, with a net-zero target by 2070.

Beneath the Surface: Techniques for Ocean-Based Carbon Capture

Carbon Capture, Utilisation, and Storage (CCUS) and Carbon Dioxide Removal (CDR) technologies have emerged as critical solutions, alongside energy efficiency and renewable energy. CDR removes CO₂ already present in the atmosphere or oceans, whereas CCUS prevents carbon emission by capturing it from sources, including industries and power plants, converting it into chemicals or fuels, for oil recovery or storing it in seawater, deep-sea sediments, or geological sites. Effective implementation of CCUS and CDR can reduce CO₂ by 14 percent by 2060 and stabilise concentrations to 450 ppm by 2100.  According to NITI Aayog, CCUS could generate 8-10 million full-time jobs by 2050.

Researchers and companies are increasingly exploring ways to harness the ocean’s natural chemical and biological processes to absorb and store CO₂.

The Blue Shift in CCUS: Approaches to Ocean-Based CCUS

CCUS technologies employ biological, geological, or ocean-based sequestration. While land-based methods such as reforestation, sustainable agriculture and biochar production have strong decarbonisation potential, the ocean, covering 70 percent of the Earth, is the largest carbon sink, storing 50 times more carbon than the atmosphere and 16 times more than terrestrial carbon. Ocean-based CCUS thus offers a strategic global decarbonisation pathway. Researchers and companies are increasingly exploring ways to harness the ocean’s natural chemical and biological processes to absorb and store CO₂.

Ocean-based Negative Emission Techniques

Ocean-based sequestration uses low temperatures and high pressure to stabilise CO₂ in liquid form, minimising leakage. Its deep-sea location prevents groundwater contamination and geological risks from tectonic activity, while remaining scalable without complex land-based infrastructure. Key ocean-based Negative Emission Techniques (NETs) include Ocean Alkalinity Enhancement (OAE), Electrochemical Seawater Processing, Biological Carbon Capture, Enhancement of Blue Carbon Sink, and Ocean Fertilisation.

• OAE increases seawater alkalinity by adding pulverised minerals (e.g., Lime) or by electrochemically boosting rock weathering to accelerate atmospheric CO₂
• Electrochemical seawater processing uses electric currents and electrochemical reactions to treat seawater, recover valuable minerals, and produce oxygen and hydrogen.
• Biological carbon capture leverages marine ecosystems and biological carbon to absorb and store atmospheric carbon. It uses photosynthesis to transfer carbon from the ocean surface to the deep sea via marine organisms such as phytoplankton, microalgae, seaweed and other aquatic media (blue carbon), soil, and seawater. It also enables long-term carbon sequestration through deep-ocean sedimentation.
• Ocean fertilisation promotes the growth of phytoplankton by adding required micronutrients, such as phosphorus, iron, or nitrogen, to specific macronutrient-rich regions of the ocean, facilitating long-term deep-ocean carbon storage.
• Marine protected areas, including coral reefs and mangroves (8.3 percent of the ocean), are vital for ocean health. Mangroves store up to 1,000 tonnes of carbon per hectare, support fisheries, and provide natural protection against storms and flooding. Coral reefs, though covering less than 0.1 percent of the ocean surface, sustain 25 percent of marine diversity, and offer coastal protection, recreation, medical and tourism benefits.

Leveraging India’s Potential for Ocean-based CCUS

India, with its 11098.8 km coastline and ~2 million sq. km of Exclusive Economic Zones (EEZ), provides vast CCUS potential. OAE offers the most durable storage - up to 100,000 years along with shellfish aquaculture and seaweed farming. Seaweed farming over 20 percent of the ocean could remove 0.6 gigatonnes of carbon annually, rising to one gigatonne with artificial ocean fertilisation. However, achieving this by 2030 requires expanding seaweed farming by 64 percent. The captured CO₂ can be repurposed for industrial applications, including food and beverage, healthcare, biofuels, biopolymers, urea, green hydrogen,  enhanced oil recovery, bioplastics and mineral carbonates used in cement and construction materials.

Global interest in ocean-based NETs is growing. Most nations have included CDR in their long-term climate strategies under the United Nations Framework Convention on Climate Change (UNFCC), with Japan and the US emphasising ocean-based CDR.

Global Efforts in Ocean-based CCUS: From Startups to National Initiatives

Global interest in ocean-based NETs is growing. Most nations have included CDR in their long-term climate strategies under the United Nations Framework Convention on Climate Change (UNFCC), with Japan and the US emphasising ocean-based CDR. The US Department of Energy (DoE) supports research funding and scale-up of CDR techniques through the Carbon Negative Shot Initiative, aiming to reduce its cost to approximately US$100 per net ton of CO₂ by 2030. Initiatives such as Horizon Europe support seaweed cultivation and electrochemical seawater processing. Several European initiatives support biorefinery value chains and ocean fertilisation to enhance biological carbon capture.

Companies worldwide are developing ocean-based CDR solutions. The StartUs Insights 2025 report identifies startups on algae- and cyanobacteria-based CCUS, direct air capture, seawater alkalisation, and CO₂-to-material conversion, mainly in Western Europe, the US, and India. Amsterdam-based Brineworks uses electrolysis to split seawater and extract CO₂ at under US$100 per ton, producing green hydrogen as a by-product. Companies like SeaO2 (Amsterdam) and Captura (California) use electrodialysis for CO₂ extraction from seawater. The treated, decarbonised seawater, returned to the ocean, continues to absorb carbon from the atmosphere. Cestore (Sweden), Limenet (Italy), Arbon Earth (Sweden), and Everest Carbon (USA) are other leading startups. Organisations such as the BidCarbon Foundation support research and technical development, sustainability, and the implementation of ocean-based CDR projects across Asia, including Thailand, Malaysia, Singapore, China, and Indonesia.

The StartUs Insights 2025 report identifies startups on algae- and cyanobacteria-based CCUS, direct air capture, seawater alkalisation, and CO₂-to-material conversion, mainly in Western Europe, the US, and India.

In India, Alt Carbon uses enhanced rock weathering with silica to remove CO₂ from the ocean, targeting a 500,000-hectare operation and 5 million metric tons of carbon removal by 2030. The Department of Science and Technology (DST) is promoting R&D on cost-effective, safe CCUS-based innovations to achieve net-zero emissions from carbon-intensive industries. Bangalore-based Sea6Energy is a pioneer in large-scale seaweed farming for CCUS and biofuel production. National Centre for CCUS at research institutes like IIT Bombay and JNCASR are actively working on coastal CCUS and mineral carbonation. India collaborates with Germany, France, Norway, Switzerland, Romania, the Netherlands, Greece, Turkey, and the United Kingdom to advance ocean-based CCUS.

What India Must Do Next?

Ocean-based CDR (OCDR) can remove several gigatonnes of CO₂ annually, reducing 10 per cent of CO₂ emissions. However, scale-up, detection, accuracy, environmental impacts, low technological readiness level (TRL), and large knowledge and governance gaps pose significant challenges. Each technique varies in efficiency, TRL, and socio-environmental impact.

Advancing Research and Development for Scalable Ocean CCUS Solutions

Currently, information on the environmental performance and potential of OCDR approaches is limited. The DST-supported National Mission on Ocean-Based CCUS must, therefore, fund studies on innovation, scale-up, safety, and detailed techno-economic and environmental impact analysis before implementation. Policies must support large-scale field research, as the available data on the effectiveness of the project scale, duration of carbon storage and environmental impacts is limited to lab-based and small-scale trials, with few field test results. India must increase its GDP expenditure on R&D from less than one percent currently to more than 2-3 percent for improving its TRL.

Fostering Technology and Innovation to Advance Ocean-Based CCUS

Public and private initiatives must facilitate the transition of OCDR technologies from lab to pilot-scale. Innovation support policies should target high-precision sensors, underwater vehicles, and equipment for monitoring seawater chemistry, including dissolved CO₂, pH, trace metals, minerals and biochemicals. Key agencies, including the Ministry of Earth Sciences (MoES), Ministry of Environment, Forest and Climate Change (MoEFCC), NITI Aayog, and DST, should provide incentives, funding, regulatory guidelines and collaboration opportunities with research institutions, industries and startups.

India must increase its GDP expenditure on R&D from less than one percent currently to more than 2-3 percent for improving its TRL.

Strengthening Standard Regulatory and Monitoring Systems

The government must implement a standardised Measurement, Reporting, and Verification (MRV) framework with transparent CCUS accounting guidelines. It must support studies on variables affecting carbon sequestration and durability, including seawater chemistry, gas exchange, and interactions; complex ocean dynamics, such as water mixing, sediment, and biological interactions; and carbon remobilisation rate variability in coastal blue carbon approaches using seagrass and mangrove ecosystems. Rigorous measurement standards and continuous monitoring by agencies, such as Voluntary Carbon Market Integrity Initiative (VCMI), are essential. While MoES must coordinate the regulatory tracking, DST and NITI Aayog can support the technological progress. Policy reforms must target enhanced efficiency, reduce bureaucratic delays, and increase international cooperation.

Empowering Coastal Community Engagement in Ocean CCUS Efforts

Policy frameworks must adopt a bottom-up approach, ensuring communities, ecological and social contexts-specific implementation, and benefit-sharing. The MoEFCC and MoES must support capacity building, skill development, and awareness programmes, as involving coastal communities, especially women, can lend momentum to blue carbon initiatives, offshore algae cultivation, and CO₂ extraction from seawater.

Towards a Net Zero Blue Economy

Ocean-based CCUS represents a critical pathway to achieving India’s net-zero target by 2070. While global and Indian initiatives are advancing in CCUS research and implementation, challenges remain in scale-up, TRL, regulatory frameworks, and community engagement. The government should integrate CCUS into core domestic and foreign policy agendas on climate change. Ocean-based CCUS can create new value chains in green fuels, bio-based materials, and carbon credits, directly contributing to sustainable blue growth. With strategic policy support and dedicated funding, India can harness the full potential of ocean resources to achieve its net-zero target and a US$100 billion blue economy.

Poornima V B is a Research Intern at the Observer Research Foundation.

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• Climate Change
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• blue economy
• ccus technologies
• co2 emissions in india
• net zero emission target
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• ocean based ccus
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