But this proposed climate solution, which aims to piggyback on the fossil fuel industry\u2019s existing infrastructure and workforce, has been slammed by critics as a means to justify continued exploitation of fossil fuels using a method<\/a> riddled with underperformance and failure<\/a>.<\/p>\n For critics, this simple picture of using the ocean subsurface as a carbon storehouse belies the need for masses of new green infrastructure, energy and finance, while also being linked to a range of environmental risks.<\/p>\n Globally, around 70 CCS facilities are in operation, storing about 61.5 million metric tons of CO2 per year, according to the Global CCS Institute. Most of these are on land, currently. So far, only a handful of offshore projects are in operation: in Brazil, China, Italy, Norway and Denmark<\/a>.<\/p>\n In the coming decades, however<\/a>, this will change if planned billion-dollar developments go ahead<\/a>. Dozens of projects are in the planning stages to store millions of tons of carbon. These include proposals to store carbon dioxide in offshore depleted oil and gas wells, but also in subsea aquifers and basaltic formations.<\/p>\n The EU<\/a>, for example, has set out plants to store at least 50 million metric tons per year by 2030, much of it in the North Sea<\/a>. Last year, ExxonMobil purchased a 110,000-hectare (271,000-acre) site off the Texas coast for carbon storage, claimed as the largest marine CCS storage<\/a> site in the U.S. to date.<\/p>\n \u201cThe exact storage potential of each field varies depending on detailed, site-specific assessments, but the scale is sufficient to support deep decarbonisation in industries that will need CCS to reach net zero,\u201d Consoli said.<\/p>\n Offshore CCS is tipped to reduce emissions from \u201chard-to-abate\u201d industries such as cement, steel, and chemicals and plastics manufacturing. But there are also plans to connect this to new fossil fuel energy, particularly gas.<\/p>\n \u201cThat\u2019s hugely concerning,\u201d said Rachel Kennerley, International Carbon Capture Campaigner at the Center for International Environmental Law<\/a>, as it may well justify increasing fossil fuel emissions.<\/p>\n Today, oil and gas companies run the vast majority of CCS projects. And while these do inject captured CO2 into oil reservoirs, the process is done chiefly to recover hard-to-reach stores of oil and gas. Known as enhanced oil recovery, it can increase rather than decrease<\/a> CO2 emissions when the oil pumped out is accounted for.<\/p>\n That\u2019s led critics to question whether some offshore CCS<\/a> will ultimately be used as another means of enhanced oil recovery by the industry. One of the largest today, operated by Petrobras in Brazil\u2019s Santos Basin, uses captured carbon to extract more oil<\/a>.<\/p>\n Kennerley also said that offshore CCS will remain a highly costly venture<\/a> with prices unlikely to fall<\/a> due to the need for customization of technology<\/a>, unlike other climate solutions like renewable energy. Likewise, the scale of infrastructure needed to build out offshore CCS capacity, including capture devices, pipelines and facilities to combine different CO2 streams. The EU, for example, estimates that as much as 7,300 kilometers (more than 4,500 miles) of pipelines<\/a> will be needed as part of the bloc\u2019s CO2 storage plans by 2030, costing around 19.5 billion euros ($22.6 billion).<\/p>\n For these reasons and more, Grant Hauber, strategic energy finance adviser for Asia at the U.S.-based Institute for Energy Economics and Financial Analysis, questions claims that offshore CCS is already a proven and viable solution.<\/p>\n Ongoing projects, such as those in Norway that are being used as a proof of concept by proponents, have run into \u201csurprises\u201d once the carbon is in the ground. Those include carbon entering unidentified subsea areas<\/a> and an overestimation of the amount of carbon actually stored, he said.<\/p>\n \u201cThese projects are statistically kind of working, but there\u2019s a lot of unknowns and things that pop up that were unexpected,\u201d Hauber said. \u201cWe really don\u2019t know what\u2019s going to happen to the CO2 until we start putting it in the ground, and then all we can do is follow it.\u201d<\/p>\n A host of environmental concerns<\/p>\n Just as offshore oil and gas extraction comes with an environmental footprint, so does the reverse process: storing carbon back in those wells. Two years ago, the the Washington and Geneva-based Centre for International Law released a report outlining the many risks and perils of offshore CCS. That report detailed a series of risks such as inducing earthquakes and the potential to contaminate groundwater and displace deposits of toxic brine<\/a>.<\/p>\n Experts Mongabay spoke to stress the risk of leakage, something that David Ho, professor of oceanography at the University of Hawai\u02bbi at M\u0101noa, said he\u2019s particularly concerned about. \u201cIf the CO2 leaks out, then we really haven\u2019t done anything for climate,\u201d he said.<\/p>\n If a leak occurs from a pipeline on the seafloor or from the storage site, it would also impact marine ecosystems, principally by contributing to ocean acidification. The oceans are by far the world\u2019s biggest carbon sink. But absorbing all that atmospheric CO2 takes its toll in the form of worsening ocean acidification \u2014 a problem that experts have already flagged<\/a> this year. There are also concerns that leaks on land will endanger human health.<\/p>\n Leakages from wells are \u201cvery unlikely as long as the geology has been properly characterized,\u201d said Jerry Blackford at Plymouth Marine Laboratory in the U.K. His research suggests that offshore carbon storage is viable and safe<\/a>. \u201cThere\u2019s more likelihood of what I\u2019d call operational leaks from the bits of kit that are injecting.\u201d In other words, the pipelines.<\/p>\n Sonja Eisfeld-Pierantonio, marine pollution coordinator at Whale and Dolphin Conservation, a U.K.-based nonprofit, said noise pollution, habitat displacement and changes to prey populations due to CCS activities \u2014 including exploration, site development and operations \u2014 could harm whole ecosystems and sensitive species such as cetaceans.<\/p>\n Understanding these effects is still a new and emerging field, Eisfeld-Pierantonio wrote in an email. \u201cThere\u2019s limited long-term evidence on how CCS might affect ecosystem dynamics, especially if linked to oil and gas infrastructure that also leaks hydrocarbons.\u201d<\/p>\n Ultimately, these activities could act as an additional stressor on species already facing pressure from other extractive industries, shipping and climate change, particularly when sited near marine protected areas or breeding grounds.<\/p>\n \u201cExpanding offshore industrial activity to justify a continued oil and gas extraction creates additional, avoidable pressures on already stressed marine species,\u201d Eisfeld-Pierantonio said. \u201cA rapid transition to truly renewable energy sources combined with habitat protection would be a lower-risk route.\u201d<\/p>\n But Consoli from the Global CCS Institute said that, so far, CCS is \u201cwell-managed and highly regulated, with stringent monitoring and reporting requirements. He adds that \u201cthese safeguards help ensure that any potential risks are effectively identified and mitigated, providing strong protection for the environment and communities.\u201d<\/p>\n Momentum is building behind offshore CCS, and in the next few years many of those planned projects may begin storing carbon in increasing volumes.<\/p>\n \u201cCCS offers a scalable, long-term climate solution essential for hard-to-abate sectors and achieving net zero globally,\u201d Consoli said. \u201cQuite simply, there are no credible pathways to net zero without CCS. Even with rapid fossil fuel reductions, CCS is critical.\u201d<\/p>\n The Intergovernmental Panel on Climate Change (IPCC) agrees, stating that to achieve net-zero greenhouse gas emissions by 2050 will require vast amounts of CCS.<\/p>\n But, experts such as Kennerley said they fear the hype, and large investment, in this climate solution is misplaced. \u201cUltimately, it won\u2019t reduce emissions in a meaningful way. So, it is a huge waste of public money that should be going elsewhere,\u201d she said.<\/p>\n For Hauber, storing carbon in depleted offshore oil and gas reservoirs comes with the double risk of placing storage \u201cout of sight and out of mind\u201d of independent monitoring and regulation. Experts Mongabay spoke to stressed the need for regulation of offshore CCS, transparency on data from offshore geological sites, and stringent independent monitoring of activities.<\/p>\n That must also include monitoring for leakages, Blackford said. \u201cMy personal view is that if CCS is becoming established, it\u2019s good to over monitor, because that will answer the question as to whether the environment is impacted or not.\u201d<\/p>\n \u201cThere\u2019s a high risk of being cavalier with CO2,\u201d Hauber said, adding that this could result in worsening climate change, risks of contributing to ocean acidification, and vast sums of investment in solutions that could be spent elsewhere. \u201cIt just seems like a series of triage and bandages that are trying to extend the life of a problem rather than solving it.\u201d<\/p>\n Banner image: A sperm whale. Offshore CCS operations could have a range of negative impacts on marine biodiversity, including noise pollution, habitat displacement and the risk of CO2 leakage. Image by Ellen Cuylaerts \/ Ocean Image Bank<\/a>.<\/p>\n Marine artificial upwelling, problematic climate solution slow to advance<\/a><\/p>\n Citations:<\/p>\n Dewar, M., Blackford, J., Espie, T., Wilford, S., & Bouffin, N. (2022). Impact potential of hypersaline brines released into the marine environment for CCS reservoir pressure management. International Journal of Greenhouse Gas Control, 114, 103559. doi:10.1016\/j.ijggc.2021.103559<\/a><\/p>\n Findlay, H. S., Feely, R. A., Jiang, L., Pelletier, G., & Bednar\u0161ek, N. (2025). Ocean acidification: Another planetary boundary crossed. Global Change Biology, 31(6). doi:10.1111\/gcb.70238<\/a><\/p>\n Connelly, D. P., Bull, J. M., Flohr, A., Schaap, A., Koopmans, D., Blackford, J. C., \u2026 Yakushev, E. (2022). Assuring the integrity of offshore carbon dioxide storage. Renewable and Sustainable Energy Reviews, 166, 112670. doi:10.1016\/j.rser.2022.112670<\/a><\/p>\n ![\"Project](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/08\/Project-Greensand-is-storing-carbon-dioxide.jpg\")
<\/a>Project Greensand<\/a> is storing carbon dioxide in the depleted Nini West oil field in the North Sea. At full scale, the project aims to store up to 1.5 million metric tons of CO2 per year in 2025\/2026 and potentially up to 8 million metric tons of CO2 per year in 2030. Image courtesy of INEOS Energy.
\nRamping up CCS<\/p>\n![\"An](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/08\/An-oil-rig-sits-in-Cromarty-Firth.jpg\")
<\/a>An oil rig sits in Cromarty Firth, Scotland. Reusing oil and gas infrastructure is a selling point of offshore<\/a> CCS as some infrastructure and pipelines can be refitted. Experts, however, underline that scaling up will require building far more pipes and storage facilities. Image by Mustang Joe via Flickr<\/a> (Public domain).<\/p>\n![\"Northern](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/08\/Northern-Lights-CCS-project-in-Norway.jpg\")
<\/a>Northern Lights CCS project in Norway. A joint operation by TotalEnergies, Equinor and Shell, this project plans to inject 1.5 million metric tons of CO2 into a subsea reservoir per year. Image \u00a9 Equinor<\/a>.<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/08\/A-steel-plant.-Storing-carbon-at-offshore-facilities.jpg\")
<\/a>A steel plant. Storing carbon at offshore facilities captured from emission-intensive industries will require a massive build-out of infrastructure including pipelines, ships and storage facilities. Ultimately, not all carbon emissions will be captured, say experts, undermining the investment required. Image by Jean-Etienne Minh-Duy Poirrier via Flickr<\/a> (CC BY-SA 2.0<\/a>).
\nNavigating hype and risk<\/p>\n <\/p>\n