Ocean-based carbon storage ramps up, bringing investment and concern

Storing captured carbon in the subsea — in depleted oil and gas wells or in aquifers — is ramping up as a climate solution, with projects planned across the globe by industry and governments. But critics say offshore CCS poses great risks and will perpetuate a history of failure that has plagued onshore efforts to store carbon.

Project Greensand 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.

Capturing carbon to ship or funnel it offshore for storage in depleted marine oil and gas wells is gaining momentum as a proposed climate solution, even as it faces criticism. Across the globe, plans are afoot to launch multiple projects — such as in the North Sea, the Gulf of Mexico, and Southeast Asia — backed by government funding in many cases.

This form of carbon capture and storage, or CCS, involves collecting carbon (often directly from polluting industries such as cement factories or steelworks) and altering it into supercritical form, the highest density of CO₂. It’s then moved via ship or pipeline to offshore infrastructure. Once there, the CO₂ is pumped into a former well and capped.

“These same formations held oil and gas for millions of years before they were extracted — this means we know the CO₂ can be stored permanently on the same timescale, and we have detailed data and a strong understanding of their geology and how much they can store,” Chris Consoli, the Global CCS Institute’s principal for storage, told Mongabay in an email.

But this proposed climate solution, which aims to piggyback on the fossil fuel industry’s existing infrastructure and workforce, has been slammed by critics as a means to justify continued exploitation of fossil fuels using a method riddled with underperformance and failure.

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.

Ramping up CCS

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.

In the coming decades, however, this will change if planned billion-dollar developments go ahead. 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.

The EU, 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. 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 site in the U.S. to date.

“The 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,” Consoli said.

Offshore CCS is tipped to reduce emissions from “hard-to-abate” 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.

“That’s hugely concerning,” said Rachel Kennerley, International Carbon Capture Campaigner at the Center for International Environmental Law, as it may well justify increasing fossil fuel emissions.

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 CO₂ emissions when the oil pumped out is accounted for.

That’s led critics to question whether some offshore CCS will ultimately be used as another means of enhanced oil recovery by the industry. One of the largest today, operated by Petrobras in Brazil’s Santos Basin, uses captured carbon to extract more oil.

An oil rig sits in Cromarty Firth, Scotland. Reusing oil and gas infrastructure is a selling point of offshore 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 (Public domain).

Kennerley also said that offshore CCS will remain a highly costly venture with prices unlikely to fall due to the need for customization of technology, 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 will be needed as part of the bloc’s CO₂ storage plans by 2030, costing around 19.5 billion euros ($22.6 billion).

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.

Ongoing projects, such as those in Norway that are being used as a proof of concept by proponents, have run into “surprises” once the carbon is in the ground. Those include carbon entering unidentified subsea areas and an overestimation of the amount of carbon actually stored, he said.

“These projects are statistically kind of working, but there’s a lot of unknowns and things that pop up that were unexpected,” Hauber said. “We really don’t know what’s going to happen to the CO₂ until we start putting it in the ground, and then all we can do is follow it.”

A host of environmental concerns

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.

Experts Mongabay spoke to stress the risk of leakage, something that David Ho, professor of oceanography at the University of Hawaiʻi at Mānoa, said he’s particularly concerned about. “If the CO₂ leaks out, then we really haven’t done anything for climate,” he said.

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’s biggest carbon sink. But absorbing all that atmospheric CO₂ takes its toll in the form of worsening ocean acidification — a problem that experts have already flagged this year. There are also concerns that leaks on land will endanger human health.

Leakages from wells are “very unlikely as long as the geology has been properly characterized,” said Jerry Blackford at Plymouth Marine Laboratory in the U.K. His research suggests that offshore carbon storage is viable and safe. “There’s more likelihood of what I’d call operational leaks from the bits of kit that are injecting.” In other words, the pipelines.

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 — including exploration, site development and operations — could harm whole ecosystems and sensitive species such as cetaceans.

Understanding these effects is still a new and emerging field, Eisfeld-Pierantonio wrote in an email. “There’s limited long-term evidence on how CCS might affect ecosystem dynamics, especially if linked to oil and gas infrastructure that also leaks hydrocarbons.”

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.

“Expanding offshore industrial activity to justify a continued oil and gas extraction creates additional, avoidable pressures on already stressed marine species,” Eisfeld-Pierantonio said. “A rapid transition to truly renewable energy sources combined with habitat protection would be a lower-risk route.”

But Consoli from the Global CCS Institute said that, so far, CCS is “well-managed and highly regulated, with stringent monitoring and reporting requirements. He adds that “these safeguards help ensure that any potential risks are effectively identified and mitigated, providing strong protection for the environment and communities.”

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 (CC BY-SA 2.0).

Navigating hype and risk

Momentum is building behind offshore CCS, and in the next few years many of those planned projects may begin storing carbon in increasing volumes.

“CCS offers a scalable, long-term climate solution essential for hard-to-abate sectors and achieving net zero globally,” Consoli said. “Quite simply, there are no credible pathways to net zero without CCS. Even with rapid fossil fuel reductions, CCS is critical.”

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.

But, experts such as Kennerley said they fear the hype, and large investment, in this climate solution is misplaced. “Ultimately, it won’t reduce emissions in a meaningful way. So, it is a huge waste of public money that should be going elsewhere,” she said.

For Hauber, storing carbon in depleted offshore oil and gas reservoirs comes with the double risk of placing storage “out of sight and out of mind” 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.

That must also include monitoring for leakages, Blackford said. “My personal view is that if CCS is becoming established, it’s good to over monitor, because that will answer the question as to whether the environment is impacted or not.”

“There’s a high risk of being cavalier with CO₂,” 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. “It just seems like a series of triage and bandages that are trying to extend the life of a problem rather than solving it.”

Author: Sean Mowbray

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This article was originally published on Mongabay under the Creative Commons BY NC ND licence. Read the original article.