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Researchers Say We Could Pump CO2 Into Ocean Rocks: Pros and Cons

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Posted August 17, 2019

There’s an ongoing push from scientists and industries alike to figure out how to reduce CO2 emissions, or at least minimize their effects on the planet. Many solutions suggested so far are impressively creative.

Injecting CO2 Into Rocks That Go Beneath the Seafloor

Scientists have come up with a method of altering oil and gas rigs in the North Sea to make them pump carbon dioxide emissions into rocks below the sea bed. They say that this approach would offer substantial cost savings compared to decommissioning those structures.

Plus, it would help manage the CO2 emissions associated with natural gas sites and could also address emissions from other sources.

Clear blue ocean water. Image credit: Tyler Lastovich via Pexels (Free Pexels licence)

Clear blue ocean water. Image credit: Tyler Lastovich via Pexels (Free Pexels licence)

Researchers in Edinburgh, Scotland targeted the Beatrice oil field, located 15 miles off Scotland’s coast. They used computer modeling technology to look at a 30-year span and determined that this tweaking of the rigs could be 10 times less expensive than decommissioning. That latter option could cost more than £260 million.

The team also discovered it’s still possible to extract large amounts of heat energy and natural gas from the saltwater of depleted oil and gas fields. Moreover, those things can generate electricity for the repurposed oil and gas rigs by being used as fuel or burned.

The researchers’ recently published paper also mentions that the process of dissolving CO2 in brine before disposing of it prevents possible leakage. Scientists who carried out other studies showed that atmospheric methane leaked from all oil and gas platforms assessed in the North Sea. That means this new research could be particularly impactful.

How Does This Carbon Capture Method Work?

This technique requires degassing methane from produced brine, then cooling the brine to extract heat. Next, CO2 gets dissolved into the brine before being injected into a formation of porous rocks. The scientists say that the relatively high density of the brine filled with CO2 will make it sink to a depth that allows storing it safely. Ultimately, the rocks would go several kilometers beneath the seafloor.

The Necessity of Looking for CO2 Management Options

The International Energy Agency (IEA) recently forecasted that the worldwide demand for oil would increase by 1.4 million barrels in 2019. The United States, China and India are the three countries accounting for the bulk of the uptick.

The continual need for oil means it’s imperative to determine the best ways to deal with emissions. Innovative approaches like the one described here could pay off and help protect the planet. Also, as mentioned earlier, this approach is much cheaper than decommissioning.

Possible Issues

It’s unclear if the scientists will get the support they need to move forward with this approach. It seems unlikely, at least, in the Beatrice oil field. In January 2019, government officials in the United Kingdom approved previously submitted plans to decommission the Beatrice oil field.

Although the researchers focused their study on that location, they remarked in their journal article that the Beatrice site was not ideal because it was overly shallow and had reduced heat capture potential. Since this accomplishment is so new, carbon-capture experts have not yet weighed in with their thoughts about the advantages and possible downsides of this method. Any new technology carries the risks of unforeseen consequences.

It’s also uncertain whether the researchers verified that the rocks would go deep enough through real-world tests or only confirmed that they would through the computer model system.

Not the Only Undersea Carbon Capture Method in the Works

The technique mentioned above is not the first of its kind. Another project involves three European ports that will pipe 10 million tons of CO2 emissions into sandstone two miles beneath the ocean floor. A couple of empty gas fields will serve as the storage sites. Members of the Dutch government remark that this is an unprecedented project, but they have concerns about how CO2 could negatively affect the deep subsurface.

The first large-scale carbon capture project got developed more than two decades ago in 1996. That setup sends more than one million tons of CO2 about a half-mile underneath the seafloor each year. European officials previously committed to financing a dozen more such projects. But the plans fell through due to prohibitively high costs.

A Positive but Unproven Development

It’s admirable and relevant that scientists engineered a way to put CO2 in rocks that plunge beneath the ocean floor. However, not enough is known at this early phase regarding if the technique has long-term promise or will get the financial backing it needs.

Written by Kayla Matthews, Productivity Bytes.

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