12.20.2019 3:15 PM

Innovation

Don't discount carbon capture just yet, study says. It could go underwater.

Environmentalists have been reluctant in the past, but scientists say it could really work.

Abstract Aerial Art / Getty

Humanity has some quick approaching deadlines to meet in the coming years if we want to stave off the worst effects of climate change, and scientists say one solution, carbon capture and storage (CCS), is ready to start today — but it’s not an option many people aren’t thrilled about.

Despite being declared an integral part of cutting carbon emissions by the Intergovernmental Panel on Climate Change, CCS is a strategy that tends to garner lukewarm responses at best. As its name suggests, the process typically works by capturing emissions (which sounds good) and injecting them into the earth for storage (which, to some, sounds less good). These storage containers are known as wells.

There are also other variations of this process in which the captured carbon is used to create other materials, like fuel. This is an approach Elon Musk has considered to create rocket fuel for SpaceX rockets.

The concerns over CCS take many forms, but they return to a few key points. One, that simply storing away these pollutants does little to deter companies from continuing to pump out harmful emissions. Two, while this approach might reduce emissions levels, it can also result in the rise of certain other air pollutants, including particulate matter, nitrogen oxide, and ammonia.

But isn’t a solution better than no solution? Maybe.

A study published at the end of November in the journal Nature Scientific Reports not only believes in the benefits of CCS, but believes it is possible to meet global emissions goals by 2050 by implementing CCS schemes in 12,000 existing wells. By doing so, they believe emissions could be cut by 13 percent.

Philip Ringrose, an adjunct professor at the Norwegian University of Science and Technology (NTNU) and a geoscientist at the Equinor Research Centre in Trondheim, said in a statement that this plethora of wells is actually minuscule compared to the number used for global oil extraction efforts.

“It turns out to be only a fraction of the historical petroleum industry — or around 12,000 wells globally,” said Ringrose. “Shared among 5-7 continental CCS hubs — that is only about 2,000 wells per region. Very doable! But we need to get cracking as soon as possible.”

A visualization of the carbon capture and injection process underground.Illustration: Equinor

In their study, the researchers outline the actionable ways their approach could begin being implemented, including a better understanding of the physical limitations of these existing wells. Instead of volume or depth determining how much CO2 could be injected, the authors write that the pressure capacity of the well is the determining factor. If the pressure is raised too much or too quickly, the well could crack and the project would be compromised.

To determine how to approach this obstacle, the researchers divided up the global wells into three categories: Class A wells without significant pressure limits, Class B wells with some pressure limits, and Class C wells that will require consistent pressure management.

The authors write that transitioning from the easiest Class A wells to the trickier Class C wells “represents a global technology development strategy for storage which is analogous to the historic oil and gas production strategy.”

That said, the speed and scalability of this approach is still in question. The authors write that all 19 implemented and four planned CCS projects would amount to only 36 million tonnes of captured carbon per year — far less than the 6 to 7 gigatons required to meet emissions goals by 2050. That leaves a lot of ground to make up in thirty-years.

Nevertheless, the researchers of this study remain optimistic.

“Using this analysis, it is clear that the required well rate for realizing global CCS in the 2020-2050 timeframe is a manageable fraction of the historical well rate deployed from historic petroleum exploitation activities,” write the researchers.

The paper’s coauthor, Tip Meckel, said in a statement that they hope their paper can act as a path forward to making real progress in tackling emissions.

“With this paper, we provide an actionable, detailed pathway for CCS to meet the goals,” said Mickel. “This is a really big hammer that we can deploy right now to put a dent in our emissions profile.”

As with most things, there’s no easy right or wrong answer to this one. But maybe keeping our eggs in a few different baskets here would be a good approach.

Abstract:
Most studies on CO2 emissions reduction strategies that address the ‘two-degree scenario’ (2DS) recognize a significant role for CCS. For CCS to be effective, it must be deployed globally on both existing and emerging energy systems. For nations with large-scale emissions, offshore geologic CO2 storage provides an attractive and efficient long-term strategy. While some nations are already developing CCS projects using offshore CO2 storage resources, most geographic regions have yet to begin. This paper demonstrates the geologic significance of global continental margins for providing broadly-equitable, geographically-relevant, and high-quality CO2 storage resources. We then use principles of pore-space utilization and subsurface pressure constraints together with analogs of historic industry well deployment rates to demonstrate how the required storage capacity can be developed as a function of time and technical maturity to enable the global deployment of offshore storage for facilitating 2DS. Our analysis indicates that 10–14 thousand CO2 injection wells will be needed globally by 2050 to achieve this goal.
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