Building an Underground 'Highway' for Carbon Dioxide

Engineers are working on ways to snag global warming pollution from the air, liquefy it and send it to underground storage sites through a pipeline network.

Reducing carbon emissions is key to combating global warming. You probably knew that. What you might not know is that scientists are working to develop a viable way to trap carbon dioxide (CO₂) emissions, squeeze them into a liquid form, and then pipe that fluid somewhere it can be injected underground (see graphic below).

The process is called Carbon Capture and Sequestration (CCS), and it's receiving considerable attention. It could allow us to cut emissions while still burning fossil fuels like coal for our electricity and other energy needs.

What Will the Pipeline Look Like?

While the first U.S. demonstration plants (like the recently canceled FutureGen project) will likely be built over a storage site, if the technology takes off, many power plants won't be so well positioned. Studies indicate that locating future carbon-capturing plants close to areas with high electricity demand will be the most cost-effective.

(Montana Environmental Information Center)

Plus, since relatively new plants nowhere near sequestration sites already have expensive systems to trap smog-forming nitrogen dioxide and acid-rain producing sulfur dioxide, they will probably be retrofitted with carbon-capturing technologies rather than abandoned. So we'll need significant infrastructure to connect those CO₂ sources to underground sinks.

Who will build the pipeline network and what it will look like remain unclear (see analysis). But its makeup, in both form and investment, will likely be complex. Here's a look at some of the complicating factors.

Multiple Players - Utilities alone are unlikely to shoulder the pipelines' costs. Storage site operators in need of customers may be motivated enough to help connect them. Oil companies like ConocoPhillips are prepping to be among these operators, and where necessary for business they will help build pipelines. Pipeline operators themselves, like Kinder Morgan, which is experienced in helping develop a CO₂ pipeline network for Enhanced Oil Recovery (see map below), are well positioned to grow a CCS network. And then there's the federal government, which might build CO₂ trunk lines to sequestration sites that power plants could tie in to.

CO2 pipelines in operation in the United States (European Energy Forum)

Sequencing - A CO₂ pipeline network will take time to evolve. Here's a likely scenario. Early-mover utilities will establish the network's first nodes by building capture-ready power plants before carbon emissions have a price (from a cap or tax). When the price becomes high enough to make joining cost effective, the remaining plants will connect. Similarly, different sequestration sites will add onto the network as demand for storage rises along with storage costs.

Routing - Factors influencing the pipelines' routes compound network uncertainty even more. Many new pipelines could end up following existing infrastructure (such as transmission lines and train tracks), as rights-of-way for these have already been established. Elsewhere it may be cheaper to forge new routes. In either case, new pipelines will require approval and regulation, the responsibilities for which are still being worked out between state and federal governments.

And then there is the issue of network redundancy. Multiple pathways from a power plant to one or more sequestration sites would ensure that the plant can discharge emissions, and sequestration sites can receive them and get paid for storing them, even if a segment of the network shuts down.

Geosequestration Potential - Finally, we need much more information about the capacity and costs of candidate storage sites. In some cases, the quality of available reservoirs may make shipping CO₂ to a faraway site cheaper than storing it nearby. And if it turns out that there are one or two sites with exceptionally large and low-cost storage, it may be more economical to connect plants far and wide to an extended pipeline network that converges on these sites rather than build a more intricate, distributed network linking smaller groups of plants to the nearest sequestration sites.

A Big Pipeline With Huge Potential

Given these unknowns and others, it is too early to predict who will ante up the construction costs for a pipeline network and what form it will assume. One thing that probably can be counted on is that CCS will be much bigger than just the utilities and government. Along with it an industry will emerge. We should help promote this.

Consider that in 1994, then vice president Al Gore argued with Robert Allen, AT&T's CEO at the time, over how to build the electronic superhighway, now of course known colloquially as the Internet. Gore thought government should build it; Allen deemed it a job for industry. Fourteen years later, the Internet is the product of industry and we can't live without it. CCS will be expensive, but we need to cut emissions. Let’s similarly engage industry in the development of this CO₂ super highway to bring it on as quickly, efficiently and economically as possible.

Lincoln F. Pratson is associate professor of sedimentary geology at the Nicholas School of the Environment at Duke University.