Hiding something in the ground is an impulse known to man and dog alike. So it's no wonder that humans, having realized that carbon dioxide in the atmosphere could warm the planet catastrophically, are looking to bury the greenhouse gas deep underground.
In the last few months, that impulse has become super-charged as a result of accelerating government support around the world for CCS – carbon capture and sequestration – a technology that promises to capture CO2 emissions, inject it deep into porous rock and store it there forever.
In the U.S., the potential of CCS has been seized on as a solution to reducing global warming emissions in pending federal legislation.
Coal supporters are using it as an argument against forcing polluters to start paying for power plant emissions now. Rep. Mike Doyle (D-Pa.) put it bluntly to Congressional Quarterly: "We want to see coal-fired utilities held harmless until such time as the [carbon capture and sequestration] technology is deployed."
But conversations with scientists and experts reveal that deploying this technology on a wide scale is still at least two decades away in the best of circumstances.
That means, despite the excitement, CCS can't be relied on in the near term as a climate policy solution.
There are not only scientific hurdles which will take years of testing to overcome, but also the financial, regulatory and legal obstacles that swirl around massive building projects of this kind, not to mention the hundreds of miles of new pipelines that will be needed to transport the carbon dioxide.
The U.S. Department of Energy's Energy Information Administration annual outlook released this week stated:
"Coal-fired plants with CCS equipment have not been fully commercialized, and it is unclear when they might be and what they would cost."
The International Energy Agency released a report last fall stating that by 2020, at least 20 full-scale CCS projects would need to be fully functioning in order to make the technology cost-effective and reliable enough to foster widespread adoption in the following years. The report noted that so many of the current CCS programs were making such slow progress that:
"If these demonstration projects do not materialize in the near future, it will be impossible for CCS to make a meaningful contribution to GHG mitigation efforts by 2030."
Right now, there are only four large-scale carbon capture and sequestration projects in operation worldwide – Sleipner and SnØhvit, off Norway's shore, Weyburn Project, a joint effort by Canada and the U.S.; and In Salah in Algeria. U.S. experts in the field say the earliest CCS could begin to be deployed on an industry-wide scale would be between 2026 and 2030 – and that's only assuming there are no technological or permitting delays and full funding is available immediately.
World governments are beginning to lavish money on the development of CCS technology. The comprehensive new climate legislation announced in the U.S. House on Tuesday would allocate $10 billion for CCS development – on top of the $3.4 billion set aside for CCS demonstration projects in the stimulus package. The European Union has pledged more than €1 billion over two years to help 12 coal-fired power plants develop the technology to store their CO2 under the North Sea in old oil and gas fields.
According to Sally Benson, a Stanford University engineering professor, right now CCS technology is not yet efficient and cost-effective enough to be easily replicated. Also a proponent of CCS and the executive director of the Global Climate and Energy Project, she believes that the amount invested in CCS will determine when it will be available. Money, in this case, is time.
"I think the question people want to ask is, 'When will it be highly replicable so that any new fossil fuel-fired power plant would adopt this technology?'" Bensen said.
If five to 10 large-scale projects storing one to two million tons of CO2 a year (equivalent to 100MW-200MW power plants) were launched in the next few years, she believes CCS technology could begin to be replicable by 2020. Even then, it would take about another decade for a first generation of new plants to come online.
It takes at least six years to get the coal plant itself running due to permitting and legal issues, notes Howard Herzog, principal research engineer at the Massachusetts Institute of Technology Laboratory for Energy and the Environment.
"It's like any of these big projects – even if you try to build a big coal plant this year, you're talking at least six years from start to start-up. Nuclear plants, you're talking 10 years plus, so I think a CCS plant is somewhere in that range," he said.
In order to be replicable, CCS technology must overcome several scientific hurdles.
CCS is composed of three main stages: capture, transportation and storage. Transportation is the easy part. CO2 can travel through pipelines, which industry already knows how to build. But all three capture techniques – post-combustion, pre-combustion and oxygen combustion – need to be refined, and storage processes need more work and testing for success over long periods of time.
Post-combustion capture, which removes CO2 after the fossil fuel has been burned, is a well-understood technology applicable in conventional power plants. However, it is only economically feasible under specific conditions, and Benson says it needs to become more cost-effective and less energy-intense.
Pre-combustion capture turns the fossil fuel into a gas composed of CO and H2. The CO is transformed into a relatively pure CO2 that can be removed easily, and the H2 is used as fuel. The challenge is to integrate gasification with electricity, and the industry must develop experience in managing such facilities inexpensively while providing reliable power, Benson said.
"If you look at how we produce electricity today, we heat up water and run it through a turbine. If you look at gasification, it's more like running a big chemical factory. The utility industry doesn't have much experience with that," she said.
The third capture process, oxygen-combustion, needs to be more cost-effective, energy-efficient and reliable. Oxygen-combustion separates the two main components of air – oxygen (21%) and nitrogen (78%) – before burning the fuel, producing water and carbon dioxide for easy separation, but again, more experience is needed in managing the process, which generates a great deal of heat.
The FutureGen plant proposed in Mattoon, Ill., was to be the first large demonstration in the United States. It became the center of a political brouhaha after the Bush administration stopped its construction in December 2007, ostensibly due to cost.
It dealt a big blow to progress. A recent Congressional report concluded that halting FutureGen set back CCS development by a decade.
The industry also must develop protocols for safe underground storage of carbon dioxide, Benson said:
"We know in principle that you can [store gas underground], because we have lessons from nature and we store natural gas all the time, but what we need to do is have good procedures for selecting good sites so we can have high retention."
Scientists are simultaneously refining the tools they need to "see" what happens to CO2 deep underground and identifying the most appropriate geological formations. In theory, porous rock can be capped, but each site still must be tested for leakage and water displacement.
Institutional issues, particularly concerning safety, also remain. The EPA is currently finalizing regulations for the underground storage of carbon dioxide to protect drinking water supplies and the environment. Additionally, each state will have to decide who has ownership rights and legal responsibility for the underground porous space. Precedents set in the oil and gas industry may help people decide how to cooperate and allocate profits, but the scale of the potential storage capacity needed is far larger and more complex.
Finally, long-term liability will need to be assigned: Who will be responsible if something goes massively wrong? The potential to contaminate groundwater and other risk factors are holding up the influx of money from big investors. A Harvard study of 19 smaller CCS projects found that such legal issues were vital to their viability. Barriers involving liability, consents and permitting caused significant delays for the projects and, in one case, cancellation of a project.
Even once all the technological and regulatory issues are settled, there still remains the problem of price.
MIT's Herzog believes that the price on carbon is currently too low to make CCS cost-competitive:
"There will need to be something beyond cap-and-trade systems to make these plants commercially viable, because otherwise the cost is too big. Maybe out in 2030 or 2040, the carbon price could support it, but 2020 is probably too short."
Susan Hovorka, a senior research scientist at the Bureau of Economic Geology at the University of Texas-Austin who works with small-scale CSS projects, is pessimistic because of CCS's political problem.
Most of the technologies required for CCS are used today, Hovorka said.
"So, why aren't we doing this? It's because we don't want to pay for it yet. At the moment, it's expensive and energy inefficient and a lot of people object to technologies that reduce the environmental impact of coal. They would rather get rid of coal altogether."
That won't be written into federal law anytime soon, but it could come to pass if CCS fails to succeed on its financial and scientific merits in time.