14 Jul 2008: Analysis
Coal’s New Technology:
Panacea or Risky Gamble?
The coal industry, political leaders, and some environmentalists have high hopes for the concept of carbon sequestration, which takes carbon dioxide emissions from coal plants and buries them underground. But so far, this new technology does not live up to the hype.
According to NASA climatologist James Hansen, there’s still time to avert a climate crisis. All we need to do, he said in a speech a few weeks ago in Washington D.C., is “phase out coal as quickly as possible.” Of course, given the fact that coal generates more than half the electricity in the United States, and is even more vital in the developing world, this is easier said than done. But if we can’t kick the coal habit, can we at least burn it in a way that doesn’t cook the planet?
The key to coal’s future — and maybe our own — is a technology called carbon capture and storage (CCS). At first glance, the idea seems straightforward: As coal is burned (or, in the future, gasified), remove the carbon dioxide, pressurize it into a supercritical liquid that's roughly the consistency of oil, then pump it underground. Depleted oil and gas wells make good storage sites, as do deep saline aquifers 2,000 feet or so underground. You can even pipe the CO2
offshore and inject it under the ocean floor. In theory, the CO2
will stay buried in these spots for hundreds if not thousands of years, thereby allowing us to continue burning coal without trashing the earth's climate.
Politically, CCS is a godsend. Both Barack Obama and John McCain are eager to carry Big Coal (swing) states like Pennsylvania, West Virginia, Indiana, and Ohio, where the promise of “clean coal” is the easy answer to every hard question about energy security, global warming, and the economy. The promise of CCS is also a central ingredient in the American Coalition for Clean Coal Electricity’s “clean coal” campaign. The coal industry trade group is spending $35 million on slick TV ads to reposition coal as an indispensable fuel for the 21st century — a task not unlike repositioning Barry Manilow as a hip-hop star.
Unfortunately, CCS is more fantasy than reality at the moment. Squirting CO2
into old oil wells is simple enough — the oil and gas industry does it all the time to help push out stubborn reserves. But capturing billions of tons of CO2
from power plants and pumping it underground — and doing it safely and cheaply, on a global scale, both in the West and the developing world — is another thing altogether. Even the Bush Administration has had doubts: Last January, the Department of Energy (DOE) canceled FutureGen, a next-generation coal plant that was being funded by the DOE and a consortium of big coal and electric power companies, citing cost overruns. Just two months earlier, administration officials had called FutureGen “the centerpiece” of their strategy for clean coal technologies. The DOE is now restructuring the program to fund a handful of smaller CCS demonstration projects.
To understand the problems with CCS, let’s start with the mechanics of capturing and storing CO2
from the stack of a coal plant. For pollutants like sulfur dioxide and nitrogen oxides, you can just bolt a scrubber on the stack and be done with it. But CO2
billows out such a diffuse stream, and in such huge volumes, that nobody has figured out a good way to capture it from a stack yet that isn't prohibitively expensive and doesn't reduce the efficiency of the plant by as much as 30 percent. Other possibilities, such as burning coal in pure oxygen, may someday make the job of capturing CO2
from a pulverized coal plant easier, but this technology is nowhere near ready for commercial deployment.
The ability to capture CO2 is likely to apply only to new coal plants. Retrofitting the thousands of existing plants is, at the moment, a pipe dream.”
It may turn out that capturing CO2
will require shifting to an entirely new kind of plant, called IGCC, or “integrated gasification combined cycle,” which uses heat and pressure to transform coal into a gas, which is then burned to generate electricity. IGCC has lots of advantages, but most important is the fact that CO2
can be removed during the gasification process, when the volume of the gas is much smaller than it is when it is released up the stack of a conventional coal plant. The disadvantage of IGCC is that it is new and different and expensive, and this industry has a long history of fighting anything new and different and expensive. In any case, the important point is that the ability to capture CO2
is likely to apply only to new
coal plants. Retrofitting the thousands of existing coal plants is, at the moment, a pipe dream.
For the sake of argument, however, let's assume a smart engineer invents a cheap, efficient way to capture CO2
from existing coal plants (lots of people are throwing money at the problem). The big question is: Can we bury enough to make a difference?
Right now, there are three major carbon capture and storage projects in operation in the world (at one of the projects in Saskatchewan, Canada, the CO2
is used to enhance oil and gas recovery; storing the CO2
is secondary). The most significant is the Sleipner Platform in Norway, where StatoilHydro, a big Norwegian oil and gas company, has been pumping nearly one million tons of CO2
into a reservoir beneath the North Sea each year since 1996. It is an enormous engineering project, deploying one of the largest offshore platforms in the world. But compared to the engineering effort that would be required to stabilize the climate, it's nothing. It would take 10 Sleipner-size CO2
storage projects to offset the annual emissions of a single big coal plant
David Hawkins, head of the climate change program at the Natural Resources Defense Council and a forceful advocate of CCS, is undaunted by such facts: “Yes, burying billions of tons of CO2
is a huge job, but that is not necessarily an argument against CCS. You can’t solve a big problem without a big effort.” But Vaclav Smil, an energy expert at the University of Manitoba, Canada, argued recently in Nature
that “carbon sequestration is irresponsibly portrayed as an imminently useful option for solving the challenge [of global warming].” Smil pointed out that to sequester just 25% of the CO2
emitted by stationary sources (mostly coal plants), we would have to create a system whose annual volume of fluid would be slightly more than twice that of the world’s crude-oil industry.
Then there are the questions about what happens to all that CO2
once it’s pumped underground. “We have confidence that large-scale CO2
injection projects can be operated safely,” a study on the future of coal by the Massachusetts Institute of Technology concluded. But since our experience with large-scale injection is so limited, no one knows for sure what the risks are. CO2
, which is buoyant underground, can migrate through cracks in the earth and around old wellheads, pooling in unexpected places. This is troublesome because CO2
is an asphyxiant — in concentrations above 20 percent it can cause a person to lose consciousness in a breath or two. In theory, you could enter a basement flooded with CO2
and, because it’s an invisible, odorless gas, you would never know it’s there.
Until CO2 is priced at about $40 a ton, power companies will find it cheaper to keep dumping it into the air rather than capturing and burying it underground.”
Liability is also a large and unresolved problem. If a micro-seep of CO2
asphyxiates five girls in a basement during a slumber party in Illinois, who is going to be held accountable? Injecting CO2
can also push briny salt water from deep aquifers up toward the surface, potentially ruining drinking water supplies. If a town’s water is ruined, who pays? One solution that is frequently discussed is a version of the Price-Anderson Nuclear Industries Indemnities Act, which assures power companies that if their nukes melt down, they won’t be liable for the full cost of the disaster. That might be a good deal for Big Coal, but not such a good deal for the rest of us, who will essentially end up holding the bag if something goes wrong.
Finally, there is the all-important question of cost. The era of cheap power from coal is over — today, the capital cost of building a new coal plant is more than double what it was just a decade ago, and if you factor in the cost of capturing and burying CO2
, the cost of a coal plant rivals a nuclear plant. Most studies show that until CO2
is priced at about $40 a ton, power companies will find it cheaper to keep dumping the CO2
into the air rather than capturing and burying it underground. However, given the political realities in America, that is unlikely to happen anytime before 2020, even if climate legislation is passed during the next administration.
Add to this the technical issues that still need to be sorted out with CCS, and you can see why Greenpeace argues that it is unlikely that CCS will be commercially deployed before 2030. Indeed, given how quickly the price of renewable energy is falling (wind and large-scale concentrated solar power are already competitive with coal in some parts of the country), you have to wonder why anyone would go to the trouble of building a coal plant at all.
I don’t mean to be entirely dismissive of coal’s future in a world that takes global warming seriously. Clearly, every ton of CO2
that is safely buried underground is a step in the right direction. But betting our future on an expensive, unproven technology like CCS is, at best, reckless. We don’t need to bury our problems. We need to reinvent our world.
POSTED ON 14 Jul 2008 IN
Energy North America