IN LATE 2007, the Intergovernmental Panel on Climate Change (IPCC), comprising thousands of scientists from around the world, published its fourth assessment on climate change, warning the nations of the world that evidence of global warming is “unequivocal” and that the link between human activities (primarily the burning of fossil fuels) and rising worldwide temperatures can be stated with “very high confidence.”
For that many scientists to agree on such a strong statement requires thousands of measurements, studies, and experiments. It should surprise no one that the scientists of the IPCC have edged slowly toward this pronouncement over the past 20 years as the evidence mounted.
In 1990 they said it “could be.” In 1996, they said “evidence suggests.” By 2001 they had seen “new and stronger evidence.” In 2005 they were saying it was “sufficiently clear to justify nations taking prompt action.” And in 2006 they admitted that “risks are more serious than previously thought.” Now it is “unequivocal.”
Although some skeptics remain — particularly outside the scientific community — a growing consensus in government and industry recognizes the need for action.
Pres. George W. Bush’s own science advisor, Dr. John Marburger, went on record saying, “[G]lobal warming exists, and we have to do something about it, and what we have to do about it is reduce carbon dioxide.”
Throughout the Boilermakers union, this news has not been received happily. Nearly all our members make a living in industries that contribute to atmospheric greenhouse gases (GHG), most notably coal-fired electric power plants, oil refineries, and cement kilns. They rightly question whether reducing carbon emissions means doing away with their jobs. And they are not alone. For the past decade, the main argument against taking action on carbon emissions has been the negative effect these actions would have on the economy.
But the same IPCC report that describes the problem also gives hope that carbon emissions can be reduced without wreaking economic havoc. Tucked deeply in that report is the statement that there is “much evidence” that reductions in GHG levels can be achieved through the “deployment of a portfolio of technologies either currently available or expected to be commercialized in coming decades.”
Among those technologies is carbon capture and storage (CCS), which will allow future generations to continue burning coal and other fossil fuels. CCS captures the carbon dioxide (CO2) before it leaves the boiler (or whatever is producing it) and stores it somewhere so it never reaches the atmosphere. Wide deployment of CCS technology would allow power plants to meet the rapidly growing demand for electric power while reducing GHG emissions.
Every technology brings challenges
SOME GLIB CRITICS of fossil fuel make reducing GHG seem easy. They advocate wind, solar, nuclear, and hydropower — even geothermal power — as alternatives to coal and oil. These are all proven power sources that can help reduce GHG. But relying on any one of them, or expecting the rapid development of all of them, to meet the demand for electricity over the next few decades is naïve.
Every technology has its drawbacks. Solar cells and wind turbines require large tracts of land. Nuclear power generators not only take a long time to build, but they have their own safety issues, not the least of which is the disposal of spent nuclear fuel. Hydropower is perhaps the most renewable of all energy sources. As long as rain and snow fill rivers, hydro units can generate electricity. But the dams needed for hydropower interfere with other uses we have for rivers — transportation and fishing, among them.
In the meantime, the United States has enough coal to meet our power generation needs for over 200 years — if we can find a way to burn it without emitting large quantities of CO2. As the IPCC study suggested, the technology to do so is already available or soon should be.
In an article they wrote for The Encyclopedia of Energy in 2004, Howard Herzog and Dan Golomb outlined several approaches to CCS. At that time, non-hydro renewable sources of energy met less than one percent of the worldwide demand. Coal provided over 85 percent of all primary energy, and the authors believed it would be the “dominant source” of energy “for the rest of the century.”
Their article discusses the three categories of CCS technology — flue gas separation, oxy-fuel combustion, and pre-combustion separation. Each method brings its own challenges.
Flue gas separation and CO2 capture are already being used at more than a dozen facilities worldwide. Typically, the flue gas is bubbled through a solvent that removes the CO2, which may then be compressed for storage. The process is expensive and uses a great deal of energy.
An alternative is to burn the fuel in pure oxygen, yielding CO2 and H20 (water vapor) as the only waste gases. Separating these through condensation is relatively easy. The difficult (and expensive) part is creating the pure oxygen from intake air. One hopeful note is that studies suggest these oxyfuel systems can be retrofitted to existing coal plants that burn pulverized coal (PC).
Coal gasification combined-cycle (IGCC) power plants can use a process that removes CO2 before combustion, sending pure hydrogen to the turbine. A significant drawback is that electricity generated by PC plants is cheaper than that generated by IGCC plants.
A drawback for all methods of CCS is the question of long-term storage of CO2. To reduce global warming, CO2 must be stored underground for perhaps thousands of years. Keeping the cost of storage low, including the cost of transportation to the site, will be a priority, as will eliminating the risk of accidents. Sudden leaks of large quantities of CO2 into the atmosphere will drive out the oxygen and kill any oxygen-breathing animals in the area. And slow leaks would frustrate our efforts to reduce atmospheric GHG levels.
Proposed storage locations are numerous — depleted oil and gas reservoirs, unmineable coal seams, deep salt formations, and the ocean. Surprisingly, the ocean may be the most promising option. Surface ocean water is too saturated to absorb our current emissions through the natural process, but the deep waters are not. Scientists believe liquid CO2 could be pumped there with no ill effect.
All of these solutions bear costs and would, therefore, raise the price of electricity. Thus, companies are reluctant to invest money into developing them, though interest is rising. A cap-and-trade system for reducing carbon emissions could provide a vehicle to encourage more investment in CCS technology research.
In the United States, resistance to addressing GHG is waning. Forward thinking companies realize that the cost of doing nothing may be far greater than the cost of tackling the problem now. As Jeffrey Immelt, CEO for General Electric put it, “We think green means green. This is a time period where environmental improvement is going to lead toward profitability. This is not a hobby to make people feel good.”