™ Emissions level needed to stabilize CO2 at 450 ppmv
^ Coal carbon (C) stored
^ Natural gas C stored
1 Natural gas C emitted
1 Coal C emitted
H Oil C emitted
society would ultimately benefit if deployment of plants fitted with CCS equipment were begun now.
First, the fastest way to reduce CCS costs is via "learning by doing"—the accumulation of experience in building and running such plants. The faster the understanding is accumulated, the quicker the know-how with the new technology will grow, and the more rapidly the costs will drop.
Second, installing CCS equipment as soon as possible should save money in the long run. Most power stations currently under construction will still be operating decades from now, when it is likely that CCS efforts will be obligatory. Retrofitting generating facilities for CCS is inherently more expensive than deploying CCS in new plants. Moreover, in the absence of CO2 emission limits, familiar conventional coal steam-electric technologies will tend to be favored for most new plant construction over newer gasification technologies, for which CCS is more cost-effective.
Finally, rapid implementation would allow for continued use of fossil fuels in the near term (until more environmentally friendly sources become prevalent) without pushing atmospheric carbon dioxide beyond tolerable levels. Our studies indicate that it is feasible to stabilize atmospheric CO2 levels at 450 ppmv over the next half a century if coal-based energy is completely decarbonized and other measures described in the box at the left are implemented. This effort would involve decarbonizing 36 gigawatts of new coal generating capacity by 2020 (corresponding to 7 percent of the new coal capacity expected to be built worldwide during the decade beginning in 2011 under business-as-usual conditions). In the 35 years after 2020, CO2 capture would need to rise at an average rate of about 12 percent a year. Such a sustained pace is high compared with typical market growth rates for energy but is not unprecedented. It is much less than the expansion rate for nuclear generating capacity in its heyday—1956 to 1980—during which global capacity rose at an average rate of 40 percent annually. Further, the
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expansion rates for both wind and solar photovoltaic power capacities worldwide have hovered around 30 percent a year since the early 1990s. In all three cases, such growth would not have been practical without public policy measures to support them.
Our calculations indicate that the costs of CCS deployment would be manageable as well. Using conservative assumptions—such as that technology will not improve over time—we estimate that the present worth of the cost of capturing and storing all CO2 produced by coal-based electricity generation plants during the next 200 years will be $1.8 trillion (in 2002 dollars). That might seem like a high price tag, but it is equivalent to just 0.07 percent of the current value of gross world product over the same interval. Thus, it is plausible that a rapid decarbonization path for coal is both physically and economically feasible, although detailed regional analyses are needed to confirm this conclusion.
Policy Push Is Needed those good reasons for commencing concerted CCS efforts soon will probably not move the industry unless it is also prodded by new public policies. Such initiatives would be part of a broader drive to control carbon dioxide emissions from all sources.
In the U.S., a national program to limit CO2 emissions must be enacted soon to introduce the government regulations and market incentives necessary to shift investment to the least-polluting energy technologies promptly and on a wide scale. Leaders in the American business and policy communities increasingly agree that quantifiable and enforceable restrictions on global warming emissions are imperative and inevitable. To ensure that power companies put into practice the reductions in a cost-effective fashion, a market for trading CO2 emissions credits should be created—one similar to that for the sulfur emissions that cause acid rain. In such a plan, organizations that intend to exceed designated emission limits may buy credits from others that are able to stay below these values.
Enhancing energy efficiency efforts and raising renewable energy production are critical to achieving carbon dioxide limits at the lowest possible cost. A portion of the emission allowances created by a carbon cap-and-trade program should be allocated to the establishment of a fund to help overcome institutional barriers and technical risks that obstruct widespread deployment of otherwise cost-effective CO2 mitigation technologies.
Delaying carbon capture and storage at coal power plants is shortsighted.
Even if a carbon dioxide cap-and-trade program were enacted in the next few years the economic value of CO2 emissions reduction may not be enough initially to convince power providers to invest in power systems with CCS. To avoid the construction of another generation of conventional coal plants, it is essential that the federal government establish incentives that promote CCS.
One approach would be to insist that an increasing share of total coal-based electricity generation comes from facilities that meet a low CO2 emissions standard—perhaps a maximum of 30 grams of carbon per kilowatt-hour (an achievable goal using today's coal CCS technologies). Such a goal might be achieved by obliging electricity producers that use coal to include a growing fraction of decarbonized coal power in their supply portfolios. Each covered electricity producer could either generate the required amount of decarbonized coal power or purchase decarbonized-generation credits. This system would share the incremental costs of CCS for coal power among all U.S. coal-based electricity producers and consumers.
If the surge of conventional coal-fired power plants currently on drawing boards is built as planned, atmospheric carbon dioxide levels will almost certainly exceed 450 ppmv. We can meet global energy needs while still stabilizing CO2 at 450 ppmv, however, through a combination of improved efficiency in energy use, greater reliance on renewable energy resources and, for the new coal investments that are made, the installation of CO2 capture and geologic storage technologies. Even though there is no such thing as "clean coal," more can and must be done to reduce the dangers and environmental degradations associated with coal production and use. An integrated low-carbon energy strategy that incorporates CO2 capture and storage can reconcile substantial use of coal in the coming decades with the imperative to prevent catastrophic changes to the earth's climate. ®
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