Limited goals for carbon-dioxide capture from coal might mean faster overall progress on climate change.
Tuesday, November 18, 2008
By David Talbot
The quickest and most effective way to deal with emissions from new coal power plants might be to capture perhaps 60 percent of the gas, and not press for more ambitious targets, according to an analysis presented today at the 9th International Conference on Greenhouse Gas Control Technologies, in Washington, DC.
Howard Herzog, a principal research engineer at MIT (where he manages an industry consortium on carbon capture and storage), explained to me that this route might be akin to the progression we are now seeing in automobiles: from gasoline-powered cars to hybrid versions, en route to a future full of plug-in hybrid or full-electric cars charged from an electric grid that conveys mainly clean renewable power.
Given that right now none of the 600 U.S. coal power plants--or virtually any other source of greenhouse gas--captures and sequesters CO2, you have to start somewhere, he said. "We are trying to look at it from an energy security viewpoint, an economic viewpoint, and a carbon-capture viewpoint," said Herzog, who coauthored the analysis with Ashleigh Hildebrand, a graduate student in chemical engineering and technology policy.
Herzog went on to explain that coal is a secure American resource that doesn't require importing liquefied natural gas. Partial capture would be cheaper than full capture (which would require extra processing steps). Depending on the type of plant, reducing coal's CO2 emissions by between 45 and 60 percent would mean that it emits as much CO2 as a natural-gas power plant. And because the partial-emission version would be more economical, it could mean faster implementation, which would, in turn, help prove the feasibility of capturing and burying CO2 (in various underground reservoirs, for the most part) on a massive scale. Research is continuing into the optimal capture levels on both coal-burning and coal-gasification designs, Herzog added.
The conference is mainly a technical affair, full of presentations on the suitability of various geologic formations for CO2 storage, how to do seismic analysis of CO2 reservoirs, and the experience of various pilot projects. Ruben Juanes, an assistant professor of civil and environmental engineering at MIT, described his new model for calculating how much CO2 a geologic formation can safely hold, for example.
But the critical importance of these various geologic and modeling studies was driven home in a keynote by Susan Solomon, an atmospheric chemist at the National Oceanographic and Atmospheric Administration, who gave a primer on climate change over lunch. It wasn't new ground, but it's always good to be reminded of some basics, such as "We have made CO2 [concentrations in the atmosphere] higher than it has been in more than half a million years, and that is the predominant cause of today's global warming."
Solomon reminded everyone that if we are to avert the worst effects of global warming and climate change--the droughts, the species extinctions, the water shortages, the catastrophic sea-level rise--we must act now and essentially dial our emissions back to something close to zero over the next few decades. Part of that will mean burying CO2 rather than spewing it into the atmosphere. Unfortunately, we were reminded of these sobering realities while being served steak--that most fuel-intensive source of protein--in a banquet hall lit by hundreds of incandescent lightbulbs.
Massachusetts Institute of Technology
Comments
JDRUBY on 11/19/2008 at 1:00 PM
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A global carbon management solution requires North America and specifically the US as a leader. By leading we assume technical and financial risks but stand to gain hard economic benefits as well as more abstract environmental improvements. The most difficult step will be to start the process; numerous diverse stakeholders will have objections and want to shift the process to favor their own smaller world. That is why it is crucial for the solution to be straightforward, even simplistic, but at the same time so flexible that individuals, industries, governments and organizations can choose their own carbon management path.
As background there are two main sources of CO2 in the US. Fossil fuel power generation accounts for some 2.6 billion tons per year and transportation another 2.2 billion. These add up to almost 75% of the US total of about 6.5 billion tons in 2006. If emissions from these 2 sources are seriously reduced carbon management is a success. The numbers are different in other regions of the world, but transportation and fossil power generation are primary sources.
The suggested carbon management solution is not a new concept; one of the ideas years ago to reduce power plant acid rain is similar. First the solution sets a time limit; it might be 30, 40 or 50 years. When the limit is reached electric power generation and transportation equipment, automobiles mostly, could not emit CO2 – no exceptions, or at least as few as technically possible. How might the industries halt their emissions? There are options with nuclear power and CO2 capture and storage for electricity production; augmented by renewable energy sources where they can compete in the market. Automobiles and other transportation systems have fewer options in the near term but given a couple of decades, batteries and electrification (with carbon management) of mass transit systems will make a big impact. Longer-range maybe hydrogen production and fuel cell technology breakthroughs can make them viable.
The elegance at the heart of the solution is that no one knows what new carbon management equipment or systems will replace existing processes. Carbon management will happen if the suppliers and consumers of electric power and transport are not constricted by a complex set of regulations but instead face the certainty of zero carbon emission with a fixed date.
Two obvious questions arise: What will carbon management cost, and how does it work globally? My own estimates for a worst-case are that if the cost of electric power generation were tripled instantaneously; this could add 10% to the costs of all the things it impacts from a loaf of bread to a house or car. But since the changes to power generation systems take 10s of years to implement, increases would be hardly noticed. The impact on automobile and transportation costs would also be spread over time.
In addition to the “time-value of money” effect on costs, odds are good that carbon management technologies will be less expensive than now estimated. Current carbon management technologies are immature at best. There are still huge energy and process efficiency gaps with fossil, nuclear and renewable options, and if history has any relation to the future, new technologies will surprise us the same as computers, gas turbines and biotech. Unplanned byproducts from carbon management advances could rival those of the space program.
On the second question about fitting the solution to global conditions; the US and Canada have to willingly lead or the job won’t get done. By leading we set the objectives and show the path to follow. Large industrial CO2 sources outside North America are part of international organizations. If the global organizations sell products in North America, they need to set carbon management standards for when the schedule expires. And I suspect that the European Union and others would happily apply similar criteria.
For developing countries where many of the carbon sources are government controlled, participation in international markets will be an important inducement for them to also choose the carbon management path.
Time, leadership and flexibility are the primary carbon management requirements. The solution requires time, both a sufficient length of time to install new systems, and a fixed closure when objectives are met. North American leadership must to encourage technology development and the formation of a global consensus to limit carbon emission. And since no one can foresee the future, government actions should be limited to setting objectives without mandating technologies or otherwise limiting the pathways forward.