Of all the problems discussed in this chapter regarding the use of coal, the one that has brought serious attention to drastically reducing our appetite for coal is the hazards of global warming caused principally by CO2 emitted from fossil fuels (see Chapter 1). The coal industry is touting “clean coal,” and indeed modern coal power plants such as Rawhide have low emissions of everything but CO2 . Coal can never be clean without solving the CO2 problem. The buzzword of the year is “carbon capture and storage,” or CCS, as the solution to the problem. What does this mean and can it really be a solution?

Carbon capture and storage or sequestration, as it is often called, is a process for absorbing or capturing the CO2 produced by a coal or gas power plant and

storing it permanently (hopefully) in a geological formation. There are various strategies for removing CO2 from a power plant, but the only one with any signif­icant experience is to absorb the CO2 in an aqueous amine solution like ammonia or MEA (monoethylamine). The amine solution then has to be heated at 150°C (300°F) for several hours to remove the CO2, which requires a lot of energy. In fact, the separation process takes 25-40% of the energy produced by the power plant (22). Even with solvent and process improvements, the best that could ever be expected is a 20% loss of efficiency of the power plant (23). If this process were actually available and retrofitted to all existing coal power plants, their electri­cal output would drop by about one-third, so about 200 coal-fired power plants would have to be built just to tread water. And as I explained earlier, energy use is continuing to increase, so additional coal power plants would also have to be built with an inherent inefficiency built in. This, by the way, is in addition to the inefficiencies already built into a modern power plant by scrubbing the sulfur oxides and filtering the fly ash. All of this means that coal mining would also have to increase at a dramatic rate. This is the fundamental problem with CCS.

But this is really the tip of the iceberg. Post-combustion capture of CO2 has numerous problems: “the equipment will be very large, comparable with the footprint size of a coal-fired power plant, large volumes of solvent are needed, heating to regenerate the solvent can produce toxic byproducts, emissions of sol­vents from recovery columns need to be scrubbed and eliminated, consumption of water needs to be reduced, and expired solvent needs to be disposed”(23). And capturing the CO2 is just the first step. After it is captured, it has to be compressed to 70 atmospheres of pressure to form a liquid before being transported through pipelines to a permanent geological storage site. There are already about 2,000 miles of pipeline in the United States that transport about 30 million tons (Mt) of CO2 per year. That is less than 2% of the 2 billion tons of CO2 produced by coal-fired power plants in the United States annually. Creating the needed pipe­lines to transport this volume of CO2 would cause tremendous environmental damage and expense.

The next problem is where to put the CO2. In order to minimize the transpor­tation problem, the site needs to be close to the power plant. Available options are to store it in depleted oil and gas reservoirs or deep salt formations, or use it to enhance oil recovery (EOR) (24). EOR is already being used in Texas, where about 30 Mt of CO2 annually is injected into wells to recover oil that can’t be easily pumped out. However, there is not a large capacity for EOR. Another option is to inject it into deep formations that contain saltwater, where there is much larger capacity. The CO2 is relatively soluble in brine, which ultimately reduces the pos­sibility of leakage, but the brine itself may migrate, and it can take hundreds of years for complete dissolution (24). Furthermore, even though there is apparently enough storage in saline deposits for hundreds of years of power plant operation, earlier estimates are being reduced to decades because only a small fraction of the available pore space seems to be accessible (22).

Major leakage from geological storage could also be catastrophic. This has already happened naturally at Lake Nyos, Cameroon, in 1986. Carbon dioxide from natural geological sources was dissolved in the cold water at the bottom of the lake but underwent a sudden inversion. The result was similar to shaking a soda can and opening it. Carbonated water shot over 200 feet in the air and released the CO2, which is heavier than air. It slowly settled in a valley and smoth­ered 1,700 people (14). Leakage from undersea storage would also cause serious problems by producing carbonic acid and killing marine life in the neighborhood. This is the same problem with ocean acidification, as is currently happening from the CO2 in the atmosphere that is being absorbed by the ocean (see Chapter 1). Lest we think that accidents from deep undersea storage cannot happen, just remember the environmental disaster in the Gulf of Mexico in the summer of 2010 from an oil rig accident that allowed 100 million barrels of oil to pour into the Gulf.

Let’s take a reality check! There are a few CCS projects in operation around the world, but they are experimental and small, capturing a small percentage of the emissions from an actual coal-fired plant. The hope is to go from experimental to demonstration plants by 2014 and finally get to commercial plants by 2020 (22). Storage sites are also being studied and pipeline routes considered, especially in Europe for storage in the North Sea, but these sites are only capable of, at most, a few Mt of CO2 per year currently (22, 25). Steven Chu, the former US Secretary of Energy, points out that the world burns about 6 Gt of coal each year, producing 18 Gt of CO2. The United States is investing a few billion dollars in experimental CCS projects, but that is a drop in the bucket compared to the trillions of dollars that will be necessary to make this a reality. In The Quest, Daniel Yergin says:

If just 60% of the CO2 produced by today’s coal-fired power plants in the United States were captured and compressed into a liquid, transported, and injected into the storage site, the daily volume of liquids so handled would be about equal to the 19 million barrels of oil that the United States consumes every day. It is sobering to realize that 150 years and trillions of dollars were required to build that existing system for oil. (26)

And don’t forget the price to be paid in loss of efficiency of power plants. It is highly unlikely that the target of 2020 will be close to being met; in the meantime, coal power plants keep spewing out CO2. So is this really feasible, or are we just dreaming to avoid making difficult choices to get away from coal and find other sources of energy?

A very interesting answer to this question is to compare the cost and effec­tiveness of reducing CO2 using CCS with using the same resources to develop alternative energy sources such as wind or nuclear. This has been done in a recent paper based on the idea of “stabilization wedges,” which represent one-eighth of the increased emission of CO2 over a 50-year time period (27). That is, one wedge would eliminate one-eighth of the emissions from coal-fired power plants over this time period. This could be done by CCS or by alternative energy sources. The authors estimate that one wedge of CO2 reduction by CCS would cost $5.1 trillion.

If this same resource were instead put into building wind turbines, 1.9 wedges of CO2 would be eliminated and $9 trillion in electricity would be generated. Even better, if this same resource were put into nuclear power plants, 4.3 wedges of CO2 would be avoided and $22.3 trillion in electricity would be generated.

So there you have it. The fundamental problem with CCS is that it does not produce any more power—and in fact reduces power—at an enormous cost with huge uncertainties in feasibility and environmental costs. It will require trillions of dollars in resources that will generate no additional electricity. Almost cer­tainly, those resources will then not be available for alternative energies. Instead, we should forget about CCS entirely and get on with developing other energy sources and begin shutting down coal-fired power plants.