Let’s Keep the CO2 Horse In the Barn

By David L. Brown

First, here’s the bad news: The world’s supply of available petroleum is about to peak just as demand is reaching record and growing levels due in part to the addition of the vast nations of China and India to the list of major oil importers. Natural gas supplies are also being drawn down at unsustainable rates. Soon, alternative energy sources will need to be found.

But there’s even worse news (you didn’t expect good news in relation to the challenge of energy use and climate change, did you?) In the near term at least, coal will be the alternate fuel of choice for energy production, through burning in power plants, gasification, and even liquification programs. There is enough coal to last for centuries at present rates and coincidentally much of the world’s coal reserves are found in places that will have the most demand, with 75% of the stuff being found in China, India, Russia, the United States and Australia.

Some see this as good news after all, but now for the even worst news: Coal produces more carbon dioxide than any other fossil fuel, twice as much as natural gas. At present coal burning is responsible for about 40 percent of CO2 emissions, and projections of energy use indicate that unless steps are taken, by the end of the century it will be cranking out fully 80 percent of the carbon entering the atmosphere.

Whoa, Nelly!

Clearly, something must be done to rein in this runaway horse before the nightmare scenarios of worst-case climate change predictions become reality.

The best alternative, at least from the point of view of the environment, would be to replace fossil fuels with “clean and green” energy sources that do not release carbon into the air. These include solar, nuclear, wind, hydro, and thermal.

Unfortunately the economics strongly favor continued reliance on fossil fuels, at least for the next few critical decades, and the focus is turning more and more toward coal. In China a coal-fired power plant is coming online on the average of once each week. In the United States there are 150 planned coal-fired plants on the drawing boards or in the approval stage. Clearly the Age of Oil is morphing into a new Age of Coal. What to do?

There may be an answer, but it is not one that is particularly appealing to those who build and operate coal-fired plants. That is to capture the CO2 they produce and sink it into the ground. This is called sequestration, and it has the theoretical ability to hide the greenhouse gas for centuries. The gas could be stored in underground saline aquifers (reserves of water too salty to be used for agriculture or drinking); pumped into depleted oil and gas fields; injected into deep layers of sedimentary rock; or even buried beneath the sea bed.

This would be an expensive proposition, which explains why exploiters of coal are not eager to embrace the idea of sequestering their greenhouse gas. They are like dog owners on the sidewalks of Paris or New York, chafing at the idea of having to clean up after their pets. And yet, eventually it will become necessary to stop the pollution and enforce a greener model for power production. Only in that way can we both continue to provide power for our economies while preventing runaway global warming.

But are we ready?

At present, the technology to make sequestration work is available mostly in theory. There are some small pilot projects underway, but far too little is known about how to capture the CO2, transport it to appropriate places, and put it into the ground. Questions abound concerning the safety and practicality of sequestration, questions such as whether we can be certain the gas will stay in the ground or whether our economy can sustain the added expense.

According to one expert, there are no significant barriers to development of a practical and effective carbon sequestration program. Writing in a recent issue of Science magazine, Daniel P. Schrag of the Harvard University Department of Earth and Planetary Sciences had this to say on the subject:

Carbon sequestration from large sources of fossil fuel combustion, particularly coal, is an essential component of any serious plan to avoid catastrophic impacts of human-induced climate change. Scientific and economic challenges still exist, but none are serious enough to suggest that carbon capture and storage will not work at the scale required to offset trillions of tons of carbon dioxide emissions over the next century. The challenge is whether the technology will be ready when society decides that it is time to get going.

Dr. Schrag’s “Perspective” article, “Preparing to Capture Carbon,” appeared in the 9 Feb., 2007 issue. In it he discusses the political and economic realities against which a commitment to sequestration must be played out, noting that “The real obstacle is political will, which may require more dramatic public reaction to climate change impacts before carbon sequestration becomes a requirement for burning coal.”

In other words, to put it in plain language we may have to wait until the horse has left the barn before steps are likely to be taken to close the door. Whoa, Nelly, indeed. But happily, some effort is being made to prepare for the coming need to capture and contain CO2.

One bright spot in this picture is a Department of Energy program, FutureGen, (see details here), a $1 billion pilot project to build a “clean” coal gasification plant as a demonstration of the technologies that could be used. The DOE website describes the program as follows:

FutureGen is an initiative to build the world’s first integrated sequestration and hydrogen production research power plant. The $1 billion dollar project is intended to create the world’s first zero-emissions fossil fuel plant. When operational, the prototype will be the cleanest fossil fuel fired power plant in the world.

Here is an artist’s rendition from the DOE of how the FutureGen plant might look:

futuregen_artistcon200px.jpg

The Science article also draws attention to programs being conducted by BP (British Petroleum) in partnership with General Electric, “with plans to build two electricity-generating plants, one in Scotland and one in California, that would sequester CO2 with enhanced oil recovery.” The captured greenhouse gas would be pumped into declining oil fields to force more oil into the wells. Another company, Xcel Energy, has also announced plans to build a coal gasification plant that features capture and sequestration.

Coal gasification is not a perfect solution, because even though it may produce a substitute for natural gas without polluting the atmosphere, in the end that gas must be burned to generate energy. That calls for a second stage of capture and sequestration at the secondary location, or use in some other way that prevents CO2 from entering the atmosphere.

As Dr. Schrag points out, government initiative is required to get things moving toward development of a mature technology that can meet the challenge of capturing future CO2 emissions. He notes that we “need carbon sequestration—not right now, but soon and at an enormous scale. Our challenge today is to ensure that the technology is ready when serious political action on climate change is finally taken.”

The future path is becoming clearer with each passing day, and despite widespread denial and avoidance of the challenges by industry and government alike, the realities of the climate change danger are pushing the need for energy reform to the forefront. There is a large and growing grassroots awareness of the problems, and as evidence continues to mount there will be no alternative to an eventual commitment to green energy. Let us hope that momentum grows swiftly, and perhaps we can close that barn door before the horse has escaped forever.

It makes an interesting footnote to mention that the vast quantities of coal contained within the Earth are evidence of Mother Nature’s own sequestration program, through which over a period of several hundred million years, trillions of tons of CO2 were removed from the atmosphere and placed safely beneath the surface. This has prevented the surface of the Earth from becoming like that of Venus, which broils at temperatures of several hundred degrees. We humans are reversing her work in a matter of a few generations, and thus creating anew a problem which had long ago been solved through natural processes.

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