Let’s face it, coal is nasty stuff. It contaminates everything it comes in contact with and creates problems at every step of its life cycle: from unhealthy and unsafe underground mines, to the environmental catastrophe of mountaintop removal, to the problems associated with handling the enormous piles of ash that are produced every day. But by far, the biggest problem is the enormous amount of carbon dioxide emitted. According to the EPA, coal contributes 31 percent of all CO2, the largest of any source.
The people who still support coal basically have one argument: that it’s a necessary evil, being the only source of energy within reach that is sufficiently abundant to keep up with our enormous and ever-growing appetite for energy. We have so much coal, they reason, and we need so much energy, how could we not take advantage of this resource? They could be right, as much as those of us who care about the environment hate to admit it. As much as we would like to believe that conservation, efficiency and renewables will meet our growing, but maybe-not-growing-quite-so-quickly demand, there is certainly no guarantee that they will. Considering that coal accounts for 40 percent of all electric generation (down from 45 percent) and 21 percent of all energy in the US, that’s a lot of energy to replace. Of course, with falling natural gas prices, that is clearly picking up a lot of the slack.
Meanwhile, renewables accounted for just over 10 percent of electric power in 2010, and most of that was from existing hydropower.
If that’s not bad enough, coal powers 70 percent of China’s electric grid, which is growing far faster than ours and shows no sign of slowing down. In fact, the only thing keeping them from increasing coal generation even faster is their limited ability to physically move the stuff. Together, the US and China are responsible for 33 percent of global greenhouse gas emissions.
The other thing about coal is, of course, that it’s cheap, usually cheaper by far than other energy sources, largely because so many of its true costs are still being externalized. It is worth noting that wind at 5-6 cents per kWh is closing the gap.
Given the reality of climate change, any talk of coal must be clean coal, an approach which enables the utilization of our most abundant domestic energy resource so that at least the impact on the climate is minimized. (To put this in perspective, note that the total amount of energy we received from coal in 2010 is equal to the amount of sunshine over the same period, hitting just 460 square miles. If we adjust for the low efficiency of solar PV (17 percent at the low end), then that number goes up to 2706 square miles, well below 0.1 percent of the land area of the US, though we are nowhere close to capturing all of that any time soon.)
Clean coal has a number of variations, but all of them involve stripping the CO2 out of the coal, either before or after it is burned and then capturing it. It is then either utilized for industrial purposes or for enhanced oil recovery, or else it is pressurized into a liquid form where it can be injected underground where it supposedly will stay indefinitely in a process called carbon sequestration. The overall process is called carbon capture and storage (CCS).
No sequestration project existing or proposed removes all the CO2 from the exhaust, because of the high energy penalty for doing so (30 percent or more). Most of them bring the CO2 level down to that of natural gas. Canada has already banned the development of any new coal generation project that does not include CCS.
No doubt the least destructive form of clean coal is underground coal gasification (UCG). This is where the coal is left in the ground and converted to gas by chemical means and then sucked up to the surface where it is burned. Most of these projects include capturing the CO2 and then sequestering it as described above. Pilot plants have been run in China, and the Swan Hills plant is supposed to come online this year in Alberta, Canada. In the US, the Texas Clean Energy Project, outside Odessa, which received $450 million in DOE funding, will apply UCG, capturing 90 percent of the CO2 and then using that CO2 for enhanced oil recovery in nearby Permian Oil Basin. This approach eliminates most problems associated with coal mining, transportation and burning, leaving only the problems associated with sequestration and gas extraction to be grappled with.
With that background, here are the pros and cons of clean coal.
- Abundant supply, concentrated in industrialized countries (US, Russia, China, India).
- Relatively inexpensive.
- Continuous power. Good utilization. High load factor.
- Substantial existing infrastructure. Mature industry.
- Can be made low carbon and clean with CCS and various scrubbers.
- Can be converted to a liquid or a gas, which burn cleaner.
- Clean coal technology is currently being used in China.
- Relatively low capital investment (compared to gas or nuclear).
- Coal is nonrenewable. There is a finite supply.
- Coal contains the most CO2 per BTU, the largest contributor to global warming.
- Severe environmental, social and health and safety impacts of coal mining.
- Devastation of environment around coal mines.
- High cost of transporting coal to centralized power plants.
- Coal ash is a hazard and a disposal problem.
- Coal mining is the second highest emitter of methane, a potent greenhouse gas.
- High levels of radiation. Coal plants release more radiation than nuclear plants.
- Coal burning releases SOx and NOx which both cause acid rain.
- Burning coal emits mercury and other heavy metals that pose major health risks.
- Coal emissions linked to increased rates of asthma and lung cancer.
- Sequestration is new, expensive and its ability to hold CO2 for long periods of time is unproven. Risk of accidental releases of large quantities of CO2.
- Clean coal is not carbon free.
- Significant energy penalties are incurred for sequestration.
- CO2 is toxic at concentrations above 5 percent. The condition is called hypercapnia.
The true costs of coal are not included in what is paid today. Coal would not be competitive if environmental costs were included. When the costs of mitigating these impacts through CCS and UCG are factored in, it will not be competitive against renewables. However we might still need to use it in some localities to meet our ever-growing demand. But with natural gas coming in just as cheap, and with the same level of GHG as Clean Coal, it's not at all clear that these investments are justified. But there's no reason I can think of that the same capture and storage technologies that were developed for coal, couldn't be used in natural gas plants to bring them down to zero carbon.
What about other energy sources?
- Pros and Cons of Wind Power
- Pros and Cons of Fusion Power
- Pros and Cons of Tar sands oil
- Pros and Cons of Solar Heating and Cooling
- Pros and Cons of Concentrating Solar Power
- Pros and Cons of Solar photovoltaics
- Pros and Cons of Natural Gas
- Pros and Cons of Fuel Cell Energy
- Pros and Cons of Biomass Energy
- Pros and Cons of Combined Heat and Power
- Pros and Cons of Clean Coal
- Pros and Cons of Algae Based Biofuel
- Pros and Cons of Liquid Flouride Thorium Power
- Pros and Cons of Tidal Power
- Pros and Cons of Nuclear Energy
[Image credit: Marc Wathieu: Flickr Creative Commons]
RP Siegel, PE, is the President of Rain Mountain LLC. He is also the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues of energy (including clean coal), food, and water. Now available on Kindle.
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