Clean(er) Coal

A single lump of coal, like the kind bad little kids might find in their stocking, is capable of producing 12,000 Btu or enough energy to power a 75-watt light bulb for 2 full days. Compared to oil, coal is easy to get out of the ground and dirt cheap, clocking in at 1/6 the cost of oil or natural gas per Btu.

So is coal the new lean, green fuel of the future? There are certainly some hoping and arguing that this is the case. With uncanny timing, considering the various discussions of capping or taxing C02 emissions, coal is being rebranded. “Clean coal” has been the buzzword on the lips of politicians and lay people alike, with the elusive promise that coal will be the low cost, low emissions fuel capable of maintaining our way of life. Heck, Senators John Kerry (D-MA) and Lindsey Graham (R-SC) even called for the U.S. to become the “Saudi Arabia of clean coal” in their recent New York Times op-ed.

While it sure would be convenient, there’s just one glaring problem with this solution: coal isn’t ever going to be clean. Sooty little chimney sweeps and blacken chutes aside, coal is one dirty little lump. It contains vast amounts of sulfur and nitrogen particulates (that cause acid rain), traces of mercury and other toxic heavy metals. Then of course there’s the unfortunate fact that coal is far and away the largest single source of greenhouse gas emissions in the United States today. And not only is coal bad for the environment, coal emissions have been determined to contribute to 10,000 premature deaths in the U.S. every year.

While we have come a long way in making coal cleaner since the early days of coal power, we’re a far cry from being anywhere near clean coal.

The crux of the clean coal pitch is carbon capture and sequestration (CCS) – essentially bottling and burying the C02 that is produced when coal is burned. While this sounds great in theory, in practice it’s pretty near impossible. Why? Because every pound of coal produces about 2.5 pounds of C02. If we flash back to high school chemistry, we’ll remember that when coal burns, oxygen in the air combines with carbon in the coal in what is called an exothermic, or heat-producing, reaction. So far so good for energy generation but with this added oxygen, the C02 now weighs more than the coal’s carbon “body”. This is where CCS is meant to step in to keep all that C02 out of the atmosphere. The process goes as follows: exhaust from the coal power plant is forced through a liquid solvent, which absorbs the C02. This liquid is later reheated to release the gas in another facility where the C02 is compressed to 100 times normal atmospheric pressure and is ready for storage.

But here’s where things really start going sideways. A typical 500-megawatt coal-fired power plant produces close to 10,000 tons of C02 a day. All together, U.S. coal power plants produce 1.5 billon tons a year. To capture all that, we would have to fill 30 million barrels with liquid C02 every single day. How are we supposed to transport and store all of that? To put this in perspective, it took about a century to build the infrastructure we use to store, transport and distribute petroleum. Serious plans to implement and finance such a vast infrastructure project have yet to be publicly proposed, let alone examined. According to the Congressional Research Service, “There are important unanswered questions about pipeline network requirements, economic regulation, utility cost recovery, regulatory classification of C02 itself, and pipeline safety.” Then there’s the increased energy CCS capable coal plants would require. Capturing and compressing C02 would increase the fuel needs of a coal-fired plant by 25-40%, which means more mountaintop mining, more fly ash, and more transportation fuel. And, of course, it’s a dangerous gamble whether the damn stuff will stay buried at the end of all this…

The frustrating part is that more practical, cost effective means of decreasing the carbon footprint of coal are out there. Though clean coal will likely remain a myth, significant and immediately viable steps could be taken right now to make it cleaner.

Blue Marble Energy offers several such solutions, though (and this is a very good thing) we are by no means the only ones. A BME AGATE plant co-located with a coal-fired power plant would provide several key steps towards cleaner coal. Like a pilot fish to a shark, this symbiotic relationship would offer the following perks: flue gas from the plant could be passed through the anaerobic digester, effectively scrubbing particulates like heavy metals, and sulfur; post-digester biomass materials like lignin and other non-digestible fibers could be fed into the plant along with coal; biogas from the digester could provide energy offset for the plant, while waste heat from the plant could be utilized to increase biochemical production.

With all the hope and drive for a more sustainable world it can be hard not to drink the Kool-Aid on things like clean coal. But the cold hard truth is there’s no easy fix to our fossil fuel addiction, and anyone who claims otherwise is trying to sell something. We have to be willing to put in the work, and take small steps towards our goals. After all, it’s only by putting one foot in front of the other that we can climb mountains.

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