This is the second entry in a series of six email exchanges between two climate-change experts on the future use of coal. The series was originally posted here.

Editorial note: Roberts argues that the key question is not “how can we best reduce carbon dioxide emissions?” Rather, we need to confront a more fundamental question of human needs vs. desires. If the earth is to sustain us all, prioritizing resources is vital. Rather than rely on coal (costly, less abundant than believed, and dirty to produce — even in so-called “clean” processes), Roberts advocates investing in more sustainable sources of energy.

Hi Sasha,

Thanks for your note. I apologize for the tardiness of my reply — I’m afraid my family and I were struck down by the dreaded H1N1 and I’ve been out of commission for the last several weeks. It’s only now that I’m beginning to feel moderately human again. I’ll be much quicker from now on!

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I agree with all your basic premises except one; it may seem like a philosophical point, but I think a great deal flows out of it, so perhaps it’s a good place to start. It has to do with how we view climate change. Your view — that it’s “mostly an energy problem” — is quite common, and suggests what I’d call engineering solutions: if CO2 from energy is the problem, figure out ways of tweaking the energy system so it emits less CO2. Done!

Another way of viewing climate change, however, is in the context of a whole suite of biophysical limitations against which humanity is colliding. A recent paper in Nature identifies 10 such systems and claims we’ve passed the danger threshold on three of them and are rapidly approaching it on several others. (I discuss this paper in greater depth here.)

Viewed in this light, climate change is less an energy problem than a symptom of a larger problem, which could be characterized (if it’s not too dramatic) as existential. The question before us is not simply how to make energy less CO2-intensive. It is, how many of us can Earth comfortably accommodate? How and where should we live? How can we change our manufacturing, transportation, energy, political, and cultural systems to bring ourselves into a sustainable relationship with the only planet we’ve got? Heady stuff, to be sure, but a more honest assessment of our situation.

Now, what’s all that got to do with “clean coal?” Just this: When we evaluate a possible solution to climate change, we should judge it not just narrowly on its ability to prevent CO2 emissions, but more broadly–does it constitute a step toward a more sustainable relationship between human beings and the planet? If a solution is simply a patch that papers over broader problems, well … we don’t have much time left for those.

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With all that throat-clearing out of the way, here are a few key points I’d begin with:

1. We do not have the oft-cited “250-year supply” of coal. Coal reserve estimates are notoriously sketchy, but several credible recent analyses have found that global coal supply will likely “peak” in the next 10-20 years — not long after a similar peak in oil supplies. That doesn’t mean that coal will “run out,” just that remaining reserves will become ever more distant, more difficult to mine, lower quality, and more expensive. For more, see here.

This puts the lie to the “abundant” claim often used in support of “clean coal.” Turns out coal is just another finite fossil fuel, and we’re heading toward depletion, within our children’s lifetimes. Creating a massive, sprawling, multi-trillion dollar carbon sequestration infrastructure to take advantage of those dwindling reserves strikes me as an inapt way to direct resources. We don’t have much cheap energy left at our disposal; we’d be better off directing it toward creating a truly sustainable post-fossil culture.

2. Coal is not cheap. Coal’s oft-cited cheapness is an illusion. It looks cheap because its market price does not reflect the full costs it imposes on society. A recent report from the National Research Council found that coal’s “hidden” costs — mainly in terms of public health — are actually larger than its market costs, on the order of $62 billion a year in the U.S. And the NRC’s assessment was quite limited. It did not account for mercury emissions, environmental remediation, opportunity costs in rail transport (our rail infrastructure is dominated by coal), and most importantly, climate change. Incorporating the full measure of coal’s “external” costs would probably double or triple NRC’s number.

A similar study a few years back found that coal imposes a whopping $248 billion a year in hidden costs on China:

These external costs are not reflected in coal’s market price, but they are paid nonetheless, in sickness, blight, and reduced economic productivity. We can’t make a rational decision among energy sources until we have a full and fair accounting of their total costs.

3. “Clean coal” is, in almost every respect, dirtier than dirty coal. “Clean coal” generally means capturing the CO2 released by coal combustion and burying it. That makes it clean in one respect: it emits less CO2. There’s a twist, though: the energy required to capture and bury the CO2 is a considerable “parasitic load.” The result is that “clean coal” power plants have to burn more coal to get the same amount of usable energy — some 10-25 percent more. That means more mining, transport, solid waste (toxic coal slurry), mercury contamination, particulate air pollution, smog … every dirty aspect of coal except CO2 will be exacerbated. To boot, we’ll run through our remaining coal reserves much faster. That might be a better deal for climate change, but it’s a far worse deal for the (generally poor and marginalized) communities ravaged by coal today, not to mention the mountains of Appalachia.

There’s more to say, but I’m probably well over my word limit already! To make a final point: no energy source is “necessary.” It’s not true that we “have to” make use of all the options. To the contrary, the size and urgency of the problem mean that smart prioritization is vital. Coal with sequestration may surprise us — I’m not opposed to research, and you never know what it will turn up — but from what we know now, it appears a wasteful, dirty, and expensive solution relative to its competitors. We’d be better off pursuing cheaper and more sustainable alternatives.