Is Fracking worse than Coal? Selected comments from the SDMB.

A partial answer. The US may be on the cusp of an oil boom.

From SDMB.

I have to take issue with Cecil Adams' latest article regarding fracking. In it, he says that fracking and natural gas use are bad, but not as bad as other options like coal. This is flatly untrue. According to a recent Cornell study, up to 8% of the natural gas released by fracking escapes unburnt into the atmosphere, and since natural gas as a greenhouse gas is much more potent than CO2, the resulting emissions make natural gas extraction three times worse for the environment than coal. This isn't to say we should be burning coal instead, but that we should reject false solutions that lock us in to a fossil fuel future. With Vermont Gas Systems trying to ram a gas pipeline extension down the throats of the Vermont public as I write, it's important that we keep scrupulously to the facts on this subject.



Martin Hyde

Fracking actually has very little to do with it in a strict sense, and it annoys me people so often confuse this issue.

In ages past people would drill for oil and gas, often times you'd find both from the same drilling effort or you'd find predominantly gas but not much oil. "Conventional" natural gas (in terms of "conventionally drilled") is found primarily in gas reservoirs that are created over millions of years as natural gas is produced in some organic-rich formation and then migrates into permeable reservoir rock where it is then trapped by an overlying layer of impermeable rock.

This helpful wikipedia diagram shows some different types of gas. You'll note what I just described most closely resembles "conventional non-associated gas" and "conventional associated gas." The broad strip of gray represents impermeable rock that has trapped the gas under the ground. Drilling straight down into these reservoirs punctures that impermeable rock, releasing the natural gas up through the hole you had just drilled and ideally it is then captured and becomes part of the natural gas supply system (where it may be put into storage, transported far away on a pipeline, transported by truck etc etc.)

Note the difference between associated/non-associated conventional gas is whether or not the gas is associated with a petroleum deposit. In that diagram if you drilled down into the underground source of oil you'd have a functioning oil well that would also produce natural gas. Much early natural gas production was incidental to oil production and would be saved off for its own uses--but many times in the past and even sometimes today natural gas was seen as so much less valuable than oil that it would just be flared off as a waste/unwanted byproduct of the oil drilling.

So in that diagram you should also see a broad dark/black strip deeper down, under the first layer of sandstone. That represents a layer of shale that is rich in natural gas. Natural gas has, over millions of years, sort of been trapped/absorbed into the shale. Unlike a traditional natural gas reservoir, just drilling into a shale formation doesn't do a lot for you, you'd get some slow gas migrating up but nothing like in a traditional well. Instead, shale must be fractured in order for shale gas to be economically extracted. For many years, naturally occurring fractures were found and gas was profitably extracted from those. In more recent years, the technique of hydraulic fracturing was developed. A process where water is forced into shale deposits under high pressure to forcibly fracture the shale, which then releases the natural gas stored in the shale formation.

Commonly, because of the layout of shale deposits it makes sense to combine this with "horizontal drilling" in the shale layer--and thus you have the two components key to the modern shale gas boom, horizontal drilling and hydraulic fracturing (fracking.)

So what must be understood is fracking is just a process for fracturing shale. Fracking in and of itself cannot be "worse than coal" because fracking is not an energy source, it isn't burned for energy, it's a process not a thing. That leaves us with a few more "appropriate" questions we can ask:

1. Is shale gas worse for the environment than coal. The majority opinion appears to be no. The Cornell study you mention is well known, but so are many peer reviewed assessments of it that have found it flawed. The EPA and the IPCC both have a more favorable view of natural gas in general than the Cornell study along with several other major universities refuting different aspects of the study (the wikipedia article on shale gas contains many links to the articles that refute the Cornell study.)

2. Is shale gas any different than conventional natural gas? The answer to this is "often times yes." There is no standard composition of natural gas, every well is slightly different. Where it's important enough to matter, natural gas transportation/distribution companies actually install gas chromatographs on their pipe to measure the composition of their gas. A given Mcf (1,000 cubic feet) is commonly said to contain 1 dekatherm of energy. This is rough "envelope" number based on historical averages. The amount of energy in a given Mcf of gas is basically based on the composition of that gas. In reality an Mcf could have 0.95 Dth or 1.05 Dth or etc. This article gives some more detail about variation in the composition of gas, specific to shale gas.

But in general, shale gas is said to contain more methane per Mcf on average than conventional gas. Methane is a greenhouse gas, a shale gas leak will introduce more methane into the atmosphere than a conventional gas leak (on average.)

3. Is burning shale gas worse than coal or conventional gas? I don''t believe there is much argument it is much better than burning coal. Is it better than burning conventional natural gas? My understanding is one Mcf burned of shale gas (on average) will produce more greenhouse emissions than a comparable Mcf of natural gas, but it is exactly proportional to the greater energy produced by the Mcf of shale gas. So while shale gas may be worse per Mcf, I think per Dth (which is what really matters), they aren't meaningfully different. [I admit to going off of supposition on this point.]

4. Is natural gas worse than coal for the environment, in total? More important than the burn question is the total production/use of gas versus the total production/use of coal. It's absolutely correct that if gas, which is much cleaner burning, produced a huge amount of greenhouse emissions versus coal in its production/transportation that natural gas could be worse for the environment than coal.

The first part of the answer is to point out that whether or not natural gas is extracted by conventional drilling or fracking probably isn't a significant part of the answer to this question. Other than the fact shale gas on average is slightly more rich than regular natural gas (and thus has more methane), from a pollution perspective drilling for natural gas in conventional versus shale plays is not all that relevant to the global warming debate. There is a whole other debate about water usage and affect on local water tables, potential to cause local earthquakes etc that I will not get into here, but those issues do not effect the climate change picture (just like the fact that coal mining and coal plants cause large increases in health risks to local communities isn't part of its climate change problem but yet another reason coal is very bad.)

The real danger then from natural gas is leakage. Leakage meaning gas that leaks out at the well, uncaptured, or gas that leaks out of the pipeline etc. Leakage directly releases methane into the atmosphere. The thrust of the Cornell study is this leakage releases so much methane that it makes natural gas a bigger climate change risk than coal. Professor Ingraffea noted an industry average leak rate of 5% in an Op-Ed that he released for the NY Times and bases much of his argument that natural gas production is worse in terms of climate change than coal on that number.

However multiple rebuttals have basically said that:

1. In practice the leakage rate is actually much lower. The EPA's most recent Greenhouse Gas Inventory suggests a methane leakage rate of 1.4%, lowered from 2.3%.

2. As Richard A. Muller (a physics professor at UC-Berkeley) and Raymond Pierrehumbert (climate scientist at University of Chicago) point out, because natural gas produciton/use generates far less carbon even a 10% leakage rate would be worth trading from coal to natural gas. Their argument is based on the fact that the effects of methane are understood to be 100% reversible, that methane is more potent but leaves the atmosphere much quicker than carbon, in roughly 20 years any impact of a specific methane leak released into the atmosphere is completely reversed. Carbon on the other hand stays in the atmosphere essentially forever in human terms. For this reason even if there is twice as much leakage as Dr. Ingraffea of Cornell suggested in his op-ed, it might still make sense to switch from coal to natural gas.

So my ultimate answer is that utilizing natural gas instead of coal, while there are serious concerns, is ultimately much better for the climate picture. I base this solely on the fact a large number of scientists say this, I have no preconceptions on the subject being a layman. A large number of these same scientists have specifically refuted Dr. Ingraffea's study, which suggests it has not well withstood the peer review process.

There are important considerations with natural gas. Just like there are many very bad things coal production and burning do aside from any impact on climate change, natural gas has non-climate related impacts that must be considered. The issue of earthquakes needs to be studied. The issue of all those trucks/drilling equipment ripping up the landscape must be considered. The massive use of water (a scarce resource) must be considered. The fact that there is little Federal regulation of what chemicals go into water used in fracking (it's a state-by-state patchwork of regulations now) must be considered. The impact on drinking water must be considered. There is also a problem with lack of information. The EPA and other bodies exercise what I would consider to be "too little" oversight of the natural gas industry so it puts a level of unreliability into any statistic we come up with about what sort of chemicals the industry uses, how often they have leaks/spills etc--and that is something it would be nice to see addressed.

Last edited by Martin Hyde; 10-31-2013 at 09:39 AM.

Another comment from Martin:

There was a New York Times article maybe 2-3 years ago where a scientist wrote at length about how yes, drilling contaminates water fairly regularly if there are spills/leaks at the well head, but how they had never really seen much evidence that the fractured shale and all the chemical infused water down in that shale seam has ever seeped into an aquifer. I think typically the shale bed is quite deep, and typically under a layer of impermeable rock, so the fracking-chemical polluted water would have a good distance to travel through some rock that doesn't readily allow water to seep through it.

I'll see if I can find the article, but searching on NYT.com hasn't yielded it yet, it also linked to some more professional-quality research articles which is why I remember it being particularly useful. 

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tracer Charter Member

Quote: Originally Posted by Chronos If you're comparing fracking to conventional natural gas production, you also have to ask which process results in more leaks. Based on the stories of people lighting their kitchen faucets, I'd have to guess that fracking is leakier, but I don't know the numbers. You DO realize that, in that famous internet video of Mike Markham lighting his tap water on fire, it was later confirmed that the methane in his water supply came from a close-to-the-surface natural gas pocket that happened to be next to his water well, and had nothing to do with fracking, right? (Colorado Oil and Gas Conservation Commission report: http://www.anga.us/media/content/F7C...%205-23-08.pdf )

See also: Is Fracking Safe? The Top 10 Controversial Claims About Natural Gas Drilling.