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Does The Methane Recapture Rule Make Sense?

I don’t intend to make every blog post here in my about climate change, but it’s such an interesting subject that sends so many numbers flying around that’s it’s hard for a math, science, and energy nerd like me to ignore. With that in mind, here’s something I came up with on the Methane Recapture Rule that might be wrong or right. Feel free to let me know how you think I did.

Back on May 10th, John McCain made news when he unexpectedly joined two moderate Republicans and 48 Democrats to maintain a last minute Obama administration rule on Methane recapture. While some have speculated that the vote may have been driven by spite over Donald Trump’s handling of the firing of former FBI Director James Comey, McCain himself had this to say about why he voted the way he did:

Improving the control of methane emissions is an important public health and air quality issue, which is why some states are moving forward with their own regulations requiring greater investment in recapture technology. I join the call for strong action to reduce pollution from venting, flaring and leaks associated with oil and gas production operations on public and Indian land.[i]

In terms of what this rule expected to accomplish, per a 2016 statement released by the EPA[ii], “The final standards for new and modified sources are expected to reduce 510,000 short tons of methane in 2025, the equivalent of reducing 11 million metric tons of carbon dioxide. Natural gas that is recovered as a result of the rule can be used on site or sold. EPA estimates the final rule will yield climate benefits of $690 million in 2025, which will outweigh estimated costs of $530 million in 2025.” For those of you playing along in the numbers game at home, a short ton is 2000 pounds, while a metric ton is 1000 kilograms, or approximately 2204.62 pounds. I’m not exactly sure why the EPA felt the need to mix their units between English and SI, but whatever, we can deal with that in an endnote later.

Methane and CO2 are both greenhouse gases. Although the effects of Methane aren’t as long lasting as CO2, it is generally considered about 20 times as effective of a greenhouse gas in the short term. That’s probably how the EPA figures cutting 510,000 short tons of Methane releases is roughly the equivalent of cutting 11 million metric tons of CO2 releases, unit goofiness notwithstanding. Assuming all this Methane was simply burned and released as COwould mean the savings were closer to 1.27 metric tons worth of CO2 releases.[iii]

My question is do these numbers make sense in the first place. The EPA release says the 510,000 short tons represent a 40-45% reduction of Methane releases based on 2012 levels, which would indicate that the US released somewhere around 1.2 million short tons of Methane that year. My first thought is to convert short tons to a number I care about, Standard Cubic Feet (SCF). To do this, we can multiply the number of lb-mols of Methane (63.75 million per footnote iii) by one of my favorite oil-industry conversion numbers that everyone should know: 379.5 SCF/lb-mol. This gives a seemingly crazy 24.2 Billion SCF of Methane releases in 2012. That number seems a little less crazy when you see that the US produced 25.3 Trillion SCF of gas in 2012[iv], in fact, a leak rate of <0.1% seems almost admirable. Of course, this also seems like a shamelessly SWAG’ed result which simply assumes a leak rate of 0.1%, especially since quantifying actual Methane leak rates is a notoriously difficult proposition – Almost as difficult as it would be to come up with the data to support the assertion 40-45% of those leaks can be recovered at a cost of 530 million dollars.

So how about those cost figures? If you assume that both the $530 million cost and $690 million benefit values are correct, then the rule has a healthy environmental profit margin of 30%. Of course, if I understand correctly, the O&G industry is footing the bill, so the only real case to be made is that this rule makes more sense than simply applying a $530 million dollar tax and deploying the proceeds towards carbon capture and sequestration (CCS) efforts.

Let’s start with the value driver, that $690 million dollars in 2025. Divide that number by the aforementioned 11 million metric tons of CO2 and you get a cost of about $63 per metric ton of CO2. If this is really the cheapest cost of CCS foreseen in the year 2025, then perhaps the rule makes sense economically. However, cut this cost down to $48/metric ton or less and your value driver vanishes, and you would be just as well off spending the 530 million on the cheapest available CCS technology.

Trying to Google the actual cost of CCS appears to be a difficult exercise, one that I don’t wish upon other people. Different applications of the technology in different scenarios will give many different results. The best resource I could find appears to be the IPCC Special Report on Carbon dioxide Capture and Storage, but it would suggest that for $48/metric ton you might find better value in applying CCS to new power plants. In addition to the IPCC work, a recently published Wall Street Journal article on peak oil demand showed that many oil companies are building in a cost of $30-$40/metric ton of COinto their future business plans, well below both the breakeven point of $48 that makes the rule profitable.

As for that $530 million number on the other side of the equation…I’m not even going to try to understand where that came from. I would be more inclined to believe the actual costs of compliance with the new regulation to be more than advertised, not less, but that’s just me editorializing on how I view the salesmanship of this particular rule. If you take the cost as stated, the math doesn’t seem to quite line up.

There’s obviously a bit of politics in play here as well (duh). It’s easier to pass a regulation advertised as low hanging fruit in the fight against climate change than to pass an actual Carbon (or in this case, Methane) Tax. The proof here is that the former was actually possible and done, while the latter appears to have very little chance at coming to fruition in the current political climate. With this in mind, an effort to do “something”, even if it does not make the most sense, trumps the desire to do the most correct thing. Also, not to be a downer, but while this number seems large, the actual carbon-offset potential of this regulation is equal to cutting Natural gas burning by less than 1% of the 2012 US gas production rate (40-45% of 20 times 0.1% of the US’s domestic gas production in in 2012). On a global scale, half a billion dollars, regardless of how it is deployed, doesn’t do a whole lot in terms of CCS.

[i] https://www.mccain.senate.gov/public/index.cfm/2017/5/statement-by-senator-john-mccain-on-blm-methane-recapture-rule

[ii] https://www.epa.gov/newsreleases/epa-releases-first-ever-standards-cut-methane-emissions-oil-and-gas-sector

[iii] 510,000 short tons equals 10.2 billion pounds of Methane, or 63.75 million lb-mols of Methane (molecule weight=16). Given that every lb-mol of Methane would stoichiometrically create 1 lb-mol of CO2, burning this amount of Methane would create about 28.05 billion pounds of CO2 (molecular weight=44), which converts to 1.27 million metric tons.

[iv] https://www.eia.gov/dnav/ng/hist/n9050us2M.htm

 

How Big is the Atmosphere, and How Much CO2 Do We Really Put into It?

Although the focus of climate change debates has shifted to the ability of climate models to accurately predict the impacts of CO2 in the atmosphere, surprisingly few people really have a firm handle on the much simpler question posed above. People love to debate and back themselves up with all sorts of information provided to them from other sources, but few actually want to put in any effort to make the transition from “knowledgeable” to “knowing” on any part of the subject. To be honest, this included myself, as I had always accepted that climate scientists had a pretty good handle and that a simple question lie this doesn’t need my analysis. Then I realized that as a chemical engineer who works in the oil and gas industry, this was a problem that I could find a solution to with a combination of Excel and Google in about two minutes. Although this also shows that this question really doesn’t need me to look into it, I needed something to do and Math can be quite a soothing activity.

random photo.JPG

This two year old photo of me pretending to turn a valve doesn’t actually have anything to do with this post, but there is a lot of math coming up so I figured I should put in a picture to liven it up. Photo credit to David Parham.

As with any scientific problem, the standard way to solve a question like this is to disprove that the opposite (usually referred to as the “null hypothesis”) could realistically happen. In our case the null hypothesis is that humans do not emit enough CO2 to significantly alter the makeup of the Earth’s atmosphere. Given that the increase in CO2 content of the atmosphere has been pretty widely documented as increasing at a rate of around 1 part per million per year since 1950[i], this should be a pretty straightforward exercise. No p value hacking or significance bands creation will be required for this one.

Having spent the last decade in the oil business, I know that the worldwide consumption of oil is about 90 million barrels per day, which translates to about 3.8 billion gallons per day, or 1.4 trillion gallons per year. To conservatively estimate the amount of CO2 this amount translates to, I will use an intentionally low estimate for the density of this oil (A lower estimate for density will give a conservative lower estimate for Carbon content). My assumption will be that this is all light crude with an API of 40, which is oil industry jargon for saying that its specific gravity is 0.825, which means each gallon will weigh about 6.9 pounds[ii]. I will also purposely assume that the carbon content of this oil is very low, using the same 75% carbon content as pure Methane (typically referred to as natural gas). In reality, both numbers will be higher, but in order to disprove our null hypothesis the best path forward is typically to make only assumptions that are clearly favorable would help the null hypothesis. This way, when the null hypothesis is disproved, there is very little wiggle room for it to fight back.

From chemistry, we know that every gram of Carbon (molecular weight 12) will yield about 3.66 grams of Carbon Dioxide (molecular weight 44). This is due to the weight of the two additional oxygen atoms added to the Carbon atom each weighing 33% more than the Carbon atom itself. Putting all this information together, I gather that from oil alone, about 26,100,000,000,000  pounds (2.61 x 10^13 pounds) of CO2 are released each year. This does not account for the fact that oil only represents between a quarter and third of the entire worldwide energy picture, and that the two other most significant chunks, coal and natural gas, would likely add a similar amount of emissions to the total.

Now while that amount of CO2 sounds huge, so is the atmosphere. One way you can tell the atmosphere is so huge is that it exerts a pressure at sea level that amounts to about 14.7 pounds of force for every square inch of the earth, because a 1 square inch rectangular prism stretching from the sea level all the way to the edge of Earth’s atmosphere will contain approximately 14.7 pounds of air. You can use this same trick to show that every 2.31 feet of water depth adds 1 psi (lb/square inch) to the water pressure. 1 square inch is 1/144 square feet. Multiply this by 2.31 feet and the density of water (62.4 lb/cubic foot) and you get one pound. This is why atmospheric pressure gives us a great way to simply calculate the weight of the atmosphere. If we can calculate the surface area of the earth in square inches, we can multiply this atmospheric pressure of 14.7 pounds per square inch to estimate the weight of the atmosphere. I should note that when I say this is a “great” way to calculate Earth’s atmosphere, what I’m really saying is that it is easy. In engineering easiness is tantamount to greatness.

Google tells me that the Earth has a diameter of 7915.5 miles. Assuming Earth to be a smooth sphere, the surface area would be equal to 4 times Pi times the square of the Earth’s radius (Area = 4 x Pi x R2). Of course, we will need to cut the diameter in half to get the radius, then multiply the radius in miles by 63,360 to convert it to inches (there are 5280 feet in a mile, and 12 inches in a foot, the product of which is 63,360). All of this math tells us the surface area of the Earth is about 7.9 x 1017 square inches, meaning the weight of the atmosphere is 14.7 times this number, or 1.16 x 1019 pounds. Dividing our earlier CO2 amount generated by this number and multiplying by a million would give us the amount of increase in annual atmospheric CO2 concentration that could be caused if all of the oil we burned simply stayed in the atmosphere as CO2. This ends up being 2.2 parts per million (ppm) per year on a weight basis, or 1.5 ppm per year on a volume basis. Gas concentrations are generally reported on a volume basis, and since CO2 is heavier than air (Molecular Weight of 44 compared to 29 for air), we’ll use the smaller number.

So there you have it, our conservative estimate says that our burning of oil on its own could theoretically increase the CO2 concentration in the atmosphere by 1.5 ppm per year, and since oil only represents a fraction of the fossil fuels being burned, the actual amount is likely several times greater, much higher than the 1 ppm per year stated earlier. I suppose the next question is “where is all that CO2” going? Or perhaps the next question is whether the rate of increase in CO2 content in the atmosphere is accelerating consistently with the increasing rate of global energy consumption. The data is out there, all we need to do is look at it to go from “knowing what climate scientists say about climate change” to actually “knowing a little bit about climate change.” Then again, maybe we’ll just keep having snowball fights on the Senate floor[iii]. That does seem more fun.

Feel free to check my work and conclusions above. This post has not been subject to peer review, and I can’t guarantee I didn’t mess something up horribly. I was a bit surpised by the result myself, so I would appreciate the feedback if someone cares to tell me how I went wrong if I did.

I’m still not sure what I want to do with this site, but I do like to write occasionally. If anybody has any suggestions for Engineering, Science, or Math related topics for future posts please leave a message in the comments or email me at cory@veryprofessionalengineer.com

[i] http://climate.nasa.gov/climate_resources/24/

[ii] Water weighs about 8.34 pounds per gallon, so oil with a specific gravity of 0.825 will weight 8.34 x 0.825, or 6.9 pounds per gallon. API gravity is an archaic measurement of specific gravity widely used in the oil industry born out of a desire to have a measurement of density that increases as oil gets lighter, since lighter oil is generally more valuable. Specific Gravity is defined as 141.5/(API Gravity + 131.5).

[iii] I’m allowed to make a joke at Senator Inhofe’s expense, we went to the same university. However, I must note that the Senator went to the business school, and to my knowledge did not spend a lot of time in the engineering building.

 

Welcome to my new site

So far, I’m not exactly sure what I’m going to write here, but I’m sure I’ll think of something. I guess I can start with the origin of the very dumb name of this site. I was sitting with my 3 year old daughter watching Peppa Pig when I couldn’t stop noticing how much the shape of Peppa’s head matches a certain style of centrifugal pump drawing I have seen on Piping and Instrumentation Diagrams. Since I was not following the plot of the episode very closely, I whipped up the following diagram with the help of MS Paint:

peppa-pump

 

Not content to let such a remarkably idiotic and engineering-specific sight gag go to waste, I decided I must find an appropriate domain to host such things. VeryProfessionalEngineer.com fit the bill perfectly. Unfortunately, when I went back to find a more appropriate web address for more serious matters, I found that most were taken. So here we are. We’ll see where this goes.