Did you know? Part 4.

In this mini-series of fun facts, we’ve looked at the fuel efficiencies of chickens, liposuction fat, and coffee beans. But what about cow farts and cow manure? I’m sure that topic’s been on everyone’s mind so let me address it. As everyone may or may not know, cows produce a lot of methane gas and many believe they’re a major contributor to global warming (especially since methane is a much stronger greenhouse gas than carbon dioxide). In fact, cow flatulence produces about 90 kilograms of methane per cow per year (source). Methane has an energy density of about 52.75 MJ per kg (source) so that’s 4,748 MJ of methane per cow per year or 13 MJ of methane per cow per day. One way to convert methane into diesel fuel is a process called Gas-to-Liquid (GTL). That process requires 10.5 GJ of natural gas (mostly methane) to produce 42 gallons (1 barrel) of fuel (source) – so 250 MJ of natural gas for 1 gallon of diesel. If a cow produces 13 MJ of methane per day and 250 MJ are required for 1 gallon of diesel, you can get 0.052 gallons of diesel per cow per day. Assuming a diesel engine has a fuel efficiency of 30 miles per gallon, you’d be able to drive 1.56 miles per day of cow farts. Stats on bovine flatulence frequency are hard to come by but this source would indicate that cows pass gas every 40-90 seconds. Assuming they do that 24 hours a day (btw, humans fart in their sleep so let’s assume cows do too), that would be about 1,329 farts/belches per day so you can drive only 0.0012 miles per cow fart. [As an aside, while the typical person farts about 14 times a day (source), human farts are much lower in methane content and therefore not nearly as useful for producing diesel fuel via GTL]

At this point, you’re probably asking yourself one of two questions: (a) “what about the methane in cow manure?” or (b) “why am I still reading this crap?” (no pun intended). I’ll assume you’re asking yourself the former question and do my best to answer. This press release says that a herd of 150,000 cattle generate a total 2,500 tons of manure a day. One (short ton) is 907.18474 kilograms so 2,500 tons would be 2,267,962 kilograms of manure for the entire herd – or 15.12 kilograms of manure per cow per day. From this page, we find out that cow dung gas is 55-65% methane. The source doesn’t specify but I’ll assume this is by weight and that all the dung can be converted to cow dung gas. So 15.12 kilograms of manure per cow per day would be about 9.1 kilograms of methane per cow per day. Following the same math as above, that would translate into 1.91 gallons of diesel per cow per day. At 30 miles per gallon, that’s a whopping 57.42 miles per day of cow manure. According to this site, cows poop 11 to 12 times each day. So we can get a very respectable 4.8 miles per cow dump.

With that, I think it’s likely time for a new hobby since I’ve probably taken this one as far as I can. =)

Did you know? Part 3.

I’m sure this post will provoke a couple of “don’t you have better things to do with your time” but, hey, we all need our hobbies and mine appears to be random biodiesel calculations at the moment. =) New fun fact regarding the fuel efficiency of coffee.

There was an announcement last week about a researcher in Brazil working on turning low quality coffee beans into biodiesel. In the press release, it says that “every 100 kilograms of coffee will produce roughly 9 kilograms of oil” and “a liter of biodiesel requires about 15% of a liter of ethanol”. So, what does that mean in terms of fuel efficiency of coffee bean biodiesel? Well, if you consult the always-handy Biodiesel Handbook and the always-handy Google, you find that the fatty acid profiles of coffee bean oil and cottonseed oil are pretty similar (source for coffee bean oil). Using Google again, we find that the density of cottonseed oil is 0.92 g/cm3 or 0.92 g/ml (source). So coffee bean oil has a density of about 7.67 lbs/gallon or 3.49 kg/gal. If 100 kilograms of coffee yields 9 kilograms of oil, that means 100 kilograms of coffee yields 2.58 gallons of coffee oil. And, if ethanol is 15% of the biodiesel by volume, you end up with 3.03 gallons of biodiesel from 100 kilograms of coffee. Now, from before, we know an average diesel engine gets about 30 miles to the gallon but biodiesel has about 10% worse fuel efficiency. So, 3.03 gallons of biodiesel takes you 81.9 miles (3.03 x 27). So, 100 kilograms of coffee gets you 81.9 miles and a diesel engine has a fuel efficiency of 0.82 miles per kilogram of coffee beans or 0.37 miles per pound of coffee beans (about 8x less than liposuction fat).

Now, if we take this one step further, 1 pound of coffee beans yields 10.8 pots of brewed coffee (source). So, another way to think about this is that a diesel engine has a fuel efficiency of 0.034 miles per pot of coffee.

Enjoy … and feel free to make fun of my hobby. =)

Praying in Color

It's been awhile since I've read something good on ExploreFaith.org. But this article caught my attention. Here's an excerpt from the beginning of the page:

How do you pray when words become barriers rather than possibilities? When thinking in sentences is too linear to express a rainbow of emotions.

The rest of the article was a bit of a disappointment but I suppose they didn't want to give up too much of the real meat since they want you to buy the book. Regardless, the doodling concept is an interesting one. It's also a good reminder that there are a lot of ways to commune with God beyond formal prayers.