Thursday, April 10, 2014


Cow fart is essentially a lot of flammable gas (Methane and Hydrogen Sulphide to be precise) coming out of a small hole (The anus to be precise). Any engineer in his right mind will think of only one thing about such a situation. Yes, you are right – Blow torch. So the question is can one hook up some piping to the correct places to build oneself a Bovine Blow torch or a Bove-torch?
First thing is first. We cannot be rude to the cow and set it’s behind on fire. Apart from facing a lot of scorn from animal activist, there is a very high probability of being kicked in the face by a cow on fire.  The revenue generated by this youtube video might make this a good business model, but we will be kind and attach a pipe with a nozzle at the end of it.

 I’ll start with a simple assumption which is probably true (Being from India, unfortunately I have rich experience with being in close proximity to cows) - Cows fart all the time they are awake, continuously. According to this research 13 million cows in USA in 2001 produced 2 million metric tons of Methane which amounts to 160 kg per cow at an average which is 0.0105g/sec. The Enthapy of combustion of Methane is 0.891MJ/mole therefore 0.0105g of Methane produce 584.7J/sec (Watt).

This is only half the story we have some (8.6kg/year) Hydrogen sulphide too being produced which is combustible at 0.519MJ/mole. This is 0.00055g/sec of Hydrogen Sulphide which is 8.8 Watt of energy. OK so this half of the story is not that significant.

Let us assume we are using the blow torch to do some brazing with copper as filler. Assuming 50% efficiency of the torch, the energy required to melt 1g of copper is 509J, in other words - the bove-torch can melt 0.6g of copper every second. You need about 20g of copper to braze a 1 inch diameter pipe joint so you might take about 35-40 seconds to do one which is impressive but not quite blow torch.

Some simple research (read: google) shows that a blow torch must be at least 50,000Watts to cause an American to boast about it. If we hook up say (50000/590 ~= 85) cows to a single tube we might have a proper blow torch that will operate 12 hours a day! So if you have 80 or more cows then you can run a small scale metal blazing / fitting industry at zero operating costs.

More interestingly, these farts also have a LOT of ammonia in there, which is unfortunately not combustible. But if you remember your 10th grade chemistry lesson well and your mind function is evil by nature you will realise that ammonia will combust if you add platinum to the mix as this video will illustrate.

So if we have a platinum nozzle bove-torch (turbove-torch?) things can get really interesting. We have 54.3kg of ammonia per cow per year which boils down to 0.00344g/sec burning with 382.81kJ/mole which is an extra 77.5Watt per cow, that’s a full 15% extra!

May I remind you that you are also contributing to saving the world by doing this as Methane is 50 times more of a green house gas compared to Carbon dioxide.

1 comment: