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How to make methane compressor from bicycle pump? Answered

Methane (biogas) is a byproduct of a number of green alternatives such as a compost heap. This methane can be captured and processed usefully in small volumes. However it must be compressed to some level that will produce a controlled flow, let's say 14-20 pounds per square inch. In fact the methane could be captured and stored in a bicycle inner tube for later processing. Anybody got any thoughts on how a bicycle or small aquarium pump could be modified to compress small quantities of methane?



Best Answer 8 years ago

This link specifically deals with reclaiming CO2 while fermenting beer to use in force carbonating the final product in the keg, but the same method could be used to pressurize methane. 


You are exactly correct, this is precisely the solution I was looking for. Thank you for taking the time to respond and point this out for me.

Why not use the bricking method? Store the methane in innertubes. When you need pressure to make the gas flow, place weight on top of the innertubes, which will force the gas out to a burner or engine. The more weight, the greater the pressure.

The simple, low-tech method I saw had the innertubes on a verticals pole. No weight was added when filling. Then, when he wanted to run his generator, he put weights on top to force the gas into the engine.

Just one option.

The bicycle inner tube is too small, methane doesn't compress well and is better stored at low pressure in large tanks. What is your source of methane ? Diaphragm pumps can work well, but not the aquarium kind. L

A few liters captured from a compost heap, septic tank or MFC array. Ideally the methane could be captured, fully combusted with the exhaust bubbled through an algae tank for a complete backyard CO2 scrub.

Yeah, those are the cornerstone technology. Of course an MFC is just an anaerobic digester with some carbon electrodes. So algae could be flocculated out, fed into the anaerobic digester, tapped for a tiny bit of power, decomposed to methane and captured. If it is then compressed it can be used to heat water for steam with the exhaust captured and routed back through the algae tanks for CO2 scrub before being released.

I am working on a startup that is engaged in very similar recombinations of these technologies.. Photobioreactor, A.D. We are also working on how to safely compress methane at fairly low Psi (not liquefaction). One problem we are running into is the presence of O2 evolved by algae. This gas if mixed with methane and then compressed could be really messy. Although we think we have figured a way to get rid of the O2.

First of all, one must have a completely sealed vacuum system. The inner tube must be new and have no other gas or air in it "new" When collecting the gas all other gases and elements must be exhausted. After collecting it one could use a diaphragm pump "Vacuum Pump" to compress it in a vacuum tight container or tank. Working with methane is like working with freaon. One needs to remove all air from a tank and replace it with methane and use a high cfm vacuum pump to compress it. If the pump is hooked to a ready supply of methane and it pumps the gas from the producing tank to the holding tank it can be set to hold a certain pressure like 20psi at all times. This will help in the process of burning like a propane tank will. Propane pressures off its boiling point temp. Methane needs the pump to make the same pressures.