Hot off the tail of my Mad Max – Beyond Thunderdome review, I have been giving the methane issue a lot of thought since the weekend.  As I have probably mentioned before, Methane (CH4) is a greenhouse gas with a global warming potential of 25.  That means that it is 25 times more potent than Carbon dioxide (CO2) and is a massive contributor to climate change.

Now, we humans use methane all the time, although it is not labelled as such.  Natural gas is mainly methane, and this fossil fuel is used in most capital cities in Australia and indeed throughout the world.  We cook with it, heat our homes, manufacture fabrics, glass, steel, plastics, paint, fertiliser, and other products out of it.  Methane is also off gassed from sewage, swamps, manure, compost, worm farms, rotting vegetable matter, and decomposing animals.  It is all around us naturally as well.

When burnt it converts to CO2, and water vapour therefore reducing its greenhouse potential and serving a useful purpose.  However, by extracting the fossil fuel type natural gas, we are adding million year old stored carbon into the atmosphere and upsetting the normal carbon cycle, not to mention that we are quickly running out of natural gas in some parts of the world.  Peak Natural gas, one might say.  Certainly North America is very close, and Europe (except Russia) peaked years ago.

What if there was a better and greener way of getting our energy needs, one that was available to most of us, right under our noses and did not upset the carbon cycle?  Well, I reckon that there is.  It is Natural Biogas, and it is very easy to make at home.  All you have to build is a Methane digester.  So what is a Methane digester?  A Methane digester is a device used to capture methane from an organic slurry that is processed anaerobically (without oxygen), and could be used for everything that we use natural gas for today.  Have a look at the picture below to see how it works. 

I certainly have plenty of chicken manure and vegetable matter around the place, in fact I have so much chook poo that I have no room left in the compost bins, and have had to bag it up for future use in the garden.  India, some African and South American nations are using this technology in a big way to make biogas for villages.  This reduces the villagers dependence on wood for cooking and heating, and therefore preventing deforestation.  Yet another win for the environment!

So, hypothetically speaking (you can see where this is going by now), if I were to build a Methane digester, and produce a decent supply of methane, what could I use it for?  I could, if I chose to build one, convert a petrol generator and make electricity to run my pool pump.  I could use it to cook on my BBQ and never have to buy Liquefied Petroleum Gas (LPG) ever again which would save me about $80 a year in LPG.  I could buy a compressor and store the methane into LPG bottles for future use.  If I was really good, I could buy an old LPG converted car and run it off of methane.  I could use it to heat our hot water when the sun is not shining.  The practical uses are endless.  Wherever you use natural gas and LPG today, you could substitute this all with natural biogas.

Check this guy out.  He made a simple digester out of two plastic barrels, for next to nothing.

The design could be as simple as this;

Or as complex as this;

Sounds like a very cool next project.  How good would it be to be independent of the natural gas grid.  Just think, no more gas bills!  Let me mull over it for a while and attempt to convince Kim that it is a good idea, and we will see what comes of it.  What do you think?

Who would like to come to my place for a biogas BBQ this summer?


  1. says

    Thanks for the response Gavin. My next question is how do you collect, store and then dispense the methane? We use methane (natural gas) for the burners on our stove. We use 5-gallon tanks which we need to take to be re-filled. Since we use it only for cooking, we probably only go through two tanks’ worth per year, if that. But those tanks are under a great deal of pressure, if I understand correctly, so that the gas flow readily through the pipes and to our burners. I don’t know how that might be replicated with this sort of digester system. And if it isn’t replicated, then how does the methane get used? If you know or could point me somewhere for more information, I’d be grateful.


  2. says

    @ Babs. Well that sounds like just the incentive to make one. If your Dad made one back in the 60’s, then I can make one in the 00’s!

    @ Aimee. Thanks for popping on over from the US. Love the goats you have at your farm. Hope the biodiesel plant gets off the ground.

    @ Kate. I have watched a few more video clips about methane digesters and some are made so that you collect the liquid. It is used as organic fertiliser. What a bonus!


  3. says

    Interesting – I wonder if you built a compressor, you could maybe hire it out to your community group? Not everyone would need one all the time, but I bet you could share it.

  4. says

    What a cool site! I wandered over here from Crunchy Chicken. I am a fellow “curd nerd” and if you’d like to see my efforts at cheesemaking (much smaller scale, just milk from my own 3 nanny goats) I’d love to have you visit my blog. My hubby is learning to make biodiesel from WVO, but so far all he’s managed to do is spend several hundred dollars at the hardware store. He’ll get there, tho, I’m sure.

  5. says

    Hiya Gav, when I was little I grew up on a smallholding (hobby farm) and my dad made a methane digester to deal with the pig muck – but I’m buggered for the life of me if I can remember how he made it ( I would only have been about 6 – which is more than 40 odd years ago !) But, I do know that to some degree it worked, so it isn’t impossible if any body thinks it is – tried an tested by Arthur Forrest in the 1960’s…

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