family size biodigester
Posted: Mon Sep 16, 2013 8:08 am
Trying to be a little self sufficient in the kitchen usually means cooking home grown food on a wood stove. We did this for a while but I found some downsides tot cooking on a wood stove, it takes more time to cook on a wood stove, the kitchen heats up beyond a comfortable temperature in the warmer seasons and in those seasons a lot of fuel is “wasted” on cooking.
So I decided it was time to solve this problem, I found another fuel to cook on which I can make myself form garden and kitchen scraps, the extra benefit would be a first class fertilizer as a by-product of the biogas process. I wanted a digester that would make the most out of the organic matter which I fed it, I wanted it to be made out of recycled parts as much as possible and I wanted it to be a closed system (no nasty smells and dangerous H2S venting out)
I did some research and found that it takes between a hundred and 2 hundred litres of gas to cook a meal. So I built very simple biodigester which could provide that gas daily. Using kitchen scraps the biodigester makes about 150 litres per kilo.
If the temperature is around 35 to 40 degrees C it takes about 30 days to convert organic matter in to gas. This time can be shortened by a higher temperature or by preparing the digester feed.
To be sure the organic matter would be fully converted I chose to design a biodigester which can hold the organic matter for 70 days at 33C. This way the full “gas potential” of the organic matter is converted making it more efficient and providing an even better fertilizer for my veggie patch.
The produced gas is stored in 2 “floating barrels” that are weighed down with some bricks. This makes an excellent low pressure gas storage and can be made using recycled parts.
The digester before it got wrapped in insulation.
After wrapping and making a little control panel.
The double floating barrel gas storage.
So I started the digester up with some active slurry from a commercial digester and gently started feeding is my kitchen waste. After two weeks of acclimatising the bacteria to their new feed and temperature I started to gently increase production.
So now we made enough gas to cook on but we didn’t have a stove. Biogas doesn’t burn that well in a normal stove, the energy content is less then natural gas (which has around 90% methane vs the 65% in my biogas) and there isn't a lot less pressure on the biogas system. So I bought a little 2 burner camping stove and pulled it apart looking for a way to adjust it to the new fuel. I soon found the “injectors” and drilled them out to 2,5mm (they were 0.62mm). The bigger holes make for an easier flow through the system, which in turn causes more gas to flow to the burner, altering the fuel/air ratio. Much to my own surprise this was all I had to do to the stove to make it work well on biogas.
The biogas burns in a clear blue flame, invisible in daylight and without any smells.
I have been cooking on biogas for over a month now and i like it better then cooking on a wood stove. The total investment in the system was 50 euros. A lot cheaper then a woodstove with chimney. It doesn't produce any smoke and works just as well as a natural gas stove.
I think biogas is a good cooking fuel for those who want to save their wood to heat the house or people who don't have a woodstove in the kitchen and don't want to pay thousands of euros to get one and put a chimney in.
Spend 50 bucks once and make the cleanest biofuel at home for free and get the best biological liquid fertizer with it.
I thought this would be something you'd like :)
So I decided it was time to solve this problem, I found another fuel to cook on which I can make myself form garden and kitchen scraps, the extra benefit would be a first class fertilizer as a by-product of the biogas process. I wanted a digester that would make the most out of the organic matter which I fed it, I wanted it to be made out of recycled parts as much as possible and I wanted it to be a closed system (no nasty smells and dangerous H2S venting out)
I did some research and found that it takes between a hundred and 2 hundred litres of gas to cook a meal. So I built very simple biodigester which could provide that gas daily. Using kitchen scraps the biodigester makes about 150 litres per kilo.
If the temperature is around 35 to 40 degrees C it takes about 30 days to convert organic matter in to gas. This time can be shortened by a higher temperature or by preparing the digester feed.
To be sure the organic matter would be fully converted I chose to design a biodigester which can hold the organic matter for 70 days at 33C. This way the full “gas potential” of the organic matter is converted making it more efficient and providing an even better fertilizer for my veggie patch.
The produced gas is stored in 2 “floating barrels” that are weighed down with some bricks. This makes an excellent low pressure gas storage and can be made using recycled parts.
The digester before it got wrapped in insulation.
After wrapping and making a little control panel.
The double floating barrel gas storage.
So I started the digester up with some active slurry from a commercial digester and gently started feeding is my kitchen waste. After two weeks of acclimatising the bacteria to their new feed and temperature I started to gently increase production.
So now we made enough gas to cook on but we didn’t have a stove. Biogas doesn’t burn that well in a normal stove, the energy content is less then natural gas (which has around 90% methane vs the 65% in my biogas) and there isn't a lot less pressure on the biogas system. So I bought a little 2 burner camping stove and pulled it apart looking for a way to adjust it to the new fuel. I soon found the “injectors” and drilled them out to 2,5mm (they were 0.62mm). The bigger holes make for an easier flow through the system, which in turn causes more gas to flow to the burner, altering the fuel/air ratio. Much to my own surprise this was all I had to do to the stove to make it work well on biogas.
The biogas burns in a clear blue flame, invisible in daylight and without any smells.
I have been cooking on biogas for over a month now and i like it better then cooking on a wood stove. The total investment in the system was 50 euros. A lot cheaper then a woodstove with chimney. It doesn't produce any smoke and works just as well as a natural gas stove.
I think biogas is a good cooking fuel for those who want to save their wood to heat the house or people who don't have a woodstove in the kitchen and don't want to pay thousands of euros to get one and put a chimney in.
Spend 50 bucks once and make the cleanest biofuel at home for free and get the best biological liquid fertizer with it.
I thought this would be something you'd like :)