Diagram: Green Farm Energy, energy from manure process
Approximately 12000 Danish farmers produce 24 millions pigs per year, of which 85% are exported. Dealing with the waste is a big part of farm management.
Manure can be gasified under anaerobic conditions and the biogas can be converted into heat and power in combustion plants or engines. Pig farmers in Denmark can choose to utilize pig manure at “farm scale plants” (where pig farmers have their own production units) and “joint biogas plants” (where several farmers share one large production unit).
The main production processes are following:
(1) pig manure is transported from the pig stable to a pre-storage tank
(2) the manure is heated to about 37ºC and transferred to an anaerobic reactor where it is mixed with organic matter from e.g. slaughter houses and fish industry
(3) biogas produced in the reactor from gasification of manure and organic matter from industry is transferred to a gas storage tank
(4) biogas is transferred to a stationary engine or a gas combustion unit which is producing heat and electricity or just heat
(5) degassed manure and organic matter from industry is transferred to a manure storage tank and distributed on agricultural fields as fertilizer
(6) electricity and heat is used locally and/or transferred to the national electric grid respectively the local district heating system.
Average manure transportation distances in step 1 and 4 range between 1.5 km and 7.5 km (Seadi, 2000) at joint scale plants. At farm scale plants, transportation of pig manure is small. About 80% of manure gasified in Denmark is gasified in joint scale units and about 20% is gasified in farm scale units (Biogasbranchen, 2004).
Biogas is to a large extent combusted in stationary engines at both farm and joint scale plants. However, gas furnaces are also used occasionally e.g. in cases of excess gas production and in cases of extraordinary heat demand (personal communication with various actors in business). All electricity produced at both farm scale and joint scale plants is utilized and most of heat produced at joint scale plants is utilized.
More general info on Danish pig farming
If you are interested in the possibility of installing such a system Green Farm Energy, in Denmark are a company at the forefront of this technology.
June 20, 2008 at 11:05 am |
Excellent idea. Yorkshire County Councils take note. Maybe the NFU. It seems crazy to me that such ‘natural gold’ should not be utilised.
When I was a child 50+ years ago! our sewage works all had vehicles running on the biogas they generated. We have the technology why don’t we use it ? If you go to my site http://www.PowertuneEnergySaver.com you will see another piece of known technology which could do so much to help mitigate this energy crisis.
Ecoanne
June 20, 2008 at 12:55 pm |
Thanks Anne, I’ll have a look.
There are so many solutions out there that have actually been around for years. It’s only when oil goes skyhigh that anyone pays attention. There’s so much invested into the oil infrastructure and industry as a whole that these energy companies simply don’t want to let go of their precious ‘black gold’. As you say, there’s so much waste material out there ready for recycling via the energy loop, utilizing heat and power as we go!
June 21, 2008 at 8:49 am |
Can you imagine if all pig farmers adopted this technology? What are they waiting for?
Just keep the oil giants out of it, they’ll be wanting to sabotage it.
June 24, 2008 at 7:26 pm |
Hi earthpal,
Well, in the US we don’t do things like that because the profit margins on our farms are far too small to allow that large an investment in something that’s not going to pay for itself for decades. The Danes, I suspect, can only do it because of Government subsidies. Our Government, at the moment, is far too interested in ethanol production to bother with harnessing the power of pig poop. On the other hand, I saw a news bit today on a new genetically engineered bacteria that can convert said poop into crude oil. Since we already have the infrastructure to handle oil, that could be a big seller.
the Grit