Is burning your manure better than spreading it or investing in anaerobic digestion?
The technology suitable for any livestock operation now exists to combust manure in order to generate power.
A company called EcoCombustion Energy Systems says it has solved two problems that have hindered previous efforts to burn manure — handling the high percentage of non-combustible material mixed in with the manure and meeting government regulations for air emissions.
Adapted from the pulp and paper industry, “Elimanure” incineration technology is the brainchild of company co-founder, Paul Schneider. After the successful testing of a 600-kilowatt prototype installed on a Wisconsin dairy farm in 2005, the technology is now commercially available.
The problem for large farms isn’t the fibre in the manure, but the nutrient-rich liquid, said Schneider, who was raised on a farm but worked in the pulp and paper industry.
“If you stretch your imagination, what we do in the paper industry is very similar to problems that you have with manure,” says Schneider. “In the paper industry, we separate the fibre from the liquid and then we need to manage the liquid as well. My concept is to evaporate the moisture in the manure, burn it and then create energy.”
High ash content
Finding a combustor manufacturer willing to work with the company was a challenge because of issues associated with the manure’s ash content. Burning sawdust produces about two per cent ash while manure produces about 15 per cent.
“We got a grant to study how to burn the manure at high temperatures,” says Schneider. “So we designed a combustor and we have the expertise for operating the combustor to burn that high ash content. Once we learned that and were able to prove it, then the combustor manufacturers had confidence to work with us.”
Farms will need to dispose of the ash, but it is considered a soil amendment and can be land applied. It is a lot less expensive to transport ash. It has a 0-8-10 chemical composition, so farmers will still be limited in how much can be applied in many areas because of its phosphorus content. Where it shines is as a seed starter soil amendment.
The system initially had issues with controlling air emissions, but the installation of pollution-control equipment has resolved the problem, says Schneider.
The owners of the Wisconsin farm are doubling the size of their operation and are expanding the Elimanure system to support the expansion, which will also double electrical output to about 1.2 megawatts. As the heat generated from combustion is used to evaporate moisture from the manure, the dairy can now dispose of 45 million gallons of manure annually either by incineration or recycling into bedding.
Along with power generation, the system reduces greenhouse gas emissions from methane, simplifies manure handling, and produces cow bedding material, says Schneider.
Schneider says he’s not in competition with anaerobic digestion, and says the latter is a better alternative when farm operations are producing very wet manure.
“We work best in systems where the manure is somewhat thicker and drier,” says Schneider, adding his system gives livestock producers a choice and can help them overcome some spreading issues.
However, he says the company must overcome skepticism about biofuel alternatives fuelled by manure
“Because of some of the problems that have been experienced from anaerobic digesters, farmers are very nervous about new processes,” says Schneider. “Farmers would like to see it work first.”