(photo credit: INGIMAGE)
While it is generally accepted that gas from cows is responsible for a quarter of global warming, manure from poultry can reduce that effect by providing biofuel to replace 10% of the coal used to produce electricity.
Treated excrement from turkeys, chickens and other poultry, when converted to combustible solid biomass fuel, could provide an alternative energy source, according to a study recently published by researchers at Ben-Gurion University of the Negev researchers in the journal Applied Energy.
While biomass accounts for 73% of renewable energy sources worldwide, crops grown for energy production place a burden on land, water and fertilizer resources. According to the Beersheba researchers, “Environmentally safe disposal of poultry excrement has become a significant problem. Converting poultry waste to solid fuel – a less resource-intensive, renewable energy source – is an environmentally superior alternative that also reduces reliance on fossil fuels.”
Researchers at BGU’s Zuckerberg Institute for Water Research evaluated two types of biofuel to find which is the more efficient poultry-waste solid fuel. They compared the production, combustion and gas emissions of biochar – which is produced by slow heating of the biomass at a temperature of 450 degrees Celsius in an oxygen-free furnace – with hydrochar, which is made by heating wet biomass to a temperature of up to 250 degrees Celsius under pressure using a process called hydrothermal carbonization (HTC). The HTC process mimics natural coal formation within several hours.
“We found that poultry waste processed as hydrochar produced 24% higher net energy generation,” said student researcher Vivian Mau and Prof. Amit Gross, chair of the BGU Department of Environmental Hydrology and Microbiology. “Hydrochar generates heat at high temperatures and combusts in a similar manner to coal, an important factor in replacing it as a renewable energy source.”
For the first time, researchers showed that higher HTC temperatures resulted in a significant reduction in emissions of methane and ammonia and an increase of carbon dioxide and carbon monoxide.
“This investigation helped in bridging the gap between hydrochar being considered as a potential energy source toward the development of an alternative renewable fuel,” Gross explained. “Our findings could help significantly reduce greenhouse gas emissions associated with electricity generation and agricultural wastes. Field-scale experiments with an HTC reactor should be conducted to confirm the assessments from this laboratory-scale study.”