Great Ynys Farm, a 90,000-head broiler farm in the UK will use anaerobic digestion to convert chicken litter into biogas for renewable energy and heat generation.
The electricity generated will power the poultry houses and the AD system, with a 90% surplus sold to the power company National Grid. The captured waste heat will provide warmth for the chicken houses, displacing fuel oil and propane gas. Generation is scheduled to start on August 1.
The AD system will have the capacity to process 700 metric tons of poultry litter and 1,000 metric tons of cattle slurry, mixed with 3,000 metric tons of maize silage per annum. Use of maize reduces the nitrogen levels in the digestion process and prevents the buildup of high concentrations of ammonia that would arrest biogas production.
Plans are in place to convert the heating system in the farm’s broiler houses within the next few months, to utilize heat from the biogas generation process. This is expected to achieve payback on investment within one year, according to the farm.
The digestion process also produces a residue of 5,000 cubic meters of odorless organic liquid fertilizer that will be injected into the soil to provide an enhanced nutrient source for the maize crop. The farm currently uses its poultry litter as a fertilizer, but by digesting it methane losses to the environment during spreading will be eliminated. A new poultry litter store has been created to protect the AD feedstock from the elements and to prevent the risk of nitrate run-off.