Environmental analysis of the use of poultry manure as fuel for combustion on broiler farms: a case study.

Abstract

Fluidised Bed Combustion (FBC) technology is not new. It has been used in power plants for the last three decades and is considered very efficient for biomass combustion. The novelty of the FBC application in BHSL’s case consists of the combustion of poultry manure on farm with the same thermal efficiency (over 86%) as the combustion of biomass (e.g. wet wood chips). BHSL has successfully miniaturised the power plant design to produce up to 2 MWh heat in a unit which is small enough to locate on the site where the fuel is generated – ideal for agricultural and by product applications with high heat demands. BHSL’s FBC 500 boiler is capable of 500 kWh thermal output, which is sufficient to provide hot water at 850C required for distribution to poultry sheds for rearing broilers from day-old to fully grown. A case study was conducted in order to measure the efficiency of the BHSL energy system for broiler production and also to evaluate its environmental benefits. Environmental benefits were measured using Life Cycle Assessment (LCA), which compared the environmental impact of 3 scenarios: (1) where the poultry manure is used for land spreading as a fertiliser and the broiler houses are heated with LPG; (2) where the poultry manure is used for combustion in the FBC 500 to generate heat, most of which is used to heating the broiler houses; (3) where the poultry manure is used for the production of steam and electricity generation with the residual steam used for heating the poultry sheds (combined heat and power – CHP). The results of the analysis show that when poultry manure is used for combustion, a reduction up to 95% in LPG use, as well as reductions in eutrophication potential of 26-32% and acidification potential of 31-40% can be achieved. An improvement in birds’ welfare was also noticed as a result of the use of dry heat that can be supplied to the broiler houses by poultry manure conversion.