The manure from broiler production has a net calorific value similar to wood chip. At 30% moisture content the net calorific value (NCV) of broiler manure is 12,676 kJ/kg. This is the equivalent of 3,521 kWh / tonne or 10.9m BTU / short ton. By comparison, wood chip at 30% moisture content has a net calorific value of 13,720 kJ/kg (see below chart).
The following chart compares the net calorific value of manure and wood chip at different levels of moisture content. Figures are based on litter made up of virgin wood shavings and use calculations from the ‘Institute of Fuel Technology’.
The BHSL process for optimising ventilation rates in order to reduce the humidity within the house also reduces the amount of moisture within the litter. This results in less ammonia being produced through microbial action.
At the end of each flock, BHSL litter has around 30% moisture content. As illustrated above, the energy value is similar to wood chip, except that it also includes nutrients which are still available in the ash (less the Nitrogen) to be land applied as required.
This process for producing manure for use as a fuel is regulated within the EU and BHSL oversee the process to ensure continuing conformance to regulation.
So how much fuel does a Poultry farm create? This will vary depending on the age of the bird and the feed used but a good rules of thumb is that the manure will be approximately half the weight of the birds removed from the house. So if a farm clears a house of 2.4 kg birds then every 1,000 birds will leave behind 1.2 tonnes of manure.
“As a guide, the manure left behind will be around half the weight of the birds that were removed.”
Within temperate climates such as the UK, each bird typically creates enough manure to meet the minimum ventilation heating needs of 3 birds. There will be very cold periods within the year when supplemental heating will still be needed, but manure can be used to replace most of the fossil fuels used for heat on a site.
This means, and in warmer climates especially, that there is manure remaining after heating that can be put to use to generate electricity. BHSL will design a bio-secure storage and handling solution that uses all the manure created on the site.
Every site is different, so BHSL model the detailed energy demands and manure production for each site as part of the design process.