On Thursday the 23rd of November the BioPAD team carried out a case study visit to the Agri-Food and Biosciences Institute (AFBI) in Hillsborough, CountyDown. Here they were taken on a tour of the Environment and Renewable Energy Centre and the Anaerobic Digestion plant.
The Environment and Renewable Energy Centre (EREC) was officially opened in January 2009 and assists the agri-food industry to maximise the potential of renewable energy and support technology transfer activities. The EREC delivers heat and electricity to the site from biomass and solar sources. The main sources of biomass are short rotation coppice willow, forest residues and miscanthus which are converted to heat in dedicated biomass heat systems. The anaerobic digestion of manures produces biogas which is converted to electricity and heat by a small combined heat and power plant (CHP). A total of 40kW electricity can be generated for the site by the CHP and solar PV panels and over 500 kW of heat can be generated from the EREC which is delivered around the site through a district heating system. Hot water is also supplied to the dairy parlour by dedicated thermal solar panels.
Following intensive monitoring of this AD Plant over the first 27months of operation with dairy cow slurry as the input, AFBI has observed that, on average:-
- 1 tonne of dairy cow slurry at 69g/kg dry matter produced 15.2 cubic meters of biogas containing 85 kWh of energy 1 tonne of organic matter in slurry produced 280 cubic meters of biogas (0.28 m3/kg organic matter)
- 32 kWh energy (as heat) per tonne of input slurry was required to maintain mean digester temperature at 37.10C (39% of gross energy produced)
- The available nitrogen concentration in digestate was 19% greater than in raw slurry
- Digestate did not require mixing before land spreading and did not crust
- The dry matter concentration of digestate was 20% lower than the raw slurry
- The COD of digestate was 28% less than that of raw slurry
- Digester operation required an average of approximately 1.3 person hours per day