The Carrowreagh Farm Anaerobic Digestion plant, located just outside Belfast on a large dairy farm, supplies biogas to a combined heat and power plant.
The plant must utilise a substantial proportion of the heat produced from the CHP plant. In order to optimise the heat consumption we were commissioned to calculate the likely heat consumption by a variety of local loads, including several domestic dwellings, large polytunnels for growing chives and commercial buildings. Having established the loads we designed a two leg district heating system incorporating a leg for the polytunnels and a leg for the remaining loads. The entire system is controlled on a demand basis with temperature calls from the polytunnels and time and temperature calls from the other loads.
The polytunnel leg incorporates remote thermal storage in the form of a second hand milk tanker to enable energy storage in the event of plant downtime and the ability to mix the temperature down to local distribution temperature requirements.
The first phase of the installation is complete, successfully supplying heat to the first polytunnel, maintaining ambient temperatures for growing chives all year round.