Our first step was to select a heat source as our main heating system. Our aim was to base the project on a sustainable system. Therefore, the possible options were to select either heat pumps or biomass boilers.
Biomass Energy This source of energy presents a huge potential in Scotland, as it is widely available. It is a renewable source of energy, and it can be a sustainable solution that can substitute fossil fuels in heat and electricity generation processes if managed correctly. However, there is controversy about its sustainability:
The forests have to be managed in such a way that at least the same amount of trees harvested is replanted to avoid deforestation.
There are significant direct and indirect greenhouse gas emissions due to harvesting, transport and storage.
Potential land displacement issues are to be considered.
Water Source Heat Pumps (WSHP) An open loop WSHP takes advantage of the relatively constant temperature of the water of the river as it passes through and exploits the low grade heat before the water is returned to the river with a temperature difference of 3-4°C. It was important to investigate the temperature of the water over a year in order to be sure that there is not risk of freezing the water which would affect the local environment and as a result the performance of the WSHP. As there are no available data for the specific location, the water temperature in nearby Loch Linhe was retrieved. The Team contacted the Scottish Environment Protection Agency (SEPA), which strives to ensure a clean and healthy environment in Scotland and their role is to protect and maintain Scotland's vital environmental resources for this data. Based on their information, the following graph was created, which indicates the average temperature of the water surface in the different months of a typical year.
Water Temperature in Loch Linhe
The next significant parameter which had to be investigated was the flow rate of the river Leven. The team collected data from SEPA over the last decade, which showed that the flow rate is significantly higher than the required part which had to be diverted through the WSHP.* This can be seen in Graph below:
*After having validated the heat demand of the community an analysis was performed in order to find the amount of water needed to operate the WSHP. This was calculated to be 70 l/s or 0.07 m3/s.
River Leven flow rate
Therefore, after having reassured all the previous aspects our Team decided to investigate the 4th Generation District Energy Network Development based on a water source heat pump (WSHP) due to the following reasons:
There are no local emissions.
It is a low carbon source of energy and zero-net carbon source in the case that the electricity consumed comes from Renewable Energy Systems.
It is efficient as 1 unit of electricity can provide 3 or more units of heat.
Exploits the almost constant temperature of the water of the river.
Can balance supply and demand - storage of hot water
Can provide refrigeration to facilities like offices, supermarkets or data centres, which can significantly reduce their electricity consumption if connected to the network.
