HOMER supplying heating demand with ASHP
Electrical and Demand
The Air Source Heat Pump (ASHP) uses electricity to produce heat at a Coefficient of Performance (COP) which equals the heating produced by every unit of electricity used. This effectively converts the heating demand into an electrical demand.
COP varies between different ASHP’s and also change depending on the outside air temperature. The heat pump chosen for the design is the Danfoss Heat Pump DHP-AL Opti6. This model has been chosen for several reasons: it comfortably meets the heating demand for the homes; it is manufactured in the uk, so lowers life cycle costs; it can provide space heating and hot water; the unit is outside to reduce noise; it can be adapted by the occupants to include other features; it has a good COP.
The average COP for the DHP-AL Opti6 is 3.26. The heating demand is divided by the COP and added to the electrical demand to provide the energy demands for energy simulation within homer.
Simulation
There were three remaining suitable renewable energy generation methods: Photovoltaic (PV’s), Solar Thermal technology and wind turbines. Solar Thermal was ruled out as an energy provider because it only provides heating which is already provided by the ASHP.
So Homer was used to determine whether, the best source of electrical supply was from PV’s, wind turbines or a mix of both.
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Figure # above is a capture of the results of the HOMER analysis. The results show that the most economical way of supplying electricity is with the use of Wind Turbines.
Figure #
Figure # above shows the electricity provided over the year by the wind turbines and by the grid. Because the grid is used as an electrical storage, it requires that the electricity received from the grid is less than the electricity exported to the grid. Figure # shows that this is indeed the case, and that 5 Gaia 177 wind turbines is sufficient to supply all power demands.
However, the difference between the import and export electrical figures is small. To ensure that community is always carbon neutral, even if demand was to rise slightly or the wind to be weaker one year to another and to give a safety factor on the energy calculations, an additional wind turbine is used.
Bellow in Figures # and # the results of the simulation with 6 wind turbines is shown.
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Figure #
The 6 wind turbines comfortably produce more electricity than the community uses and means the community slightly better than carbon neutral.
Below in Figure # is a plot from a random day within the year showing the electricity produced by the wind turbine, the electrical demand and the electricity exported and imported by the grid.
Figure #