| return temperature | Tinj | Application dependent | °C |
The depth dependent salinity s (ppm) is based on the following equation:
s=s₀+ s<sub>grad</sub> (z+0.5H)
*s=s₀+ s<sub>grad</sub> (z+0.5H)*
where z is top depth and H thickness of the aquifer, both in m.
where z is top depth and H thickness of the aquifer, both in m
- s₀ is the salinity at the top of the aquifer (z=0), typically 0 ppm for freshwater aquifers.
- s_grad is the salinity gradient, which is the increase in salinity with depth, typically around 47 ppm/m for freshwater aquifers.
- The salinity gradient is typically around 45-70 ppm/m for sedimentary aquifers, which means that the salinity increases by 47-70 ppm for every meter of depth below the top of the aquifer.
- s<sub>grad</sub> is the salinity gradient, which is the increase in salinity with depth, typically around 47 ppm/m for freshwater aquifers.
- The salinity gradient is typically around 45-70 ppm/m for sedimentary aquifers, which means that the salinity increases by 47-70 ppm for every meter of depth measured from surface
In the Netherlands aquifers with salinities up to 180,000 ppm do not give any problems in production.
Key Performance Indicators (KPIs) are essential metrics used to evaluate the performance of geothermal projects. In pythermogis, KPIs are calculated based on the results of the DoubletCalc and economic model calculations.
The KPIs provide insights into the efficiency, profitability, and sustainability of geothermal energy projects.
The KPI have been subdivided into the following categories:
## technical KPIs
Reservoir and well performance indicators are calculated based on the results of the DoubletCalc calculation
-**Reservoir Temperature [C]**: The temperature of the geothermal fluid at the reservoir, which is crucial for determining the energy potential. This temperature is corrected for any thermal losses in its trajectory
to the surface leading to 1-2 degrees temperature drop
-**Reservoir Depth [m]**: The depth below surface of the reservoir
-**Hydraulic Transmissivity [Dm]**: A measure of the reservoir's ability to transmit fluids, expressed in Darcym,
in agreement with permeability times thickness of the reservoir.
-**Flow Rate [m3/h]**: The rate at which geothermal fluid is produced from the reservoir.
-**Pressure Drop [bar]**: The pressure required to drive the thermal loop. The doublet model takes into account hydraulic resistance of the reservoir,
friction in tubing and thermosyphon effects.
-**Power[MW]**: Power production, which is the net power output of the geothermal plant after accounting for conversion efficiency and parasitic losses.
-**PowerHP[MW]**: share of Power which is used as source in the heat pump
-**COP[-]**: The system Coefficient of Performance (COP), which is the ratio of useful power provided to the energy consumed by the ESP and heat pump system.
In case of the direct heat adnd direct heat with heat pump, the usefull power is equal to predicted Power * (1+ 1/(1-COP)), for chill and ORC it is equal to Power.
-**COPHP[-]**: The Coefficient of Performance (COP) of the heat pump system, which is the ratio of useful heat provided to the energy consumed by the heat pump.
## economic KPIs
-**CAPEX [million€]**: The total capital expenditure for the geothermal project, including well drilling, plant construction,
and other initial costs.
-**OPEXfirstyear [k€]**: The operating expenditure for the first year of the geothermal project,
which includes maintenance, repairs, and other ongoing costs.
-**Hprod [MWh]**: The discounted total amount of geothermal energy produced over the economic lifetime
-**LCOE [ct/kWh]**: The levelized cost of energy, which is the average cost per unit of energy produced over the lifetime of the project,
expressed in cents per kilowatt-hour.
-**NPV [million€]**: The net present value of the project, which is the difference between the present value of cash inflows and outflows over the project's lifetime.
