The cost of producing geothermal energy is calculated using a discounted cashflow model The assumption is that the investment must be earned back in fifteen years. This is also the duration of the SDE+ scheme (Stimulation of Sustainable Energy Production). The economic model uses a number of parameters to calculate the CAPEX and OPEX.
The CAPEX consists of well costs and other installation costs. The well costs are depth dependent. They are calculated as:
Well CAPEX = 375000 + 1150 x depth + 0.3 x depth² [€]
The depth is the along-hole depth, which is calculated from the true vertical depth using the stepout of the wells and a curvature factor. A scaling factor of 1.5 is applied to the well CAPEX. Other CAPEX factors include constant (3 M€) and variable costs (300 €/kW). The contingency is 15%
The OPEX depends on the size of the installation (expressed as its power, 100 €/kW) and the produced heat (19 €ct/kWh). Apart from this, the electricity cost for running the pump is used. The discounted cash flow model calculates the cost price per unit of energy [€ct/kWh].
Next, the economic potential is calculated by comparing the cost price with a reference price. The reference price is 5.1 €ct/kWh, which corresponds to the SDE++ amount for geothermal energy (status 2021). For doublets deeper than 4,000 m another SDE++ category is valid, which uses a reference price of 6.5 €ct/kWh (status 2020). For the maps shown in the Map viewer, the following classes are defined:
- Unknown: P10 cost price > reference price
- Indication: P10 cost price < reference price
- Moderate: P30 cost price < reference price
- Good: P50 cost price < reference price