The impact of reduction of doublet well spacing on the Net Present Value and the life time of fluvial Hot Sedimentary Aquifer doublets

•Well spacing design is discussed to improve financial competitiveness of doublets.•Doublet well spacing is related to geological uncertainties and Net Present Value.•Detailed fluvial aquifer models are generated based on geological subsurface data.•Numerical heat flow simulations relate well spacing to doublet life time.