Abstract: The invention relates to a method for configuring a geothermal circulation system in a target underground region, comprising at least one injection wellbore (1) and at least one production wellbore (2), a hydraulic connection being created between the injection wellbore (1) and the production wellbore (2) via a crack system (4, 4?) in the target underground region, and a heat transfer medium being circulated via the injection wellbore (1), crack system (4, 4?), and production wellbore (2), comprising the steps of creating a plurality of cracks (4, 4?) in the target underground region by the incremental hydraulic separation of short wellbore sections and hydraulic crack generation starting from the respective separated wellbore section.

Abstract: The invention relates to a filter arrangement including a pleated nonwoven layer for use as a motor vehicle interior filter. The nonwoven layer is in the form of a single-layer, self-supporting micro-spunbonded fabric, the weight per unit area thereof being between 70 g/m.sup.2 and 200 g/m.sup.2, preferably between 110 g/m.sup.2 and 150 g/m.sup.2, the thickness thereof being between 0.7 and 1.5 mm, and the fibre thickness being between 2 and 20 .mu.m with an average fibre thickness of 3 to 5 .mu.m.