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Increasing the proportion of renewable energy in the transport sector and therefore the reduction of the dependence on fossil oil is a prime political and economic goal in Europe and also in many other parts of the world. In the diesel sector, especially vegetable oil methyl ester is introduced. The blending of commercial diesel fuel with up to 7 % of biodiesel leads to a lot of problems in the range of engine oil in cars. Because of the regeneration of diesel particle filter, there is an increase entry of unburnt fuel into the engine oil. The first effect of this fuel entry is the engine oil dilution which can be observed for all diesel fuels. Unlike biodiesel, commercial diesel fuel can mostly evaporate out of the engine oil because of its boiling range between 165 °C and 360 °C (73 % of the fuel has a boiling point under 320 °C). The boiling range of fossil diesel fuel was measured in preparation of this study.

A new water treatment method for the prevention of carbonate scaling is described. This method uses carbon dioxide for adjusting the water to fulfill Tillmans Equilibrium. The pH is lowered and therefore no scaling occurs. The experimental plant used in the experiments is sketched and results of a field test in a Swiss ATES system are presented. This water treatment method proved to be economical, effective and environmentally beneficial.

The storage of thermal energy, either heat or chill, in aquifers or impoundments creates local perturbations of the indigenous microflora and the environmental properties. Within an international working group of the International Energy Agency (IEA Annex VI*) possible environmental impacts of ATES**-systems were recognized and investigated. Investigations of storage systems on natural sites, man-made aquifers and large-scale models of impounded aquifers showed changes in microbial populations, but until now no adverse microbiological processes associated with ATES-systems could be documented (Winters, 1992). However, examinations with a model system indicate an increased risk of environmental impact. Therefore, the operation of ATES-systems should be accompanied by chemical and biological investigations.