Extensive and Intelligent Exploitation of Renewable Energies at Sewage Treatment Plants
The work deals with comprehensive energy harvest in large wastewater treatment plants in order to make them utmost independent from external energy supply at reasonable energy cost. Thus, the complete system investigated makes not only us of biogas from sludge digester in a small combustion engine driven combined heat and power (CHP) unit which is state of the art at many places already; rather solar thermal sludge drying and subsequent incineration for a small scale steam power plant is included with usage of waste heat from CHP and steam unit for support of sludge drying. Furthermore, wind and solar based power harvest on the ground of the plant is integrated, including a hydrogen energy storage path for compensation of fluctuations, as well as small hydro generation at the clear water output. The thesis illustrates the composition and global power streams of such innovative kind of plant, describes the optimal sizing of particular plant components by use of a meta-heuristic approach, and presents several results of simulative plant operation over a full year for two examples with different conditions (Germany and Vietnam), in particular highlighting the mutual dependencies of plant devices, altogether proving that reasonable performance at vast energy independence and equitable cost can be achieved.