Optimization of Load Flows in Urban Hybrid Networks

A sustainable supply of energy in urban regions requires an adequate infrastructure and operation. At present, the different energy sources (i.e., electricity, gas, district heating) are used separately without any connection to each other. To increase the flexibility of energy supply, the usage of energy hubs is a possible way. Energy hubs are connection points between the energy sources that comprise the key elements of so-called hybrid networks. Using the energy/hub approach, surpluses and power shortages from a specific energy network can be avoided. The hubs offer various technologies of energy conversion and can include electrical and thermal storage. Thus it is possible to convert electrical into thermal energy (heat pump, electric heating), chemical (gas) into thermal (furnace), or electrical energy (micro gas turbine) into, respectively, thermal and electrical energy (combined heat and power) depending on the used technology. The correct operating strategy for these energy hubs is an essential factor in order to minimize CO₂ emissions of urban energy systems. Therefore, a simulation model was developed in MATLAB^®. The minimization of CO₂ emissions is based on a mixed-integer linear optimization of the overall system, consisting of the supplying infrastructure, energy hubs, and thermal/electric loads. First results have been obtained by a case study for an urban region supplied by three different energy carriers (gas, electricity, and district heating).