Bringing together nine partner organizations from Germany, Austria, and Sweden, the European research project OrPHEuS started in October 2013 and came to a close in December 2016. It investigated the concept of hybrid energy grids as a way to increase the usage of renewable energy in urban areas in a resilient, flexible and cost-effective manner. Project results can especially bring value to energy utilities, DSOs, municipalities and actors of the ICT sector.
In practice, hybrid energy grids are energy systems in which existing individual grids (typically electricity, district heating and gas) are interconnected and operated collaboratively. The scheme relies on two key elements. Firstly, a number of so-called coupling points are required to transfer energy from one grid to another as needed. Examples of coupling points include gas boilers (gas-to-heat), heat pumps (electricity-to-heat) and gas power plants (gas-to-electricity). Secondly, an overarching controlling infrastructure is necessary to collect information from the various grids involved and to apply an optimal collaborative control strategy to the coupling points. Detailed work was conducted by the OrPHEuS consortium to develop such a suitable control architecture and to analyse the benefits derivable from the proposed approach.
As part of this work two demonstration sites were studied and modelled accurately with multi-domain simulation tools. Results showed in both cases that the coupling of electric and heating domains combined with adapted collaborative control strategies allows for increased utilization of distributed renewable energy sources in a cost-efficient manner. In neighborhoods of Ulm (Germany) where a large fraction of home-owners have solar photovoltaic systems installed on the roof of their house, the conversion of surplus PV production into heating with electric boilers can easily lead to a yearly reduction of PV curtailment of 35% while slashing fossil fuel consumption by 60%. In the city of Skellefteå (Sweden), the use of oil boilers to provide peak district heating in the winter can be completely avoided by the implementation of a large electric boiler and new control strategy, thus making heat supply for the city completely CO2 neutral. An extensive socio-economic analysis further proposed new business models allowing all market actors and consumers to benefit economically from the developed concepts.