OrPHEuS explains that hybrid energy grids are energy systems in which existing individual grids (typically electricity, district heating and gas) are interconnected and operate collaboratively. The scheme relies on two key elements: 

• Coupling Points, e.g gas boilers (gas-to-heat), heat pumps (electricity-to-heat) and gas power plants (gas-to-electricity); 

• and Controlling Infrastructure. 

The OrPHEuS consortium conducted research to develop suitable control architecture, and to analyse any benefits derived from the proposed approach.

As part of OrPHEuS project, two demonstration sites were studied. According to a statement, the results showed in both cases that the coupling of electric and heating domains combined with adapted collaborative control strategies allowed for increased use of distributed renewable energy sources in a cost-efficient manner. 

For example, in Ulm (Germany), a large proportion of home-owners have solar photovoltaic systems installed on the roof of their house. The conversion of surplus PV-generated energy into heating by electric boilers could lead to an annual reduction in PV curtailment of 35%, while at the same time reducing fossil fuel consumption by 60%.

In Skellefteå (Sweden), the implementation of a large electric boiler and new control strategy could remove the need for oil boilers to provide peak district heating in the winter, thus making heat supply for the city CO2 neutral.