Renewable Energy Balancing with Thermal Grid Support

Waste heat valorisation in process industry is a common strategy today. The residual heat is converted to electricity by using steam turbines or organic Rankine cycles. As this energy conversion is likely constructed as an integral cooling capacity for the primary process, loss of electricity production will result in reduced process cooling and hence production capacity loss. This restriction prevents these generators to deliver supporting services to the electrical grid. In this paper, it is proven that coupling waste heat recovery with a district heating network provides ?exibility to the electricity generation while ensuring cooling capacity to the process. This ?exibility can be utilised by a Virtual Power Plant (VPP), e.g., to compensate for the variable output of renewable energy sources. Today, the power ?uctuations are only compensated by traditional power plants (gas, coal) due to the scale and ?exibility of these power plants. In this paper, a strategy is de?ned to balance variable (renewable) production with industrial waste heat. As such, some grid support tasks can be transferred from the central power plants to decentralised generation units. The backup of the variable sources is provided by utilising the local available capacity, while maintaining or improving energy ef?ciency of exothermal industrial processes. Operational boundaries are de?ned and new challenges identi?ed. In this paper, ?rstly, the heat sources available for this concept are identi?ed. Secondly, the properties of the different conversion technologies are described. Thirdly, the bene?ts of a virtual power plant utilising waste heat are determined. Finally, this VPP concept is veri?ed by means of a case study in Belgium, Ostend Energy port. Available heat from biomass, chemical processing and waste incineration is used as primary energy source to balance local renewable production.