Design of dairy systems as active Net-Zero Energy Factories. Technical and economic analysis of the German decarbonization process

Industrial plants designed as net-zero energy factories (NZEF) and functioning as prosumers provide the grid operator the opportunity to serve as an additional instrument besides conventional control measures to support grid stability. The planning and implementation of own flexibility measures for the grid operator are associated with high costs, risks and efforts. Accessing the external flexibility capacities of companies or groups of companies in industrial energy hubs offers a more cost-effective control measure for grid operators. In this paper, a cheese factory in Germany is modelled as an NZEF to analyse the potential of flexibility that the cheese dairy factory could provide to the grid operator. The electrification of thermal treatment methods using a heat pump system result in a dairy system with a maximum annual power demand of 581kW (including a 324kW heat pump system), resulting in an annual energy consumption of 2.25GWh for the factory. The redesign of the production chains for drinking milk, yogurt, and cheese enables a significant increase in flexibility of 30.2% over a five-hour period from 11:00 a.m. to 4:00 p.m. This enhancement allows the daily energy demand to be reduced below its nominal value, while providing an additional increase of energy demand of 86.8% for another five hours, starting from 4:00 p.m. to 9:00 p.m. The extrapolation of the production volume of the dairy products drinking milk, yogurt and cheese for the whole of Germany shows that there are daily load shifts of up to −2.38 GWh and 2.5GWh by maximum power −540MW and 930MW, which could be offered daily to the grid operator as external flexibility.