Towards low carbon business park energy systems: A holistic techno-economic optimisation model

In this paper, an energy model is developed customised for the design of low carbon energy systems on business park scale. The model comprises two sequential stages: In the first stage, heat recovery within the system is maximised, while utility system and energy storage are optimally integrated and designed to fulfil remaining energy requirements at minimum total annualised costs. Simultaneously, heat networks can be deployed to transfer heat between separate parts of the system. Intra-annual variations in thermal and electrical energy demand and supply are taken into account, next to a carbon emission cap. In the second stage, the model generates an optimal multi-period heat exchanger network (HEN) enabling all required heat exchanges. The proposed model builds upon a multi-period energy integration model that can deal with restrictions in heat exchange. This model is combined with a generic technology model that can be manipulated to represent the various thermal or electrical energy conversion technology units in the utility system. Moreover, simple models for thermal and electrical energy storage are included that allow for calculation of storage levels subject to energy loss over time, without increasing the number of time steps to be analysed. A method for automated superstructure expansion is incorporated in the solution procedure to enable the optimisation of the number of units per technology in the configuration of the utility system. The HEN is automatically generated using a multi-period stage-wise heat exchanger network model. The energy model is applied to a literature example and to a generic case study demonstrating its holistic and integrated approach towards the synthesis of low carbon energy systems.