Development of the ReHeat Decision Support Tool for Evaluating and Optimizing Hybrid Industrial Process Heat Systems: Proof-of-Concept

This report presents a summary of NLR's ReHeat tool, a proof-of-concept decision support tool (DST) to assist decision-makers in identifying and evaluating the best options to supply industrial process heat (IPH) while considering their goals and respecting site constraints. The tool leverages a Linear Programming (LP) and Mixed-Integer Linear Programming (MILP) framework, which facilitates the solution of the design problem and for which established solvers exist. Focus was given towards technology hybridization, either by increasing overall system efficiency or by supplementing temperature deltas. Fuel, electricity, and solar technologies were considered. An important part of the framework is a built-in catalog of technologies, unit prices, efficiencies, and characteristics, which are customizable to ensure user-specific results. At a high level, ReHeat computes the system design - rated or maximum heat generation of each technology, in kWth, or kWhth for storage - that optimizes an objective, typically life cycle cost (which may include environmental metrics), and respects site constraints such as available area. Considered technologies include solar (flat plate and parabolic trough collectors), electricity (high temperature heat pumps and resistive), and fuel (natural gas boilers). In this report, only the core model of ReHeat is presented. Extensions to the model that perform different tasks, such as identifying the optimal process configuration or topology and using different heat sources for the heat pump, are currently being investigated and will be reported separately.