A Computationally Efficient Formulation for a Flexibility Enabling Generation Expansion Planning

This paper presents a new mixed-integer linear programming formulation for combined generation, storage and demand response expansion planning. The proposed formulation captures flexibility dynamics in integrated energy systems in long horizons with large temporal resolution. The objective function considers costs related to: investment, operation, emission penalties, fixed and variable maintenance. The considered units are: generators, storage (batteries and hydro pumped) and demand response units (desalination, power-to-X, electric vehicles and electrolysers). The operation is modelled as an hourly unit commitment including time-dependent startup costs and intertemporal constraints such as ramping limits and minimum up and down times. This flexibility enabling formulation boosts renewable integration and contributes towards decarbonisation of other energy sectors such as transport. A commercial solver is used to evaluate the formulation for large scale cases considering 20 years horizon and 12 full weeks per year imposing minimum renewable shares of 50 and 100% in year 9 and 19, respectively. The formulation exceeds tractability limits of previous works, achieves lower over-installation and renewable curtailment by integrating flexibility in the generation expansion problem, and allows to size demand responsive units if desired.