Assessing storage and substitution as power flexibility enablers in industrial processes

Renewable energy sources are currently presented as an economically viable and environmentally safe option in the near future. A major constraint to the incorporation of wind and solar generation at large scale is the increase of variability in the power system. To assure the perpetual balance between power production and gross consumption a significant improvement on power systems flexibility is required. Such flexibility in the power system can be achieved by two options on the demand side through demand response obtained through industrial processes: Storage and Substitution. The power system model in study contemplates the purchase of electricity from the Dutch Balancing Market. The electricity prices of the Balancing Market are considered unpredictable. The storage system is characterized by the size of the storage tank and by ramp up/down rates, reflecting the changing speed of the production levels. The substitution system is characterized by the ramp rate of substitution between electricity and an alternative energy carrier as input. The impact of the parameters on the Power System Flexibility when connected to the balancing market under several scenarios was analyzed by Linny-R, a software tool that applies Linear Programming optimization. For the storage system a bigger tank size, a higher ramp rate and a high level of predictability will increase the flexibility of the system. As the actual predictability of the balancing market is limited, the flexibility is limited too, which makes the storage system a questionable option. For the substitution system flexibility is increased by a higher ramp. The effect of the predictability is less dominant, which makes substitution a suitable flexibility enabler for the current Dutch market system. In this context, a restructure of the energy markets, considering the prices predictability, is suggested, as a way of easing the penetration of renewable energy sources.