Integration of wind generation into the electric supply and transmission systems poses some well-characterized challenges. First, as shown in Figure 1, a significant portion of wind generation occurs at night, when the value is low. Second, electric energy produced by wind generation at night contributes to an increasing number of hours during which “negative prices” prevail. This is because electricity supply exceeds demand and output from the generation that is on-line cannot be reduced without significant cost or performance penalties.
An especially attractive response is to use distributed electricity storage systems (DESS) to store the low value energy generated at night, by large central wind farms (see Figure 1). Coincidentally, the energy is transmitted and distributed to the storage when the T&D systems are lightly loaded so they operate more efficiently.That increases utilization of those T&D assets because more energy is transmitted and delivered using the same amount of capacity throughout the year. Conversely, that T&D capacity is freed up to transmit and deliver more energy, real-time, during peak demand times.By reducing T&D energy losses during peak, less total generation, transmission and distribution capacity is needed to offset the energy losses.
The same storage system could also be used to provide most of the “ancillary services” needed by grid system operators to keep the electricity grid operating in a stable and reliable manner. Depending on the location of the storage, it may also provide benefits related to improved local electric service reliability and power quality. By accommodating the variability of the wind generation, the storage also improves the overall performance of the electrical generation fleet because generation output does not have to be varied to accommodate (i.e., offset) wind generation variability.
Two notable examples of regions in the United States with excellent potential for this value proposition include New York and California. In New York, there is significant potential for wind generation located “up-state” near the Great Lakes of Lake Ontario and Lake Erie. The potential is significant because of what is often called “lake-effect” winds that occur at night and that are relatively steady and predictable. Furthermore, transmission corridors into the New York City area are heavily loaded during the day and “in-city” generation is limited. In that case, storing energy from up-state lake-effect wind generation in distributed storage (located in New York City) offers compelling benefits. Similarly, transmission into the “Los Angeles basin” (L.A. basin) in Southern California is increasingly congested while a significant portion of RE generation development – including wind generation – is in less populated areas to the North and East of the L.A. basin. Adding more generation in the L.A. basin is challenging due in part to air emissions related siting challenges. So, charging in-basin distributed energy storage using off-peak energy from remote wind generation may be quite attractive.
This value proposition could involve a bilateral contract between: a) the wind generation owner and the storage owner or b) the wind generator and “aggregators” of distributed storage or possibly even wing generators and utilities.