Economic and environmental benefits of coordinating dispatch among distributed electricity storage

The increasing use of small-scale, distributed electricity storage for residential electricity storage in individual homes (e.g., Tesla Powerwall (R) batteries) and storage-based demand response has introduced an emerging challenge for current electricity grids in the form of raised peak loads or "new" peaks on the grid caused by unconstrained charging of the distributed electricity storage. Such a challenge poses a critical need for practical dispatch strategies which have been addressed in previous studies, e.g. for electric vehicles. However, few previous studies were conducted in the context of micro-grids. In addition, although there are alternatives such as distributed and central control strategies, it remains unclear which strategy and to what extent could outperform the other in terms of economics and environmental impacts. Here, we study such dispatch strategies for a large number of residential electricity storage devices in a micro-grid, along with their economic and environmental benefits. A central control scheme is proposed for coordinating dispatch among multiple distributed electricity storage devices that are interconnected through a micro-grid network, thus enabling storage based loadshifting. A case study based on New York State tariffs and generation assets is performed to verify the effectiveness of the proposed scheme. Our simulation results show that the proposed central control scheme can yield annual profits (i.e., reduced time-of-use tariff costs minus levelized storage cost) ranging from 4.3% to 24% of the annual cost without storage. These profits are up to 43% higher than those achieved under the distributed control strategy. In addition, the central control strategies yield positive impacts for the environment by effectively alleviating state-wide emissions from electricity generation.