  Existing modeling approaches for long-duration energy storage (LDES) are
often based either on an oversimplified representation of power system
operations or limited representation of storage technologies, e.g., evaluation
of only a single application. This manuscript presents an overview of the
challenges of modeling LDES technologies, as well as a discussion regarding the
capabilities and limitations of existing approaches. We used two test power
systems with high shares of both solar photovoltaics- and wind (70% - 90%
annual variable renewable energy shares) to assess LDES dispatch approaches.
Our results estimate that better dispatch modeling of LDES could increase the
associated operational value by 4% - 14% and increase the standard capacity
credit by 14% - 34%. Thus, a better LDES dispatch could represent significant
cost saving opportunities for electric utilities and system operators. In
addition, existing LDES dispatch modeling approaches were tested in terms of
both improved system value (e.g., based on production cost and standard
capacity credit) and scalability (e.g., based on central processing unit time
and peak memory usage). Both copper plate and nodal representations of the
power system were considered. Although the end volume target dispatch approach,
i.e., based on mid-term scheduling, showed promising performance in terms of
both improved system value and scalability, there is a need for robust and
scalable dispatch approaches for LDES in transmission-constrained electric
grids. Moreover, more research is required to better understand the optimal
operation of LDES considering extreme climate/weather events, reliability
applications, and power system operational uncertainties.
