Background and objective

Under the intermittency of renewable energy and other fluctuation of demand and supply sources, we need a variety of energy storage system (ESS) of different specifications to keep a secured and stable operation of a power system. The needs to balance demand and supply vary according to characteristics of fluctuation and we need to find the optimum alternatives of ESS specification of the storage technology which most fits to the needs of a power system.

In this study, we analyze the impact on operational cost under different scenarios of generation, flexibility supply from traditional generators, distributed generators, demand responses and ESSs in Japan in 2040.

Methods used

The method used is a production cost analysis tool “MR” with network constraints using real demand and supply condition of the future power system of Japan.

MR has a capability to set the requirement for different flexibilities and to define supply capability of various sources including traditional generation and distributed resources to optimize the generation dispatch, flexibility dispatch and demand shift to minimize the operational cost. MR also has a capability to analyze transmission system congestion and short circuit capacity of the nodes in the transmission system.

Main results obtained

In the simulation, we first use a linearized production cost analysis, one of a functions of MR to analyze a more-than-one-day production of a power system to decide a SoC of an energy storage at the end of a day, and secondly, we analyze daily production simulation to make the detailed evaluation of the system operation. For the analysis, we estimate the several demand and supply scenarios of a power system in Japan in 2040. The scenarios are set according to the 7th Strategic Energy Plan of Japan and publicly available data. We also estimate the future requirements for flexibilities (FCR, S-FRR, FRR, RR, and RR-FIT) dependent on the capacity of vRES and demand level.

The results of the production cost analysis will show the followings:

For seconds-to-minutes fluctuation, ESS supply the balancing service in cooperation with traditional generators.

For minutes-to-hourly fluctuation, ESS supply the balancing service in cooperation with traditional generators, demand-side technologies and demand response.

For hourly-to-daily fluctuation, we have options of batteries, pumped hydro systems, and other LDES technologies.

The combined requirements for flexibilities have a critical impact on the cost of system operation to affect the selection of ESSs in a power system.

The implications from the analysis results are:

It is essential to combined the energy storage technologies of different characteristics and specifications for the future power system.

It is critical to establish process to decide the specification of ESSs.