Saft is working with its project partner Schneider Electric at the Bellac substation in the Haute-Vienne region of western France, which produces a significant amount of solar energy. Saft and Schneider Electric have a long track record of working together in partnership on several R&D demonstrator and commercial projects. These include the VENTEEA project for French distribution operator Enedis, as well as a contract to deliver ESS for two solar plants in Corsica for Langa Group. Schneider is supplying the AC/DC power converters, transformers, and protection and control equipment. Saft is delivering a lithium-ion (Li-ion) ESS based on 2.5 MWh standard, containerised building blocks. Saft’s containers are developed entirely in-house, including thermal management, safety management, and control systems. Saft started work on-site in January 2020, with power-up scheduled for January 2022. The ESS is housed in self-contained 20 ft shipping containers that are fully assembled and tested in Saft’s facility in Bordeaux, France, and will be delivered to site at Bellac ready to plug and play.
Substation locations The second substation receiving an ESS with 10 MW power and 30.2 MWh from Blue Solutions and ENGIE Solutions is located in Ventavon in the Hautes-Alpes region of south-east France, which
is also rich in solar energy. The site is due for commissioning in July 2021. At the final site of Vingeanne in Cote d’Or, eastern France, Nidec ASI is supplying a 12 MW power and 37 MWh energy capacity solution. This region has a high penetration of wind energy and RTE plans to start experimental operations in March 2021. All three consortia worked on similar specifications from RTE, although they were adapted to suit local conditions. RTE wanted to ensure good value for its customers, therefore it put in place highly demanding specifications in terms of functionality and performance guarantees. In addition, it ran a lifecycle assessment (LCA) to evaluate the environmental impact of its new facilities from cradle to grave.
Simultaneously storing and releasing energy The RINGO project will establish battery systems that work together to relieve congestion on the grid. To illustrate the need for this approach, consider a typical city with a peak demand of 130 MW. Although this can be matched by the generating capacity of a nearby wind farm, the existing transmission lines are limited to 100 MW. By installing an ESS at either end of this grid bottleneck, the operator can store 30 MW upstream at the same time as releasing 30 MW into the city. Once peak demand has subsided, the upstream ESS can release power down the transmission line to the ESS in the city. However, if a network of ESS substations was deployed, RTE could use them flexibly depending on renewable energy production and demand. For example, at times of high solar production in Haute-Vienne but low wind in Cote d’Or and overcast weather in Hautes-Alpes, the Bellac site could absorb 10 MW while Vingeanne and Ventavon release 2 MW and 8 MW respectively.
The trend towards high energy
Figure 1. The ESS has the flexibility to provide energy over long and short durations.
Figure 2. Saft and Schneider Electric worked together to deliver ESS for two solar plants in Corsica for Langa Group.
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The Bellac site is capable of storing up to 30.8 MWh and a power rating of 10 MW. This is equivalent to the production of five wind turbines or the demand from a town of 10 000 people. It is one of the first deployments of Saft’s Intensium® Max 20 High Energy (HE) containerised ESS. This was launched in 2019 to meet the growing demand for solutions to provide energy over long durations, typically several hours. This is an example of how energy storage is changing. The first generation of grid-connected energy storage had the primary role of frequency regulation. This requires a battery to act fast to inject and absorb energy to help the grid operator maintain a stable frequency within closely defined limits. It requires a battery system with high power capability over a short duration, typically of a few seconds. This creates a ‘little and often’ pattern of cycles, which is ideal for preserving long life, as battery life is closely related to the depth of discharge (DOD) and charge cycles. However, the RINGO project and other energy storage applications require greater energy storage capacity over a longer duration. The most energy-intensive example would be power shaping, where an ESS could absorb the entire daytime output of a solar plant and deliver that energy throughout the evening and morning demand peaks in the same way as a baseline power station.
