World’s biggest merchant battery system opened in Texas

Finnish energy technology group Wärtsilä and Californian energy investor Eolian have inaugurated two major interconnected storage systems in South Texas that they are dubbing the largest merchant battery system in the world.

Most big batteries are built with contracts with utilities, customers or grid operators to some part of their system offerings, such as balancing renewables or acting as a type of shock absorber to the grid, and they usually have some part of “merchant sale”, meaning charging and discharging at the market rate.

Wärtsilä and Eolian say that the two batteries, with a combined capacity of 200MW and more than 500MWh make it the biggest to go entirely merchant.

The Madero and Ignacio energy storage plants were brought online on Monday and will be operated using software developed by Eolian which will allow the two battery systems to participate fully in the Electric Reliability Council of Texas (ERCOT) market.

Each energy storage plant boasts a capacity of 100MW/250+MWh.

According to Wärtsilä, the facilities’ multi-hour continuous dispatch capability is the longest duration of any energy storage assets operating in the ERCOT market and, as a combined site is, in terms of megawatt-hours, the world’s largest fully-merchant and market-facing energy storage facility built to date.

The dual project is also the first to make use of the Investment Tax Credit (ITC) for standalone utility-scale energy storage systems which was part of the much-heralded Inflation Reduction Act (IRA) passed in 2022.

“Wärtsilä was determined to deliver the Madero and Ignacio energy storage facilities on time, despite challenging industry forces, to ensure additional dispatchable resources to improve reliability for the ERCOT market,” said Risto Paldanius, vice president for the Americas at Wärtsilä Energy.

“Texas needs more flexible capacity solutions like energy storage for grid support and energy resource optimisation. This will help the state as it faces the natural replacement cycle of older inflexible generators and adapts to more frequent extreme weather events.”

Wärtsilä’s is also building the Torrens Island big battery in South Australia, which is nearly complete and going through its connection processes.