Elon Musk sparked a competition for the world’s biggest battery.

Ever since Tesla completed the 129-megawatt-hour Hornsdale Power Reserve battery plant after Musk’s high-profile Twitter bet, others have been looking to beat it.

This summer, for instance, saw two “world’s biggest battery” announcements coming out within days of each other. Given different commissioning dates, both might actually claim the prize for a while. But which country will ultimately end up with the biggest battery?

Here is a rundown of the top contenders, based on announcements made to date.

South Korea

LS Industrial Systems (LSIS) and Macquarie Capital Korea have won the contract to build and operate a 175-megawatt-hour battery storage system across five sites owned by SeAH, a steel conglomerate, LSIS announced in July.

LSIS did not give a commissioning date for the energy storage project but said it would be used to save cheap nighttime electricity for use in the daytime, creating savings of around KRW 130 billion (USD $116 million) over 15 years.

United Kingdom

The U.K. bagged a new national record for battery size in July with the opening of Stocking Pelham, a 50-megawatt-hour facility containing 150,000 lithium-ion cells.

However, the SMA Sunbelt Energy-owned installation could be dwarfed if plans for a 350-megawatt-hour battery system move forward in Graveney, near Kent in southeast England.

The battery is due to serve a 300-megawatt solar plant proposed by Hive Energy and Wirsol Energy. But both projects face significant opposition from campaigners concerned about their impact on nearby marshland ecosystems.

Australia

Despite worries that Hornsdale may have killed the business case for other big batteries in the market, Australia seems keen to stay at the forefront of massive battery development.

In March, GTM revealed that a British businessman, Sanjeev Gupta, plans to build a 120-megawatt, 140-megawatt-hour battery complex in the same region where Tesla completed its Hornsdale plant late last year.

And in May, Reuters reported that a consortium including JERA of Japan, Australian developer Lyon Group and battery provider Fluence was planning to develop a 400-megawatt-hour storage system in South Australia. Construction could begin “within months,” Reuters said.

Germany

As previously reported in GTM, German engineers are working on a city-scale energy storage system that could boast a capacity of up to 120 megawatts and 700 megawatt-hours, said to be enough to power Berlin for an hour.

Unlike other planned big batteries, the project being led by gas storage firm EWE Gasspeicher would not rely on cheap lithium-ion technology but would instead fill 100,000 cubic meters of salt caverns with brine to create a massive redox flow battery.

The experimental nature of the project means the technology, dubbed brine4power, will likely not achieve full commercial scale until 2023.

United States

The U.S. may take the title in 2020, when Vistra Energy switches on a 300-megawatt, 4-hour battery lithium-ion battery system as part of plans by Pacific Gas and Electric to replace gas peaker plants with energy storage.

Vistra might not be the most prominent name in energy storage, but the power producer and retailer is working on a 42-megawatt-hour project in Texas, being built by microgrid developer FlexGen, which should go live at the end of the year.

The 1,200-megawatt-hour Vistra Moss Landing Energy Storage project is just one of four massive batteries being commissioned by PG&E at South Bay’s Moss Landing.

Also at the site, Tesla is slated to build a 730-megawatt-hour plant, Hummingbird Energy Storage is looking to install 300 megawatt-hours and Micronoc has a contract for 40 megawatt-hours. All the projects will have 4 hours’ duration and use lithium-ion technology.

The Vistra and Tesla projects, the world’s largest so far, will both be online by 2021 and are scheduled to operate for 20 years.

It may not be long before those are taken over by something bigger.