It all started when two billionaires exchanged a few tweets.

And now, the world’s largest lithium-ion battery will be installed in South Australia within just 100 days, solving our energy problems.

For those in need of a refresher: back in March, Tesla vice-president Lyndon Rive garnered nationwide attention for his claims that the company’s batteries could single-handedly solve our state’s energy problems. Remember the state-wide blackouts when storms hit last September? Rive proposed a reserve battery to provide power in cases where renewable energy sources drop out.

This statement was picked up by Australian billionaire Michael Cannon-Brookes, founder of software company Atlassian, who re-posed the question to Tesla CEO Elon Musk (whose current net worth stands at US$16.7 billion).

Musk responded with a firm “yes”, promising that, should Tesla not manage to install a 100-megawatt, 129-megawatt-hour, lithium-ion battery within 100 days of the signing of necessary contracts, the entire project would go ahead free of charge.

Today, just over three months on, Musk held a press conference at the Adelaide Oval officially announcing the commencement of the project. An agreement was made between Tesla and the South Australian government, as well as French renewable energy company Neoen, whose Hornsdale Wind Farm near Augusta will expand to accommodate the Hornsdale Power Reserve and house Tesla’s battery.

Speaking to the ABC, Musk named the upcoming project as “the largest battery installation in the world by a significant margin” – the second-largest being Tesla’s last installation, which took place in California in December of last year. When completed, the battery will be “three times more powerful than any system on Earth”, Musk says.

If the project wraps within 100 days – which will commence once the agreement for interconnection is signed – the battery will be up and running before the summer.

And if it doesn’t? Musk is determined to stick to his word that it will be completely free. “That’s what we said publicly, and that’s what we’re going to do.”