If only we could all be as optimistic, and energetic, as Tesla CEO Elon Musk.

Even as Tesla gears up for mass production of the Model 3 electric car and a hoped-for annual production rate of 500,000 total cars by next year, Musk has found time to place a high-profile bet on the renewable energy part of Tesla's businesses.

In this case, it has to do with the electric grid in South Australian, which gets more than 40 percent of its energy from wind power.

DON'T MISS: Tesla's battery farm on Kauai opens, large-scale solar energy for Hawaii

The region has experienced several recent, high-profile blackouts that were blamed on wind intermittency, although the sudden closure of coal power plants and the fluctuating gas market may have as much to do with the actual causes.

So Lyndon Rive—now Tesla's vice president of energy products—stepped in, claiming Tesla could solve South Australia's energy problems in 100 days with lithium-ion battery packs, reports the Australian Financial Review.

Rive is Musk's cousin, and previously helped to run SolarCity before Tesla bought the solar-energy company last year.

Tesla and SolarCity energy storage array on Ta'u, American Samoa

Tesla and SolarCity energy storage array on Ta'u, American Samoa

Rive said Tesla would "commit" to installing 100 to 300 megawatt-hours of battery energy-storage capacity within 100 days of signing a contract.

Mike Cannon-Brookes—the billionaire co-founder of software company Atlassian—subsequently tweeted at Musk, asking if the Tesla CEO could guarantee the installation of 100 Mwh in 100 days.

"Tesla will get the system installed and working 100 days from contract signature or it is free," Musk tweeted back, adding "That serious enough for you?"

"You're on mate," Cannon-Brookes responded. "Give me 7 days to try sort out politics & funding. DM me a quote for approx 100MW cost - mates rates!"

Musk answered with a quote of "250/kwh at the pack level for 100 mwh+ systems." That would bring the cost to $25 million for the packs alone, excluding costs like shipping and installation.

This morning, South Australian premier Jay Weatherill announced a $550 million plan to build both a large battery storage facility and a 250-Mw gas-fired power plant.

According to a report in News.com.au, the plan was immediately slammed by the Green Party as a giveaway to the natural-gas industry for its lack of new solar-thermal generating capacity.

Weatherill confirmed that the government was speaking to a range of battery-storage providers, among them Musk, about the $150 million renewable-energy fund that would pay for the renewable-energy storage facility.

Tesla Energy for utilities

Tesla Energy for utilities

Rive originally said prices would run from $400 to $600 (U.S. dollars) per kilowatt-hour, depending on configuration, or about $50 million for 100 mwh, with reductions for large-scale installations.

Tesla recently completed two large energy-storage installations for U.S. utilities.

One is a battery farm linked to a SolarCity solar array on the Hawaiian island of Kauai, which will supply power to local utility Kauai Island Utility Cooperative under a 20-year agreement.

It also recently completed an energy-storage installation for Southern California Edison, near Chino, California.

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