Tesla and SpaceX CEO Elon Musk isn't convinced of the long-term prospects of fusion energy, the long-deferred dream of fusing atoms together under extreme conditions as a way to generate green electricity.
As cool as that sounds, though, the richest man in the world is put off by the logistics and cost.
"Fusion would be expensive energy, given difficulty of obtaining and transporting source fuel, plus maintaining the reactor," Musk argued in a Thursday tweet. "Far better to use the Sun — thermonuclear reactor with no need to refuel or service."
Those criticisms aren't entirely misplaced, either. Try as they might, scientists have yet to crack the code of fusion, with current reactors still requiring far more energy to get started than they're able to produce, despite many decades of research.
To Musk, we already have the answer to a much greener future.
"The primary solution to a sustainable energy future is solar/wind with batteries for when sun doesn’t shine or wind doesn’t blow, interconnected with conventional high voltage lines," he added in a follow-up. "No unknown technology is needed!"
Of course, Musk's car venture Tesla is heavily invested in solar energy and battery storage technologies, so his comments don't exactly come as a surprise. And financial incentive or not, he's right that a renewable grid is a worthy goal.
The billionaire hasn't entirely dismissed fusion, but he seems to think there are already better options out there.
"But I suspect its best case will be more costly than wind & solar (aka big fusion reactor in sky)," he added at the time.
Other billionaires, like Amazon founder and noted Musk rival Jeff Bezos, do believe in a greener future powered by fusion reactors. Last year, news emerged that Bezos was investing in Canadian fusion energy startup General Fusion.
The jury is still very much out on the viability of fusion energy. Every year, scientists claim they've come closer to achieving fusion, a dream of a perfectly safe and entirely renewable source of energy.
But the reality has so far left much to be desired.
If it were up to Musk, seemingly, our efforts would be better spent developing renewable energy and battery storage technologies.