Microsoft founder and billionaire technology investor Bill Gates has cast doubt on Tesla CEO Elon Musk’s  plan to introduce long-haul electric trucks to the world in what is the latest stoush between the two technologu identities.

“The problem is that batteries are big and heavy,” Gates wrote in a blogo post in late August.

“Even with big breakthroughs in battery technology, electric vehicles will probably never be a practical solution for things like 18-wheelers, cargo ships, and passenger jets,” said Gates.

“Electricity works when you need to cover short distances, but we need a different solution for heavy, long-haul vehicles,” he added.

Gates pointed to biofuels–rather than battery power–as a possible solution for commercial vehicles.

Musk has reportedly directed Tesla to ramp up production of the Semi, a commercial vehicle with a range of up to 800km, for its upcoming debut, Reuters  reported in June.

Companies including Pepsi, FedEx, Walmart, UPS and Sysco have placed orders for Tesla Semis.

In his blog post, Gates also left Tesla out of a list of companies that have made breakthroughs in electric vehicle technology, even though Tesla has furiously promoted its yet-to-debut Cybertruck.

“Increased competition in the market means there are more choices available to customers than ever before, from compact sedans to sleek sports cars,” Gates wrote.

“You’ll even be able to buy an all-electric pick-up truck soon thanks to legacy companies like GM and Ford and new carmakers like Rivian and Bollinger.”

The two billionaires clearly don’t always see eye to eye. Musk has repeatedly claimed that the coronavirus panic is overblown, while Gates has warned about the possibility of a world-changing pandemic for several years.

Musk has called Gates “underwhelming” and trolled  the Microsoft founder with posts like “The rumour that Bill Gates and I are lovers is completely untrue.”