Elon Musk said on Wednesday that Tesla would “most likely” resume taking bitcoin when the digital currency is mined with more renewable energy.

“It looks like bitcoin is shifting a lot more toward renewables and a bunch of the heavy-duty coal plants that were being used…have been shut down, especially in China,” Musk stated at the Crypto Council for Innovation’s B-Word conference on Wednesday.

“I want to do a little more due diligence to confirm that the percentage of renewable energy usage is most likely at or above 50% and that there is a trend toward increasing that number. If so, Tesla will most likely resume accepting bitcoin,” he said.

When Musk said in May that Tesla will stop taking bitcoin as payment because the so-called mining of the currencies consumed too much fossil fuel-generated power, the price of bitcoin plummeted.

Since then, Beijing has stepped up its anti-crypto campaign, expelling the country’s crypto miners, who have since fled to other countries. According to new statistics from Cambridge University, many miners are heading to the United States, which is now the world’s second-largest destination for bitcoin miners.

Using a cryptocurrency that is mined using dirty energy, according to Musk, would go against Tesla’s green ethos.

Some Tesla investors, as well as environmentalists, have been more skeptical of the way bitcoin is “mined” using massive quantities of fossil-fuel-generated energy.

The United States has some of the world’s cheapest electricity sources, which are almost always renewable. Most new miners in North America, according to Marathon Digital’s Fred Thiel, will be powered by renewables or gas offset by renewable energy credits, while Compass CEO Whit Gibbs estimates that bitcoin mining in the United States is more than 50% powered by renewables.

“Tesla’s mission is accelerating the advent of sustainable energy,” he said. “We can’t be the company that does that and also not do appropriate diligence on the energy usage equipment.” Musk said.

“Long-term, renewable energy will be the cheapest energy, but it doesn’t just happen overnight,” Musk said. “But as long as there is a conscious and determined, real effort by the mining community to move toward renewables, then obviously Tesla can support that.”

Apart from bitcoin that Tesla and SpaceX held, Musk said that he personally owned bitcoin, ethereum, and dogecoin.

“I might pump, but I don’t dump,” Musk said. “I definitely do not believe in getting the price high and selling … I would like to see bitcoin succeed.”

Musk made the comments at a panel discussion at the B-Word Conference, which was organized by crypto supporters like as Jack Dorsey’s Square and Cathie Wood’s tech-focused investment firm Ark Invest.

Musk refuted allegations that his public remarks regarding cryptocurrencies like bitcoin and dogecoin — which often cause markets to move — are part of a pump-and-dump strategy elsewhere during the event.