Elon Musk has once again sent tremors through the bitcoin market, with the cryptocurrency's price close to $40,000. Musk's hints weren't quite enough to get bitcoin over the mark, however, as its price has since fallen back around $38,000.

The fluctuation was prompted by Musk announcing he had met with "North American Bitcoin miners" to discuss sustainability. Concerns about crypto mining's environmental impact led Tesla to halt bitcoin purchases.

Musk's tweet sent bitcoin into wild swings. As of 11:38 a.m. ET, bitcoin was trading at about $38,300.00

More details about the meeting came from Microstrategy CEO Michael Saylor, who said participants had created a Bitcoin Mining Council to drive sustainable cryptocurrency networks.

Details are still scarce, leading many of the responses to express some skepticism about the idea. Cryptocurrency mining requires titanic amounts of energy, enough to rival entire countries and warp the market for high-end computer parts.

Others argued that the fluctuation following the announcement shows exactly the problem with decentralized currencies, saying it gives famous individuals too much power over markets.

Major world governments would seem to agree. Both China and the U.S. recently announced they would clamp down on cryptocurrency, imposing tighter regulations and bringing trading into line with tax law.

The Treasury Department has also been speeding up work on creating the infrastructure needed for a digital dollar, a long-term goal it says could give the benefits of a cryptocurrency without the instability or penchant for fraud.

Elon Musk
Tesla boss Elon Musk's tweets have sent the values of cryptocurrencies rising and falling Photo: dpa / Christophe Gateau