The Tesla (TSLA) chief is back at it on Twitter this evening: "To be clear, I strongly believe in crypto, but it can’t drive a massive increase in fossil fuel use, especially coal."The comments seem to be behind a modest bounce in the price of Bitcoin (BTC-USD), which has returned to just under $50K.Maybe more interesting, Coinbase (COIN) President and COO Emilie Choi - appearing on Bloomberg after the company's first public earnings release - talks about a number of misconceptions surrounding Bitcoin mining and energy usage. She notes 75%+ of miners use renewable energy to do their work. She suggests there's more to the Musk tweets than meets the eye.Coinbase was initially down sharply following results, but is currently higher by 2.2% in after hours action.