"Tesla (TSLA) has suspended vehicle purchases using Bitcoin (BTC-USD)," tweets company CEO Elon Musk."We are concerned about rapidly increasing use of fossil fuels for Bitcoin mining and transactions, especially coal, which has the worst emissions of any fuel."He adds that cryptocurrency is a good idea, but its use cannot come at a great cost to the environment.He further adds that Tesla won't be selling any of its Bitcoin stash, and plans to begin re-using for transactions once mining transitions to more sustainable energy. He also says Tesla is looking into other cryptos that use only a fraction of Bitcoin's energy.Bitcoin has tumbled to the day's low, now at $52.7K.