U.S. Senator Elizabeth Warren sends a letter to Greenidge Generation Holdings (NASDAQ:GREE) CEO Jeff Kirt, with concerns about the impact of its crypto mining operations on the environment, Bloomberg reports. "We need to better understand how much energy facilities like Greenidge are using, how much they're emitting into the environment, and what impact they're having on electricity prices for American consumers," Warren told Bloomberg via email. This is the first time Warren seeks information from a specific Bitcoin (BTC-USD) miner, Bloomberg notes. Recall in August, Warren said crypto markets may need a bailout someday without proper regulation. Keep in mind that New York-based Greenidge (GREE) is a carbon neutral, vertically integrated power generator and bitcoin miner, according to its website. Shares of GREE extended losses on Thursday's session, down 12% in the past five sessions and nearly 40% M/M. On Wednesday, Greenidge Generation's existing Title V permit didn't get suspended.