Marathon Digital (NASDAQ:MARA), +18%, and CleanSpark (NASDAQ:CLSK), +26%, stocks both surged in Wednesday afternoon trading after the bitcoin miners posted lower-than-expected quarterly results earlier this week. The gains also come against a backdrop of bitcoin (BTC-USD) strength, up 3.7% to $23.9K.Both stocks have a green energy connection. CleanSpark (CLSK) uses low-carbon energy sources, such as wind, solar, nuclear and hydro, to power its mining operations. Marathon Digital (MARA) started energizing miners in Texas after its power generator received confirmation for the tax-exempt status of its wind farm.CleanSpark (CLSK) shares drove up even though its fiscal Q3 top and bottom lines trailed Street estimates on Tuesday. At the same time, it announced the acquisition of a new facility and its intention to sell its energy business.Another bitcoin miner also focusing on sustainable power sources, Bit Digital (BTBT) saw its stock jump 15%. On Monday, the company said its July bitcoin production more than doubled from the prior month.Shares in Greenidge Generation Holdings (GREE), which commits to 100% carbon-neutral datacenter operations, were up 13%.Bitcoin mining stocks, overall, are having a good day as investors feel comfortable taking on risk as the consumer inflation softened in July from its hot June pace.