Several major bitcoin miners, including Tom Lee, Jack Dorsey, and Michael Saylor, have come together to defend the environmental impact of cryptocurrency in a letter to the Environmental Protection Agency (EPA), coming as a rebuttal to a letter sent last to the agency by members of Congress.

A group of House Democrats from the Committee on Natural Resources led by California Representative Jared Huffman penned a letter last month stating their concerns with the environmental impact left by the power demands of cryptocurrency mining. In the letter, the group noted the air and water pollution caused by the energy needs of cryptocurrency mining and the e-waste produced by the giant server farms necessary for mining.

"Of particular concern is the inherently energy-inefficient "Proof-of-Work" (PoW) mining technology to validate transactions," the group wrote. "Less energy intensive cryptocurrency mining technologies, such as 'Proof-of-Stake' (PoS), are available and have 99.99 percent lower energy demands than PoW to validate transactions."

In their rebuttal, Lee, Dorsey, Saylor, and their compatriots counter by noting that cryptocurrency mining operators purchase their electricity from the grid and that the blame lies with energy producers. The reply pointed to the studies cited by the representatives, noting the widespread criticism of one study regarding crypto mining's power needs and questions the lack of evidence on some claims.

While the debate over cryptocurrency's environmental impact may rage, solutions are currently coming to the cryptocurrency market that addresses environmental concerns. Some major energy producers, such as Exxon Mobil (XOM  ) and ConocoPhillips (COP  ), have begun selling excess natural gas to cryptocurrency miners to self-power their operations as an alternative to the environmentally destructive practice of gas flaring.

In addition to ventures between energy suppliers and miners, some projects, such as Tesla's (TSLA  ) planned Texas solar-powered bitcoin mining facility, are being prepared to demonstrate the viability of environmentally friendly crypto mining.