A handful of leading cryptocurrency miners have the electrical capacity equivalent to nearly every residence in Houston, Texas, according to data released by Democratic members of Congress on Friday.


In a letter to Energy Secretary Jennifer Granholm and Environmental Protection Agency (EPA) Administrator Michael Regan, members led by Sen. Elizabeth Warren (D-Mass.) noted that leading cryptominers have developed more than 1,045 megawatts in mining capacity as of February.


Companies that responded to the members’ inquiries included Riot Blockchain, Bit Digital, Bitdeer, Stronghold, Marathon and Greenidge.


Following a crackdown on cryptomining by the Chinese government, mining operations have increasingly moved onshore in the U.S., according to the members. The U.S. share of global mining for Bitcoin, the largest cryptocurrency, increased from 4 percent in August 2019 to nearly 38 percent in January.