The New York Times claims the tech giant burnt $70,000 (£43,177) worth of power over three days in a "commercially unproductive manner" to avoid a penalty for overestimating its energy use.
Microsoft was slapped with a $210,000 (£129,527) fine last year for falling below its quota at its Quincy data centre, which houses data for Hotmail and Bing. The penalty was later reduced to $60,000 (£37,007).
"For a company of that size and that nature, and with all the 'green' things they advertised to me, that was an insult," said Randall Allred, a utility commissioner and local farmer.
A spokesperson for Microsoft dismissed the incident as "a one-time event that was quickly resolved".
Back in February, Microsoft was ranked in 13th place on Greenpeace's 'Cool IT' leaderboard, which rates tech firms on how environmentally friendly they are.