It probably seemed too good to be true: A corporation promising to build a carbon-negative residential community powered by a groundbreaking new type of alternative energy, all of which would yield investors returns of anywhere from 17 to "infinite" percent.

It turns out it was too good to be true, according to the Securities and Exchange Commission, which on Nov. 17, 2009, charged Philadelphia-based Mantria Corporation with securities fraud, calling it a "green investment Ponzi scheme." But by that time, Mantria investors — most of them from the Denver area — had already been bilked out of a reported $54 million.

Writer James Carlson outlines the rise and fall of Mantria in the July issue of Denver-based 5280 magazine.

According to Carlson, most of the blame for Mantria's Ponzi scheme lies with employee Wayde McKelvy, the company's Colorado-born lead investment broker who told the reporter he was in it for "the game," not the money — although the money went into McKelvy's extravagant lifestyle, heavy drinking and a steady stream of prostitutes.

So what was the Mantria promise? As Carlson writes, Mantria said it "was constructing the country's first carbon-negative residential community, where energy-efficient housing would be built with sustainable materials, and the whole thing would be powered by alternative energy. As if that weren't enough, Mantria was also supposedly on the verge of releasing an unprecedented technology that turned garbage into usable materials and produced something called biochar, a charcoal that when used as a fertilizer was carbon-negative."

The biochar claim may have had some hint of truth — on Aug. 3, 2009, Mantria sent out a news release claiming it had opened the world's largest biochar plant, which would eventually generate $10 million a year in revenue — but according to Carlson, the company only sold one bag of biochar the whole time it was operating. That sale — for $97 — was Mantria's sole real income while its doors were still open.

Like all Ponzi schemes, Mantria relied on new investors to pay supposed profits to its earlier investors. Along the way, McKelvy and Mantria's owners, including Troy Wragg, took out massive salaries for themselves and blew millions on luxury hotel rooms, jewelry, cars, condos and more.

Not all of Mantria's employees were in on the scam. The company's web designer, Taylor Romero, told Carlson that "We were going to save the planet, and we were having a blast doing it."

McKelvy, his wife, and Mantria owners Wragg, Amanda Knorr, and a related company called Speed of Wealth, LLC were all named in the 2009 complaint by the SEC. To date, the SEC has not levied any fines or criminal charges against the Mantria crew, although further action may be pending.

Meanwhile, McKelvy is operating new businesses — including more investment schemes and a porn site — under the name "Clint Brashman," although he told Carlson he isn't making any money. "What good does it do for me to make any money? The [SEC] is just going to take it."

According to Philly.com , a court-appointed receiver is in the process of liquidating Mantria assets, including the $3.2 million biochar plant in Tennessee, to help raise some of the money lost by investors.