The Greenasium really wants to be green. To do it, the new gym in San Diego is turning its customers into real gym rats. The Greenasium , which opened Wednesday, has three specialty spin bikes that push electricity back into the grid, helping provide power to the gym and other electricity customers. Its the first human-powered fitness studio in San Diego, according to its owners. "The bike's are retrofitted by a company up in Seattle that we work with called Resource Fitness," said Greenasium's co-owner Byron Spratt. "As the bike (spins), the wheel creates DC power, converts it to AC...