Wind power is now cheaper than coal in the U.S., according to a study published in the journal Science. The study’s researchers, two Stanford engineers, priced wind power at 3 to 4 cents per kilowatt hour, already competitive with the market price for coal power. After factoring in health and environmental costs, they put the true price for coal power at 5.5 to 8.3 cents per kilowatt hour. For wind power to take off, however, the researchers say that lawmakers will need to give the industry the same investment opportunities and tax breaks historically given to fossil fuel industries. The researchers propose this bargain-basement deal: eliminating nearly two-thirds of coal-generated electricity and single-handedly dropping the country’s greenhouse gas emission levels below 1990 levels by building 225,000 wind turbines — at an initial cost of $338 billion.