Consumers may not want to shell out thousands of dollars to buy electric cars, but it seems they are willing to pay $10 or $20 a month more to buy cleaner power.

That’s what the city of L.A. Department of Water and Power has found out during the 11 months its green-power program has been up and running. As of April 21, the DWP had signed up 34,000 customers, at a rate nearly twice as fast as the statewide average for power providers. And this has been accomplished with only minimal marketing efforts so far largely through inserts in DWP bills.

“People are voting with their pocketbooks for cleaner power,” said DWP General Manager S. David Freeman. “But the green-power program is only now just leaving the runway. In the next few years, it will really soar as the price of clean power falls.”

Surprisingly, the greatest demand for green power has not been from wealthy Westside environmentalists, but from customers in South L.A. and the San Fernando Valley.

“Clean” or “green” power is generated from renewable resources, including wind, the sun, geothermal power, hydropower and even methane gas emitted from landfills.

These alternative energy sources chiefly hydropower already generated more than 10 percent of the state’s power supply before electricity deregulation kicked in two years ago.

But until now, the DWP has not delivered any additional clean power to its customers since launching its “green” program last June. That’s because the L.A. City Council required the agency to reach a 20,000-customer threshold before it could sign its first contract with an alternative energy source.

With that threshold now surpassed, the first additional clean power generated from wind turbines is set to flow through the DWP’s power grid beginning this week.

The DWP is far from alone in signing up more green-power customers than expected. In fact, the green-power market is by far the fastest growing segment of California’s electricity marketplace.

But more people have signed up than the CEC expected, largely because of a rebate program set up by the state Legislature to encourage the use of green power. So many people have signed up that the commission earlier this year was forced to scale back the rebate from 1.5 cents per kilowatt hour to 1.25 cents per kilowatt hour, and is now considering cutting the rebate further to 1 cent.

Meanwhile, the DWP is signing up customers even faster than the rest of the state’s power providers. In less than a year, it has signed up about 3.5 percent of its total customers; statewide, about 2 percent of power customers have signed up for green power over the course of two years.

When consumers sign up for green power, they don’t necessarily receive power generated from alternative sources. Rather, the electricity provider uses the premium paid by such customers to buy additional power from one or more of these renewable sources and put it on the power grid, thereby reducing the overall percentage of power generated from fossil fuels.

Power from alternative sources typically cost anywhere from 5 percent to 30 percent more than fossil-fuel-generated power; much of that additional cost is offset by the California Energy Commission rebates.