Regulators on Wednesday approved both companies' requests to let customers buy renewable energy certificates for some or all of their electricity usage.
The companies will purchase these certificates from "green" power sources equal to the amount of renewable energy purchased through customer contributions.
The energy purchased will come from sources like wind, solar, falling water, biomass, energy from waste, wave motion, tides and geothermal power.
Customers will see the additional costs for participating in the program on their bill.
(Copyright 2008 by The Associated Press. All Rights Reserved.)