The state of Delmarva is making an effort to become greener

The state of Delmarva is making an effort to become greener and conserve more energy to set an example for its corporations from a corporate social responsibility standpoint. The state would therefore like to ban the power utilities from using any advertising if conservation could be accomplished by less restrictive means. Is Delmarva within its rights as a state to pass this legislation in the interest of energy conservation? Why or why not? What type of speech is the state trying to limit? What, if any, protections are available for the utility companies?