Medford officials are pursuing an initiative to save city residents on their electricity bills through an “energy aggregation plan” approved by the City Council. Such programs allow cities and towns to contract with a power supplier to provide electricity to all their residents and businesses at a negotiated rate below what the local utility would normally charge. Residents are automatically enrolled unless they opt out. The plan, created with help from a consultant, Good Energy, L.P., can be viewed at medfordenergy.org. Now that it has been finalized, the plan will be submitted to the state for approval. Medford will then use a competitive bid process to choose an electricity supplier. City officials said that in addition to providing them with lower and more stable energy prices, the program’s standard option will contain 5 percent more renewable energy than required under state law. Residents also can choose a plan that provides for 100 percent renewable energy and another that offers no additional renewable energy above the state requirement.