Net-zero housing, an electrical grid that adapts to supply and demand, and incentive programs that offer free fuel for electric cars may sound like the stuff of science fiction — but Rocky Mountain Power believes it is time for Utah to stride into the future. The electric company offered the first glimpse of its Sustainable Transportation and Energy Plan at the Governor’s Air and Energy Symposium on Tuesday. Company officials said the plan, which includes a call for the creation of a prototype net-zero community, is aimed at answering customer’s calls for a future with fewer emissions, cleaner energy and economic vitality.