The California Public Utilities Commission hearings began in San Diego and will move to San Francisco.
They are scheduled to run until early May.
SDG&E's Chief Operating Officer Michael Niggli said the line will help the utility comply with a state requirement that 20 percent of its electricity come from renewable energy sources, like solar and wind, by 2010.
The executive was pressed for details on how the transmission line will deliver on its promise of renewable energy and whether the company considered other routes.
The commission is expected to vote on the project later this year.