By the Governor’s executive order, California is to reduce greenhouse gas emissions to 80 percent below 1990 levels by 2050, while energy demand is projected to double. This order presents the opportunity for a case study to determine the kinds of energy systems that would meet both projected needs and these targets. There are four key questions whose answers will determine the energy system of the future: How much can we control/decrease demand? How fast can we electrify light duty transportation and most heating? How can we decarbonize electricity through a combination of nuclear power, carbon capture and sequestration, and renewable energy? How much sustainable carbon-neutral biofuel will we have? The answers to these questions will determine how much fossil fuel will still be used and therefore what the state’s emissions will be. If emissions are greater than the target, what can we do about it? Options include faster rollover to electric vehicles, making fuel from decarbonized electricity, changing behavior, and major new breakthroughs in technology. This session will explore the construction of energy system portraits for meeting stringent emission standards and what we can learn about what must be focused on now. These portraits represent idealized targets, and it remains for us to create policies to help reach these goals.