Greenhouse gases in California could be cut from 134 million metric tons in 2005 to 23 million metric tons by 2050 without implausible technical evolution or radical changes in lifestyles, according to scenarios discussed by the California Energy Commission and California Air Resources Board during a workshop held May 31. A key and possible path to cutting those greenhouse gas emissions would be to increase average vehicle mileage from 20 miles per gallon in 2005 to 70 miles per gallon by 2050. Such mileage improvement is possible if plans for extensive energy efficiency measures, new vehicular technologies, and low carbon alternative fuels are implemented, according to 2050 Vision Forecast, an analysis by the Energy Commission and Air Board on strategies to increase alternative transportation fuels, reduce petroleum use and achieve greenhouse gas emission reductions in on-road and off-road transportation markets. The scenarios identified potential market penetration based on projected fuel consumption in new vehicles in five specific milestone years--2012, 2017, 2022, 2030 and 2050--and the circumstances and conditions required to achieve the projections. Also discussed were actions needed to increase alternative fuel use, including government interventions, such as mandates, standards, incentives and programs. Staff assessed how the widespread use of alternative fuels, efficiency measures, and changes in travel habits would impact transportation fuel demand and diversity, at least within the personal transportation sector. The assessment found that there are \u201cchallenging but plausible ways\u201d to meet 2050 goal. According to the scenarios, an 80 percent reduction in GHG emissions associated with personal transportation can be achieved even if the state population grows to 55 million, an increase of 50 percent, provided the following occurs: -Lowering the cost of plug-in hybrids, battery powered electric vehicles and\/or hydrogen fuel cell vehicles so they can compete for a large share of the vehicle market; -Designing most liquid fueled vehicles sold after 2030 so they can be operated on a flexible mix of biofuels and gasoline, or on lower carbon diesel blends; -Designing most hybrid electric vehicles sold after 2030 to be capable of being plugged into the electricity grid where they are charged with efficient and low carbon electricity so that owners have strong economic incentives to plug in; -Further improvement in the design and efficiency of new personal vehicles so that by 2050 the average in-use vehicle achieves 70 mpg and derives half of its fuel energy from electricity or hydrogen sources; -Ensuring the fuel delivery infrastructure is fully diversified and provides consumers with reliable and convenient access to cost competitive, very low greenhouse gas emission biofuels, electricity, and hydrogen; -Expanding the choice of travel modes for most trips and reducing the need to travel via technology and improved land use planning; and -Increasing use of mass transit and public transportation as an alternative to personal motor vehicle use. The information presented and gathered during the workshop will be considered for a plan that responds to Assembly Bill 1007, which requires the Energy Commission and Air Board to examine strategies to increase the use of alternative transportation fuels through 2022.