Q: I recently bought a Ford C-Max plug-in electric hybrid to reduce my gasoline consumption and global warming emissions. I have read reports that for each gallon of gasoline we burn, about 20 pounds of carbon dioxide are released into the atmosphere, but I’ve never seen any figures on how much CO2 is released by producing gasoline. Taking into account the CO2 emissions from drilling, pumping, refining, transportation, and electric pumps at the gas station, how much more is released in addition to every gallon burned in a car? Is there any research that gives figures on how much is generated by producing and transporting a gallon of gas?

 —Robert in Carnegie, Pennsylvania

A: A recent study from Stanford University indicates that there is quite a bit of variation in these “upstream” emissions because of different field conditions and production methods. Take a look at their numbers (translating from grams and megajoules to pounds and Btus), and you'll see that the CO2 eq emissions from well to gas pump, before you burn a drop in your tank, can range from about 3.35 pounds per gallon to 6.7 pounds per gallon. (CO2 eq includes not only CO2 but also other global warming gases such as methane.) Obviously, this is a hefty percent of the roughly 20 pounds of emissions from burning the gasoline!

According to the EPA, your plug-in should average 39 miles per gallon, and can travel a mile on 0.35 kilowatt-hours when it runs on electricity only. Unfortunately, because your region's electricity is still so heavily dependent on coal, operating your car on electricity alone doesn't reduce CO2 emissions very much below the emissions generated when the gasoline engine kicks in.

I recommend that you look into obtaining carbon-free, clean electric power, if you haven't done so already. You don't even have to install solar panels on your roof or erect a windmill in your backyard. Simply buy power from clean sources. Of course “clean” electricity doesn’t go directly to your house or car, but it offsets equivalent amounts of “dirty” electrons slithering through the power grid from fossil-fuel-powered generators. The Sierra Club has teamed up with Arcadia, a wind-power company (phone 866-526-0083) and clean-power producer. There are also Community Solar options, where a neighborhood, club, church group, or any organization with available space puts up a solar installation that can serve multiple households.