Mileage report and CO2 footprint

This week we added 196 miles to the Volt.  Unfortunately we used just over a gallon of gas.  This was because yesterday we went to San Francisco in the morning, and then out to Hercules in the afternoon.  Since the San Francisco trip used most of the electric miles, the Hercules trip used mostly gas (about 40 of the 50 miles).  So for the two weeks we've been home in Oakland we've gone 507 miles on 4.7 gallons of gas, just over 100 miles per gallon.

I'm thinking that by planning ahead, we can avoid other errands on Mondays when I go to Hercules, so that those trips to Hercules will be mostly electric.  The problem with using one gallon of gas in a week is that a gallon of gas produces about 20 pounds of carbon dioxide.  If we did that every week, we would produce about 1000 pounds of CO2 in a year from the gasoline.  A sustainable level of CO2 emissions is about one ton per person per year.*  Therefore, producing 1000 pounds on driving makes achieving that goal very difficult--we need heat, food, other basic products, all of which produce CO2.  What's more, we like to fly places, which produces a lot of carbon dioxide, so it would be desirable to avoid any CO2 from driving.  Hopefully we'll achieve that in the weeks to come.  Of course getting over 100 miles per gallon is a good thing, and is a lot better than any internal combustion engine, so I feel good about that.

*Joseph Romm in the book Hell and High Water argues that the earth can only absorb about 8 billion tons of CO2 in a year.  Since there are about 7 billion people on earth, that means that each of us should limit our CO2 production to about one ton.  Unfortunately the U.S. currently emits about 20 tons per person, so we have our work cut out for us!  Solar power and electric cars are an important step to the one ton goal.