Saturday, May 28, 2011

May Leaf Update

Nearly another month of driving with electrons. May's not quite over yet, but I have time to post this morning so here goes. In the first 27 days of May, we've put 568 miles on the odometer and 172 KWh on the emeter, for an average of 3.3 miles/KWh. Up slightly from March and April, when we averaged 3.1 miles/KWh. It's getting a bit warmer, so we're using the heater less.

I also started tracking MPGe, the EPA's fuel efficiency metric for EVs. According to the EPA, a gallon of gasoline contains the equivalent of 33.7 KWh of energy. If you disregard how each is produced (more on that later), it gives a like-for-like comparison between gas-powered vehicles and EVs. For March and April, we averaged right around 105 MPGe. With the arrival of (slightly) warmer weather, we're now up to 111 MPGe. Using that same 33.7 ratio, our fuel cost us the equivalent of $3.90 per gallon, or about 3.5 cents/mile.

Something I've blogged about before, but bears repeating: lack of volatility in fuel prices for EVs. Electric rates are typically controlled by a public utility commission. They go up (and down), but on a timescale of months or years, not days. Since we got the Leaf, our fuel price has not changed. In that same time, gasoline has gone from $3.20 to $4.10, and is now back down to $4.00

What good is an electric vehicle if all it does is move CO2 emissions upstream to a coal-fired power plant?
Answer: It doesn't. Let's start with "base load". Coal, nuclear, and hydroelectric are all base load sources of electricity. Utilities use base load power to service the typical needs of their customers. Utilities keep base load plants running 24x7 whether they need the electricity or not, because they can't be started or stopped quickly.

So what type of power is used to recharge EVs? Most EV owners plug their cars in at night, when overall demand for electricity is low. They make use of capacity that would otherwise go to waste. Remember, base load plants run 24x7, producing CO2 whether or not they're generating electricity. EVs are an option for turning the waste CO2 into something useful.

Finally, sources of electricity will get cleaner over time. Wind, solar, geothermal, tidal are all means of generating electricity without producing CO2. Gasoline will just get dirtier. Deep-water wells, tar sands, oil shale, and coal oil are all methods for squeezing out the last drops of fossil fuel, but at an ever-increasing cost to the wallet and the environment.

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