Review of State of Charge by Union of Concerned Scientists

Review of State of Charge by Don Anair & Amine Mahmassani, Union of Concerned Scientists (UCS)

This new report, subtitled Electric Vehicles’ Global Warming Emissions and Fuel-Cost Savings across

the United States, provides excellent and accurate factual support for conversion of the U.S. transportation system from gasoline to electricity.  The report correctly notes:

·         Even if electricity is generated by coal, electric vehicles produce less greenhouse gases than the average gasoline powered vehicle.  However, high mileage hybrids would be cleaner in this case.

·          For the typical mix of coal, natural gas, and other energy sources, electric cars are much cleaner than average cars and are cleaner than high mileage hybrids

·         For regions that use little or no coal, electric vehicles are "far and away the best choice"

·         The real goal should be to run electric vehicles on electricity generated by renewables, with practically no greenhouse gases.

 The analysis is based on full life cycle costs of energy production.

The report uses a technique similar to the way that EPA measures the efficiency of electric vehicles.  For example,  EPA estimates that the electricity used to power a Chevy Volt creates greenhouse gases comparable to a hypothetical gasoline car that would get 94 miles per gallon.   

State of Charge computes the miles per gallon equivalent of greenhouse gases for different methods of producing electricity.  The report uses a conservative 2.9 miles per kilowatt hour (0.34 kwh/mile); I say conservative since our first year with the Volt gave us 3.1 miles per kwh (0.32 kwh/mile).  But this does not change the general thrust of the UCS conclusions.  For the four cases above, the report provides a useful rule of thumb comparing regions based on coal use:

Region	Equivalent miles per gallon	Greenhouse gas reduction compare to 27 mpg gasoline vehicle
High Coal	31-40	11 - 33%
Average mix	41-50	33% - 46%
Low coal	51+	More than 46%

Here is a map of the U.S. from the report showing where the high, average, and low coal areas are located in the U.S.:

The report also includes a good discussion of the advantages of Time of Use (TOU) electric rates, since most EV charging happens overnight in the low cost periods.  Certainly people living in areas that do not offer TOU rates should push their utilities for such rate structure improvements.

The report also discusses the advantages of adding separate meters for an EV, where the utility allows that.  This feature ensures that the electric usage of the EV does not push the house rate into higher rate tiers as a "Whole House" rate might do.  For example, the report estimates that in our home town of Oakland, using the straight electric rates, we would save $50 per year vs. buying gasoline at $3.50 per gallon and getting 27 mpg.  Using the TOU rates for the whole house we would save $500 per year.  And using a separate meter we would save $1,120.  (more on this below).

Finally the report discusses various pros and cons about plug-in hybrids and all electric vehicles, providing useful price comparisons of different cars now on the market.

My main criticism of the report is that I feel it could be stronger on the urgency of eliminating fossil fuels from electricity production to address global warming.  The report seems OK with "achieving greater than 80% reduction in global warming pollution by 2050".  True, this is an admirable goal given U.S. political reality, but, as Bill McKibben has said, "You can't negotiate with chemistry and physics."  At 394 parts per million (ppm) the earth is already way over the safe level of atmospheric CO₂-- 350 ppm-- and CO₂ is rising by 2.3 ppm per year.  At this rate, even if we gradually achieve zero CO₂ emissions by 2050, we'll have added another 46 ppm to the atmosphere, bringing the total to 440 ppm.  Given the current climate chaos being created by 390 ppm, can we survive 440?  The report does note that the goal is a "zero emission future" (page 21), but I think the urgency of the situation is downplayed.

Another weakness is the report's handling of solar power. The report quotes a study by the California Center for Sustainable Energy that found that 33% of electric vehicle owners have solar panels.  And on page 25 it tepidly points out that solar panels "may be an option" for generating electricity.  But in discussing utility prices of electricity, it fails to understand what a great combination solar and EVs make.

How do I explain this without short circuiting my brain and yours, dear reader?  Let me try:

The key is to understand net metering.  Under net metering solar power is credited to your bill for the same price that the utility charges.  Fortunately, the sun is most powerful in the afternoon, right when electricity is most expensive, especially in the summer while all those air conditioners are running.  This means that solar is credited at around 35 cents per kwh in peak summer months.  Averaging summer peaks, weekend off peaks, and winter off peaks--solar earns about 15 cents per kwh for the whole year.

Now with low interest rates, tax credits ,and the dropping price of solar, the actual cost of solar is, coincidentally, as low as 15 cents per kwh.  Since PG&E's average rate is about 18 cents per kwh, it would pay most people to keep adding solar until their full PG&E bill is covered.  The trick is not to add so much solar that you end up having a negative bill.  Net metering will not pay you that negative amount.  If your solar panels generate more electricity than you use, PG&E pays a small amount.  It would be great if all the solar were reimbursed at its true value--i.e. a feed-in-tariff, but we're not there yet.  We need to learn from Germany on this, and work on our elected officials.

The cost of charging at night is around 7 cents per kwh--i.e. half of the amount paid for solar.  Therefore, it takes roughly 500 kwh of solar power to pay for 1000 kwh of car charging at night.  That means that the solar only costs 7 cents per kwh for the energy used to charge the car.  Not bad!

The TOU rate for solar only works if you use the "whole house" rate.  I.e. you can't use the solar just for the car at night, so the actual rate depends on how much electricity you use at home and when you use it.  Using the example of our house (with rounded numbers) for 2011:  Our 3.2 kilowatt solar system generated 4350 kwh.   Since the solar is paid at about 15 cents per kwh, it earned $650 in credit.  The car used 2400 kwh at 7 cents =  $170 and the house used 4,000 kwh at 12.5 cents per kwh for a cost of $500.  So the total net bill was $650 - 170 - 500 =  $20, which was covered by minimum charges.  For more details, see my two posts: "Everything is going according to plan"  and slight miscalculation .

Got it?  Solar is the way to go!

Now back to the UCS report:

I don't mean to diminish the value of the report by pointing out where I think it could be improved.  I feel that it is an important contribution to the effort to promote electric vehicles as a critical step in our attempts to reduce greenhouse gases.  I certainly agree with the following statement from the report's conclusion:

 "Only by making improvements to our electricity grid—by decreasing the use of coal and increasing the use of clean and renewable sources of electricity—will electric vehicles deliver their greatest global warming and air pollution benefits. Initiatives to clean up the electricity grid are occurring around the country, but additional efforts are needed both at the state and national level to ensure continued progress."