Summer 2012

How Clean Are Electric Vehicles? | Catalyst Summer 2012

By Don Anair

The automotive world is buzzing about electric vehicles (EVs). Last year, the Chevy Volt plug-in hybrid, which operates on both electricity and gasoline, and the Nissan Leaf, which runs exclusively on electricity, made their showroom debuts. This year, domestic and foreign manufacturers including Ford, Honda, Mitsubishi, and Toyota are unveiling their own EVs.

A Tale of Three Cities

We examined the benefits of electric vehicles in 50 U.S. cities. Here are three that span the savings spectrum.

EVs can save money and cut global warming emissions no matter where you live, but the savings vary from region to region. Detroit, MI, for example, is located in a GOOD region, where EV emissions are equivalent to those from a 38 mpg gasoline vehicle. EVs in Miami, FL, a BETTER region, have emissions comparable to a 47 mpg gasoline vehicle. But EVs in a BEST region such as Oakland, CA, have emissions equivalent to a 79 mpg gasoline vehicle—and as you probably know, no such vehicle exists!

Fuel-cost savings also vary widely depending on EV owners’ utility prices and rate plans. Drivers in Detroit and Miami on a standard rate plan can save an average of $880 and $940 (respectively) each year, compared with a 27 mpg gasoline vehicle. Enrolling in a time-of-use rate plan could allow these drivers to save even more: $1,000 or more per year. Choosing the right rate plan is even more important to drivers in California—under a standard plan, EV owners in Oakland may only save $50 per year, but switching to a time-of-use plan could produce $1,120 in annual savings. Switching to a time-of use plan may require some upfront costs, so consumers should contact their utility for details first.

Drivers on the Bay Bridge connecting Oakland, CA, with San Francisco.

By drawing some or all of their power from the electricity grid instead of the gas pump, EVs slash oil consumption and eliminate tailpipe emissions, but still produce global warming emissions (because the electricity they use is generated from a mix of energy sources, including fossil fuels such as coal and natural gas). How these emissions compare with those of gasoline-fueled vehicles depends on your electricity mix, which can vary significantly by region.  Similarly, the cost of charging an EV depends on your local utilities’ electricity rates.

This localized information was not readily accessible—until now. Our new report State of Charge helps consumers make a more informed vehicle choice by comparing the global warming emissions and fuel-cost savings of EVs relative to gasoline-powered vehicles where the consumer lives.

Good News for Everyone

No matter where you live in the United States, an EV slashes oil consumption and has lower global warming emissions than the average new compact gasoline-powered vehicle. But in regions that depend heavily on coal-fired electricity, charging an EV will generate more global warming emissions than in regions that obtain more of their electricity from cleaner sources such as natural gas, solar, and wind power.

State of Charge analyzed the U.S. electricity grid’s 26 regions and rated each as “GOOD,” “BETTER,” or “BEST” for EVs based on the global warming emissions produced by charging the vehicles. We took a “well-to-wheels” approach, measuring emissions from fuel extraction all the way to moving the vehicle down the road. Emissions associated with EVs do not come from the tailpipe but from producing the electricity needed to charge the vehicle.

Nearly half (45 percent) of the U.S. population lives in regions rated BEST—where an EV will have lower global warming emissions than a gasoline vehicle getting 50 miles per gallon (mpg), topping even the most fuel-efficient hybrids on the market. About 37 percent of the population lives in areas rated BETTER—where an EV will have global warming emissions similar to a 41 to 50 mpg gasoline vehicle, including the most fuel-efficient hybrids on the market: the Honda Civic Hybrid (44 mpg) and Toyota Prius (50 mpg). The smallest fraction, only 18 percent, live in areas rated GOOD—where an EV will have global warming emissions similar to a 31 to 40 mpg gasoline vehicle, including the most fuel-efficient non-hybrid gasoline vehicles available: for example, the Ford Fiesta (34 mpg) and Scion iQ (37 mpg).

Across the country, electricity is expected to continue getting cleaner as the production of renewable electricity expands and older, high-polluting coal power plants are retired. Unlike conventional wisdom for a gasoline car, an electric vehicle purchased today can be expected to have lower global warming emissions as it gets older.

(Click on image for full-size view.)

Notes: Ratings are applicable to midsize electric vehicles of average efficiency. Gasoline mpg comparisons are for combined city/highway EPA fuel economy ratings.

More than 80 percent of the U.S. population lives in areas where an EV will match or surpass the most fuel-efficient hybrids on the market in terms of global warming emissions.

Save Big on Fueling Costs

Today’s EVs vary widely in price, ranging from $100,000 luxury sports cars to more modest passenger vehicles such as the four-passenger 2012 Mitsubishi i, which costs about $22,000 after factoring in an available $7,500 federal tax credit. While EVs cost more to purchase than comparable gasoline vehicles, EV owners can realize significant fuel cost savings compared with operating a gasoline vehicle because driving on electricity is cheaper. UCS looked at utility rates in 50 cities across the United States and found that, compared with the average 27 mpg compact gasoline vehicle, an EV could save its owner between $750 and $1,200 per year assuming a gas price of $3.50 per gallon—a 50 to 85 percent savings. This yields significant oil and fuel cost savings over the vehicle’s lifetime (see the chart). And if gas prices continue to rise, so do the savings.

It is important to note that most consumers pay a flat rate for their electricity based on the amount consumed. However, many utilities offer “time-of-use” rates that charge a lower rate for electricity used at off-peak times—typically overnight, when EVs are most likely to be charged.  EV owners in some cities may need to switch to one of these plans to maximize their savings (see the sidebar).

(Click on image for full-size view.)

Notes: Assumptions include gasoline cost of $3.50 per gallon, a national average electricity price of 11 cents per kilomatt-hour (dWh), and cumulative lifetime mileage of 166,000 miles. Electric-drive efficiency is that of a Nissa LEAF (0.34 kWh/mile) and is representative of toda's small to midsize EVs.

Electric vehicle owners could save more that 6,000 gallons of gasoline and nearly $13,000 in fuel costs over the vehicle's lifetime compared with a car getting 27 miles per gallon.

Look at the Bigger Picture

As our analysis shows, switching to EVs can help reduce oil consumption, global warming emissions, and fuel costs for consumers across the country. But as the report title suggests, this is just a snapshot of the potential benefits based on today’s electricity mix. Some regions of the country have farther to go to clean up their electricity grids, and electric utilities can help increase consumer access to low EV charging rates.

Using renewable energy to charge EVs makes them virtually emissions-free.

Consumers can maximize the global warming emissions benefits of EVs by installing rooftop solar panels to charge their vehicles, making them virtually emissions-free. You can also help reduce global warming emissions in other ways by enrolling in a utility’s “green power” program or purchasing renewable-electricity certificates (which provide additional revenue for clean energy projects). Pushing your elected state and federal officials to support policies such as renewable electricity standards and tax incentives that accelerate the transition to cleaner electricity sources is also important.

The growing number of EVs on the market may be an early signal of our transition toward a virtually zero-emissions and oil-free transportation future. U.S. investment in clean energy and advanced vehicle technologies can make this transition happen sooner rather than later.

Don Anair is a senior engineer in the UCS Clean Vehicles Program. Read more from Don on our blog, The Equation.


How much can you save with an electric vehicle? Go to State of Charge to read the full results of our research.