Saturday, September 4, 2010

Key Electric-Vehicle Myths We Need To Know



I noted that the roll out of electric cars by the automotive industry has led to a lot of uncertainty among potential consumers.

I want to focus on larger infrastructure questions about the impact of the electric car on the NV Energy electricity grid system and the environment.

Q: Are gasoline-burning internal combustion engines more efficient than battery-powered electric motors?

A: The power density of gasoline is about five times greater than the best storage battery at this time, but an electric car gains ground when you compare overall efficiency from its fuel storage area to the wheels of the car.

Internal combustion engines are inefficient in utilizing the power density of gasoline because they only generate about 25 to 30 percent of the potential horsepower available from the gasoline tank to the wheels of a vehicle.

Electric motors and electronic drive trains can generate 80 to 90 percent of the potential horsepower from the electrical energy stored in the vehicle's battery pack to the wheels of an EV.

Q: How can consumers calculate the cost-per-mile to operate gas-burning cars versus electric cars?

A: To compare the two competing fuels and drive train technologies in economic terms, use dollars to calculate refueling costs.

For example, the Nissan Leaf battery-powered electric car will drive approximately four miles on one kilowatt-hour of electricity that costs 11.8 cents from NV Energy. That's about 3 cents per mile.

A similar gasoline-powered vehicle such as a Honda Civic Si with a combined city/highway rating of 24 miles per gallon costs around 10 cents per mile when you start with gasoline priced today at about $3 per gallon and remove 58 cents worth of taxes.

What happens if the price of gasoline starts to rise back up to 2008 levels, when a gallon of regular gas at local service stations spiked above $4 nationwide?

Q: EV battery packs eventually have to be replaced. Won't this add to the refueling cost of electric cars in the long term?

A: The manufacturer's warranty for the battery packs of the Chevrolet Volt and other emerging electric-powered cars are being announced at eight years or 100,000 miles, whichever comes first.

Even then, lithium-ion battery cell technologies age much slower than lead-acid battery cells after repeated use. An eight-year-old lithium-ion battery pack may still retain 80 percent of its original capacity if properly maintained, which means that the electric-only range of a Chevrolet Volt would drop from about 40 miles to 32 miles before the hybrid gasoline engine needed to begin recharging the battery pack.

Automotive manufacturers anticipate that battery pack replacement costs will decline by that time and the life cycle of battery packs for electric cars will continue to improve to eventually exceed a life span of 10 years.

Q: Will charging EVs call for extra electricity to be generated, thus requiring burning more fossil fuels?

A: Charging up an electric car at night does not necessarily have to consume extra power from the grid or require the burning of more fossil fuels.

Between 10 p.m. and 6 a.m., excess energy may be wasted on the grid network because it has nowhere to go other than to continue traveling around the grid transmission line infrastructure, gradually becoming dissipated in the form of heat.

During 2009, NV Energy initiated a special electric vehicle Time of Use program that allows EV owners a discount on their monthly electricity consumption rates when recharging during late night hours.

Studies by the National Renewable Energy Laboratory in Colorado have shown that displacing internal combustion engines with electric cars will reduce overall nitrogen oxide emissions, even if the electricity used is generated from a coal-fired "smokestack."

Stan Hanel has worked in the electronics industry for more than 30 years and is a long-time member of the Electric Auto Association and the Las Vegas Electric Vehicle Association. Hanel writes and edits for EAA's "Current Events" and LVEVA's "Watts Happening" newsletters.

source: lvrj