Electric Vehicles

Electric Vehicles:  A Better Environmental Choice

EVs are 24% Efficient

According to Transport Watch, only about 30% of the energy generated by a power plant in fact reaches an Electric Vehicle (EV) because of losses in the transmission route.  Of the energy delivered to the vehicle, 20% is then lost to the batteries and electric motor. This means that most EVs are only about 24% efficient. So, if your electric vehicle is charged with electricity from a coal-fired power plant, then the CO2 emissions to fuel your EV are about double the amount emitted by a diesel engine, due to the inefficiencies in electrical power generation and transmission.

So they conclude that the notion that electric cars will reduce emissions is fiction unless we hypothecate that the UK electricity generating industry will be de-carbonised.

Power Generation and Transmission Are Important Factors

But if we want to consider this issue carefully, we will find that the electric vehicle is environmentally friendly and efficiencies in electrical power generation and transmission.  First, let us consider some definitions:

• Hybrid-electric vehicle (HEV): This uses an internal-combustion engine for most of its power, but also has an electric motor run from batteries recharged by the engine. Typically the engine shuts off whenthe car is stopped. HEVs include the Toyota Prius and the Honda Insight.
• Plug-in hybrid-electric vehicle (PHEV):  An HEV that can charge its batteries by plugging into a charger, permitting all-electric short trips. The forthcoming Chevrolet Volt is such a car.
• Battery-electric vehicle (BEV): an electric car powered only by batteries.
  

All three can charge their batteries using regenerative braking, which recaptures energy otherwise lost as heat when bringing the car to a stop. That’s a big benefit for electrics.

Power Transmission

How much energy is lost getting electricity from the power plant to your PHEV or BEV?   Plenty. In the U.S. right currently, about 70 percent of the energy used to make electricity - more than four million gigawatt-hours - comes from fossil fuels. About 70 percent of that amount is wasted generating the power and transmitting it to your door. Additional energy is lost when charging batteries and operation electric motors. Generally, electric cars use fossil fuel at 20 to 25 percent efficiency, but dismal as that sounds, it beats an internal-combustion car, which usually operates at about 15 percent efficiency.   An HEV uses around 0.48-0.74 kilowatt-hours per mile, while PHEVs in electric mode and BEVs use 0.18-0.46 kWh per mile.  By contrast, a conventional car getting 25 MPG uses 1.35 kWh/mile. To put the issue in more well-known terms, a PHEV or BEV offers fuel economy equivalent to as much as 188 miles per gallon.

Pollution

Now let’s talk pollution.  A huge advantage of PHEV and BEV cars is that their energy can come from renewable sources, such as hydroelectric, wind, or solar.  Even if the energy source is fossil fuel, installing state-of-the-art emission controls on a few big power plants is way easier than installing ’em on hundreds of millions of motor vehicles. What’s more, since many electric plants use natural gas, carbon dioxide emissions from power generation are a modest 1.27 pounds of CO2 per kWh - 1.9 pounds per productive kWh once we account for losses during battery charging and so on.   Compare that to gasoline, which produces the equivalent of 3.9 pounds of CO2 per productive kWh.

EV Batteries:  A More Environmentally Friendly Alternative

The electric car battery is far more environmentally friendly than conventional car batteries.  For example, Tesla's Electric Roadster Battery can maximize the amount of materials that can be reused, recycled, and minimize energy consumption utilized during the transportation and recycling process.  They can separate the elements and re-use what can be re-used (cobalt, aluminum, nickel, and copper, etc). So the battery pack saves thousands of gallons of gasoline/diesel over the life of the vehicle, it is less toxic than the lead-acid batteries that are in regular cars, and at the end of its life it is recycled.

Comments

[me]

Please provide the reference to the "Transport Watch" claim that 70% of energy from the electrical grid is lost to heat.
Thanks.

[Steve Auger]

Perhaps you are reading this incorrectly. There is only one reference to heat in this article and it has to do with recovery of heat lost due to braking. This has nothing to do with transmission of electricity to the end user which is quoted as 70% loss.

Here are some references:

http://greenlivingideas.com/topics/alt-fuels-and-transportation/electric-cars/green-electric-car

http://www.transport-watch.co.uk/transport-fact-sheet-5c.htm

I hope this helps.

[Sarah]

Hi,

Batteries and electric vehicles: http://www.sustainable-mobility.org/month-issue.html
You’ll find all you need to know

[Alex]

Any good sites on electric vehicles?
Why not use a petrol generator to supply continuous power to an electric vehicle? Yes, it will be a hybrid, but wont the fuel consumption be very low.