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.
Monday, November 23, 2009 at 12:01AM | 