The Total Carbon Emissions and Energy Cost of a Hybrid
When you drive a hybrid you are helping to reduce carbon emissions and are also saving money because a hybrid gets better mileage than a conventional gasoline-powered vehicle. The hybrid gets better mileage because it combines a gasoline engine with an electric motor that provides extra power when needed, such as for accelerating or climbing hills. This means that a smaller, more efficient engine can be used. Also, the engine shuts off automatically when you come to a stop and restarts when you press the accelerator. This avoids wasting energy while idling.
A hybrid doesn't have to be plugged in. The electric power for the motor is generated from the gasoline engine, and from a regenerative braking system. The energy that is normally wasted when you are coasting or braking is converted into electricity and stored in a battery until it is needed by the electric motor. But there are also plug-in hybrids with batteries that can be recharged by plugging them in to a standard electric outlet.
Data from the U.S. Department of Energy reported on the website www.data360.org shows that a Honda Civic Hybrid can get up to 50 mpg, compared to around 30 mpg for a gasoline Honda Civic. That equates to around 2 tons less of CO2 emissions each year by driving the hybrid version. The Toyota Prius Hybrid gets from 45 to 48 mpg and the Toyota Camry Hybrid gets close to 40 mpg. Mileage depends of course on driving habits, whether in the city or on the open highway, and the condition of the vehicle. But those are averages.
The Honda Insight Hybrid and the Toyota Prius Hybrid are on the low end in terms of CO2 emissions, generating around 3.5 tons per year. That compares to almost 9 tons per year emitted by the Toyota Highlander SUV and over 10 by the Hummer. So driving a hybrid makes a considerable difference.
Plug-in hybrids have the potential to reduce CO2 emissions even more. It all depends on how the electricity is generated. According to an article by Michael Graham Richard on the Treehugger website, a conventional gasoline-powered light duty sedan emits 452 grams of CO2 per mile driven. A comparable hybrid electric vehicle emits 294 grams/mile. When looking at plug-in hybrids the numbers vary considerably depending on the source of the electrical energy. Emissions range from 326 grams/mile for electricity generated from a conventional coal-powered plant down to 150 grams/mile for wind or solar generated electricity.
Diesel-powered vehicles, which are more popular in Europe and other parts of the world than in the U.S., can achieve very good mileage, with low CO2 emissions. And the advent of the mini or micro cars may also have a significant impact on our future driving habits and help to reduce CO2 emissions further. The Toyota iQ, a very compact city car, that can get up to 57 mpg with CO2 emissions of around 160 grams/mile, will be coming to the U.S. in 2010. A variety of new technologies are in the works to improve motor vehicle efficiency and reduce emissions. Until some of these more advanced technologies are incorporated into cars on the market, driving a hybrid can be an environmentally responsible way to go.
