What is a "series hybrid"?
All of the hybrid cars available today are considered "parallel hybrids," for the ability of both the electric motor and gasoline engine to provide power to the wheels. A "series hybrid," by contrast, uses the gasoline engine to turn an electric generator, which then either powers the car or charges on-board batteries. As such, the gasoline engine is not used to make the car go. The Chevy Volt, the much-hyped concept car from General Motors, is such a hybrid, though as HybridCars.com notes, "The folks from GM don't want to use the term 'series hybrid' to refer to their Chevy Volt concept vehicle (for marketing purposes), but that's what it is."
Taken as a whole, hybrids offer a mixed bag of issues, when it comes to their environmental considerations. They offer greater fuel efficiency and fewer greenhouse gas and particular emissions than conventional cars, but still run on gasoline, a finite and (some say) diminishing resource. They represent a technological step forward, but cost more money to buy and ultimately maintain than conventional cars. The electric batteries offer a way to power a car without using gasoline, but add weight to the car (reducing its efficiency) and are very costly (both financially and environmentally) to produce and dispose of. Green car enthusiasts generally accept hybrids as a positive step forward in greener personal transportation, but not as a long-term solution for a greener future.
Plug-in hybrid electric vehicles
In addition to the Chevy Volt series hybrid mentioned above, the next development in hybrid cars is likely to be the "plug-in hybrid electric vehicle" (PHEV), which has a larger battery pack more capable of powering the vehicle on its own, without the need of the gasoline engine, for a number of miles. Though not required, these cars can be plugged in to help charge up the batteries; stay tuned for a future "Green Basics" column, all about plug-in hybrids.
Read more about hybrid-electric cars and vehicles
There are lots of resources for further reading; check out Wikipedia, hybridcars.com and hybrid-car.org to get started. Here at TreeHugger, have a peek at our Cars + Transportation category for more, or type "hybrid" into the search engine above to dig in to our coverage of hybrids.
Turn the ignition on other green topics with TreeHugger's Green Basics series that appear regularly on these pages.