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Maybe I Was Wrong About Hybrids

I used to think that hybrid vehicles were a waste of time and energy. It made sense to me that a car that used an electric motor directly inline with the engine would never be efficient and would pretty much always be limited to the efficiency of the engine. If you’re new to the workings of gasoline hybrid technology, I’ll try to bring you up to speed. We’ve all heard of hybrid vehicles by now, they have a gasoline engine that is assisted by an electric motor and a bunch of batteries. There are two types of hybrids, series and parallel. Series hybrids have an electric motor mounted directly to (or basically on the same shaft as) the gas engine. The Toyata Prius and Honda Civic hybrids are the two best examples of these. Parallel hybrids have an electric generator mounted to the engine for the sole purpose of generating electricity for the electric motor that drives the wheels. Big diesel locomotives are a perfect example of this type of hybrid, which in my opinion, is the best type. For more information on hybrids, check out this Wikipedia page.

My big problem with hybrids was the fact that there have never been any commercially produced of the parallel type, they have all been series. This means that the engine still has to run at varying engine speeds depending on the speed of the vehicle, which is inefficient because gasoline engines are most efficient at a set speed and load. Upon researching the Prius, I came across the technical page explaining the Hybrid Synergy Drive. I now realize that vehicles that use this type of powertrain can function as both series and parallel hybrids. They accomplish this with two motor/generators that are connected to the engine and each other by a type of clutch and a continuously variable transmission (CVT). With this setup the engine can run independent of the wheels for the sole purpose of charging the battery, acting as a parallel hybrid. It can also function as a series hybrid by using one of the motors to assist the engine in acceleration and provide regenerative braking. The CVT in combination with the two motor/generators allows the engine to run mostly in it’s most efficient speed and load range. It seems to me, now, that the new technology added to these hybrids has utilized much more of the potential efficiency of gasoline engines, without the extra baggage of a full-out split parallel hybrid.

Despite this great new technology, I still don’t think that gasoline engines are the way to go. Diesel engines are far more thermodynamically efficient than their gasoline counterparts, we’ve known this for a long time. It’s all about the combustion process, compression ignition will always be more efficient because higher compression generally gives higher efficiency. A good running car with a four-cylinder diesel engine gets better mileage than one of the newer gas hybrids. I think we need a vehicle that features a small diesel engine coupled to one of the newer hybrid drive systems. That, in my opinion, would be the ideal hybrid.