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Old 03-22-2005, 01:35 PM   #1
curtis73
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Hybrids from an engineering standpoint

I want to open a dialogue with you all about Hybrids. I personally feel that they don't work and waste energy. I'm gonna post my thoughts and I want some unbiased rebuttal. Please, nobody saying that their Hybrid is the pinnacle of whatever just because they recently shelled out the cash for it. I'm talking objectively. Remember as you type... keep it engineering-based, so I'm talking hypotheticals, not "honda is better than toyota," or "but the Prius is so quiet."

Here's why I don't think they work as far as saving energy. It is a chemical and physical proof that anytime you change states of energy, you lose some. Most of the time its lost to heat, either directly (like a wire getting hot) or indirectly (an electric motor's bearings getting hot from friction). It gets lost other ways, too, but let's look at it just as "energy," not necessarily as heat, kinetic, electric, chemical... just energy.

In a regular vehicle, the energy changes states once. The energy in the fuel is converted to motion. Throughout the rest of the driveline, some of the motion is converted away through friction and heat, so the original energy package gets diluted, but not converted as part of the function of operation.

In a hybrid vehicle, there are two state changes. The energy from the fuel is converted to electricity, then the electricity converted to motion. Each time it changes, it loses energy.

Let's take some hypothetical numbers. Let's say you have a hybrid vehicle with a 50 hp engine. Until you convert that to electricity, let's say you're down to 40hp worth. Now you have to convert it to motion, so maybe only 30 hp makes it to the ground. Small engine, good MPGs, mission accomplished, right?.

Why not make a 50hp car that's not a hybrid? Then the customer is happy since they're still getting the good mileage of a 50 hp engine, but now they're getting 40 hp to the ground. Or, why not make a 40 hp car non-hybrid? Then they still get the same performance at 30 hp with better mileage than the hybrid.

I guess what I'm saying is, why on earth would it be more economical to change states of energy twice? Why not just do it once? My theory is that it was just a marketing ploy, but if you folks know something I don't, spit it out. Engines like the VW TDI have proven that we can get 80 hp to the ground at 45 or so MPGs, so why are we even bothering with expensive, complicated hybrids that get 50 mpgs?
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