Quote:
Originally Posted by darcane
I've been wondering why these systems aren't more widely used too. Other than some delivery trucks, there really aren't any Hydraulic Hybrids in production yet that I'm aware of.
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Ever scuba dive? Remember how heavy those tanks were?
To store energy in a hydraulic hybrid (or pneumatic - same principle), you need to hold gas at high pressure. That means you need a strong storage tank, which - material properties being what they are - means the tank is going to be heavy. (It also means the tank is potentially subject to catastropic failure - search for "scuba tank explosion"). Put this together, and you have a pretty bad energy/weight ratio, which means the hydraulic hybrid doesn't really work for normal driving, but is suited to applications like delivery & garbage trucks, where the drive cycle is almost all stop & go.