The internal combustion engine, as we've known it for over a century, is what's known as an open cycle device. That is, the so-called working fluid flows into and out of the engine and is constantly circulated. A closed cycle engine keeps the same working fluid contained within the device and heat is generated externally rather than from combustion inside the cylinder. The best known example of the latter is the stirling cycle engine. The advantage of the stirling cycle is that the heat source can be anything since the combustion (or non-combustion) occurs outside of the mechanism. The theoretical thermodynamic efficiency of the stirling cycle is 100 percent although creating a 100 percent efficient mechanism has proved elusive. Nonetheless, the flexibility of the stirling engine has made it a popular choice among those researching alternative powertrains.
When it comes to alternative anything, few people rank with Dean Kamen. Kamen is best known to most people as the creator of the oft-derided, but certainly innovative Segway scooter. For some time now, Kamen and his staff have been working on a extended range electric vehicle. As with most other EVs of late, energy storage comes in the form of the usual array of lithium ion batteries. The stirling engine will be used to recharge the battery pack making the car useful for more than just urban commuting. If anyone can make the stirling engine work in a car, Kamen might be the one. We'll have to wait and see.
[Source: The Telegraph]