Jet Engine on a Chip

Roland Piquepaille writes "Today, our handheld devices are powered by batteries, which are heavy and inconvenient. Fuel cells are just arriving on the market as a replacement. But there is a new contender: micro gas turbine engines under development at the MIT. Engineers there shrunk jet engines to the size of a coat button. And their blades which span an area smaller than a dime can spin a million times per minute and produce enough electricity to power your PDA or your cell phone. While there are still a few hurdles to overcome, these micro turbine engines should be operational in two or three years, with commercial products available four years from now. These micro jet engines also have the potential to free soldiers or travelers from carrying heavy batteries. The engineers even think their engines on a chip could be used in poor countries to bring electricity there. This summary gives you the essential details about a technology which promises to free us to carry extra fuel instead of batteries."

Comments

Re:Cool, but misleading title

[kaszeta]

Gas Turbines are some of the most efficient fuel -> energy converters known to man.

Actually, in terms of the overall thermodynamic efficiency, they aren't all that great. 40% efficiency is *very* good for a Brayton cycle (i.e. turbine engine) system, but is fairly easily done with a large-scale steam system. Microturbines tend to run around 25%, which means that (a) you need a fairly big recuperator to run efficiently (which doesn't seem to be part of the MIT design), and (b) you need to be able to reject a lot of waste heat (so running your laptop on one of these means you'll be blowed 200+ watts out the back).

Not that gas turbines are without their advantages. Their specific power (weight per kW) is very good, so for the same amount of power the engine is very light compared to most other engine types (which is why they use them in aircraft). They also start and stop quickly compared to steam turbine systems. And they can be nicely combined with other systems like a steam system to make a combined cycle, the whole system can be fairly efficient.

But, by themselves, they aren't all that efficient.

Can we PLEASE STOP linking to this guy's blog???

[sczimme]

In all seriousness, why does /. continue to link to his ramblings instead of to articles that contain real, useful, technical content?

Yes, this is probably off-topic (as in "not about tiny turbines") but it is still relevant. At least give us the option to ignore him.