I was reading the latest issue of PC Pro (145) when I found a news item on the development of gas turbines for powering laptops and other mobile devices. The MIT research team claim that such a turbine built up of silicon components could provide power for 10 times as long as conventional batteries for the same mass. This is an interesting use of gas turbine technology, not least because I used to design large power generation turbines.

The competing technologies are likely to be enhanced batteries and fuel cells. Based on my experience, I can’t help wondering why there is any practical advantage to the gas turbine option since all mobile devices struggle against temperature and fragility problems.

It’s hot!

Gas turbines burn fuel in order to generate mechanical power through rotation. In conventional turbines this results in a lot of radiated heat energy which, as the MIT team suggests, can be contained by controlling combustion air flow. However, this doesn’t reduce the thermal load, just redirects it. You still end up with a hot exhaust that must be vented somewhere, not comfortable if it’s your lap!

Don’t drop it.

Modern mobile devices are generally reducing the number of vulnerable moving parts. The last remnant is usually in data storage media where solid state components are gaining in popularity and I suspect may become the norm in future years. The spinning platters of a hard drive are not unlike the rotor in a gas turbine, give it a good knock and the spinning parts hit the static parts resulting in… well have you ever heard the grinding of a hard drive failure? Not pretty as components spinning at thousands of revolutions per minute carry a lot of kinetic energy.

What type of power?

As you might have noticed above, a gas turbine alone generates mechanical power not electrical power. Unfortunately, it’s electrical power that your laptop enjoys most. In conventional power generation you need to attach a generator set to the gas turbine to convert the mechanical power of the rotating parts into electrical power. None of the articles I’ve read so far mention MIT developing a tiny generator set!

Interesting it may be, but useful?

The attractions of the fuel cell lie in its ability to convert chemical fuel energy directly into electrical energy without any moving parts and at a much lower temperature than a combustion gas turbine. Whether you really want a computer full of highly flammable fuel sitting on your lap is open to debate, especially since batteries have been exploding recently. But if you do, I personally feel that a gas turbine is definitely not the way to use it. The future of power for the mobile technophile is much more likely to be small polymer based fuel cells or advanced batteries.