The problem with the classical chemical batteries

We live in a world of increased demand for mobility. Phrases like "Ubiquitous networking, mobile computing and such are in everybody's everyday's language (well, almost everybody's). I will not say much. In order to be able to play/work with your laptop or PDA during your flight, or during a train trip, or even at the beach, or in general to use an electronic appliance out of your home, one is your restriction: power.

Since Alessandro Volta created the first electric battery somewhere in 1800, very little (compared to other science fields) has been achieved in improving The Battery. It still remains this annoying sine qua non thing which makes our laptops 35 percent heavier while occupying about 20 percent of their volume, and make all of our appliances die after some time of function (which time is usually surprisingly inadequate). Anyway, no need to say more, everybody has used batteries and knows the little devils they are. I read an interview once, of an well-known engineer who said that 'Today, how small our appliances can get is only depending on our battery technology'...

In short, batteries...

• are heavy
• are large
• are full of toxic materials
• are not able to store significant amounts of energy
• although some of them are rechargeable, soon lose their ability to fully recharge
• need replacement

The idea of gas turbine micro-engines¹

1_{Or 'jet batteries' as they are usually called}

So, the story goes like this: Some guys at the MIT (well, where else...), thought that somehow, something has to be done for the fact that in some grams of gas there is energy that equals the energy contained in some dozens of batteries (to say the least).

Of course, there was available since many years the gas turbine technology which transforms chemical energy into any other form of energy required with plausible efficiency: The turbines of 3 Boeing 747s can produce as much power as a medium sized nuclear power plant. However, a combination of material technology immature* for small-scale engines (with almost nanoscale parts), along with no great need for portable devices with great energy consumption, made the prospect of using ordinary fuel (such as gas) to power electrical appliances, to seem very far away. Until now.

_{*The problem which needed solving was the high-cycle fatigue phenomenon, which may break even the highest steel quality blades after some time because of the vibrations caused to the blades due to air pressure changes.}

During the very last years, the great shrinking of electronic components spurred innovation in battery technology because what's the point in a wonderful PDA if it cannot be supported by its energy source for more than 30 minutes, which energy source incidentally weighs almost as much as the PDA itself...

So, engineers at MIT sat down and using the latest material technology designed a miniature gas turbine the size of a small coin whose little blades spinning at million times per minute can produce enough electricity to power a PDA or a cell phone. I should here note that the whole concept of gas microturbines (whose father is Alan Epstein) relies heavily on Micro-electro-mechanical systems.

The deployment of gas turbine micro-engines

For the time being, all individual parts of such a machine are developed and tested, i.e. the fuel burning combustion chamber, the spinning turbine blades and the encasement (with the necessary holes for the air intake and the fume exhaust) of the whole apparatus. The only problem now is that the scale of the blades in conjunction with their millions per minute rotations causes them instability and the turbine cannot run continuously. But as engineers note, it is a trivial matter of time to correct it and they expect to present us with fully functional micro turbines in 2 to 3 years, with commercial products starting to appear in up to 4 years from now.

What about fuel cells?

The research team accepts that fuel cells are their big competitor. But as they say, micro gas turbines have inherent advantages which will soon make their invention much more effective than fuel cells. First they are much smaller even from the smallest available fuel cells today. Second, and most important, where a typical fuel cell can produce 1 or 2 watts of electricity, the micro gas engines can produce some 20 or more watts, making them ideal for deployment in energy demanding appliances like laptops where more than one micro engine could be used to provide the required energy. Last (but not least I guess), there is the issue of the fumes produced by the gas burning, which in the case of a fuel cell is pure water. But what do you know? Nobody's perfect...

Future prospects

Such small engines (or perhaps somewhat bigger) could be used in home environments, to provide electricity in cases of power outages or even to completely disengage a house from the power grid. (Personal thought: Why would we want to further tie up our lives with oil consumption, I do not know...) At the very least, the engines could be used as backup scheme for appliances like computers, TV sets etc. The engineers even think their engines on a chip could be used in poor countries to bring electricity in places where no company would deploy a power grid due to high costs with no profit prospect (ahh, capitalism...)