Traditional internal combustion engined cars are noisy, complex and inefficient, wasting a lot of the energy from the fuel they consume as noise and heat. They’re also pretty bad for the environment.
Electric cars are efficient, powerful and simple to maintain, but they too are limited by the relatively low energy density, long recharge time and limited shelf life of the battery packs which usually power them. And in order to produce electricity from liquid fuels, you’ve had to burn the fuel first, releasing energy to drive a generator.
But now a team of scientists from MIT say they’ve figured out the underlying physics of a new type of energy generation which could one day make it possible to generate electricity directly from liquid fuels using a process called a Thermopower Wave.
There’s no heavy pollution, no noisy engine, and intermediary energy state, although the technology is still very much in the experimental stage.
First discovered four years ago by researchers in Prof. Michael Strano’s chemical engineering lab at MIT when they impregnated a piece of carbon nanotube yarn with TNT and lit it with a laser, thermopower relies on the controlled chain-reaction of burning fuel one molecule at a time.
Many times thinner than a human hair, carbon nanotubes are covered in a tiny layer of liquid fuel which dries almost immediately. It is then lit from one end by a heat source and the fuel is burned uniformly along the length of the nanowire in a controlled chain reaction.
As the energy in each individual molecule is released, so too are free electrons, which pass up the carbon nanotube ahead of the reaction, creating a current along the wire.
The actual chemical reaction taking place isn’t something that’s easy to describe here, but the actual process of freeing the electrons to create a current flow doesn’t create large amounts of noxious gasses.
“The fuel need not form polluting emissions,” Professor Strano told us in an email earlier today. “Only the heat is used in the generation.”
So far, the team has launched thermowaves using ethanol, sugar and formic acid (from fire ants). The specific energy density of the process depends greatly on the fuel being used but, say the researchers, the process has the capacity to be many many times more energy dense than even the latest lithium-ion battery technology.
Since the carbon wire nanotubes are heat resistant, they can easily be reused time and time again, while the coated nanotubes can be stored indefinitely, making them ideal for backup energy storage applications.
Recently, Professor Strano and his team discovered that switching from nanotubes to flat sheets of single-atom materials — like graphene — not only allowed them to improve the performance of the thermowave but also boost the efficiency.
Eventually, it is hoped that nanowire thermowave generators could be built with thousands of nanowires joined together to continually generate pulses of energy from liquid fuels, using conventional electrical circuits to smooth out the power and use it to drive a electrical gadgets, devices and even electric cars
In the case of a transportation fuel, refuelling would take place in a similar way to a gasoline vehicle — but without the harmful emissions associated with internal combustion engines, while increased energy density would make it possible to have a far greater range vehicle than with current battery technologies.
If you’re into physics and want to understand the process better, you can see Professor Strano’s presentation from MIT two years ago. He discusses the Thermopower Wave in detail around the 14:28 mark.
In the meantime, let us know what you think of this new, very experimental yet promising technology. Do you think it could take over from battery packs as a way of storing energy? Would you like to learn more? Or do you want to see it in a practical application before you get excited?
Leave your thoughts in the Comments below.
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