I was recently reading about thermoelectric generators. The thermoelectric effect was discovered in the early 19th century, it uses a temperature differential at the junctions of two different types of metal to generate electricity directly from a heat source. The effect also works in reverse, if a voltage is applied across the junctions one becomes hot and the other becomes cold. A common application of these devices is small scale cooling, like for computers of tiny beer fridges.
Despite it's early discovery and extreme simplicity thermoelectric power generation is limited to fairly niche applications. The Voyager space probes launched in the 1970's are powered by thermoelectric generators heated by radioactive decay. Voyager 1 is now the furthest distant artificial object from earth, having passed out of the solar system into interstellar space. After 38 years of operation it's thermoelectric generator still provides enough power for the radio transmitters. Closer to home thermoelectric generators heated by gas or kerosene were used for electroplating, and even powering radios.
So far as I know thermoelectricity has never been used to power a vehicle before, so I thought it would be fun to try and build one.
A small thermoelectric module, commonly used for computer cooling. This will be the basis of this project. These cost about $3 from China.
I made small methtylated spirit burner to provide the heat. Standard small scale live steam technology.
This is the complete generator unit all assembled. The burner heats a block of aluminium inside the firebox, which is attached to the hot side of the thermoelectric module. Heat is dissipated from the cold side by a CPU heatsink.
A test was made to see if the generator would actually work, and to confirm the rates of heating and cooling were adequate. Initial results were promising, so a small tram like vehicle was built for it to power.
The heatsink sits on the roof, with a cooling fan to draw air past the radiator fins. The tram is powered by a small 3v motor and home made gearbox.
Of course it needed a paint job. I imagined it might have been used as an alternative to steam on unelectrified lines, so it's got a bit of a Sydney thing going on. This is the firebox end. The methylated spirit tank sits under the end platform.
And of course a few photos actually running (in the rain!)
I'd say the experiment was a success, it actually works pretty well. The thermoelectric generator makes about 2.5v at 150ma, which is enough to not only power the motor but also the lights and cooling fan. It takes about five minutes to warm up to running temperature after lighting up, then trundles around quite happily as long as the fire is burning.
Based on how the tram runs it looks like it would be quite possible to build a moderately powerful locomotive with multiple thermoelectric modules.
So how does this compare to steam as a form of traction? In this small scale the efficiency is comparable, but I'd say steam would win on thermal efficiency in larger sizes. On the other hand it is extremely simple to build and operate, no pressure vessels or need to carry water.
Here's some dodgy hand held video of it running:
Despite it's early discovery and extreme simplicity thermoelectric power generation is limited to fairly niche applications. The Voyager space probes launched in the 1970's are powered by thermoelectric generators heated by radioactive decay. Voyager 1 is now the furthest distant artificial object from earth, having passed out of the solar system into interstellar space. After 38 years of operation it's thermoelectric generator still provides enough power for the radio transmitters. Closer to home thermoelectric generators heated by gas or kerosene were used for electroplating, and even powering radios.
So far as I know thermoelectricity has never been used to power a vehicle before, so I thought it would be fun to try and build one.
A small thermoelectric module, commonly used for computer cooling. This will be the basis of this project. These cost about $3 from China.
I made small methtylated spirit burner to provide the heat. Standard small scale live steam technology.
This is the complete generator unit all assembled. The burner heats a block of aluminium inside the firebox, which is attached to the hot side of the thermoelectric module. Heat is dissipated from the cold side by a CPU heatsink.
A test was made to see if the generator would actually work, and to confirm the rates of heating and cooling were adequate. Initial results were promising, so a small tram like vehicle was built for it to power.
The heatsink sits on the roof, with a cooling fan to draw air past the radiator fins. The tram is powered by a small 3v motor and home made gearbox.
Of course it needed a paint job. I imagined it might have been used as an alternative to steam on unelectrified lines, so it's got a bit of a Sydney thing going on. This is the firebox end. The methylated spirit tank sits under the end platform.
And of course a few photos actually running (in the rain!)
I'd say the experiment was a success, it actually works pretty well. The thermoelectric generator makes about 2.5v at 150ma, which is enough to not only power the motor but also the lights and cooling fan. It takes about five minutes to warm up to running temperature after lighting up, then trundles around quite happily as long as the fire is burning.
Based on how the tram runs it looks like it would be quite possible to build a moderately powerful locomotive with multiple thermoelectric modules.
So how does this compare to steam as a form of traction? In this small scale the efficiency is comparable, but I'd say steam would win on thermal efficiency in larger sizes. On the other hand it is extremely simple to build and operate, no pressure vessels or need to carry water.
Here's some dodgy hand held video of it running:
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