Possible to make a cheap and simple steam electric generator for camping/rural use?

[GrahamF]

Would it be possible to make a very compact and lightweight steam engine powering an electric generator that can be taken back country camping and used to keep lights and other devices charged the entire time just by looping it into the campfire? And could it be expanded to being hooked into the wood stove of a cabin to keep the lights and other devices running as long as there is a fire in the stove? How cheaply could such a generator be made while still producing an acceptable amount of power, such as charging a smartphone at full speed in the small camping version and possibly running a full cabin's lighting and a computer and Starlink internet connection in a larger version?

[exchemist]

54 minutes ago, GrahamF said:

Would it be possible to make a very compact and lightweight steam engine powering an electric generator that can be taken back country camping and used to keep lights and other devices charged the entire time just by looping it into the campfire? And could it be expanded to being hooked into the wood stove of a cabin to keep the lights and other devices running as long as there is a fire in the stove? How cheaply could such a generator be made while still producing an acceptable amount of power, such as charging a smartphone at full speed in the small camping version and possibly running a full cabin's lighting and a computer and Starlink internet connection in a larger version?

Probably not. You need a heat pipe to get heat out of the fire, the engine and generator and a condenser/radiator. I have seen pictures of a Stirling cycle engine used for this, but it was not very lightweight or compact. 

If you just want to run low power electronics and an LED light or two, and light weight is a priority, I would think a thermocouple (thermoelectric generator) might be a better bet. I've had a quick look on the web and it appears such devices are in fact commercially available.

[studiot]

3 hours ago, GrahamF said:

Would it be possible to make a very compact and lightweight steam engine powering an electric generator that can be taken back country camping and used to keep lights and other devices charged the entire time just by looping it into the campfire? And could it be expanded to being hooked into the wood stove of a cabin to keep the lights and other devices running as long as there is a fire in the stove? How cheaply could such a generator be made while still producing an acceptable amount of power, such as charging a smartphone at full speed in the small camping version and possibly running a full cabin's lighting and a computer and Starlink internet connection in a larger version?

Very interesting proposition and well worth discussing.  +1

Compact  ?  

Efficient  ?

Simple  ?

You missed one  -  Safe ?

 

I don't think steam is the way to go but it is certainly possible.

 

Let us say that your power requirements are up to a couple of hundred watts and work with that.

This is available from Hero's steam engine in Ancient Greece a couple of thousand years ago.
Modern estimates, base on available model engineering place the efficiency as between less than 0.1% and up to 1%.

But there are many practical and safety drawbacks to steam since you loose the working fluid by expansion and have to keep topping up the water supply.

Speed regulation would also be required as the output would otherwise vary over a very wide range, as the device spin speed is heavily temperature dependant and a camp fire is not a steady temperature.
From a safety point of view, the exhaust steam would need safe dissipation.
Topping up the water is not only  a chore, but also a safety matter since any boiler could explode with too little water.

So  a closed system should be devised.

 

By using hot water rather than steam this could be achieved.

Any electric moter can be run as a generator so thinking about central heating pumps, with come in a 20 to 200 watt range their technology could be employed.
Such pumps are available with an impellor rotor sealed in a chamber and driven magnetically by the mains supply.
Reversing the idea could produce wattage in the desired range,
So a sealed chamber heater with some tubing could provide a ciculating system which drives a gravity hot water flow, safely and more controllably than with steam.

 

However other modern technology, as described by exchemist (+1) also fall within this wattage range.

Quote

https://www.intechopen.com/chapters/65239

A single TEG generates power from 1 to 125 W. The use of more TEGs in a modular connection may increase the power up to 5 kW and Δ T _max could be bigger than 70°C. Heat source , for example, a heat pipe system (the TEG devices and the heat pipe system can be used together in waste heat recovery systems).

In this case the device would be indirectly heated by the campfire to keep within its operating temperature range.

 

So these are practical points for thought and discussion.

[GrahamF]

Could you have a device where instead of a large boiler tank you just had a fireproof pipe loop with a flash boiler of some sort and a steady water source? It could have a water bag or a feed from a river that it pumps to the flash boiler on demand which is then fed to the generator for electricity. So there would be a thin hose that's fed from a bucket or a bag which gets fed into a self-contained device that pumps the water into a very thin pipe that ends with a metal bulb you place directly into the fire, which turns the water into steam which goes into a different pipe (or the other channel on a combined hose or pipe) back to the device, which converts it to electricity for use, with a battery or capacitor acting to regulate the electrical power.

[Sensei]

If your goal is to have electricity, solar panels and wind turbine are the best option, not some steam engine, unless you are in northern Canada, Norway, Russia or Antarctica and have six months of night..

It's even illegal in most countries. You would have to steal the wood.

Some modern campers have built-in solar panels on the roof..

 

[sethoflagos]

They're out there. See Green Steam Engine

[Sensei]

5 hours ago, GrahamF said:

Would it be possible to make a very compact and lightweight steam engine powering an electric generator that can be taken back country camping and used to keep lights and other devices charged the entire time just by looping it into the campfire?

Only a small portion of all energy will be converted into electricity.

5 hours ago, GrahamF said:

How cheaply could such a generator be made while still producing an acceptable amount of power, such as charging a smartphone at full speed in the small camping version and possibly running a full cabin's lighting and a computer and Starlink internet connection in a larger version?

Start by using a wattmeter on these devices, and then find out what the heat conversion factor of a steam engine is to electricity, and you'll know how much you need to burn to make it work.

Quote

Possible to make a cheap and simple steam electric generator for camping/rural use?

Cheap, simple, that means not advanced, that means inefficient, that is, the fuel-to-electricity conversion ratio unsatisfactory...

 

[GrahamF]

17 hours ago, Sensei said:

Cheap, simple, that means not advanced, that means inefficient, that is, the fuel-to-electricity conversion ratio unsatisfactory

If you have unlimited access to water and have a campfire going anyways, how important is it to be 100% efficient?

[exchemist]

2 hours ago, GrahamF said:

If you have unlimited access to water and have a campfire going anyways, how important is it to be 100% efficient?

Indeed. In fact the thermoelectric devicesI was talking about are only ~10% efficient at best, I think.  But that doesn't matter to a camper. You have plenty of heat available and what doesn't get turned into electricity performs a useful function of providing the heat of the campfire.  

[Ken Fabian]

If it is electricity from collecting plant material you want you might do better with gasification and running an internal combustion engine off that - you won't need a steam boiler which is a dangerous piece of equipment that usually requires regular testing and certification for safety - and possibly certification for the operator as well.

But not sure that steam or gasification will be compact or easy to transport.  A small, mobile gasifier generator -

 

[GrahamF]

16 hours ago, Ken Fabian said:

If it is electricity from collecting plant material you want you might do better with gasification and running an internal combustion engine off that - you won't need a steam boiler which is a dangerous piece of equipment that usually requires regular testing and certification for safety - and possibly certification for the operator as well.

But not sure that steam or gasification will be compact or easy to transport.  A small, mobile gasifier generator -

 

A gasification kit would be unrealistic to take backpacking, but I suppose a tiny (like smaller then a 2l milk jug) ice generator that uses a standard kerosene tank might be doable, if it has a small battery and start-stop technology. It wouldn't be as cheap and would need to be very efficient but it's an avenue worth exploring.