an inexpensive wind turbine to start with: http://www.a4.fr/realisation-dune-eolienne_c747_1010.html they also sell a 10Farad supercapacitor at 2,7V or 27s of current at 1A or 270s at 100mA or 2700s at 10mA but a insufficient voltage for an LED. Several must be used with care. Supercars...

Funny, the simplest is a bicycle with its lighting dynamo (alternator in fact), a bridge of 4 rectifier diodes, and commercial LED lighting lamps at 3,6V (for Li ion battery), which give a good lighting, almost without work (a few wires) and with little effort (10 to 30Watts). We sell...

The plastic of the commercial plastic bottles is not resistant to the UV of the sun and becomes brittle and friable and is colored in more opaque brown, so we must change them after a few months (2 to 3 months in summer). Good for troubleshooting only.

Did67 wrote "There, I think this is a false lead. Because wood (or even pellets) already contain a variable quantity of water, to which is added that resulting from combustion (therefore from the oxidation of H atoms). Unlike "fatty" fuels (oil, etc.)" Hum...

https://www.econologie.info/share/partag ... oTQMGa.jpg

this image of the yield abuk with T and CO2 comes from elsewhere and I can not insert it into the text;
take on the site. This system is too complicated.

more exact answer on stove and boiler combustion efficiency more exact used by professionals: It is necessary to measure the CO2 rate which measures the quantity of gas or wood burned per liter of smoke: https://www.econologie.com/fichiers/partager2 /1263832553oTQMGa.jpg note as for long...

The thermometer stuck on its support (pipe) only has the same temperature as its support if the cold outside air does not cool it. So we insulate it with a little glass wool the size of the thermometer and we measure the exact temperature of the support. It's the same with a medical thermometer, we...

If we want the precise yield we risk never finishing because the maximum energy or enthalpy available in the wood depends on the conditions chosen to measure it in the laboratory or the same problem of quality and mode of combustion exists. The measurement temperature intervenes why 0°C p...

Instead of looking for the unknown value of the emissivity, and remaining confused, you measure T by sticking an ordinary thermometer going at least to 100°C on the pipe, insulated with a little glass wool, (value of T exact to within a few degrees) and you compare with the temperature reading...

Given the outlet temperatures 200°C outside and more in the gases, the efficiency is low and the fairly long evacuation pipe serves as an exchanger to heat and improve the efficiency if the heat goes into the house!! The actual gas temperature must be measured with a thermocouple or probe...