Lets add a little bit bionics into the energy system of autonomous house
Our autonomous house energy system should be omnivorous

Bionics - application of biological principals to the study and design of engineering systems (especially electronic systems)
(KThesaurus by Daniel Naber, under GNU License)

No living being eats some especially standardized food, for example, only apples, that are larger than 10 centimeters.

In order not to become similar to designers of gigantic wind farms, we have decided to construct our autonomous house energy system as omnivorous and undemanding to the nourishment regularity. That's mean, if there is wind - it feeds by the wind. If there is sunlight - feeds by the sunlight. The same concerns also the thermal energy of air and soil. But if there is nothing - it feeds by its own fat reserves.

If now there are apples smaller than 10 cm, then it is possible to eat them either. That's mean, if there is cloudy weather, the temperature of air is -15 degrees C, the temperature of soil at depth 10 meter is +3 degrees C, wind is 5 m/s - then the energy system of autonomous house must eat these drops of the environmental energy.

Usual wind turbines are economically effective for wind speed more than 8 metres per second. At the air temperature under +5 C air heat pumps (and air-conditions) expend much energy to unfreeze the air radiator and extract little heat energy from air. Geothermal (soil, ground) heat pump and solar collectors will bring little heat too.

But to produce useful energy, the geothermal heat pump should consume some energy. It is possible to use wind power, to gather energy for the heat pump compressor. If, instead of the classical wind turbine to use the method of low-speed wind energy extraction, which is more economical (for example, low-speed wind engine-propeller with the working blades made from the durable synthetic fabric for tents), then from one megajoule of kinetic energy of weak wind, it is possible to gather a little bit more, than one megajoule of heat energy.

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