Renewable energy-it is not only solar and wind energy.

There are also more original solutions.

One of them is osmotic power plant.

Mixing one liter of fresh water and one liter of sea water (3.4% salt solution) we increase entropy on about 8 J / K.

A = TΔS

If the temperature of the environment is 300 K, such entropy growth allows us to convert 2400 J of heat into 2400 J of electrical energy. In our previous work we developed a device for electrical energy generating by mixing salt and fresh water [1],[2].

So, as we could see entropy growth allows us to convert  heat energy into electrical energy.

Photon gas entropy. Now I’d like to say several worlds about thermodynamic properties of an object such as a photon gas.

As is known, the entropy of the photon gas depends on the number of photons.

If photon gas is irradiated by heated body, an entropy of each photon radiation is about 4 * 10^-23 J / K.

Total entropy can be defined as ΔS = 4 * 10^-23N, where N-number of photons.

I would like to pay your attention to the fact, that the energy of the photon in this expression is not included.

Truth, when we speak about thermal radiation, the expression ΔS = 4 * 10^-23N  could be converted to standard expression for entropy change

ΔS = Q / T,  where Q = Nhν  and ν (middle frequency) could be approximately defined as Tc / b (according to Wien’s law).

Much more interesting results are obtained by the consideration of entropy of non-thermal photon gas (for example, irradiated by radio antenna).

In that specific case  the entropy per one photon could be calculated by the Boltzmann formula :

S = k Σ p_i ln (p_i)

where p_i-is the probability to find a photon with the frequency ν_i in photon gas.

Thus, only the monochromatic radiation does not take away the entropy from the system.

If the generator produces a mixture of 2 frequencies ν₁ and ν₂, and the probability of radiation photon with frequency ν₁ and ν₂ are the same, each photon will carry out from the system an entropy, which approximately  equals 10^-23 J / K.

So, photon gas which containing 5 * 10²⁶ photons with frequency ν₁ = 1 MHz and 5 * 10²⁶ photons with frequency ν₂ = 2 MHz will have an energy of 1 J and entropy 10 000 J / K.

Increasing the entropy of 10000 J / K at a temperature of 300 K allows us to convert 3 MJ of heat energy into 3 MJ of electricity.

Lets make an analogy with heat engine.

Why, from the point of view of thermodynamics, heat engine needed a fridge?

Fridge is necessary for  heat engine to take away an entropy.

Classical heat engine receives from the heater entropy

(ΔS₊ = Q₁ / T₁), and gives it to the refrigerator (ΔS- = Q₂ / T₂).

If  ΔS₊ =ΔS-, and

Efficiency = (Q₁-Q₂) / Q₁, is easy to get the classical expression for the maximum the efficiency of the heat engine efficiency = (T₁- T₂) / T₁.

But as it was shown earlier heat dissipation in the fridge- is not the only way to take out an entropy.

Non-thermal photon gas could carry out an entropy too.

Irradiation of photon mixture with frequency ν₁ = 1 MHz and

frequency ν₂ = 2 MHz (number of photons with frequency ν₁ approximately equals the number of photons with frequency ν₂)   is equivalent of having a fridge  with an effective temperature in 10^-4K.

So, theoretically it is possible to create a machine, which will convert heart energy into electrical energy and irradiate a mixture of photons in radio band, and it will not be a violation of the second law of thermodynamics.

We can suggest, that not only radio waves carry out an entropy from the system, but gravitation waves carry out an entropy from the system too.

An equation S = k Σ p_i ln (p_i) could be used for calculation of the graviton gas entropy too.

This equation could explain the facts of self- organization in gravitation field.

Conclusions.

1. The entropy per one photon of non-thermal photon gas could be calculated as S = k Σ p_i ln (p_i), where p_i-is the probability to find a photon with the frequency ν_iin photon gas.
2. The calculations shows, that mixture of photons, irradiated by radio antenna, carry out from the system considerable entropy.
3. The equation A = TΔS shows as, that entropy growth allows us to convert  heat energy into electrical energy.
4. Theoretically it is possible to create a machine, which will convert heart energy into electrical energy and irradiate a mixture of photons in radio band, and it will not be a violation of the second law of thermodynamics.