One of the success of the 20-th century science is connected with the realization of methane fermentation phenomenon in artificial way and the installation of them widely in everyday life. Such kind of devices, where the generation of biogas is fulfilled, are called plants or reactors of biogas [93]. Today, in the world, the number of such devices reaches several millions.

We built the reactor of biogas generator. It was the first industrial reactor in Armenia. In a number of problems, it helps to understand also peculiarities of methane and carbon dioxide origin in anaerobic way in caves.

The reactor has 2,5 tons of a liquid massif and gasgolder with ~1m³ in volume. The device is installed in Giulagarak village of Lori region. It was built in 1991 - 1992 ( Figure 82 ).

Figure 82. General look of a biogas reactor form and incision.

The principle of the work of the device is the following: the organic substance is filled through one tube in the reactor and the manure goes out of the reactor through the other tube. In the reactor the phenomenon of methane and CO₂ origin takes place and generated gases are collected in under the gasgolder. The reactor gave the opportunity to understand the methane and CO₂ origin regularities in caves. So, if a dry raw material is filled in the reactor, methane doesn't occur. The same way in dry inventilated caves, where draughts dry the organic material existing in caves, methane doesn't occur. In the reactor, the obligatory condition of methane origin is humidity of a raw material. The same way it is obligatory that that part of the cave, where the organic raw material is, to be badly ventilated. In that case, water, being contained in poultry manure or guano, keeps the raw material in humidity constantly, which is the necessary condition of methanic bacteria activity. Stability of the temperature regime is also important. As much as it is less subjected to fluctuations, so the percentage of methane origin remains stable. With change of a cave temperature CH₄ : CO₂ correlation subjected to changes. It decreases with the increase of temperature, and increases with the decrease of temperature.

Anaerobic generation of methane and carbon dioxide has two regimes: constant and periodic. The constant generation exist in those caves, in which fresh plant remains are provided the whole year. The other way round, those caves which are habitable only periodically, methane and carbon dioxide gas are generated only the part of the year, till a poultry manure accumulated in a cave hasn't lost its freshness.

Investigation of biogas reactor feeding regime give the opportunity to calculate the quantity of methane and carbon dioxide gas every day origin in caves in general. 1 kg of fresh poultry manure everyday provision steadily ensures several ten litres of biogas receiving.

Let's say that comparison of " methanic " caves with biogas generation reactor has the applied meaning as well as theoretical interest. The thing is that methanic reactors, though they are widely spread all over the world, have an important deficiency, which makes their productivity less in winter months.

In low temperatures, the uninterrupted work of the reactor can be ensured only in the case if it is possible to discover bacteria group able to generate methane, in low temperatures. It is known, that caves, being separated places, create peculiar conditions: constant humidity, insignificant temperature fluctuations, ionization high level and others. In such peculiar conditions, when the conditions of life development change, special animal world is formed. It is testified on the main dwellers of the caves insects many times. It can also refer to bacteria with great probability. It is possible to discover such bacteria in caves, which are able to transfer the organic row material into methane in low temperatures. It will give the opportunity to receive reactors able work efficiently the whole year.