This paper describes three operating biogas plants with a comparable electrical power of 600 kW. The plants are situated in Germany and were constructed between 2007 and 2013. They belong to one owner who has a farm with an area of ca. 1,200 ha, oriented towards plant production. The article presents technological solutions applied in biogas plants; an attempt was also made to determine their effect on the amount of electricity consumed in the process (operation of stirrers, substrate feeders, pumps, control systems, lighting, etc.). Despite similar electrical power, the biogas plants differ in terms of construction and technological solutions. The differences stem mainly from the number and capacity of digestion chambers, the method of biomass stirring and the method of substrate supply. The preliminary conclusions from observations of these facilities confirm the literature data concerning the consumption of electricity in the process compared to total electricity production. The paper also presents the capacity factor for each facility and the level of heat use from cogeneration.
The paper presents a concept of building a passive heat transport system based on the use of an antigravity thermosyphon with a bubble pump. Such solutions are suggested when the heat source is located above the place of its reception, e.g. in the case of solar collector installations. One of the components of the system is the device forcing the circulation of the heating medium. In the presented system, this process is carried out without the use of additional external sources of energy, such as electricity, to supply the circulating pumps. Such an installation is autonomous, so the risk of failure is diminished. It is also possible to automatically adjust the system to changing operating conditions without the need for additional automation. Other known solutions of this type are not used due to their imperfection. The challenge is to select the right working medium, whose physical properties should on the one hand transmit as much heat as possible, and on the other hand enable the pumping of the heating medium to be performed with low energy consumption. In the opinion of the authors of the paper, it is possible to achieve with the use of two working media in one system: water and a substance with a low boiling point.
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