Wind power systems for heat supply of settlements: Comparative assessment of existing analogs

 

Heat pumps, water and air solar collectors, solar thermal power stations and other can be considered in some measure as analogs of wind power heat supply systems.

Heat pumps. Heat pumps employ energy of surrounding for thermal power production. The main benefits (fig. 4.5) of heat pumps are high economical and energy effectiveness and ecological security. Heat pomp consumes electrical power more effectively than other power equipment. According to developers when using of 1 kWh of electrical energy about 3…4 kWh of thermal power are produced.

The deployment of such systems for heat supply and hot water supply permits to save about 70 % of natural gas. But the deployment of heat pumps is characterized by large initial investments, large areas necessary for posing of heatexchanging tubing and low temperature in the output of system. Technological process of taking heat from environment is not ecologically clean and problemless. The drilling of deep bore holes and taking heat from the environment have a sufficient negative impact on the environment, as at operation heat pumps  destroys natural balance, that was sustained in some ecological space volume: underground, in the air or in the natural water pool. So at analysis, this type of geothermal technologies was rejected in the reason of low energy effectiveness and non-correspondence to ecological requirements.

 

Solar thermal technologies. Solar equipment is the most promising type of thermal renewable power technologies that will provide in the near future the enormous quantity of clean and sustainable energy. Antic philosophers emphasized an important role that Sun plays in emergence and sustenance of life on the Earth. But today solar systems produce only small part in a total balance of consuming electrical and thermal powers.

 

Water and air solar collectors. Active method of solar heating (cooling) of buildings with the solar collector is based on the greenhouse effect. Solar absorber of sun radiations include as the components a transparent for solar radiations window, copper tubing, filled by heat carrier and a substrate. Thermal receiver absorbs solar radiation flux, whose intensity does not exceed the value of solar constant or 1250 W/m2. That why it is involved to create the low temperature systems for heat supply and can not be used as a basic element of heat supply system taking into account low energy effectiveness.

 

Concentrating thermal solar power systems (fig. 4.6). Sun energy can be converted into thermal and electrical energy using well known technologies: thermal and photonic. The most frequently employed thermal solar technology allows converting the sun energy into a heat. The heat can be stored and saved in thermal capacities for the subsequent use, especially, for production of electric power by means of the proper equipment. In the sun thermal power equipment the energy of sun radiation is used as a source of heat in the thermodynamics cycle of transformation of thermal energy into mechanical energy with the aid of solar steam generator and then into electric energy. The thermochemical cycle of solar energy conversion consists of successive reverse endo- and exothermic reactions, in which sun energy is employed in the first stage in the endothermic reactions, and in the second stage the energy is liberated in the exothermic reactions and is supplying to the users.

The key advantage of thermal solar power plants is storage of thermal energy in sunny day hours and its use for electrical energy production in night hours. This factor permits to regulate load in the electrical network. Another important benefit is a possibility of direct employment of accumulated thermal energy for heat supply of buildings and industrial processes. Unfortunlly in the most constructions a heat supply function is auxiliary.

The further development of the solar power plants is hindered by the next technological problems (fig. 4.7):

 

·        Instability of thermal and electrical powers production. The limited periods and climatic zones for energy production;

·        using of high capacity electric batteries for powering consumers in the absence of sun radiations;

·        indirect action of macroscopic solar power systems, necessity in several stages of energy transformation, and dependence of electricity from the stable flux of solar radiations;

·        using of complicated thermochemical cycle for solar energy conversion into thermal and electrical power;

·        using of complicated solar tracking systems;

·        relatively low employment of the installed capacity (30%);

·        high cost of building and high cost of electrical energy.

 

 

By Vasil Sidorov on October 10, 2012 

Technopark QUELTA, Queltanews from

Nizhyn Laboratories of Scanning Devices

sidorovvasil@gmail.com

 


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