The challenges of hydropower engineering. River flows and wind are considered as the oldest renewable energy sources that were used by people for implementation of certain mechanical works, beginning from the water-supply of settlements, irrigation of agricultural lands, grinding of corn and concluding by putting into motion of industrial machines.

 Development of hydraulic and wind technologies took place in parallel, independently one from another. In localities situated near the rivers, dikes were built and energy of streams of water was used. In localities remote from rivers, the wind technologies based on the use of air flows got development.

In new times with appearance of electric generators, electric engines and lines of electricity transmissions the direct use of mechanical energy of water and wind practically ended and was taken to building of the hydroelectric power stations which along with thermal and atomic power-stations provided the necessities of population and industry in «universal» electric energy. Thus the amount of electrical energy that is produced on the hydroelectric power stations in general balance of production of electrical energy in the industrially developed countries went down constantly. The reason of this is reduction of hydrotechnical resources and low cost of electricity, which is produced on thermal power-stations that are working with the use of organic fossil fuel.

In today’s power engineering the hydroelectric power stations, in that number pumped storage type, play the role of regulator of the peak loading in powerful electric networks. They take in the surplus of electric energy at its over-production, providing hydro-accumulation of energies by pumping of water onto upper level (classic HPS), and add an electrical energy to the electric network in the case of increase of consumption (classic HPS and PSHPS).

The challenges of a new millennium, which are related to reduction of world fossil organic block fuels, and also threat of rise in the temperature of Earth which scientists correlate with influencing of greenhouse gases, again came into notice of humanity to the renewable energy sources, in particular, to hydropower and wind power engineering. The experience got in recent years during exploitation of the hydroelectric power stations and wind power-stations allows to do a conclusion: steady development of hydraulic and wind technologies is possible only in the case of combination of advantages of both directions.

Indeed, hydroenergetic potential in a world yet it is far not exhausted and, pursuant to given UN reports, makes 50 000 billion of kWxhour during a year, while the total set power of HPS is equal 630 GW at annual production electric power by them of 2200 billion of kWxhour. If also take into account relatively low cost of building, large term of service of HPS, which can exceed 100 years, and competitive cost of electrical energy, the considerable prospects of hydropower engineering do not cause the doubt.

From other side, today HPS work only on 40% of the power, because of insufficient amount of the involved water flows. In separate countries, in particular, in the countries of Europe, hydrological potential is almost fully exhausted. Building of new power-stations creates the considerable ecological problems related to the submergence and swamping of territories, to the reduction of areas of agricultural lands. Building of dikes also inflicts considerable harm for migration of fishes. Public and authority of the developed countries with the large warning behave to building of a new hydroenergetic stations and spare large attention to conducting of previous researches of consequences of such building for an environment. In particular, Congress of the USA in April, 2009 directed the considerable finances onto the research of the newest hydraulic technologies of generation of electric current, onto the search of integration possibilities of classic hydroelectric technologies with the projects of the pumped-storage hydroelectric power stations. In the program on partner rights both state agencies and industrial enterprises are involved.

The specialists of Nizhyn laboratories of scanning devices during a few last years work to create new technologies of receipt of electric energy and of hydro-accumulation with the use of renewable energy of streams of water and wind subject to the condition of saving of ecosystem and providing of steady development of society. In accordance with our calculations by perspective directions of development of hydropower engineering are the dam-less hydroelectric power stations, the combined hydraulic and wind power systems of hydro-accumulation and productions of electric power onto the operating hydrotechnical buildings.

Dam-less hydroelectric power stations. One of ways of development of hydropower engineering is the building of the dam-less hydroelectric power stations with the semi-submerged and submerged hydro-turbines.

The sectional semi-submerged hydro-turbine (Fig. 1) can be set on a pontoon across a river, to use a force of water stream of only part of river-bed.  Power of turbine is determined by a diameter and width of the blades of turbine, and also by the velocity of water stream. In the case of necessity of increase of power on a pontoon a few cascades of sectional hydro-turbines can be set (Fig. 2). In this case total power of the cascade hydroelectric power station is determined as a sum of electric powers of separate components.

Similarly the submerged hydro-turbine can be used (Fig. 3). Construction and principle of work of the submerged hydro-turbine remind construction and principle of work of wind turbine, after the exception of that the water is an active body for the submerged turbine, and for a wind turbine – an air. Of course, water has greater specific gravity; therefore at other permanent geometrical parameters the power of the submerged hydro-turbine, which is determined by the diameter of turbine and speed of water stream, practically by eight hundred times is higher. In the case of necessity of increase of power into the river-bed of river a few cascades of the submerged hydro-turbines can be set (Fig. 4).

Combined hydraulic systems for hydro-accumulation and productions of electric power. At the variable unstable streams of water the sectional hydro-generators with the semi-submerged turbines and hydro-generators with the submerged turbines need the use of the complicated systems of stabilization of velocity of rotation of turbines and accordingly of stabilization of parameters of electric current, which is supplied to the users, or is sent into a general network. Adaptation of these hydro-generators is a not simple task and strongly affects energy effectiveness of such systems, adding new costs.

The rational use of the semi-submerged and submerged hydro-turbines foresees their parallel work with the operating classic hydroelectric power stations and pumped-storage hydroelectric power stations. In this case such systems can be used both for the direct generation of electric current with the use of remain of kinetic energy of stream of the «worked» water, and for hydro-accumulation of electric energy, by pumping of water from a lower level onto a top level, in other words, returning of water into a storage pool for the repeated use for production of energy at the help of regular hydro-turbines of HPS. Such method allows prolonging the operating cycle of regular hydro-turbines and promoting energy effectiveness of all hydroenergetic building.

On Fig. 5 and 6 the charts of the combined hydroenergetic systems for hydro-accumulation and productions of electric energy are shown accordingly with the semi-submerged and submerged hydro-turbines. Such hydroelectric power plants are set on lower level of hydrotechnical building on safe distance from a dike in the stream of the «worked» water that saves part of kinetic energy after passing through basic working hydro-turbines of HPS. The value of remain of kinetic energy after passing through regular hydro-turbines depending on the parameters of building and type of hydro-generators hesitates between 5…7%. High kinetic energy of water on lower level of HPS is stipulated not only by the remain of kinetic energy of the «worked» water, that go out from hydro-turbines, but also by the additional origin of flow of stream of water due to a natural hydrological flow.

Semi-submerged and the submerged hydro-turbines during work in the mode of hydro-accumulation are used for energizing of mechanical pumps, which return water into a storage pool. Implementation of these functions in a certain measure lowers the requirements claimed to stability of parameters of rotation of rotors of hydro-turbines.

Hydroenergetic system by power of 1 MW every second is able to lift 10 m³ of water into a storage pool onto the height of 10 meters. Accordingly, for days only one such system is able to accumulate in a storage pool more than 860000 m³ of water. System of hydro-accumulation, that is equivalent to five such options, is able during 24 hours to accumulate almost 10^-3 km³ of water and gives a possibility the regular hydro-turbine by power of 20 MW to produce electrical current during 6 hours.

Thus, the sectional hydroelectric power plants with the semi-submerged and submerged hydro-turbines allow completer to use hydroenergetic potential of natural water flows and promote energy effectiveness of existent hydroenergetic building.

Combined wind systems for hydro-accumulation and productions of electrical energy. Yet more economically justified can be the use of wind turbines for hydro-accumulation and productions of electric energy. At variable unstable air flows the wind turbine needs the use of the complicated systems of stabilization of velocity of rotation of turbines and accordingly of the systems of stabilization of electrical parameters of current, which is supplied to the users or is sent in a electrical network. Adaptation of wind turbines to the electrical networks is a not simple task and strongly affects the power efficiency of such systems. Other limitation of wind equipment is the necessity of the use of high-capacious electric accumulators to provide the feed of the electric systems at absence of wind.

The rational use of the wind systems is their parallel work with operating classic HPS and pumped storage hydropower-stations (PSHPS). In this case such wind equipment can be used both for the direct generation of electrical current with the use of energy of wind, and for implementation of mechanical work in the systems of hydro-accumulation by pumping of water from a lower level onto a top level, in other words, returning of water into a storage pool for the repeated production of energy with the help of regular hydro-turbines of HPS (PSHPS). Such method allows prolonging the operating cycle of hydro-turbines and promoting energy effectiveness of all hydroenergetic building.

On Fig. 7 the chart of the combined wind power equipment for hydro-accumulation and productions of electric energy is shown. Such wind turbine is set on an upper level of hydropower building, on safe distance from HPS (PSHPS). Construction of wind turbine includes the channel of generation of electrical energy and mechanical pump system for lifting up of water.

In the mode of generation of electric energy the kinetic energy of moving air grows into kinetic energy of rotor of wind turbine and rotor of electrogenerator hardly connected with rotor of wind turbine. The electrodynamic system converts kinetic energy of rotor into electric energy, parameters of which correspond to the standards of electrical network.

When working in the mode of pumping of water the kinetic energy of moving air grows into kinetic energy of rotor of wind turbine and of rotor of mechanical pump connected with rotor of wind turbine. The pump system provides lifting up of the «worked» water from the lower level of HPS into a upper storage pool and, thus, allows to stock a potential energy of water. In future the accumulated potential energy of water grows into kinetic energy of falling stream, and then into kinetic energy of regular hydro-turbines and rotors of electrogenerators of HPS (PSHPS) and into electrical energy. 

At work of WPP in the mode of hydro-accumulation the requirement to stability of rotatory motion of wind turbine is less critical, than during work of wind turbine in the mode of production of electrical energy. Power efficiency of combined WPP for hydro-accumulation and productions of electric energy is considerably higher in comparison with WPP that works exceptionally in the mode of production of electrical energy.

Wind power plant by power of 1 MW is able every second to levitate in an upper storage pool by a height of 10 meters about 10 m³ of water. Wind power station by power of 10 MW that is used in the mode of hydro-accumulation is able to accumulate during one days almost a 2х10^-3 km³ of water and gives a possibility to the regular hydro-turbine by power of 20 MW to work during of 12 hours.

The hydraulic and wind systems can be also used jointly. On fig. 8 the chart of optimization of energy effectiveness of the existent hydroelectric power stations by means of the increase of the level of hydro-accumulation of «worked» water with the use of wind turbines and hydro-turbines is shown. The generalized chart of balancing of the peak loading of powerful electrical networks is shown on Fig. 9. This modernization is done by the increase of the level of hydro-accumulation of «worked» water on the existent hydroelectric power stations with the use of wind turbines and hydro-turbines.

The sphere of the use of hydraulic and wind systems can be widespread onto the realizations of functions of water-supply of settlements (Fig. 10), water treatment (Fig. 11), dehydration of soil layers and prevention of flooding of territories and settlements by underground waters (Fig. 12) and irrigation of agricultural lands (Fig. 13).

Thus, the combined hydraulic and wind systems allow to use hydroenergetic potential of natural water flows and to promote energy effectiveness of existent hydroenergetic building. The necessity of creation of additional reservoirs for hydro-accumulation energy falls off also.

The joint use of the hydraulic and wind systems allows to extend the sphere of the use of alternative energy sources and to lower the ecological loading on the densely populated districts.

Vasil Sidorov on June 13, 2010 from Technopark QUELTA

Queltanews Office e-mail: sidorovvasil@gmail.com