The great importance of small hydropower
Intensive work is underway on the construction of the Small Hydroelectric Power Plant in Dobroszów Wielki. The new SHP, which is being built on the Bóbr River, will produce an estimated 6,000 MWh per year. This will reduce the emission of harmful substances to the atmosphere, especially carbon dioxide causing the greenhouse effect, by as much as 6,600 tons per year!
Works on the construction of SHP Dobroszów, of which WODEL is the general contractor, started at the beginning of September.
- First, the humus layer was discovered and the excavation was made to the top of the sheet piling. At the moment, we have two chambers one hundred percent killed on the design ordinate. We are starting the excavation - informs the works manager Krzysztof Gałązka from B4 Sp. z o.o.
Let us recall that the scope of works includes the construction of a weir with a shell closure with a control room, construction of hydroelectric chambers, power plant building, inflow and outflow canal, protection of the bottom and slopes of the river, construction of an earth dike and a steel wall on the left bank, and construction of a new fish pass and stone rapids. A transformer station will also be built at SHPM. The power plant will be equipped with automatic grate cleaners and, of course, turbo-generators.
In Dobroszów, Kaplan water turbines with a rotor diameter of 2,100 mm and a speed index of 650, manufactured by WODEL, were selected. These are the best selected turbines for the hydrological conditions in this section of the river. Furthermore, Kaplan 2100 turbines are proven turbines.
This time, however, we would like to draw attention not only to the technical specification of the investment, but also its enormously positive effect on the natural environment.
In the world, there is an attempt to intensify the production of energy from renewable sources. It is no different in Poland. All this to reduce the emission of harmful substances into the atmosphere, especially carbon dioxide (CO2) causing the greenhouse effect. The emissions of harmful substances are a derivative of energy processes occurring in the production of electricity from conventional sources - e.g. heat and power plants.
MEWs are considered to be one of the most environmentally friendly energy sources. Production of 6 GWh of energy per year at SHP Dobroszów will save nearly 4,000 of steam coal, will reduce CO2 emissions by 6,600 tons, SO2 emissions by approx. 66 tons, NOx by over 20 tons. It will also make it possible to reduce the amount of slags and ashes discharged to the landfill by approx. 800 tons per year.
Other benefits of SHP are the so-called microretention, improvement of soil moisture in areas adjacent to the power plant and a significant improvement in water quality, which has a positive effect on agriculture.
Construction of a Hydroelectric Power Plant contributes to the improvement of water quality in several ways. - We are creating an additional tank. In practice, damming up increases the tank capacity and the amount of water. This rule applies to a run-of-river plant. Water flows all the time, its replacement is quite quick. By introducing a trellis, we protect our devices, but at the same time we protect the river against the accumulation of sediments, e.g. branches, leaves, trees, carcasses and everything that people throw into the river. In our other power plant - in Dziećięćowice - we throw away 150 tons of sludge per year - emphasizes Tadeusz Wawrzykowki, investor of SHP Dobroszów.
The introduction of a hydroelectric unit to the SHP causes the flow of water through the turbine, and this has the property that it sucks in air along with the water and oxygenates it. This is the first stage of water treatment, such as is used in sewage treatment plants. The water is also oxygenated by the weir which guards the damming ordinate at SHP. When there is more water, it overflows through the weir, which creates a direct contact between water and air, and oxygenation takes place here.
Another positive effect of SHP is protection against rubble movement. The water carries stones, sand, gravel, etc. in some place it accumulates and the so-called Backwaters (islands). This in turn causes the flooding of the river at higher water levels. It is possible to eliminate this problem thanks to the weir, which makes the speed of the water at the bottom low.
We should also mention a few words about bottom freezing, which occurs in winter when there is little water in the river. As a result, everything that lives in the river is lost - frozen in the water. We have no plants and animals to withstand this. Piling up effectively eliminates this problem, because a large layer of flowing water is created, which does not freeze and thus gives the possibility of a greater resource for fish.
There is still a lot to be said about the advantages of MEW, but what are its disadvantages? These are hard to find as long as the objects are well designed and made. Certainly, the so-called intact flow (or biological flow). The conditions of this flow must be specified in the water permit. Another "problem" may be ichthyological issues, which are especially important on rivers where fish migrate. The solution used in SHPs are the fish ladders to keep fish free. Fish passes are costly and significantly reduce the annual production from renewable energy sources, as they reduce the flow through the turbines, but in many cases necessary. A fish pass is also being built in Dobroszów. Another important issue is the proper selection of cleaning grids, which protect the turbine from damage and, on the other hand, must stop fish that could be damaged while passing through the turbines.
For the construction of SHPs to only have a positive impact on the environment, the goodwill and common sense of everyone involved in the project is necessary - from designers, through builders, officials, experts to explorers.
