Hydropower

Hydropower (also: Hydro Energy ) is a renewable energy source. She calls - physically inaccurate - the conversion of potential or kinetic energy of the water via a water engine into rotational energy. Until the early 20th century, this mechanical energy was mainly used in mills. Today, an electric current by means of generators are almost always generated. With a share of 15.58 % of world electricity generation in 2011 after she was from coal and natural gas and nuclear energy before the third important form of electricity production.

• 4.1 classification
• 4.2 types

• 5.1 Energetic
• 5.2 Hydrological
• 5.3 Legal
• 5.4 Economics

History

Use

In 2012, hydroelectric power plants were installed worldwide with a cumulative capacity of around 990 GW together, which produced about 3700 TWh of electricity. This corresponds to slightly more than a half times the production of nuclear power plants, which provided 2012 2.346 TWh. Thus, the hydropower provided 16.5 % of the world demand for electrical power and about 3 /4 of the total electricity generation from renewable sources, which covered 21.7 % of world electricity needs.

In Germany at the end of the year were 2006 7.300 plants and made active 2007 total electricity a contribution of 3.4%. In Austria, there are approximately 56.6 % and approximately 52.2 % in Switzerland. Among the Member States of the European Union to pay Sweden's hydropower most for supply from renewable energy sources: In 2011, 66 TWh were produced - the equivalent of more than 20 % of the total energy produced in the EU countries from hydropower. Secondly, Italy and France are around 45 TWh, respectively.

Hydropower is currently the most important renewable energy source contributing to power the world's population. The other renewable forms of energy such as solar, wind, geothermal and biomass together contribute around 2.1 %. The potential of technically exploitable hydropower depends

• Of the rainfall and topographical conditions that are very different global and regional, as well as
• Of geographical conditions.

One sees high growth potential of hydropower in the Third World; in densely populated Europe, a further expansion seems problematic.

Hydropower plants

Classification

There are a variety of different types of water turbines. Your division is not always clear-cut and can be produced by various aspects. One can make the following classifications:

Plant types

• Laufwasserkraftwerk
• Storage power plant and pumped storage power plant
• Wave power plant
• Tidal power plant
• Gradientenkraftwerk ( osmotic power and ocean thermal power plant)
• Glacier Power Plant

Turbines

Classification

As with the types of power plants, turbines can be differentiated according to various aspects: After applying ( partially or vollbeaufschlagt ), the wheel shape (radial, diagonal, axial), the design (vertical or horizontal to the shaft position ) and the mode of action, which probably is most common distinguishing feature. Thus, there is direct pressure turbines and reaction turbines.

Types

• Pelton turbine or impulse turbine
• Crossflow / Ossbergerturbine
• Francis turbine
• Kaplan turbine
• Jonval turbine
• Waterwheel

Depending on the type of turbine and operating point there is a risk of damage due to cavitation.

General principles

Energetically

Energy occurs in various forms. Taking into account the laws of thermodynamics, the energy can be converted into work. For the use of hydropower kinetic energy and the potential energy are crucial. Water above the sea level has potential energy and is deflected by the gravity acceleration, whereby a portion of the initial energy is automatically converted into kinetic energy. This fluid- mechanical energy is converted into water turbines through turbines into mechanical energy ( rotational energy ) and ultimately transformed by generators into electricity. To determine the maximum transformable energy must be calculated using the extended Bernoulli equation carried out in which all losses are accounted for by turbulence or by friction on system components. Losses in energy conversion escape in the form of heat or sound energy. The power, also referred to power flow is influenced by the height of fall of the water, the amount of water, the density of water and the efficiency of the system, the overall efficiency of the turbine and includes all the losses of the generator. For hydro power plants, the overall efficiency is 80 % or higher. Compared to other types of power plants, this value is the largest. After energy- economic point of hydropower is one of the primary energy because it comes directly from a natural source of energy.

Hydrological has great significance for the water power of the water cycle. He describes the movement of water on a regional and global level. Powered by the radiant energy of the sun passes through the water, various states. In principle, the circuit works as follows: water evaporates from surface water (oceans, lakes, rivers) and increases in the form of water vapor in the atmosphere. There it condenses what it mainly comes again as rain or snow on the surface. Due to topographical constraints arise catchment areas where the precipitation accumulates rivers with water.

The amount of water out of a river is highly variable, mainly caused by seasonal fluctuations in precipitation and climatic and meteorological conditions. The drain is a very important parameter for the design of hydropower plants. Above all, extreme values ​​have to be considered, so that eg no damage occurs during floods. Possible long-term measurements over the drainage basin of a help. Useful for addition to the hydrograph of a river, the flow duration curve, the sum line and the fill line, all of which are described in a drain -day chart.

• The transition line, starting point for hydrological runoff studies are for time intervals (eg, days, hours) to a runoff.
• The duration curve is sorted according to their runoff values ​​and thus indicates on how many days a year, a certain outflow value is exceeded or undershot.
• The total line is for the design of hydroelectric power plants with storage of importance. It is obtained by summing the transition line over time.
• In order to describe the runoff during flood events, the fill line will be used. If there are not enough data for a particular location to be tested, statistical methods for the collection of data can be applied. From the knowledge of the runoff data, the type of the power station, the choice of turbines and other planned uses of water, such as shipping or environmentally induced minimum water output, designed design flow can, for the particular power plant can be determined. When it is, at the same time with favorable efficiency, the power can be maximized. Depending on the size of the power plant design flow is designed so that it is exceeded at about 100 days a year.

Whether a hydropower plant is profitable, results from the costs, the quantities and values ​​for recoverable electricity prices (see also cost-benefit ratio).

Terms of Use

In Germany, deal with the Water Resources Act ( WHG), the Law on Environmental Impact Assessment ( EIA Act ) and the Renewable Energy Sources Act ( EEG) with hydropower.

Economics

The cost of a hydroelectric power plant are made up of the plant and the operating costs. The plant costs, also called investment costs, consisted in turn of all expenditure on the construction of the plant together. Unlike combustion power plants has little or no cost for the desired resource are paid on hydropower generation, since it is almost unlimited. This means that the operating costs - with the exception of pumped storage power stations - will be very small compared to the investment costs in fully functional hydroelectric plants.

The question of economic efficiency depends on the ratio in which the plant and operating costs are for gross revenue. Overall, it can be said that the essential factors are the equipment cost and the use of time. Hydropower is mostly base load for the energy industry. Thus, in these cases almost constantly stream are produced, creating a profit calculation can be performed with the specified in the EEG remuneration fees. In principle, hydropower plants generally have very long service lives and are amortized over the term very well.

Hydropower and ecology

Although the use of hydropower is mostly recognized for energy to be particularly ecologically, some significant intervention in nature and landscape associated with it. So one of the most important natural monuments on the Rhine, the little running at running castle was blown for the first stream crossing power plant on the Rhine. The plant went into operation in 1914. Even for the Rhine Falls of Schaffhausen (also Great running) have been made from 1887 multiple efforts to supply the waste to the valley rushing water masses of energy. A recent example in which the hydroelectric development is a serious intervention in an ecosystem at the same time, the Three Gorges Dam on the Yangtze River in China.

In many cases, small hydropower plants are considered to be ecologically sustainable. Here, proponents argue so that the installations which are built to the latest standards and professionally, do not pollute the waters and they are partially " upgraded ecological" through the construction of fish ladders or by accompanying measures. Critics, however, one often that small hydropower plants and related procedures such as damming, barriers or reduced residual amounts of water represented in particular by their wide and scattered distribution in a river basin heavy cumulative interventions in the affected ecosystems.

Advantages:

• Water is a renewable raw materials, ie it is not consumed
• Fossil energy resources such as coal, oil and natural gas are conserved
• Independence from conventional energy sources
• Climate change, since low-CO2
• System components are recyclable at the end of the operating time
• Flood protection for downstream areas
• Reservoirs are at the same time drinking water reserve

Cons:

• Due to the diversion of water, the amount of water is reduced in the stretch of water between damming and re-injection beneath the turbines. This reduction to the so-called residual amount of water represents an intervention in the water budget and they can arise where large-scale changes in the ecological balance in individual cases
• Ecological barrier: fish and microorganisms can no longer perform their usual walks, or die when they are drawn into the turbines
• Reduced flow rate due to the Gewässeraufstaus leads to reduced oxygen concentration and increasing the water temperature
• Water table in the area of the lower reaches may decline sharply, while he will rise in the impoundment. Depending on the composition of flora and fauna, this has destructive effects on the coexistence
• Sediment retention and thus sedimentation above and increased erosion below the barrage connected
• Large dams can have a negative impact on the climate. Especially when areas are flooded in warm regions and with lots of vegetation, it comes through Faulungsprozesse the emission of the greenhouse gases methane and carbon dioxide
• In dam failure is a risk of destruction of habitat for humans and nature
• When you create the storage space huge areas are partially flooded, with only biological diversity but also the habitat for humans is lost
• Reservoirs can gases such as CO ₂ and methane ( with 25 times the global warming potential such as CO ₂) produced which fuel the global warming. The amount depends in particular on growth before the congestion from, and the age of the lake ( from the flooding decreasing). Under very unfavorable conditions, that is, a very shallow reservoir under tropical conditions, greenhouse gas emissions, the bituminous coal power plant can achieve.

Solutions for coexistence:

To be the voltage potential between climate, nature and water protection can meet some engineering measures will now be presented that attempt to reduce this conflict. The easiest way to protect nature from other interventions, this refrain completely. Therefore it should be completed in the first line of the development of hydropower at existing plants. Through innovative technical improvements of the system components can be a performance increase, reach at the same time improving water environmental situation. The further development is therefore in the replacement and modernization of existing plants. Through the Renewable Energy Law, the remuneration of new or upgraded facilities is controlled so that the ecological status of the water body needs to improve with the construction or modernization of such cases. In addition, especially the nature and water protection must always be respected. But as long as the environmental aspects are taken into account, the construction of new hydropower plants is nothing to prevent. Various design and compensation measures, it is possible to improve the ecology of a body of water. Imperative to improve the aquatic ecology or maintain a minimum water supply to the underflow and the sediment continuity must be guaranteed. In addition, include fish ladders as ascent and descent aids or bypass channels to improve the ecological continuity of living things as a crucial building project. There are now technically improved turbines, which make it possible that fish they can usually pass unharmed. Also the problem of low oxygen content can be solved by so-called "air" turbines Enter oxygen into the water. A natural as possible shaping of waters through the creation of deep and shallow water areas, oxbow lakes and an improvement in the structural diversity in the reservoir area of the power plant about by gravel banks leads to a natural water profile and improve the habitats of flora and fauna. In order not to destroy the scenic appearance, the plants should be harmoniously integrated into the landscape.

Provide an entirely novel approach to ecologically largely acceptable use of hydropower represents the use of specially designed turbines to generate electricity in sewers, in which even when retrofitting into existing sewers neither intervention in the landscape still give impairments of fish ways. In addition, can be decentralized and thus close to potential consumers through the use of sewers, electricity production due to the areal distribution of sewers.