Water Energy

Water energy (hydropower) is the most important renewable energy source. Water as an energy source is considered to be renewable because of the water cycle in nature. Radiation of the sun causes the evaporation of water from the oceans and rivers and its transformation into water vapor. When water vapor reaches the colder air in the atmosphere, it condenses and creates clouds, thus creating rain or snow and renewing the water in the oceans and rivers. Gravity moves the water from a high pitch to low. The power of flowing water can be very large.

Hydropower Potential

The hydropower potential is an important source of energy, and examples of the use of waterways can be traced back to ancient times. It is estimated that about 25% of world's energy potential comes from  hydropower. Most of unused potentials are located in undeveloped countries, therefore they expected a significant increase in energy production. The largest projects planned or already started are in China, India, and Brazil. However,energy needs  often outweighs concerns about environmental impacts.

There are two phases to obtain hydroelectric energy. In the first phase, the potential energy of water masses drives hydraulic turbine and is transformed into mechanical energy. In the second phase, this mechanical energy powers a generator that converts it into electricity. The generated power depends on the flow of water masses and the difference in level between the source and drain water streams accumulation (fall).

There are several methods for the production of electricity from hydropower:

- Conventional (dams)

- Pumping hydro power plants 

- River hydropower plants

- Tide

- Wave energy

Water as source of energy

It is pivotal to emphasize that water is also the only renewable energy source that is competitive to fossil fuels and nuclear energy. However, use of hydropower has its limitations. In the last decades, production of energy in power plants has tripled, but contribution of hydro energy has been increased by only 50% (from 2.2% to 3.3%). In the same time, nuclear power plants increased production nearly a hundred times. The main problem is that energy from the water cannot be produced anywhere because it involves plenty of fast flowing water, but it is preferable that there is enough all year, because electricity can not be cheaply stored. In order to negate the effect of fluctuations in water level, dams and artificial lakes have been built. This significantly raises the price of the whole plant, and rising groundwater levels around the reservoir. The groundwater level has a lot of impact on wildlife, and hence hydropower is not completely harmless to the environment. There is also a big problem with the accumulation of water and earthquake protection.

The increased price of fossil fuels and enhanced concern about their negative impacts on the environment has increased interest in using hydropower potential of small rivers in various parts of the world. Consequently, it accelerated the development of modern turbines, which can operate under conditions of low flow and small drops of water. There are significant advantages of small hydropower plants, where especially stands out relatively low cost of installation, as well as they are environmentally friendly. Their price is competitive with new thermal and nuclear power plants, and the impact of new (smaller) dams on the environment is minimal in comparison to the large hydroelectric projects. Therefore, small hydropower plants represent a great potential for the production of electricity. They are suitable for power supply of isolated areas such as, tourist destinations, mountain facilities, and rural households.

Types of hydro power plants (hydroelectric, hydroelectric power plants)

There are three basic types of hydroelectric power plants: flow, accumulation and hydro electric power plant.  There are three basic types of hydroelectric power plants: instantaneous, accumulative (Hydroelectric Dam), and reversible (Pumped-storage Plants) hydro power. River hydropower plants are those that do not have upstream accumulation or its accumulation can be emptied in less than two hours at rated power. Kinetic energy of water is used directly to run the turbines. This type of hydroplants is easiest to build, but they are very dependent on the current water flow. The advantage of this type is very small impact on the environment and the fluidity of the water. The picture to the right shows the principle of Hydroelectric (dam). The main parts of the plant such as reservoirs, dams, clench, gravity intake, water chamber, valve chamber, penstock, power and drainage. There are two types of Hydroelectric Dams: near the dam and diversion. The dam is located below the dam itself, and derivational is located much more below the dam with pipelines as connectors to accumulation. Hydroelectric dams are the most common way of getting electricity from water power. Problems occur in the summer months when natural flow gets too small for the operation of the plant. In this case, the dam must be sealed and it is necessary to at least maintain water level which is biological minimum. The problem that cannot be neglected is the level of underground waters.

Power consumption depends on the time of day, day of week, season, etc. During the weekdays consumption is very high. Weekend usually means lower energy consumption. For filling week's consumption built hydro electric power plant. In the case of small energy consumption, water is pumped from the bottom of the lake in the upper reservoir. This is usually done at night, because then the lowest power consumption.