In the past, Electricity is generated by using fossils fuels like woods, oil and natural gases. Non renewable source like fossil fuel which takes millions of years to form, are depleting continuously due to dependability of human being as only source of energy for generating electricity. So, the alternative way of production of electricity must be implemented.
Renewable source of energy like hydro, solar, wind, wave energy are the alternative source of energy. Renewable energy is the energy generated from the natural resources like sunlight, wind, water, tides and geothermal heat. Renewable energy is naturally replenishing and does not deplete over time. So, this report is mainly based up on the hydro and wave energy as the viable source of generating electricity.
Hydro means water, due to hydro cycle, water is constantly evaporating by sunlight from the ocean and form as cloud when it get condense and then precipitates as rain and snow again flowing back down to earth. Hydro power uses the kinetic energy of the flowing river under the action of the gravity. This energy can be collected and use. Hydroelectric power is generated by the falling of the water through the turbine.
Figure 1: Appendix 1 (Water cycle)
Hydro Energy technology:
Kinetic Energy (K.E)
Potential Energy (P.E)
Dam Penstock turbine generator
Figure 1: Block diagram of Energy conversion in Hydro Power.
A reservoir and dam is built on the large river which accumulate large quantities of water that has a large drop of elevation. The water is now allowed to flow through the channel (pipes) called penstock and then through the turbine. This rotates the turbine which drives a generator connected at the other side of it and creates the electricity. This is then fed into the electrical grid to be used by homes, business and industry.
Figure 2: Appendix 2 (hydroelectric dam)
Factors effecting the production of electricity:
The amount of the electricity generated during the hydro power generation process will depends on following factors.
Height: Height is the one of the factors that the channel water falls from which is referred as a head. Height means the distance between the water source and the turbine. So, Higher the distance between them, more the electricity will generate.
Volume: Another factor that determines the amount of electricity generated is the volume of the water flowing through the penstock. The more the volume of water flow through the penstock, more the electricity will be produced.
Development stages of Hydro energy:
Hydro power development process is divided into 4 main parts which are as follows:
In this stage, the projectâ€™s technical and economical feasibility are determined.
Draft design and government permitting:
All the necessary document required like law, regulation and agreements are prepared and documented to make a decisions about the project. All components of the physical, biological and human environments likely to be affected by the project are analyzed also the projects characteristics and technical design are also described.
During the construction phase, all the mitigation measures provided for in the impact statement are implemented.
During the operation phase, an environmental follow-up program is conducted. All the facilities of the actual impacts are measured analyzed and compare with the expected impact and necessary adjustment are done.
Calculation of Hydro energy:
The amount of power supplied to the turbine by the water is given by the following equation:
Where, P = Power supplied to the turbine (KW), = Specific mass (), = Volumetric discharge (), h = Net head of water (m), m = Mass flow rate (tonne/sec), g = Gravity = 9.81
Power can also be generate from the wave power which uses the energy created by waves. Wave energy is caused by action of the winds on the oceans. Wave power varies considerably in different parts of the world. So, It cannot be harnessed effectively everywhere. It is suitable only for areas where wind blows consistently providing continuous waves.
Wave Energy Technology:
The energy from the wave is captured by varieties of technologies which is converted to mechanical and then to the electrical energy. Wave technologies are designed to be installed in near-shore, offshore and far-offshore locations. The three basic systems are as follows:
Channel systems that funnel the waves into reservoirs
Float systems that drive hydraulic pumps
Oscillating water column systems that use the waves to compress air within a container.
The mechanical power created from such system either is transferred to a working fluid (i.e. water) or due to up and down movement of a wave that push air which drives a turbine and generator attached to it or by directly starting a generator and hence produces the electricity.
Majority of companies develops the devices called point absorber as wave energy technology device. This is because of their ability to absorb energy from oncoming waves in all directions. These devices bob in reaction to multi-directional ripples. Point absorbers resemble offshore floats/buoys.
Factors affecting the production of wave energy:
The amount of the electricity generated during the wave power generation process will depends on following factors:
Height of the wave:
Height is one of the factors that affect the quantity of electricity production. Power generated is depends up on the square of the height of the wave. High the wave, greater the production of wave power.
Speed of the wave:
Speed is also another factor that affect in production of the electricity. Power is directly proportional to the square of speed of the wave. High the speed, greater the production.
The amount of electricity from the wave energy depends on the wavelength of the wave creates by the movement of water. So, increase in wavelength will results in more production of power.
Density of the water:
The production of wave power is also depends on the density of the water. So increase in density will increase the production of the wave power.
Calculation of wave energy:
Linear wave theory assumes that the motion of the water past a point is sinusoidal. The period (T) for one wave to pass this point can be expressed by:
Where, = wavelength (m)
g = Gravity = 9.81
The power contained in the wave can be expressed in terms of the length of the wave (kW/m). This is given by the following equation
Where, a = wave amplitude (m)
Economical and political aspect of hydro and wave energy:
Generally, hydroelectric power requires huge civil engineering effort and associates huge amount of money to build the hydroelectric dam. As, it is large-scale project which take some considerable time to built but its produce the electricity for hundreds of years. The payback on this investment can be lengthy process so, the governments or large corporations fund these schemes. Which develop the economics of the nation. Local are also economically benefitted during construction. The recreational facilities can be built which attracts the tourism in the area which raises the economy of the nation. Even the places with high Mountain and hilly area are benefited by hydro power. In such area it could be the best option for the production of the electricity. For example Norway, after development of the hydropower their economy has raise so high now only below 20% of people live under poverty line. Even the politician forwards their campaign by assuring their pubic, that they would build the hydro power plant and boost the economy of the nation.
As the wave technologies have not yet been completely proved, It is hard to get companies to invest. So government has a very important role to play if this industry is to be given the chance to fulfill its potential. It has a great potential in long-term run. Scotland has deployed LIMPET 500 that has brought recognition to the technology available in Scotland. This improves the growth of the industry interest and invests allowing other technologies to advance and realise their potential.
It can conclude that hydro energy is one of the best alternative sources of renewable energy for the production of the electricity. Whereas, Wave energy is also alternative source of renewable energy but still there need to development in technology for maximum utilizing of itsâ€™ potential.
The hydropower development process. Available at: http://www.hydroforthefuture.com/approche/6/the-hydropower-development-process (Accessed: 8 March 2011).
Ocean wave energy. Available at: http://ocsenergy.anl.gov/guide/wave/index.cfm (Accessed: 10 March 2011).
Wave power. Available at: http://www.esru.strath.ac.uk/EandE/Web_sites/01-02/RE_info/wave%20power.htm (Accessed: 18 March 2011).
Image of the water cycle. Solar energy heats water on the surface, causing it to evaporate. This water vapor condenses into clouds and falls back onto the surface as precipitation. The water flows through rivers back into the oceans, where it can evaporate and begin the cycle over again.
Figure 1: Water cycle.