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13.2.3 oTher meThodS
Numerous other methods are also used to generate hydroelectricity [1–32] (Zainuddin
et al., 2012, pers. comm.). Some of these combine the principles of hydrokinetic
energy to generate power and electricity. If there is small or no reservoir capacity, the
water from the upstream is used for generation according to the need and bypassing
the dam. This method is called run-of-the-river hydroelectric station. Hydroelectricity
can also be generated using rise and fall of ocean water due to tides. The conditions of
tides are predictable, and if reservoirs can be constructed, it can supply hydroelectricity during high demand periods. Sometimes tides are so high (>40 ft [33]) that they
provide both potential and kinetic energy for the power generation. This subject is
further discussed in Section 13.3.
An underground power station can make use of a large natural difference between
two waterways such as waterfall or a mountain lake. An underground tunnel can also
be constructed to take the water from high reservoir to the power-generating hall built
in an underground cavern near the lowest point of the water tunnel and a horizontal
water pipe taking the water away to the lower waterway. The size of the hydroelectricity generated by these methods can be large, small [14–16], micro (<100 kW) [17–25],
or pico (<5 kW) [26–32] (Zainuddin et al., 2012, pers. comm.). These different levels
of hydropower generations are further discussed in Section 13.2.6.
13.2.4 AdvAnTAgeS And diSAdvAnTAgeS oF hydroeleCTriC PoWer
Hydroelectric power offers various advantages and disadvantages, some of which are
listed in Sections 13.2.4.1 and 13.2.4.2.
13.2.4.1 advantages
Hydroelectric power offers the following advantages:
1. Hydroelectricity is flexible and relatively inexpensive.
2. The operating costs for dams are usually low because of automation and
low manual labor requirement during normal operations.
3. A new plant for specific purposes can be added with relatively low construction cost. The life of dam can be 50–100 years.
4. Hydroelectric plants can also be suitable for specific industrial purposes.
For example, dedicated hydroelectric plant provides a substantial amount
of electricity needed for aluminum electrolytic plants. There are numerous
examples of the use of hydroelectricity in aluminum plants in the United
States and New Zealand.
5. Hydroelectricity does not produce carbon dioxide emissions, although some
CO 2 emissions can be produced during the manufacture and construction of
the project.
6. Hydroelectric dams can also provide water sports, an attraction for tourists,
aqua culture, and irrigation support to agriculture industry with constant
water supply.
7. Large dams can control floods that can affect people living downstream of
the dams.