50% in best power plants fed with fossil-C. The reason is that with the use of
hydropower, it is saved the loss of proper energy of the combustion of fuels and
generation of high-temperature and high-pressure steam. Moreover, hydroelectricity
is very clean: no emission of toxic or polluting species occurs. The cost of production (excluding CAPEX) is around 0.01 US$/kWh, compared to 0.032–0.035
US$/kWh of fossil-C-based power plants. The difference is due to the fact that
“fuel” (water) is free [11]. The world’s largest hydroelectric plant in terms of
installed capacity is Three Gorges (Sanxia) on China’s Yangtze River, which is
2.3 km wide and 185 m high. Conversely, the Itaipu plant situated on the Paraná
River between Brazil and Paraguay generates the most electricity annually. As said
above, hydroelectricity is a clean and relatively cheap form of energy. OPEX costs
are very low, “fuel” is free (river water). The power produced can be regulated with
water falling on the turbines. What is negative is the environmental impact of
building the basin and the dam. However, big dam projects can disrupt river
ecosystems and surrounding communities, harming wildlife and forcing out residents. The Three Gorges Dam, for example, displaced an estimated 1.2 million
people and flooded hundreds of villages. Hydroelectric power is not ubiquitous and
depends on the existence of rivers and on the orography of the territory.
A different form of hydro energy that can be used for generating electric energy
is the “tidal energy” [12] that is not yet widely used, but has potential for future
electricity generation.
The advantage of tidal energy is that it is clean, is more predictable than the wind
and the sun, and is continuous. In fact, the gravitational forces of celestial bodies
will not stop nor will have unforeseen delays. However, it is far easier for engineers
to design efficient systems, than, say, predicting when the wind will blow, its
direction and speed, or when the sun will shine and the intensity. As for today, the
largest tidal project in the world is the 2011 Sihwa Lake Tidal Power Station in
South Korea, with an installed capacity of 254 MW. The project took advantage of
a 12.5 km wall built in 1994 to protect the coast against flooding and to support
agricultural irrigation. Just for comparison, the Roscoe wind farm in Texas, US, the
first single wind park in the world, second only to the multiple wind park Gansu in
China that generates 5.1 GW, takes up 400 km
2 of farmland and generates
781.5 MW with 627 wind turbines.
Tidal turbines can generate electricity at speeds as low as 1 m/s; in contrast,
most wind turbines begin generating electricity at 3–4 m/s. Even if today tidal
power converters may appear costly for their output, technological innovation will
only drive it cheaper and more sustainable. A rough estimate sets at ca. 10–20% of
global electricity demand the contribution of wave power. Tidal power plants can
last much longer (over 100 years) than wind or solar farms, which come with a
warranty of 20–30 years (some have reached 40 years) and are reported to
degenerate at a yearly rate of ca. 0.5% efficiency. The La Rance tidal power plant in
France has been operational since 1966 (53 years now, with a old technology) and
continues to generate significant amounts of electricity each year. Tidal barrages are
long concrete structures usually built across river estuaries (Fig. 5.8). The barrages
have tunnels along them containing turbines, which are turned when water on one
5.2 The Use of Perennial Energy Sources
69
hydropower, it is saved the loss of proper energy of the combustion of fuels and
generation of high-temperature and high-pressure steam. Moreover, hydroelectricity
is very clean: no emission of toxic or polluting species occurs. The cost of production (excluding CAPEX) is around 0.01 US$/kWh, compared to 0.032–0.035
US$/kWh of fossil-C-based power plants. The difference is due to the fact that
“fuel” (water) is free [11]. The world’s largest hydroelectric plant in terms of
installed capacity is Three Gorges (Sanxia) on China’s Yangtze River, which is
2.3 km wide and 185 m high. Conversely, the Itaipu plant situated on the Paraná
River between Brazil and Paraguay generates the most electricity annually. As said
above, hydroelectricity is a clean and relatively cheap form of energy. OPEX costs
are very low, “fuel” is free (river water). The power produced can be regulated with
water falling on the turbines. What is negative is the environmental impact of
building the basin and the dam. However, big dam projects can disrupt river
ecosystems and surrounding communities, harming wildlife and forcing out residents. The Three Gorges Dam, for example, displaced an estimated 1.2 million
people and flooded hundreds of villages. Hydroelectric power is not ubiquitous and
depends on the existence of rivers and on the orography of the territory.
A different form of hydro energy that can be used for generating electric energy
is the “tidal energy” [12] that is not yet widely used, but has potential for future
electricity generation.
The advantage of tidal energy is that it is clean, is more predictable than the wind
and the sun, and is continuous. In fact, the gravitational forces of celestial bodies
will not stop nor will have unforeseen delays. However, it is far easier for engineers
to design efficient systems, than, say, predicting when the wind will blow, its
direction and speed, or when the sun will shine and the intensity. As for today, the
largest tidal project in the world is the 2011 Sihwa Lake Tidal Power Station in
South Korea, with an installed capacity of 254 MW. The project took advantage of
a 12.5 km wall built in 1994 to protect the coast against flooding and to support
agricultural irrigation. Just for comparison, the Roscoe wind farm in Texas, US, the
first single wind park in the world, second only to the multiple wind park Gansu in
China that generates 5.1 GW, takes up 400 km
2 of farmland and generates
781.5 MW with 627 wind turbines.
Tidal turbines can generate electricity at speeds as low as 1 m/s; in contrast,
most wind turbines begin generating electricity at 3–4 m/s. Even if today tidal
power converters may appear costly for their output, technological innovation will
only drive it cheaper and more sustainable. A rough estimate sets at ca. 10–20% of
global electricity demand the contribution of wave power. Tidal power plants can
last much longer (over 100 years) than wind or solar farms, which come with a
warranty of 20–30 years (some have reached 40 years) and are reported to
degenerate at a yearly rate of ca. 0.5% efficiency. The La Rance tidal power plant in
France has been operational since 1966 (53 years now, with a old technology) and
continues to generate significant amounts of electricity each year. Tidal barrages are
long concrete structures usually built across river estuaries (Fig. 5.8). The barrages
have tunnels along them containing turbines, which are turned when water on one
5.2 The Use of Perennial Energy Sources
69