Other Energy Sources and Technologies
In theory it is possible to generate electricity from a fast flowing river without a fall but the amount of energy available is very small in comparison to sites where the head (fall) of water is at least 2 metres. It is the combination of head and flow that maximise the potential to generate energy from a river not just fast flowing water.
There are a few products out there that claim to work with no head and just relying on fast flowing water, but at a small scale these just don’t make any kind of economic sense.
According to the estimates of the Indian government, the country has a potential of 8,000 MW of tidal energy. This includes about 7,000 MW in the Gulf of Cambay in Gujarat, 1,200 MW in the Gulf of Kutch and 100 MW in the Gangetic delta in the Sunderbans region of West Bengal.
But despite the huge potential, India has no policy on tidal energy. A clear policy is very important for developers to have clarity on tariff and commercial development of tidal energy in the country. The government must also provide subsidy to reduce the cost of importing wave technology so that consumers can get the cheapest rate on per unit consumption.
The Ministry of New and Renewable Energy should prepare a proper policy on tidal energy since the development of this sector is primarily their responsibility.
Energy from waves
Waves are caused by the wind blowing over the surface of the ocean. In many areas of the world, the wind blows with enough consistency and force to provide continuous waves along the shoreline. Ocean waves contain tremendous energy potential. Wave power devices extract energy from the surface motion of ocean waves or from pressure fluctuations below the surface.
Ocean Wave Energy Resource
Wave power varies considerably in different parts of the world. Areas of the world with abundant wave power resource include the western coasts of Scotland, northern Canada, southern Africa, Australia, and the northwestern coast of the United States, particularly Alaska.
Whereas wind resource potential is typically given in gigawatts (GW), wave and tidal resource potential is typically given in terawatt-hours/year (TWh/yr). The The total wave energy resource along the outer continental shelf at 2,640 TWh/yr.
While an abundance of wave energy is available, it cannot be fully harnessed everywhere for a variety of reasons, such as other competing uses of the ocean (i.e. shipping, commercial fishing, naval operations) or environmental concerns in sensitive areas. Therefore, it is important to consider how much resource is recoverable in a given region.
Ocean Thermal Energy
Ocean Thermal Energy Conversion (OTEC) is a process that can produce electricity by using the temperature difference between deep cold ocean water and warm tropical surface waters. OTEC plants pump large quantities of deep cold seawater and surface seawater to run a power cycle and produce electricity. OTEC is firm power (24/7), a clean energy source, environmentally sustainable and capable of providing massive levels of energy.
Recently, higher electricity costs, increased concerns for global warming, and a political commitment to energy security have made initial OTEC commercialization economically attractive in tropical island communities where a high percentage of electricity production is oil based.
In OTEC, we use the temperature difference between the hot surface of the ocean and the cooler, deeper layers beneath to drive a heat engine in a broadly similar way—except that no fuel is burned: we don’t need to create a difference in temperature by burning fuel because a temperature gradient exists in the oceans naturally! Since the temperature difference is all-important, we need the biggest vertical, temperature gradient we can possibly find (at least 20° and ideally more like 30–40°). In practice, that means a place where the surface waters are as hot as we can find and the deep waters (perhaps 500–1000m or 1000–3000ft beneath ) are as cold as possible. The best place to find such a combination is in the tropics (between the latitudes of about 20°N and 20°S).
Geothermal energy is the heat from the Earth. It is clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth’s surface, and down even deeper to the extremely high temperatures of molten rock called magma.
Almost everywhere, the shallow ground or upper 10 feet of the Earth’s surface maintains a nearly constant temperature between 50° and 60°F (10° and 16°C). Geothermal heat pumps can tap into this resource to heat and cool buildings. A geothermal heat pump system consists of a heat pump, an air delivery system (ductwork), and a heat exchanger-a system of pipes buried in the shallow ground near the building.
In the winter, the heat pump removes heat from the heat exchanger and pumps it into the indoor air delivery system. In the summer, the process is reversed, and the heat pump moves heat from the indoor air into the heat exchanger. The heat removed from the indoor air during the summer can also be used to provide a free source of hot water.
In India, exploration and study of geothermal fields started in 1970. The GSI (Geological Survey of India) has identified 350 geothermal energy locations in the country. The most promising of these is in Puga valley of Ladakh. The estimated potential for geothermal energy in India is about 10000 MW.
There are seven geothermal provinces in India: the Himalayas, Sohana, West coast, Cambay, Son-Narmada-Tapi (SONATA), Godavari, and Mahanadi.
Ongoing Projects in India:
- Magneto-telluric investigations in Tattapani geothermal area in Madhya Pradesh
- Magneto-telluric investigations in Puga geothermal area in Ladakh region, Jammu & Kashmir