The world today stands at the threshold of an energy crisis. With petroleum and coal reserves looking to be exhausted in the next few decades, there has been a rush for innovations in the renewable energy sector. An answer may be found in the blue seas which cover more than 70% of the earth’s surface and are thus huge reserves of energy. Tidal energy is one of the forms of this energy having big prospects in being utilised by man.
As is well known, tides are the periodic rise and fall in the level of ocean and sea surfaces with one cycle lasting about 24 hours and 52 minutes that is caused by the gravitational pull of the moon and the sun.
There are two technologies currently used for harvesting tidal energy. First, through construction of tidal barrages which create a difference in the water level between the two sides of the barrage during tides, allowing us to harvest the potential energy of the water due to tides. This method was the first one to be used in obtaining tidal energy, with the first power plant established in the Rance river in France, as far back as in 1966 and this technology is possible mainly in the estuaries of various tidal rivers or lakes. However the construction of a barrage and its effects on the ecology of the estuaries has been raising a few environmental concerns. Due to this reason, the second method has been gaining more and more popularity in recent times as it has relatively little effect on its environment. It is through construction of tidal turbines, which harvest the kinetic energy in the flow of water during such tides.
With respect to making tidal turbines, the company Andritz Hydro Hammerfest is at the forefront. In 2004 the company had installed a 300 KW tidal turbine, in Kvalsund, Norway and connected it to the national grid. These turbines manufactured by Andritz Hydro Hammerfest, will be used to set up a 10 MW project in Sound of Islay, Scotland by 2013. This will be done through an array of ten 1 MW turbines. In December 2011, a 1 MW device was installed in Orkney Island, Scotland for a non-commercial testing, and in May this year, the testing was successfully completed. We at Ek Titli, had a brief chat with a spokesman of Andritz Hydro Hammerfest:
In what way would you call yourself, pioneers in Tidal turbines?
Andritz Hydro Hammerfest was the first company in the world who successfully grid connected a tidal current stream turbine to the commercial grid in 2004. This device has been tested/operated for more than 17,000 hours, and showed 98% availability during endurance testing.
A tidal turbine’s running principles are that of a windmill underwater. Here is a brief look at the turbine’s manufactured by Andritz Hydro, which is named HS1000.
For a detailed view of the turbine and the project, view this video
How were you first inspired to work in this field?
Due to the new energy law in 1990 inNorway, the local utilities needed to produce electricity from local resources. The history of the local electricity utility company, Hammerfest Energi, shows an innovative way of thinking since they installed thefirst streetlights inNorthern Europeback in 1891, powered by hydro power. Tidal energy was one of the sources Hammerfest Energi chose to look at, and as a spin-off, Andritz Hydro Hammerfest was established in 1997 to take this idea to the commercial market.
Hydropower represents the most important renewable resource of energy by far, while tidal power, with its worldwide availability can be considered as one of the most promising future energy sources. The Ocean Energy council estimates the total world potential for ocean tidal power to be more than 560 TWh (about 64 GW). This number is expected to increase with technology.
Though filled with promise, the technology involved is the chief difficulty in abstracting feasible power from tides. The world is just at the beginning stages in innovating the methods to harvest energy from tides, which are both commercially viable and have minimum detriment to the environment. In this the role of tidal turbines comes into picture. Though tidal turbines may not be producing a huge amount of power as a couple of tidal barrage systems (Sihwa Lake Tidal Power Station, Rance Tidal Power Station), are producing right now, their low effects on their surroundings, simplicity of installation and production, and the promise to grow with increase of technology, certainly puts them to be an apt contender to be a major energy source of the future. In this aspect the role of Andritz Hydro Hammerfest and the few other companies innovating in this method needs to be appreciated.
Other tidal power harvesting methods are also filled with promise. A new technology-Dynamic Tidal Power is in its theoretical phase, which utilizes both the kinetic and potential energy of water and environment effects similar to those of the tidal barrage. In 2011 tidal power of 254 MW began to be extracted from the Sihwa Lake Tidal Barrage in South Korea, which places it as the largest tidal power generation plant in the world. Click here to view more details on the same.
As can be seen from the list, the South Korean government is the most aggressive government in building Tidal energy plants and the large number of tidal power plants are the parts of its plans of generating 5,260 GWh through tidal power by 2020. However, Tidal power does not have the full backing of the other governments of the world, which it requires at this stage.
The Indian scenario:
In India the maximum tidal ranges are found at the Gulf of Cambay and the Gulf of Kutch in Gujarat on the west coast with maximum tidal range of 11m and 8m and average tidal range of 6.77 m and 5.23 m respectively. The maximum range of the Ganges Delta in the Sundarbans is approximately 5m with an average tidal range of 2.97m. The total identified economic power potential in India is of the order of 8000 MW- about 7000 MW in the Gulf of Cambay, about 1200 MW in the Gulf of Kutch in Gujarat, and about 100 MW in the Gangetic Delta in the Sunderbans region in West Bengal.
The Ministry has sanctioned a project for setting up a 3.75 MW demonstration tidal power plant at Durgaduani Creek in Sunderbans, West Bengal to the West Bengal Renewable Energy Development Agency (WBREDA), Kolkata. The National Hydro Power Corporation Ltd. (NHPC) is executing the project on a turnkey basis.
The Gujarat government is all set to develop India’s first tidal energy plant. The state government has approved Rs 25 crore for setting up a 50 MW plant at the Gulf of Kutch.
Although today a lot of work is ongoing in the renewable energy sector, our major energy dependence is still on fossil fuel energy, which will soon be exhausted. We can only look forward to the day when we will be obtaining all our power from clean and commercially viable renewable resources. And on that day, owing to its rich potential, the role and contribution of tides and tidal turbines to energy is bound to be a significant factor. Therefore it is important that the field of tidal power generation gets the required interest, involvement and innovations required to harvest its huge potential.
A good thing about Renewable energy sources is that they have exceeded predictions [+]. So an optimistic view would be to expect a rush of developments in tidal energy in the near future. But before that, there must be sufficient awareness and thus interest on this power source from the government, power companies, and the general public.
Deepraj Sarmah is pursuing his chemical engineering from BITS, Pilani. The eye-watcher for developments in Renewable Energy hails from Gogamukh, a small beautiful town in Assam, India. An avid reader of classics, a buff of good movies and TV series also holds random and diverse interests- singing, quizzing, painting, creative writing, inventing pjs (poor Jokes).
To have a chat or share your thoughts and ideas, you can reach him at Deepraj.Sarmah@EkTitli.org
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