Energy Security and the Role of Renewable Sources

[Guest guest]

ENERGY SECURITY AND THE ROLE OF RENEWABLE SOURCES

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Energy security is an issue debated globally. Alongwith ensuring energy security is the issue sustainable and eco-friendly ways of cheaper power generation, without having any conflict with food security. Can the various options for harnessing energy and generating power lead us to this goal? Here are several options for harnessing energy from different renewable sources discussed in details-----

 

1. Options on eco-friendly power

2. Throwing light on SPV systems

3. Focus on wind power generation

4. Many hurdles to harnessing the tide’s boundless energy

5. Fuel of the future: hydrogen

6. Energy, the geothermal way

7. OTEC : Tapping megawatts in the oceans

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Options on eco-friendly power

 

http://www.financialexpress.com/news/Options-on-ecofriendly-power/329403/0

 

ASHOK B SHARMAPosted online: Tuesday , July 01, 2008 at 2253 hrs IST

 

Energy needs of the country are growing in tune with the needs of the liberalised economy and the annual fossil oil import bill now stands at $76.9 billion. But unfortunately very little has been done to reduce the country’s dependence on fossil oil by developing alternative sources of energy that can be eco-friendly and sustainable.

 

Leaving aside all other viable options for promoting eco-friendly and sustainable power generation, the Union ministries of new and renewable energy and rural development are aggressively promoting the bio-fuel programme, which has already caused food scarcity and environment problems across the globe.

 

According to the government’s estimate, the potential for grid-interactive renewable power generation from commonly known sources other than bio-fuels is about 84,776 mw. The government has launched the programme for promoting power generation from renewable sources since last 25 years, but unfortunately the cumulative power generation from these sources is only around 11,272.13 mw.

 

India boasts to be the fourth largest producer of wind power in the world, but the cumulative achievement of wind power generation is only 7,844.52 mw against a potential 45,195 mw. There are about 1,284 wind pumps in use in the country. Aero-generator/hybrid systems have generated 675.27 kW power on a cumulative basis.

 

It is not the fact that the technology for wind power generation is in a nascent stage I the country. In 2006-07 indigenously produced wind turbines valued at $ 250 million have been exported to US, China , Brazil , Australia and European countries. Wind turbine blades vaued at $ 25 million have been exported to Germany , China , Spain and US.

 

The wind power programme was initiated towards the end of the 6 th Plan in 1983-84. A market-oriented strategy was adopted since its inception, supported with fiscal incentives. But despite this the progress has been very slow. Wind is a nature's resource and scientists have estimated its speed in different parts of the country, optimal for setting up of wind power plant. At places there may be barriers like forest cover which cannot be removed in the interest of the ecology.

But there are ample areas in dessert areas and high altitude suitable for wind power generation

 

Sun is an inexhaustible source of energy to mankind and India is ideally located for utilisation of the solar radiant energy. Optimal solar energy is received in most parts of country throughout the year, expect at times of cloud cover in the rainy season and in the times of extreme winter. The daily average incident of solar energy varies between 4 kWh and 7 kWh per sq km, depending upon the location. Solar energy can be used through thermal as well as photovoltaic route. The potential for solar photovoltaic programme in the country is estimated at 20 mw per sq km and that of solar water heating systems at 140 million sq m collector area. But the cumulative solar power generation by installed plants is only about 2.12 mw. The achievements in solar photovoltaic programme is miserably low and that of solar water heating system is limited to only 2.15 million sq m collector area.

 

A wide variety of technologies have been developed to harness solar energy. Efforts were made in 1980s and 1990s aiming at research & development, demonstration and large-scale promotion of these technologies. Some of these solar technologies were found to be user-friendly and suitable for decentralised applications and having no negative impact on the environment. However, the applications in public life has been quite low with 1.4 million solar PV systems, 7,068 solar PV pumps and 6,17,000 solar cookers. There are 61,549 solar street lighting systems, 3,63,399 home solar lighting system, 5,85,001 solar lanterns.

 

India is quite advanced in solar technology and solar photovoltaic production and exports have been rising. Solar photovoltaic production has reached 100 mw per year and about 85% of it is being exported to developed countries.

Small hydro-power projects generating up to 25 mw power are also categorised as renewable sources of energy. The country has an estimated potential of about 15,000 mw power generation through small hydro-power projects, but the cumulative power generation from these projects have been only 2,045.61 mw. However there are socio-economic problems associated with small hydro-projects at place where it has caused blockade or diversion in drown stream water affecting farming operations and causing drinking water availability problems in villages.

 

India is also lagging behind in power generation from biomass, bagasse and waste despite its high potential. According to government estimates, cumulative power generation from biomass is only 605.80 mw against its potential for 16,881 mw. The cumulative power generation from bagasse has been only 710.83 mw as against its potential for 5,000 mw. Cumulative generation of energy from waste has been only 55.25 mw as against its estimated potential of 2,700 mw. ------------------------------

 

Throwing light on SPV systems

 

http://www.financialexpress.com/news/Throwing-light-on-SPV-systems/335634/0

 

ASHOK B SHARMAPosted online: Tuesday , July 15, 2008 at 01:43 hrs

 

Solar energy can show the way to decentralisation of energy use. Most parts of the country have about 300 sunny days, with average solar radiation incidence ranging between four to seven kWh a day. Unfortunately the country has not been able to tap enough solar energy to meet its needs.

 

The present total installed power generation capacity in the country is more that 1,35,000 mw. But there is a large gap between the demand and supply position. India is a vast country with an area of over 3.2 million sq km and a population of over one billion people. Several experts have said that use of various renewable sources of energy, approach for decentralised power generation and distribution and a judicious energy mix use can solve the energy needs of the country to a great extent.

 

Solar photovoltaic (SVP) technology enables direct conversion of sunlight into electricity. A number of solar photovoltaic cells joined together make a solar photovoltaic module necessary for harnessing energy. A combination of solar modules in series or parallel combinations, storage battery, interface electronic, mechanical support structure, cable and switches constitute a solar photovoltaic system.

 

The electrical output of a SPV module is rated in terms of peak watt (wp) which is the maximum power output that SPV module can deliver under standard test conditions of incident solar radiation of 1,000 watts per sq metre are, spectral distribution of solar radiation as air mass 1.5 and measurements being made at 25 degree C ambient temperature. A SPV system can be used to provide electricity for lighting, water pumping, battery charging. Some of the advantages of SPV systems are the long-life time, reliability, no recurring needs for fuel, low maintenance and zero pollution.

 

According to the union ministry for new and renewable energy sources during the last three decades, some efforts have been made for development and evolution of SPV technology and its deployment in the country. Some SPV systems and products are now commercially available which offer an economically viable solution as compared to the use of fossil fuels in certain situations.

 

Though, according to the government, India today has among the world’s largest programmes for deployment of decentralised SPV systems, the achievement figures show a lot of untapped potential. The cumulative grid-interactive solar power generation has been only 2.12 mw till the end of the previous year. Among decentralised approach to power generation and distribution 69,549 solar street lighting system, 3,63,399 solar home lighting systems, 5,85,001 solar lanterns, 7068 SPV pumps have been installed. About 268 Aditya Solar Shops have been opened. Some solar plants installed could generate 2.18 megawatt peak (mwp) power on cumulative basis till the end of the previous year. The total cumulative SPV power generation has been only 110 mwp against a potential for 20 mw per sq km.

 

Solar thermal energy technology is another way of harnessing solar power. When incident sunshine is captured and transferred as heat to perform various useful activities, it is called as thermal application of solar energy. Depending on the technology, the temperature of the output thermal energy can vary from as low as ambient temperature to as high as 3,000 degree C.

 

This opens up a vast area of applications including water/air heating, cooking, drying of agricultural and food products, water purification, detoxification of wastes, cooling and refrigeration, heat for industrial processes and electric power generation. Solar architecture for designing of energy efficient buildings based on the concepts of solar energy is an important emerging application.

 

However, solar thermal programmes have progressed at a slow pace. Achievement on cumulative basis for solar water heating systems has been in only 2.15 million sq metre collector area as against the assessed potential for 140 million sq metre collector area. Only 6.17 lakh solar cookers have been distributed so far. -----

 

Focus on wind power generation

 

http://www.financialexpress.com/news/focus-on-wind-power-generation/341522/0 ASHOK B SHARMAPosted: Jul 29, 2008 at 2326 hrs ISTUpdated: Jul 29, 2008 at 2326 hrs IST

 

India is the fourth largest wind power producer in the world after Germany, US and Spain. Over the last decade, significant progress was made in harnessing wind for power generation across the world, particularly in Europe, US and India. Wind energy has emerged as the most promising renewable energy technology. Wind power installation capacity worldwide has crossed 78,200 mw, with about 48,000 mw capacity in Europe, 11,600 mw capacity in the US and 7,844.52 mw capacity in India.

 

The development of the wind power sector in the country was primarily due to the technology imported from Europe, which is more suited for European conditions. Machines meant for lower wind regimes—wind class II and III as per International Electro-technical Committee classification—are finding their way to India. In the recent times, however, there have been some attempts to develop Indian designs and technologies suited to local conditions, but most of the wind turbines and components produced are for exports, rather than for deployment in the country.

 

According to the union ministry for new and renewable energy, in 2006-07, indigenously produced wind turbines valued at $250 million were exported to the US, Europe, China, Brazil and Australia. Wind turbine blades valued at $25 million were exported to Germany, China, Spain and the US. In the year 2007-08, till December 31, 2007, indigenously produced wind turbines valued at $425 million were exported to the US, Australia, Brazil, Spain, Portugal etc. Wind turbine blades valued at $50 million were exported to Germany, China and Spain. According to a gross estimate, the exports of wind turbines and components would be around $900 million in 2007-08.

 

Wind electric generators are being manufactured in the country by a dozen manufacturers through joint venture or under licenced production or through subsidiaries of foreign companies under licenced production. Some Indian companies are manufacturing wind electric generators with their own technology. The level of indigenisation of the technology has been only to the level of 50%. The current annual production capacity of indigenous wind turbine is about 2000 mw.

 

It seems that the wind power companies are more interested in export earnings than in expanding the wind power generation in the country. Both the state and central governments have plans to render various incentives to the sector. The policymakers should reassess the situation and see if the incentive regime could to reviewed to encourage the wind power companies to expand the generation capacity in the country.

 

According to official estimates, India has the capacity to generate 45,195 mw wind power, assuming 1% of land availability for wind farms each requiring 12 hectares/mw, in sites having wind power density in excess of 200 watts/sqm at 50 metre hub-height. But so far, only 7,844.52 mw wind power has been generated in the country. The Centre for Wind Energy Technology (C-WET) has found 216 sites in 13 states and union territories having wind power density in excess of 200 watt/sqm at 50 metre hub-height. These are 41 in Tamil Nadu, 38 in Gujarat, six in Orissa, 31 in Maharashra, 32 in Andhra Pradesh, seven in Rajasthan, eight in Lakshadweep, 26 in Karnataka, 17 in Kerala, seven in Madhya Pradesh, one each in West Bengal, Andaman & Nicobar and Uttarakhand.

 

The wind power companies should, therefore, take up the opportunity for expanding the power generation capacity in the country, rather than concentrating on exports. Wind power generation is eco-friendly, as long it does not destroy forest cover. It can substitute the use of fossil fuel to a great extent. -----

 

Many hurdles to harnessing the tide’s boundless energy

 

http://www.financialexpress.com/news/many-hurdles-to-harnessing-the-tides-boundless-energy/353128/0 ASHOK B SHARMAPosted: Aug 26, 2008 at 2248 hrs ISTUpdated: Aug 26, 2008 at 2248 hrs IST

 

Generation of power from ocean tides holds out the promise of helping to meet India’s burgeoning energy needs. Oceans store renewable energy in the form of temperature gradients, waves, tides and ocean currents, which can be used to generate electricity in an environment-friendly manner, if the aspects of coastal ecology are carefully considered

 

Countries like France, Russia, China, Canada, the UK and Korea all make use of tidal energy on a commercial basis. According to one estimate, around 30-lakh mw of power is continuously dissipated through the motion of tides across the globe. However, we have still managed to tap only a small fraction from this source.

 

The first large-scale modern tidal electric plant of 240 mw was launched on November 26, 1966 at La Rance in France and is reported to be operating successfully. China has set up some small-capacity tidal plants. Canada has set up a 20 mw tidal power plant. In the UK, a major tidal power plant is being envisaged in Wales, where extensive technological, environmental, sediment dynamics and other aspects of associated problems have been investigated for more than a decade.

 

According to one estimate India—which is bounded by seas on three sides—has the potential to harness10,000 mw of energy from ocean tides. Ideal sites are the Gulf of Kutch, Gulf of Cambay and the Ganga delta (the Sunderbans) in West Bengal. Preliminary studies indicate a tidal potential of 6,000 mw in the Gulf of Cambay and 1,000 mw in the Gulf of Kutch. The Sunderbans of West Bengal have a potential for smaller tidal power plants of 1-10 mw.

 

One of the main reasons for the slow pace in tidal power generation is the extremely high cost of exploration and exploitation. Extensive investigations on technological, environmental and sediment dynamics are needed before setting up a power plant. However, harnessing tidal power is more economical in the long run due to the perpetual nature of this abundant energy source.

 

Though India has yet to see a single tidal power station, some preliminary techno-economic feasibility studies have been conducted. The Central Electricity Authority (CEA) completed one such study in 1988 to set up a 900-mw station in the Gulf of Kutch. The irrigation & power department of the Orissa government completed a preliminary survey in 1983 on the tidal power potential of the Panchapada river in Balasore district. The CEA in 1992 conducted a preliminary survey to assess the techno-economic feasibility of generating tidal power around the Andaman & Nicobar Islands.

 

The Union ministry of new & renewable energy sources supports the setting up of a 3.65-mw demonstration tidal power at Durgaduani Creek in the Sunderbans in West Bengal through the West Bengal Renewable Energy Development Agency. The main objective of the project is to supply power to 11 villages in Gosaba and Bali Bijaynagar islands in South 24-Parganas district. A detailed project report is under consideration.

 

Tidal power is created by the periodic rise and fall of ocean waters, which leads to differences in water levels, thereby creating water pressures that can drive turbines. A tidal power plant involves construction of a relatively long barrage across an estuary to create a large basin on the landward side. The basin is filled during high tide through a number of sluices.

 

Turbo-generators capable of efficient generation at low heads and consequently handling large flows are installed in the tidal barrage.

 

Energy can be produced during ebb tide (falling tide) or rising tide or in both phases if compatible turbines are installed. Single-basin single-effect, single-basin double-effect and double-basin single-effect are the possible options that are engaging the attention of experts worldwide. -----

 

Fuel of the future: hydrogen

 

http://www.financialexpress.com/news/fuel-of-the-future-hydrogen/364491/0 ASHOK B SHARMAPosted: Sep 23, 2008 at 2234 hrs ISTUpdated: Sep 23, 2008 at 2234 hrs IST

 

Hydrogen—nature’s bounty, which is available in abundance—has the potential to help resolve the global energy crisis. India has already joined the global quest to find ways to harness this valuable resource for large-scale commercial application.

 

India is one of the founder members of the International Partnership for Hydrogen Economy, along with Australia, Brazil, Canada, China, the European Union, France, Germany, Iceland, Italy, Japan, South Korea, New Zealand, Norway, Russia, the UK and US. All these countries are pursuing their own research, development and demonstration programmes with sizeable budgets. India participates in the partnership’s steering committee meetings.

 

For its part, India has set up a National Hydrogen Energy Board (NHEB), with public-private partnership under the chairmanship of the Union minister for new & renewable energy sources Vilas Muttemwar. The NHEB’s steering committee under the chairmanship of noted industrialist Ratan Tata and with the help of five expert groups formulated the National Hydrogen Energy Road Map for the country on November 21, 2005.

 

The road map envisaged an ambitious plan for 1 million hydrogen-fuelled vehicles on the roads by 2020, which includes 7,50,000 two- and three-wheelers, 1,50,000 cars and taxis and 50,000 vans and buses. It also called for decentralised hydrogen-based power generation of about 1,000 mw aggregate capacity by 2020, which includes 50 mw internal combustion engine-based stand alone generators, 50 mw fuel cell-based stand alone power packs and 900 mw centralised power plants.

 

Hydrogen has a high gravimetric energy content of 120.7 MJ/kg, which is the highest for any known fuel. However, its volumetric energy content is rather low. This poses challenges for developing safe and effective capacities for storage and transportation. Hydrogen can be used be either directly as a fuel to produce mechanical and electrical energy in internal combustion engines or in fuel cells to generate electricity for stationary, portable and transport applications. When burnt in air, hydrogen produces water as a by-product and does not produces carbon dioxide—this offers the advantage of hydrogen being an environmentally benign fuel and an efficient energy carrier. However, at high temperatures, hydrogen produces nitric oxide.

 

There have been several demonstration and pilot projects around the world that have proved the efficacy of hydrogen energy and fuel cell technologies, but most of these are suitable for small-scale operations. The challenge before the world is to harness this natural bounty for commercially viable large-scale operations, which includes production, safe storage, transportation and delivery, evolving hydrogen safety codes and standards, hydrogen applications, public awareness and capacity building.

 

In addition to the existing methods of hydrogen production based on steam methane reformation, the National Hydrogen Energy Road Map has proposed the production of hydrogen through nuclear thermo-chemical water splitting and also through solar energy, photo-electrochemical and photolytic routes, coal gasification and carbon dioxide sequestration routes and from biomass, biological and renewable sources.

 

It has suggested hydrogen storage in inter-metallic hydrides, complex hydrides like alanates, amides, clatherates, liquid hydrides, carbon nano-structures, glass microspheres, zeolites, and high-pressure hydrogen tanks. It has also suggested the development of internal combustion engines for hydrogen fuel and proton-exchange membrane and solid-oxide fuel cell technologies.

 

Many scientific institutions in the country are exploring the possibilities of viable hydrogen production from different sources. They include Shri AMM Murugappa Chettiar Research Centre, Chennai, from industrial waste containing sugar; Benaras Hindu University, Varanasi, from bacteria in bagasse and laboratory-scale hydrogen production via the photo-catalytic route, IIT, Kharagpur, from Enterobacter cloacae IIT-BTO8 through the fermentation route.

 

BHU is working on the development of hydrogen storage in metal hydrides. The Central Electrochemical Research Institute, Karaikudi, and Spic Science Foundation, Tuticorin, are developing a portable hydrogen generator. IIT, Delhi, is developing a dual-fuel compression ignition engine that would use hydrogen as one of the fuels, Rajasthan University is developing polymer membrane gas filter for hydrogen purification.

 

Jadavpur University, Kolkata, is developing a hydrogen-fuelled agriculture pump set. IIT, Chennai, is developing hydrogen storage facilities. Bhel is developing proton-exchange membrane fuel cell technologies, and the Central Glass & Ceramic Research Institute, Kolkata, is developing a solid-oxide fuel cell technologies system. -----------

 

Energy, the geothermal way

 

http://www.financialexpress.com/news/energy-the-geothermal-way/370066/0 ASHOK B SHARMAPosted: Oct 07, 2008 at 2233 hrs ISTUpdated: Oct 07, 2008 at 2233 hrs IST

 

Geothermal energy is an alternative renewable source of energy, derived from natural heat stored in the deep interior of the earth. In the last few decades there is an increase in the use of geothermal energy all over the world, both for power generation and direct heat applications.

 

There is a total globally installed geothermal capacity of over 8,900 MWe for power generation and 27,825 MWt for non-electrical purposes, according to the data available till 2005. Largest users of geothermal energy are US, Philippines, Italy, Mexico, Iceland, Indonesia, Japan and New Zealand. World over the most common non-electrical uses of geothermal energy in terms of installed capacity are heat pumps (33%), bathing (29%), space heating (20%), greenhouses (7.5%), aquaculture (4%) and industrial processes (4%).

 

In power generation from geothermal energy, US is a major producer with 2,544 mw reported in 2005, followed by Philippines with 1,931 mw, Mexico with 953 mw, Indonesia with 797 mw, Italy with 790 mw, Japan with 535 mw, New Zealand with 435 mw, Iceland with 202 mw, Costa Rica with 163 mw, El Salvador with 151 mw, Kenya with 127 mw, Russia with 79 mw, Nicaragua with 77 mw, Guatemala with 33 mw and China with 28 mw. Besides there are nine other countries generating power from geothermal energy.

 

India has made a humble beginning by conducting explorations & surveys and identifying 340 perennial hot springs with surface temperature ranging between 37°C & 90°C. However, most of these hot springs are low temperature hot water resources and can be utilised for direct heat applications. Only a few of them are suited for of about 10,000 mw. The hot springs identified in the country are grouped into seven zones:

 

* Himalayan-Puga Chhumthang

* Sohana valley

* Cambay basin

* Son-Narmada lineament belt

* West Coast

* Godavari basin

* Mahanadi basin.

 

Geothermal explorations carried out so far have generated data through extensive scientific studies backed by drilling at selected sites like Puga, Manikaran, Tatapani, Tapovan and Cambay. The data generated relate to structural, geological, geo-chemical, hydrological and thermal parameters.

 

An experimental geothermal power plant of 5 mw capacity has been set up at Manikaran in Himachal Pradesh. A cold storage plant has also been set up in the area to utilise geothermal energy at 90°C for preserving vegetable and fruits.

 

The Jammu-based Regional Research Laboratory has taken up an R & D project for harnessing geothermal energy in Puga valley for mushroom cultivation and poultry farming. A 30x20 feet insulated hut has been constructed and temperature maintained in the range of 20°C to 25°C. A pre-feasibility report on development of geothermal fields in the Puga valley for power generation has been prepared by NHPC.

 

According to surveys and studies conducted by NGRI, Hyderabad geothermal reservoir is found at a depth of about 1.5 to 2 km in the Puga valley. The estimated depth of geothermal reservoir is about 4 to 5 km and the estimated temperature of the deep geothermal reservoir is 200 to 250°C. In Tatapani the geothermal field found at a depth of 3 km has a temperature of about 260°C.

 

The use of geothermal energy, however, has certain limitations as it may cause some pollution of land and air due to certain dissolved gases. Excessive removal of gas from the deeper regions of the earth may cause some problems in the future. ----------

 

OTEC : Tapping megawatts in the oceans

 

http://www.financialexpress.com/news/mega-watts-in-the-oceans/380886/0 ASHOK B SHARMAPosted: Nov 04, 2008 at 2300 hrs ISTUpdated: Nov 04, 2008 at 2300 hrs IST

 

Oceans, covering more than 70% of the earth's surface, are the world's largest solar energy collector as well as the storage system. In a day tropical seas, spread over 60 million sq km, absorb solar radiation that equals heat content of 250 billion barrels of fossil oil. So, ocean thermal energy conversion (OTEC) can be an effective option for energy generation.

 

OTEC is a process that converts solar radiation to electric power by using the ocean's natural gradient. It uses the temperature differences between deep and shallow waters. If the temperatures of the warm water surface and the cold deep water differ by about 20°C, the OTEC system can harness significant power.

 

According to experts, OTEC systems can produce about 1,000k million watts of base load power. If less than a tenth of one per cent of the solar energy stored in oceans can be converted into electricity, it would supply more than 20 times the total energy consumed in the US per day.

 

India has piloted a 1 mw floating OTEC plant near Tamil Nadu and the government continues to sponsor various research projects in developing floating OTEC facilities. Among other countries Japan is interested in funding researches in OTEC technology.

 

French physicist Jacques Arsene d'Arsonval first thought of tapping thermal energy from the oceans in 1881. Years later a d'Arsonval's student, George Claude, built the first OTEC experimental plant in Cuba in 1930 for producing 22 kW of electricity with a low-pressure turbine. In 1935, Claude also constructed another plant aboard a 10,000-tonne cargo vessel off the coast of Brazil, but was destroyed by waves. Later in 1956, French scientists designed another 3-mw plant for Abidjan, Cote d'lvoire but couldn't be completed. In 1962, J Hilbert Anderson and James H Anderson Jr focused on developing new and more efficient component design with a view to complete Claude's unfinished agenda.

 

The US got into OTEC research in 1974 when the Natural Energy Laboratory of Hawaii Authority was set up at Keahole Point on the Kona coast. This laboratory is one of the world's leading test facilities for OTEC technology. In 1978, Richard Meyer became a well-known figure among OTEC technologists. In 1979, a tiny OTEC generator was set up off the coast of Hawaii for producing 18kW power. Another plant, which continuously produced more than 50 kW power soon followed.

 

In 1984, the Solar Energy Research Institute (now known as the National Renewable Energy Laboratory) developed a vertical-spout evaporator to convert warm seawater into low-pressure steam for open cycle plants. Energy conversion efficiency, which was as high as 97%, was achieved on them. In May 1993 an open-cycle OTEC plant at Keahole Point produced 50,000 watt during a net power-producing experiment, breaking the record of 40,000 watt produced by the Japanese system in 1982.

 

Some proposed OTEC projects across the world include a small plant for the US Navy base on the British-administered island of Diego Garcia in the Indian Ocean. It is proposed that a 8-MW OTEC plant, backed up by a 2-mw gas turbine, would replace the existing 15-mw gas turbine plant. A US company has proposed building a 10-mw OTEC plant at Guam.

 

OTEC plants can be of open, closed or hybrid cycles. In an open cycle system, lowering the pressure above warm water turns it into vapour, effectively 'steam' which runs a turbine before it is re-condensed by cold water. In closed cycle and hybrid systems, the water heats and cools—vaporises and recondenses—an intermediary fluid/gas that powers a turbine within a closed sub-system, which enables much larger energy output.

 

Newer designs and material choices have reduced the capital investment costs of OTEC plants. Indian Ocean, Caribbean, South Pacific and the Hawaii regions are the most cost-effective sites for OTEC plants. More works are needed to reduce plant costs further. But certainly, harnessing the wealth of the oceans to replace the fossil fuel is an idea whose time has come.

 

Another hassle in the way of OTEC plants are laws and treaties governing the seas. The UN Convention on the Law of the Seas gives coastal nations rights over waters in the specified zones of varying legal authority along the coast. OTEC facilities which are stationary surface platforms and may be considered as artificial islands and, therefore, may invite legal problems. OTEC plants may be perceived as either a threat or potential partner to fisheries management or to future seabed mining controlled by the International Seabed Authority. World leaders need to put in place appropriate international law so that objective of tapping megawatts from oceans is not hindered.

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