Ocean Thermal Energy Conversion (OTEC) can slow climate change.

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We are desperately looking for water on Mars, but are ignoring that water on Earth. Seas and oceans, on average 3.5 kilometers deep, can supply us with all the energy we need, prompting us to switch from the climate-changing fossil and nuclear economies to a clean ocean-energy economy, in the form of ocean thermal energy conversion, OTEC.

The idea of energy from the oceans originated from the fertile imagination of Jules Verne in 1869.

Twelve years later, in 1881, the French physicist d'Arsonval (1851-1940) patented the idea of using the large difference of temperatures at the surface of some warm seas and that of water 1000 meters lower, to generate electricity.

In the d'Arsonval patent, the working fluid, ammonia, is contained in a closed circuit, which is known as Closed-Cycle Ocean Thermal-Energy Conversion, or CC-OTEC.

The surface temperature makes the ammonia boil and become a gas under pressure, sufficient to power a turbine generating electricity. The ammonia gas is then condensed back to its liquid state in a condenser, cooled by cold water piped up from the depth of 1000 metres.

A younger colleague of d'Arsonval's, the French chemist Georges Claude (1870-1960), developed an OTEC variant where the seawater itself is the working fluid. It is evaporated under vacuum, and so loses its saline components, now providing both electricity and invaluable desalinated water.

Because the working fluid is not in a closed circuit, this cycle is known as Open-Cycle Ocean Thermal-Energy Conversion, or OC-OTEC.

Dr Luis Vega took the bases of these earlier inventions, and from 1993 to 1998 set up a 210-kW land-based CC-OTEC test facility with an OC-OTEC parallel test facility in Hawaii, where he was able to confirm system designs, workings and efficiency figures. This seminal work should be recognized, as it took proven OTEC into the 21st century.

Unlike many other renewable-energy resources that are variable, OTEC delivers electricity with or without desalinated water continuously all year round, using no fuel.

OTEC is now economically competitive in its closed-cycle mode with offshore wind farms costing on average $5600/kW (NREL), compared to $4000/kW for 100-MW OTEC plant (Dr Vega).

It is competitive with large desalination plants in its open-cycle mode.

A $1bn reverse-osmosis desalination plant expected to supply 120,000 m3/day in San Diego would be matched by a 51-MW OC-OTEC plant supplying the same and costing twice the cost of CC-OTEC at $8000/kW, a total of $408M, less than half the cost of the reverse-osmosis plant.

Dr Paul Curto, previously NASA chief technologist, wrote in OpEdNews on 12/15/2010:

"OTEC is a true triple threat against global warming. It is the only technology that acts to directly reduce the temperature of the ocean (it was estimated one degree Fahrenheit reduction every twenty years for 10,000 250 MWe plants in '77), eliminates carbon emissions, and increases carbon dioxide absorption (cooler water absorbs more CO2) at the same time. It generates fuel that is portable and efficient, electricity for coastal areas if it is moored, and possibly food from the nutrients brought up from the ocean floor. It creates jobs, perhaps millions of them, if it is the serious contender for the future multi-trillion-dollar energy economy."

This ocean cooling corresponds to 1 degreesC cooling every forty years, a century resulting in a 15 cm sea-level fall, an appreciable amount, having a dramatic effect on erosion-menaced small islands.

This reversal of sea-level rise must be seen as one of the major contributions of large-scale OTEC use.

Fall in sea temperature will result in lower air temperatures and lesser cyclonic activity.

Dr Gerard Nihous has investigated extracting up to 5TW of electricity by OTEC.

Sea-level fall would be affected proportionately, 30 cm for 5TW OTEC use / century.

5 TW is equivalent to the 5 TW world-generated electricity (2008) from 15 TW of prime energy.

Conventional generation uses 15 TW to give 5 TWe, an efficiency of only one-third.

As an illustration, a 50-MW OTEC plant ship design shows both open-cycle and closed-cycle OTEC modes.

As OTEC is the only energy resource that has the benefit of slowing ocean warming and climate change, it should have the immediate support of island nations, whose very existence is menaced by rising sea levels.

If used on a 5TW scale, replacing all fossil fuels, OTEC has the potential to stop global warming, and over a period of time, of gradually reversing its effects.

Because seas and oceans are great distributors, the possible location of OTEC plants to serve menaced island countries first is immaterial, as the benefits of their examples will be spread worldwide.

For the same reason, it will be beneficial for countries not having OTEC waters to invest in OTEC, wherever located, since it will have a positive effect on planetary climate change.

Dr Robert Cohen, appointed in 1973 by the NSF to manage the US OTEC program, has stated that OTEC has the potential to help provide energy-security, water-security and food-security.

OTEC is worth supporting, and should be seen as a favorite "green" investment.

Backing OTEC will fight climate change.

The author declares his conflict of interests, since the advancement of OTEC, pro-activated by such firms as Lockheed Martin, will bring more work to his consultancy.

Authors Website: www.energyisland.com

Authors Bio:
Dominic Michaelis was educated in England and in France,
going to Trinity College, Cambridge as a major scholar, to read Architecture and Engineering, his thesis, in 1964 being a solar house and a floating solar village.
He then went to Cornell to do an Msc in Architectural Structures and Town Planning.
His first Job was as an architect with Arup Associates,
and later with Piano Rogers. He then set up his own
practice, in 1972, Dominic Michaelis Associates, to which
he linked a consultancy:- Solar Energy Developments.
His combined practices carried out a number of solar projects in the UK, ranging from solar individual houses, carrying out both passive and active housing projects In Milton Keynes, and a solar factory office building in
Stockport, opened by Prince Charles, that won a joint RIBA award.
He built a number of solar houses in France, and also in Italy, where he designed and built some low cost passive solar 5-storey housing outside Pisa and Siena. In Rome, he designed the headquarter building for Agip-Jacorossi, cooled and heated by an innovative roof mounted air to water heat pump.
He built an evaporative cooled "pisé" walled house in Marrakech, and was selected by the EU to design 5 health Centres in Mali, built of pisé walls with thin concrete vaults protected by sun breaking tiles. In the same
spirit, for a Polytechnic in Barbados, he used inclined hollow roofs to create natural air conditioning.
He also worked with well-known architects, Oscar Niemeyer for an Oxford college, and the Nervi brothers on a shaded stadium in Riyadh.

Feeling that solar energy had limits in the UK, he looked at wave energy,
and patented an all flexible system, based on a floating upper membrane and a lower weighted and valved membrane linked by hose pumps, developed with Peter Rice (see Wikipedia) of Arup. A sea going prototype proved the viability of the system.

He carried on, his work after 1990 with Solar Energy Limited. He worked with Noor Web, Morocco, to establish a network of village photovoltaic battery recharging centres for the agricultural communities not served by the grid.
He also attempted to introduce low cost solar cooking methods at those centres.

In 2002, a call for Ideas by one of the scientific advisers of the International Ocean Thermal Energy Conversion, OTEC, Association sparked the idea of an "Energy Island", which was published in their summer newsletter.

The idea is to provide a floating or coast based platform able to convert the many different forms of energy available at sea, mainly wind, wave, sea current, and submarine geothermal energies, and above all, OTEC,
which, powered by the difference of temperature of surface tropical waters and of waters 1000 metres below, can yield tens and hundreds of MW levels of electricity with the simultaneous production of desalinated water at the rate of two million litres per day per megawatt generated.
OTEC creates upwelling of low level plankton rich cold waters, which can serve for valuable fish farming.

As it extracts all its energy created from the seas, it effectively cools the seas, rather than warm the seas or rivers or atmosphere, as do other forms of energy generation.

Energy Islands could produce a considerable proportion of world energy and water requirements.

Energy Island Limited has formed a team linked to Southampton University, Dr Luis Vega, a world authority on OTEC, Noble Denton, marine engineering specialists, Halcrow power, Parsons Brinkerhoff, and Dominic's son Alex, who is the company's MD.


Dominic Michaelis's interests have also been in solar ballooning, solar cooking and distillation.

He has recently published an article on bilateral crossed vision in "StereoWorld".

Dominic Michaelis
MA (Arch) Cantab
Dip Eng Cantab
Msc Eng Cornell.
RIBA

Websites:- www.energyisland.org

www.solarenergyltd