Jul 25 2012
History
Jacques Arsene d'Arsonval
The idea to the use of ocean temperature differences to produce electricity was first seen in Jules Verne’s “Twenty Thousand Leagues Under the Sea” published in 1870 (Vega, 1999). Eleven years later in 1881, French physicist Jacques Arsene d’Arsonval kick started the physical development of trapping the thermal energy stored in the ocean. A student of d’Arsonval’s by the names of Georges Claude first built an experimental open-cycle OTEC system in Matanzas Bay, Cuba, in 1930 (Claude, 1930). Using a low-pressure turbine, this first OTEC system produced 22 kilowatts (kW) of electricity. By 1935 Claude had established his second open-cycle plant on a 10,ooo-ton cargo vessel that he had moored off the Brazilian coast. Both plants were eventually destroyed by waves associated with severe weather. Claude failed to reach his goal of a net power yield, as his open-cycle systems both required more power to run than they produced.
In 1956, French researchers continued development to design a 3-megawatt (electric) (MWe) open-cycle plant. This plant was designed for Abidjan off of Africa’s west coast. However hydroelectric power was inexpensive at this time. Because of this, OTEC failed to compete and the Abidjan plant was never finished. But by 1974, the Natural Energy Laboratory of Hawaii (NELHA, then NELH) established an OTEC facility at Keahold Point on Hawaii’s Kona coast. This facility became known worldwide as the test center and laboratory for OTEC technologies.
Mini OTEC
The first 50 kWe closed-cycle OTEC plant went up at NELHA in 1979 for demonstrative purposes. It was named “Mini-OTEC.” More information can be found on this plant on the page “Closed-cycle.”
Two laws were enacted in 1980 promoting OTEC development. The first was the Ocean Thermal energy Conversion Act, Public Law 96-320, later modified as PL 98-623. The second was the Ocean Thermal Energy Conversion Research, Development, and Demonstration Act, PL 96-310 (“NOAA office”). Neither law did much in terms of commercial development of OTEC facilities, however during this time Hawaii’s Seacoast Test Facility was beginning to produce desalinated water through open-cycle processing. A warm-seawater supply system was sent to the facility to demonstrate how cold-water pipes had developed as well.
Japan demonstrated a 100 kWe closed-cycle plant in the Republic of Nauru in the Pacific Ocean in 1981. Using a cold-water pipe on a sea bed extending up to 580 meters deep, Freon was utilized as the working fluid, going through a titanium heat exchanger. Net power was 31.5 kWe, surpassing expectations (Takahaski 2010).
The U.S. Department of Energy (DOE) soon determined aluminum alloy to be a better material option than titanium for heat exchangers. This alloy was cheaper to make and tests by DOE showed that biofouling could be controlled on the alloy, naturally in cold water and with small amounts of intermittent chlorination in warmer water.
1984 marked the development of a vertical-spout evaporator by DOE. This device converted warm seawater into low-pressure steam and could be utilized in open-cycle plants with efficiencies as high as 97%. Direct-contact condensers were also developed and aided in efficiency levels. British researchers also developed more cost friendly heat exchangers. The concept was patented and helped make size limitations obsolete for OTEC piping (“OTEC technology”).
In May 1993, an open-cycle OTEC plant produced 50,000 W of electricity during testing. The plant was located at Keahole Point, Hawaii, and broke the Japanese 40,000 W record. Since, scientists have continued to develop OTEC technologies to be more effective and affordable (“Technical readiness”).
5 Responses to “History”
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Wow, it has been a while. I never would have guessed that the idea of using a temperature gradient to produce energy came from a work of literary fiction! I enjoyed this write-up quite a lot as I am an avid history nerd. I did, however, find it interesting that the last year mentioned is 1994-present, with vague mentioning of technologies becoming “more effective and affordable.” From the very start, has this not been the main problem preventing people from heavily investing in and installing these sorts of technologies? Sure, wind and solar energy seem to be yielding promising results in the real world, but OTEC remains as one of the more expensive, less efficient options and has for some time. While I am all for research into any technology that might help human beings reduce their carbon emissions, because global climate change is a very serious threat, at what point do we give up on alternative technologies like OTEC that just aren’t up to snuff? It has been over 100 years since the idea of OTEC was first introduced, and yet we are still trying to push the wheel up the hill, as they say.
http://www.gizmag.com/otec-plant-lockheed-martin-reignwood-china/27164/
^This article discusses a small prototype OTEC plant being constructed off the coast of China, but, as the article mentions, OTEC prototypes have been being built since the 19th century. They can produce energy, but a miniscule amount compared to the costs of construction and maintenance of the OTEC facilities. I’m not calling for abandonment of OTEC since it would seem that human beings are making technological advances at a faster rate than they ever have before, and OTEC could prove a highly useful technology if only it could be swept up by the current wave of innovation. No, I’m merely curious as to how people are deciding this is the thing that continues to deserve our attention when there are numerous seemingly more viable options in the realm of renewable energy.