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Wednesday, August 6, 2008


The following derives from Chapter 4 of SIMPLE SOLUTIONS for Planet Earth, except that adjustments were made for the sudden rise of oil prices. The key new point is that OTEC electricity should today be competitive at those locations continuing to use primarily oil to generate electricity. Hawaii is now a particularly attractive site.
The electricity from next generation one MW OTEC facilities will cost more than $0.25/kWh. There have been island communities long in this price range, with some approaching an unsubsidized $1/kWh. With freshwater, aquaculture, air-conditioning and other co-products, a major resort or military base could justify the installation an OTEC power plant, and Diego Garcia in the Indian Ocean appears to be a potential customer for the U.S. Department of Defense. If they were interested when oil was selling for $50/barrel, certainly, at $120/bbl, the economics must now look more reasonable.

A 1 MW OTEC facility can produce up to 3500 cubic meters per day of potable water. The value added operational and marketing benefits of natural energy and self-sustainability are exploitable advantages. While the U.S. Department of Defense has carried out several studies to consider this alternative, there are hopes that an international funding organization, such as the World Bank or Asian Development Bank, will have the will to break from tradition to symbolically demonstrate the value of this sustainable option.

With water credit, it has been reported by PICHTR that a land-based 1 MW plant could be built to produce electricity at $0.25/kWh and 5 MW for about $0.10/kWh. A 50 MW floating closed cycle hybrid OTEC facility, with water sold at $3/1000 gallon, could produce electricity for $.06/kWh (1990 dollars). Appreciating that nothing much has been researched over the past two decades, and using 2008 dollars, this latter estimation should now be a bit more than 10 cents / kilowatt-hour, certainly of interest in Hawaii, when the residential rates are hovering in the range of 30 cents / kWh.

Can 100 MW and larger OTEC plantships someday produce hydrogen and other clean energy products? Studies are available detailing the production of hydrogen via water electrolysis on 50-400 MW OTEC platforms at costs low enough to manufacture on board and delivered to land-based users of ammonia and fertilizers to compete with conventional options. A 64 MW system could produce 8270 tons (one million GJ net heating value) of hydrogen per year.

A floating plantship can process 107 tons of coal per day (1.24kg/sec) to produce 47,400 tons of methanol annually, and because of the hydrogen from OTEC electrolysis, provide a 1:1.3 ratio of coal to methanol, whereas, typical plants today have a 1:0.6 ratio. There would also be the carbon sequestration benefit as mentioned earlier. Another variation, a renewable one, would use marine biomass as the feedstock to replace coal, for a large portion of the overall coal cost is just the delivery.

The rise of crude prices have now made OTEC electricity commercially competitive for sites using oil products to generate electricity. With water, carbon, and/or co-product credits, the promise increases for niche island applications today. In the mid term, as oil becomes even more expensive, OTEC hydrogen and other fuels and chemicals can become attractive substitutes to carbon fuels. In the very long term, the concept of artificial upwelling for broad scale marine development with concomitant environmental benefits looms large as a productive future.
Crude continues to slip on reports of higher inventories, down to $118.70 today. The DJI jumped 40 to 11656.
Edouardo has weakened to 15MPH and is headed for the Dallas vicinity. It dumped more than 6 inches of rain on portions of the coastal zones and 3 inches in the Houston region. ALERT! Two organizing storms suddenly popped up in the Pacific, both now tropical depressions. One formed just southwest of the Big Island, will head west and pass at least 600 miles off South Point. Kika will most likely become a hurricane. Hope it doesn't suddenly turn north over the weekend. Remember Iniki? The real historic monster occurred in 2006, when Superhurricane Ioke formed south of the Big Island and went on to become a Category 5 hurricane, lasting for 19 days and dissipating over Alaska. Yes, Alaska. The second storm at 35 MPH is further east, should also strengthen, and is predicted to head towards Hawaii.

1 comment:

Jolee said...

Thank you so much for your article! The upcoming high school debate topic for 2008 is alternative energy development; I'll be promoting OTEC, both off and onshore. The article you published is key to my argument: the USFG should provide incentives for the development of OTEC. Once again, thank you; I'm sure this article will be widely used in the debate community.
Jolee Nebert, Seattle, Washington