Ocean thermal energy conversion was the subject ofEnvironment Hawai`i in [url=/members_archives/archives1991.php]May 1991[/url] (scroll down on linked page to see the article listings and links). Several people (primarily in the Department of Business, Economic Development and Tourism) informally conveyed their disagreements with our generally negative view of OTECs potential. One person committed his comments to writing. Herewith is the critique of Tom Daniel, currently the scientific and technical program manager of the Natural Energy Laboratory of Hawai`i Authority. Daniel’s remarks have been slightly edited for publication, but every effort has been made to be faithful to his meaning.
Lessons from the Trench
I’m disappointed that you chose to highlight the story about the offshore trench. As I told you on the phone, we learned a lesson from its installation and do not intend to use such techniques again. As you briefly note by implication, the main reason for the duration of the environmental impact of the trench has been the unusual absence of strong waves in the years following its installation. You quoted me correctly as saying that the rubble left by the project was not completely dissipated by this last winter’s waves. This was probably because most of the big waves we had were related to the “devastating storm” which blew off several roofs in Kona but did not generate the more destructive long period waves which typically come in the winter from powerful distant storms. We expect that more typical energetic waves in future years will rearrange the material (not “sweep it away from the seafloor”!).
I’m glad you mentioned that we are proceeding with investigation of the promising alternative of slant drilling. I wish you’d highlighted this positive step a little more, however.
Your history of the OTEC programs in Hawai’i is similar in scope to one which I published about two years ago in a Seagrant Publication MR89-01, OTEC Aquaculture in Hawai’i. [Editors’ note: We were unaware of this publication.] Your discussion would have been more accurate if you had indicated that this is only a part of a worldwide program. Though you deplore the amount of taxpayer funds being expended on OTEC (and I agree that there have been problems with program management and guidance) it would have been more complete and fairer to note how small these amounts are compared with those being spent on other, even more questionable alternatives. Specifically, what about the $400 million per year being spent on fusion research? I believe that a properly directed increase in funding of OTEC would produce real electrical power and technological gains that would demonstrate the viability of the resource.
Most of your facts are correct and well presented, but I wish you’d stated some a bit more completely. It maybe that filings with the Department of Land and Natural Resources said that “no immediate use was anticipated” for the 48-inch cold-water pipe following its planned deployment in the fall of 1983, but if so, it was meant only in terms of the very immediate future. The Department of Energy had a large program specifically designing a plant to use that pipeline. The present Net Power-Producing Experiment is the eventual outgrowth of that program, delayed significantly by the loss of the 48-inch pipeline. Many of the remaining sections of the 48-inch pipe are already in use in various aquaculture projects around the state, and that which is left is now being installed as the drain line for the NPPE project.
Technological Advances
I wish you had included a bit of the positive results about OTEC that have resulted from our work at Keahole. Specifically, DOE-sponsored projects have shown that heat exchanger biofouling can be controlled in an environmentally benign fashion and that aluminum can be used in the heat exchangers, greatly decreasing plant cost. More recent work by Aluminum of Canada (ALCAN) working with the Marconi Division of the General Electric Company of Great Britain (GEC) has achieved a truly significant breakthrough in heat exchanger design using “roll-bonded” aluminum sheets, which permits construction of the very large heat exchanger surfaces needed for OTEC at significantly reduced cost. Initial estimates indicate that an 80 percent reduction in plant cost maybe achievable by using this technology.
This leaves the cold-water pipe as the biggest remaining obstacle to development of commercial-scale OTEC, and many of us feel that new concepts may provide cost-effective solutions here, too. Unfortunately, it is very difficult to test innovative new concepts for such large structures on a small scale, thus necessitating further large expenditures just for testing. I point out again, however, that the sums required are paltry compared to those being thrown at nuclear and thermonuclear alternatives.
Volume 2, Number 2 August 1991
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