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and 1-page Executive SummaryOcean Thermal Energy Conversion can exploit natural temperature gradients in the oceans to generate usable forms of energy (for example, cost-competitive baseload electricity in tropical regions such as Hawaii) free from fossil fuel consumption and global warming emissions.The #1 acknowledged challenge of constructing an OTEC plant is the Cold Water Pipe (CWP), which draws cold water from 1000m depths up to the surface, to serve as the coolant for the OTEC Rankine cycle. For a commercial-scale plant, the CWP is on the order of 10m in diameter. This report describes work done by LMSSC developing the CWP for LM MS2 New Ventures' emerging OTEC business. The work started in early 2008 deciding on the minimum-cost CWP architecture, materials, and fabrication process. In order to eliminate what in previous OTEC work had been a very large assembly/deployment risk, we took the innovative approach of building an integral CWP directly from the OTEC platform and down into the water. During the latter half of 2008, we proceeded to a successful small-scale Proof-of-Principles validation of the new fabrication process, at the Engineering Development Lab in Sunnyvale.During 2009-10, under the Cooperative Agreement with the US Dept. of Energy, we have now successfully validated key elements of the process and apparatus at a 4m diameter scale suitable for a future OTEC Pilot Plant. The validations include:•Assembly of sandwich core rings from pre-pultruded hollow "planks," holding final dimensions accurately •Machine-based dispensing of overlapping strips of thick fiberglass fabric to form the lengthwise-continuous face sheets, holding accurate overlap dimensions •Initial testing of the fabric architecture, showing that the overlap splices develop adequate mechanical strength (work done under a parallel US Naval Facilities Command program) •Successful resin infusion/cure of 4m diameter workpieces, obtaining full wet-out and a non-discernable knitline between successive stepwise infusions.After an introductory section describing the background and initial work, the major sections of this report describe (mostly by graphical means) the results of these validations at 4m scale. Within each section, the key results, evidence, and future improvements are summarized concisely in tables.The last section of this report describes future plans to complete the CWP risk retirement and implementation.An extended Executive Summary at the end provides the key results from this work at the level of one photo montage and one • Can we use an off-the-shelf composite fabrication process?• Various possible liquid resin infusion processes as applied to vertical stepwise molding of a CWP • VARTM -A quick summary tutorial • VARTM of a large wind turbine blade shell • Recent applications of large-scale VARTM technology • CWP processing steps using stepwise VARTM • Tooling strategy • Elements of VARTM that are "tweaked" for our application • Holding, lowering, and supporting the CWP during on-the-water fabrication 20...

Ocean Thermal Energy Conversion (OTEC) was a subject of intense research in the late 1970s and early 1980s in response to a historical jump in oil prices from the 1973 oil embargo. The principal author for this paper first met Prof. Paulling as a participant in a National Research Council (NRC) Panel to review OTEC Technology around 1982. Prof. Pauling had authored a frequency domain program to analyze the coupled response of a platform and OTEC pipe. The author was involved in model tests to validate the program. The United States (U.S.) Department of Energy (DoE) and National Oceanic and Atmospheric Administration (NOAA) had sponsored this work, along with the development of other numerical methods. Shortly after the NRC completed its review, oil prices fell and interest in renewable energy, including OTEC, evaporated. Fast forward to the 2000s, the price of oil skyrocketed again, and OTEC research saw a rebirth. Lockheed Martin and others have been working on new OTEC designs over the course of the last several years. As was the case thirty-five years ago, the cold water pipe remains a key technical challenge. A commercial scale OTEC plant requires a pipe diameter of about 10-meter (m) and a length of 1,000m to pump about half the average discharge of the Colorado River from the deep ocean to the surface and through heat exchangers. Because of the large effective mass of the CWP and entrained water, the dynamic response of the OTEC CWP and the platform can only be considered as a coupled system. This conclusion is not new, but is worth repeating and doubly important to consider when the supporting platform is a semi-submersible as opposed to a large water plane ship shaped vessel. A new generation of software is available to analyze the cold water pipe-platform responses, including the important effect of the fluid flow inside the pipe and the local effects at the connection of the pipe to the platform. The DoE and Lockheed Martin recently sponsored a 1:50 scale wave basin model test of a commercial OTEC platform with an elastically scaled model of a 10m pipe. The purpose of the test was to validate the use of current software for the large CWP diameters in the designs of a pilot or commercial systems in the near future. This paper will briefly review past work on the OTEC cold-water pipe and present the current state of the art in numerical modeling and the results of the model tests recently completed. It will include recommendations for further experimental and numerical work to be prepared for the future design of OTEC systems.

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