David and Goliath
SCALE OF OTEC
David and Goliath scalability of OTEC -- The barriers to development regarding cost and the potential to reduce those costs.
One of the areas of concern for development of OTEC systems is the issue of scalability – the ability for a facility to be either ramped up in size smoothly, or ramped down, considering both the operational and financial implications of scaling. While many “green” energy applications are concerned with being scaled down, OTEC presents barriers to successful increase or decrease in scaled size.
Take wind energy, for example. Current turbines are easily being upsized to produce significant wind power. However, smaller, home sized units remain cost- inefficient. Solar has yet to reach an affordable per-watt cost, with prices not yet breaking the $1 per watt barrier for home-based units. Biogas facilities focus on large, while small-scale biodiesel plants cannot hope to compete, unless relying on a closed market.
The current cost of OTEC infrastructure has inhibited development of commercial facilities. With a price tag in the millions for the smallest plant, investors have demonstrated a reluctance to finance construction, although the technology has been proven. This hesitancy means that a large commercial project has yet to be financed and built privately.
Yet, OTEC systems have limitations for sizing up units. The largest proposed land-based OTEC facility does not exceed 40 MWe. This limitation means that per MW costs are quite high. On the other hand, ocean-based plantships currently can scale up to 400 MWe, reducing per MW capital costs.
Unfortunately, many small island developing states (SIDS) do not need the large power outputs (due to financial constraints as well as population), but are strategically located where large facilities are warranted. Smaller plantship facilities incur much of the same infrastructure costs, and, therefore, carry very high capital and start-up costs.
Smaller, land-based facilities that could work in some SIDS cannot be built because coastal land is at a premium.
System types also determine scalability. Open loop systems can scale to 10 MW, while closed loop systems scale to 100 MW.
The incorporation of modular (component) system design into current energy plans may ameliorate scaling problems, however, as would use of polypropylene vapour turbines and aluminum heat exchangers. Use of these materials also helps to reduce per kw costs to as low as $0.004 per kw.
Until scalability issues have been properly addressed, there will continue to be hesitancy in funding & launching OTEC systems of any commercial size.
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