A case study of a hypothetical 100 MW OTEC plant analyzing the prospects of OTEC technology

A hypothetical case study has been made of a 100 MW OTEC plant, which would require around 400 m3/sec of warm water feed (with 200 m3/sec of cold water feed) and resulted in the following data: CO2 saving compared to coal power plant, as determined from lifecycle assessment (LCA)studies, would be 98.62 % for CC-OTEC, 97.41 % for the hybrid type, and 94.4 % for OC-OTEC. Energy payback period value would be 1.33 years. Cost of power generation from NPV concept of such plant is estimated to be of 2.9 p/kWh. 172,800 m3 of potable water/day could be available from OC-OTEC (but none from CC-OTEC though a hybrid type may yield appreciable potable water). More than 68,000 kg shellfish/day could be availed for all types of 100 MW OTEC. Upwelling of the nutrient rich cold water along with abundant plankton from sea-bottom and the mixed discharge of it in the ocean during OTEC operations is likely to help growth of the oceans’ flora and fauna for the abundant supply of seafood. But the danger posed from simultaneous upwelling of toxic algal bloom endangering the marine species, are also apprehended. However, by and large positive marine species growth has been opined. Such increased species growth becomes instrumental in burying CO2 in the deep ocean floor with the carcasses of dead marine species grown. This phenomenon known as sequestering of CO2, appreciably increases the ocean’s CO2 storage capability and thereby in addressing the problem of global warming. This is in addition to the amount of CO2 saved from use of alternate energy source on OTEC, against the conventional fossil fuel resources. Upwelling of cold water may be utilized in cold storages/air conditioning saving 600 times the power required for running the same. Hydrogen production, as may be made at expense of the net power generated, from a 100 MW plant, would amount to over 35,000 kg/day or 20,000 kg of NH3/day. 21,773 kg of CO2/day from OC-OTEC (also from the hybrid type but not for CC-OTEC) would be available, which can be utilized as raw material for soda ash manufacture/urea production (along with NH3 as may be availed from H2 production). Also a huge quantity of oxygen enriched air – near 33 % O2 content, against 20.93 % of normal air may be availed. 188,812 kg/day of methanol utilizing the H2, as may be generated can thereby be the resource raw material for petrochemical industries, opening up the scope of availability of a chemical hub in the vicinity of the OTEC plant. Such OTEC plants can help sustainable development, particularly small island developing states (SIDS), arresting coral bleaching (decreasing acid rains etc.), and generating employment; and also help in reducing global warming from sequestering of CO2, in addition to saving CO2 emission compared to conventional fossil fuel power generators.