(152a) Carbon Management By Deployment of Large-Scale Otec Plants in the Gulf of Mexico

The world’s oceans are the largest collectors and storage of solar energy. Global energy. Environment and economic settings have drastically changed: uncertain energy costs; carbon-management policy; increased energy demands; realization of impact of CO2 emissions and reorganization of Energy-Water-Nexus. This is specifically true for the Gulf of Mexico, which has been one of the favorable sites for Ocean Thermal Energy Conversion (OTEC) plants. The Gulf of Mexico is a major producer of oil and natural gas and it can be major producer of green power when oil sources decline. At current production rate of about 1.6 million barrels per day, the oil reserve will start depleting by 2040. OTEC can be the next major source of energy from the Gulf of Mexico. OTEC is 24/7 renewable energy utilizing temperature natural temperature gradients of the ocean between surface warm seawater and deep-ocean cold seawater. This energy and environment study focuses on the following key elements of large-scale deployment of OTEC plants in the Gulf of Mexico: a) production of ammonia as hydrogen carrier; b) freshwater production for the water-stressed Caribbean Islands and the Gulf States; c) conversion of captured carbon dioxide from the Gulf States to specialty chemicals; and d) recovery and conversion of carbon dioxide from seawater. The critical aspect of large-scale OTEC plants in the Gulf of Mexico is to extract the energy from the surface seawater and return the deep-ocean cold seawater at an environmentally acceptable depth. The extraction of thermal energy from the surface water and upwelling of deep-ocean cold water would reduce systematic rise of the surface water temperature of the Gulf of Mexico. This is a visionary and ambitious goal. However, in the recent years, surface temperature of the Gulf of Mexico has increased by 1-2°C, which has believed to cause severe storms with unpredictable intensity. Large-scale OTEC plants would have a positive impact on the moderation of the Gulf of Mexico seawater temperature, beside direct impact on the abatement of green-house gas emissions. Based on the previous DOE studies, an analysis was performed for production of 3,000 tonnes per day of ammonia along with desalination of seawater for assessment of techno-economic merits of large-scale OTEC plants in the Gulf of Mexico. In a similar study, techno-economic analysis was performed of utilization of captured and transported carbon dioxide from the Gulf States for conversion to methanol, dimethyl ether (DME) and alkyl carbonates. The analysis revealed that conversion of out-of-service oil platforms into OTEC platforms would significantly reduce the total-installed-cost (TIC) by taking the credit of dismantling and disposal of oil platforms. The Technology Readiness Level (TRL) of the OTEC technology is at such a stage that first of the large-scale OTEC plant can be deployed in foreseeable future with low risks.