This paper examines the effect of including a tuna aquaculture component to a proposed integrated system utilizing ocean energy and microalgae to produce biofuel. Cost-benefit analysis and carbon footprint estimation show a significant improvement on both economic and environmental performance of the system. The results suggest that climate change mitigation activities in ocean area should take biological resources into account rather than concentrate on energy products.
Climate change is one of the top concerns related to the sustainability of human society. The IPCC reports called for all kinds of activities for mitigating the global warming in order to avoid serious impacts on natural system. However, the contributions from the anthropogenic activities in ocean area, despite it covers over 70% of the earth surface, were less important in almost all of the future scenario analysis (IPCC, 2014).
The typical climate mitigation option of the activities in ocean area is the utilization of ocean energy including offshore wind, ocean thermal energy conversion, wave energy, current energy and tidal energy. Conventionally, electricity is to be generated using the ocean energy, then transmitted onshore or converted to other energy carriers and delivered onshore. As the result, the cost of energy product from ocean including production cost and transportation cost is usually higher than that of the same kind of product produced on land area (IEA OES, 2015). This higher cost limits the large scale application of the ocean energy utilization. Thus, in order to provide larger contribution to climate change mitigation, some concepts have been proposed to improve the economic performance through integrating other economic activities to the ocean energy development.
Meanwhile, an increasing request of the ocean development was generated by maintaining sustainable economic growth due to limited land-based resources during the past decades. Various applications to produce food, water and other necessary products were carried out mainly in coastal area for a long period. However, these applications together with the activities in river drainage basins have caused serious degradation of the ocean environment and the marine ecosystem. To avoid this limitation, the proposed concepts concentrated on offshore utilization systems.