Environmental and Sustainability Aspects of a Recirculating Aquaculture System Adnan Midilli, a Haydar Kucuk, a and Ibrahim Dincer b a Department of Marine Engineering, Energy Technologies, Turgut Kiran Maritime College, Rize University, Rize 53900, Turkey; haydarkucuk@hotmail.com (for correspondence) b Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, ON, Canada L1H 7K4 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ep.10580 This article presents some new exergy-based pa- rameters for Recirculating Aquaculture System (RAS) for Black Sea trout (Salmo trutta labrax) at the Trab- zon Central Fisheries Research Institute, Turkey. On the basis of the actual data employed, some environ- mental and sustainability aspects of the RAS are parametrically studied in terms of exergy parameters. In this regard, the exergetic parameters, such as exer- getic efficiency, waste exergy ratio, exergy recover- ability ratio, exergy destruction ratio, environmental impact factor, and exergetic sustainability index are proposed and investigated. The results show that mainly based on the operating principle of the RAS, increasing waste exergy ratio decreases the exergetic efficiency and exergetic sustainability index. How- ever, any increase in waste exergy ratio results in an increasing environmental impact of the RAS. Thus, the RAS requires much more improvement because of the higher environmental impact factor and lower exergetic sustainability index during the operating the system. This is evident from the exergy recover- ability ratios ranging from 0.27 to 0.37. Furthermore, studying these parameters indicates how much improvement is possible for the RAS to achieve better sustainability. Ó 2011 American Institute of Chemical Engineers Environ Prog, 00: 000–000, 2011 Keywords: recirculating aquaculture system, ther- modynamics, exergy, environment, sustainability INTRODUCTION Energy is a key element in the interactions between nature and society and considered a key input for the environment and sustainable develop- ment. During the past decade environmental and sustainability issues have become major burdens to overcome since they have caused regional and global consequences. Some of these concerns arise from observable, chronic effects on, for instance, human health, whereas others stem from actual or perceived environmental risks, such as possible accidental releases of hazardous materials [1]. In the past, an increase in the energy consumption of a country was considered a positive impact on the economic and social developments of the country through energy intensity. It is now seen as meaning- less by many since it mostly increases the negative impacts on the environment and sustainable develop- ment. Moreover, the supply and utilization of low- priced and clean fuel is particularly significant for environmental sustainability as well as social, eco- nomic, and institutional sustainability because energy plays a vital role in industrial and technological developments around the world [2–4]. On the basis of energy consumption, it is well-known that Ó 2011 American Institute of Chemical Engineers Environmental Progress & Sustainable Energy (Vol.00, No.00) DOI 10.1002/ep Month 2011 1