Renewable-energy-based multigeneration systems

This article develops the concept of renewable-energy-based multigeneration options for producing a number of outputs, such as power, heat, hot water, cooling, hydrogen, fresh water, and so forth; and discusses their benefits. Such multigeneration options obviously lead to improved system performance and reduced environmental impacts. First, single-generation (power generation only) and cogeneration systems are compared with respect to the energy utilization efficiency, exergy efficiency, green house gases (GHG) mitigation, and payback period. It is found that the cogeneration increases GHG mitigation about 2 to 4 times, whereas the payback time decreases about 2.8 times with respect to the single-generation case. Exergy efficiency is found to be between about 55% and 65%, depending on the degree of cogeneration. The exergy efficiency shows the maximum values for certain source temperatures. For the case studied here, the optimum source temperature is taken as 200 degrees C for analysis purposes. The results show that multigeneration of energy systems helps increase both energy and exergy efficiencies, reduce cost and environmental impact, and increase sustainability. Copyright (c) 2012 John Wiley & Sons, Ltd.