Electrical generation compared with process stream

For low electricity costs ( 75% compared with the reference case). Cases IE and IG will be more attractive compared with the other cases. These cases are still attractive even with higher electricity cost (125% compared with the reference case), with a payback period of 0.88 years. As expected, a higher electricity price reduces the attractiveness of all cases. Waste LLP steam can be recovered economically from the steam condensate system. Alternatively, waste heat can be recovered as hot water from process streams. Petroleum refineries often discard a lot of waste heat through furnace stacks, fin-fan coolers and product coolers, which can be used to generate LLP steam (Reddy et al., 2013b). In such situations, where LLP steam is available at zero cost, a single-stage absorption chiller (Cases ID and IF) becomes feasible and attractive with a payback period of 0.93 years (Table 11.2). 

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