Energy conservation in buildings : cogeneration and cogeneration coupled with thermal-energy storage

Energy-conservation opportunity in an institutional building is studied through cogeneration with double-effect absorption chiller. Both, technical and economical feasibility is evaluated and presented. The typical electrical energy and cooling-load demand profiles of the buildings concerned are determined. Payback period, internal rate-of-return (IRR), net present value (NPV) and net profit of the Institute is determined through cash-flow analysis. Then, cogeneration coupling with thermal energy storage (TES) is studied and its technical and economical feasibility is evaluated and compared with that of cogeneration. On-site cogeneration with a double-effect absorption chiller provides a potential of at least 13% peak demand reduction and about a 16% savings in energy consumption. It provides IRR greater than 21% but the saving potential is limited by the low demand of co-generated chilled water within the community of the Institution. Cogeneration coupling with thermal energy storage offers a simple and economically more attractive approach for maximizing the utilization of co-generated chilled-water and shows 23% reduction in peak demand and a 21% savings in energy consumption. It provides a higher IRR, greater than 25%.