Shu Yoshida

An Optimal Renewal Planning of Energy Supply System From Economic Viewpoint

An optimal planning method of renewal planning for energy supply systems is proposed to determine the proper renewal year and selection as to what kind of equipment is suitable for several types of buildings from economic viewpoint. In this method, they are determined together with maximum contract demands of utilities such as electricity and natural gas so as to minimize the annual total cost in consideration of system’s annual operational strategies corresponding to seasonal and hourly energy demand requirements during every evaluation year considered. A numerical study is carried out for an office building with a total floor area of 15 000m2 , where the system is consisted of an electric refrigerator and a steam boiler. Through the numerical calculation, the influence of the following items are clarified on the optimal renewing year and selection of renewing equipment of the system by the parametric study; (a) upgrading technology of the equipment in the future; (b) initial capital cost of equipment; (c) renewing construction cost and trade-in value rate; and (d) interest rate.© 2005 ASME

Optimal Renewal Planning of Energy Supply Systems for Buildings (Problem Formulation and Economic Analysis)

An optimization method has been proposed for the renewal planning of energy supply systems installed into buildings. Assuming the raise of future equipments energy efficiency, the renewal year is determined optimally together with the structure of renewal system. In the mathematical optimization formulation, the average value of the annual total cost of the system during the evaluation period is minimized in consideration of systems operational strategy corresponding to seasonal and hourly energy demands requirement. Through the numerical study for an office building, it is shown that 2-3% reduction of the average value of the annual total cost could be achieved if the renewal planning could be optimized based on the proposed method. The influence of the following items on the renewal solution is also clarified; i.e., available types of equipment to be installed newly, upgrading rates of performance, and so on. For example, it is recognized that the optimal renewal year becomes later if the future upgrading rate of equipments performance is assumed to be high enough.

Structural Synthesis of Energy Supply Systems by Multiobjective Optimization Approach

Based on multiobjective optimization approach, a planning method is proposed for structural synthesis of energy supply systems, by which types, numbers and capacities of systems equipment can be determined rationally from economic, energy saving and environmental viewpoints. Assuming a super-structure system for an office building, the economically optimal system is synthesized with the hybrid structure of electric and gas-consumed equipments. Through the trade-off analysis, it is also clarified that by permitting the total cost increase up to 4%, 22% primary energy and 18% CO2 emission reductions can be achieved, where high efficiency electric-consumed equipments are installed preferentially.