A Proposal for a Method of Estimating Energy Saving Effect and its Application to Factory Energy Supply Systems

In order to carry out energy saving service, it is indispensable to calculate the energy saving effect quantitatively by presuming the energy cost at the time of not executing the energy saving measure. However, it is difficult because the energy cost changes from A to A’ as in Fig.1(b) when environment (energy demand, unit prices of fuel or electric power, and so on) changes even if an energy saving measure is not executed. Although the effect has been conventionally evaluated by the difference between the energy costs before and after the energy saving measure as C in Fig.1(a), the effect cannot be calculated correctly when environment changes. In this paper, we propose the method of estimating energy saving effect by presuming the energy cost after an energy saving measure, assuming that the measure is not executed, and show the result of its application to the practical power plant. Proposed method Total cost before an energy saving measure is distributed to each cost, Cbr(i), such as power and steam costs by a method of distribution using calorific value in Fig.2. Each real unit price before an energy saving measure, Ubr(i), is calculated by Eq.(1). Here, i ∈ {power, high-pressure steam, middle-pressure steam, low-pressure steam}. Gbr(i) is each energy consumption. ( ) ( ) ( ) br br br C i U i G i = ................................................................ (1)