Abstract
Reducing electric power usage in the water distribution system, which accounts for 60 to 70 percent of overall usage, is seen as a key to making water supply facilities more energy efficient. Earlier research devised an estimation equation for electric power usage by water distribution pumps at each water supply facility (filtration plants, water supply stations), and applied Mixed Integer Linear Programming (MILP) to a model for minimizing electric power usage in the system as a whole (MILP model). The model used at the time of that research, however, suffered from a flaw, namely, the equations contained a constraint condition that the amount of water stored in the distributing reservoirs and the amount of fluctuation in that amount were matched at each point in time. This study therefore proposes a new model that corrects the constraint flaw, with the aim of achieving a further reduction in electric power usage.
Simulations were conducted using the new model for a specific area in Tokyo. The results indicated that an alternate proposal for water supply control and management can be expected to reduce electric power usage by 6.9 percent while satisfying the circulation constraints. The study further analyzed the extent to which electric power usage worsens when fluctuations in the amount of water stored in distributing reservoirs are controlled. The validity of the model was shown as a result of simulations conducted from the standpoint of avoiding disaster risk. The strength of the model is its ability to find the optimal water distribution method that mostly meets demands from an energy efficiency standpoint while accounting for the constraints on water volume fluctuations in distributing reservoirs.
