Takaaki Furubayashi

Decentralised electricity generation system based on local renewable energy sources in the Honduran rural residential sector

Abstract This article addresses the selection of electricity generation technologies for a decentralised electricity generation system based on local renewable sources for a rural area of a developing country (six municipalities in Western Honduras). In this work, rather than designing a high-reliable electricity generation system with high-quality power, our objective is to provide the basic configuration of an energy mix for a rural area for which energy data are not of high resolution. The selection of technologies is accomplished through a non-linear integer programming model that minimises the levelised cost of electricity (LCOE). The model uses as inputs information related to the energy resources, the conversion technologies, the Honduran economic framework, the electricity demand of the study area, and the energy storage cost. The evaluated energy resources are solar, wind, and local biomass, while the electricity generation technologies considered include solar photovoltaics, wind turbines, biomass direct combustion with a steam turbine, and biomass gasification with a gas engine. Three different case studies were proposed as functions of power capacity: off-grid, mini-grid, and grid-connected. For each case study, the model outputs are the electricity supply share for each technology, the LCOE, and the number of power plants with the respective power capacity required to satisfy the electricity demand of the study area. This work can serve as a reference for preliminary feasibility studies of electrification projects based on renewable energy sources for other rural areas in Honduras or in other developing countries.

Induced technological change and the timing of public R&D investment in the Japanese electricity sector considering a two-factor learning curve

The UNFCCC has stated that energy policies and measures to address climate change should be cost-effective to ensure global benefits at the lowest possible cost. To mitigate the bulk of carbon emission from the electricity sector, a large market penetration of renewable energy technologies with as low cost as possible is a key research topic. The energy-related R&D policy in Japan aims to achieve a green economy. In our study, based on this context, we demonstrated how to optimize the timing of public R&D investment within the framework of a bottom-up partial equilibrium model. The developed optimization model represents the Japanese electricity sector and minimizes the total system cost subject to an accumulated carbon emission constraint. Our main research focus is the role of R&D activity, especially in the innovation stage of renewable technologies. We employ a two-factor learning curve and quantify the impact of the learning effect on the dynamic diffusion of major renewable technologies. The study shows a dynamic technology transition in the Japanese electricity sector and the optimized R&D investment schedule for each renewable technology. With the first-best energy policy, an R&D budget of more than 2000 million USD would be allocated to PV in 2050, which corresponds to 45% of the energy-related Japanese R&D budget in 2050. Because some have criticized the uncertainty problems with dynamic simulations and learning models, supplemental sensitivity analyses are included.

Size Effects on Short‐Time Self‐Diffusion in Dilute Highly‐Charged Colloidal Suspensions

We treat not only macro ions as charged colloids but also small ions as counter ions dispersed in a solvent by Brownian‐dynamics simulation. The size and charge of particles are changed, while the other parameters are fixed. We compare the simulation results with theoretical results by Tokuyama [Physca A 352 (2005) 252–264]. The results are in good agreements with the theory. Thus, it is shown that the short‐time self‐diffusion coefficient is decreased as the radius is increased.

Effect of Coulomb Collisions on Low Gas Pressure Plasmas

A recent trend in material processing plasmas is the use of a low gas pressure and high plasma density. In such plasmas, Coulomb collisions among charged particles has been considered to have a significant effect on plasma structure. By use of Bobylev and Nanbu’s theory [Phy. Rev. E, 61(2000), 4576], this effect on argon plasmas and oxygen plasmas generated by a capacitive discharge is examined. It is found that the effect is appreciable only for oxygen plasmas.