Hirohisa Aki

A Review of Hybrid Renewable/Alternative Energy Systems for Electric Power Generation: Configurations, Control, and Applications

Summary form only given. This paper, prepared by a special task force of the IEEE PES Renewable Energy Technologies Subcommittee, is a review of hybrid renewable/alternative energy (RE/AE) power generation systems focusing on energy sustainability. It highlights some important issues and challenges in the design and energy management of hybrid RE/AE systems. System configurations, generation unit sizing, storage needs, and energy management and control are addressed. Statistics on the current status and future trend of renewable power generation, as well as some critical challenges facing the wide-spread deployment of RE/AE power generation technologies and vision for future research in this area are also presented. The comprehensive list of references given at the end of the paper should be helpful to researchers working in this area.

Effect of Heat and Electricity Storage and Reliability on Microgrid Viability:A Study of Commercial Buildings in California and New York States

E RNEST O RLANDO L AWRENCE B ERKELEY N ATIONAL L ABORATORY Effect of Heat and Electricity Storage and Reliability on Microgrid Viability: A Study of Commercial Buildings in California and New York States Michael Stadler, Chris Marnay, Afzal Siddiqui, Judy Lai, Brian Coffey, and Hirohisa Aki Environmental Energy Technologies Division Revised March 2009 http://eetd.lbl.gov/EA/EMP/emp-pubs.html The work described in this paper was funded by the Office of Electricity Delivery and Energy Reliability, Renewable and Distributed Systems Integration Program in the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.

Operational strategies of networked fuel cells in residential homes

Residential fuel cells (FCs) have been recently launched in the commercial markets in Japan. The introduction of FCs in residential homes has become a realistic option. We previously proposed energy networks that enabled the interconnection of homes via electricity, heat, and hydrogen networks in order to allow consumers to interchange energy. Further, we have developed a PC-based simulator and an experimental system to evaluate the proposed energy networks. In this paper, analyses on the strategies of the electricity dispatch of FCs and their load sharing in the interconnected homes equipped with the energy networks were performed. The analyses were conducted with the experimental system, PC-based simulator, and a newly constructed mathematical model that optimizes the operation of the FCs with the minimization of both annual energy cost and CO2 emission. The basic characteristics of FC stacks were obtained by experimentations, and these were stored in the PC-based simulator. Four different operational strategies were carried out for four FC stacks, and these strategies were compared. It was concluded from the results that the operational strategies, which have different advantages with regard to efficiency in electricity generation and heat recovery, should be applied depending on the seasonal demand variations

Analysis of energy pricing in urban energy service systems considering a multiobjective problem of environmental and economic impact

Introduction of an integrated energy service system in an urban area is assumed. An energy supply plant is installed in the area to provide integrated energy service. It supplies electricity, gas, cooling, and heating to consumers. To consider CO/sub 2/ emission constraint in the area, analyses of energy pricing, economic impact on energy consumers, and operation of the system under the constraint of CO/sub 2/ emission were performed. CO/sub 2/ emission and economic impact on the consumers and the supplier of various energy pricing scenarios were calculated using linear programming models. The solution that satisfied the CO/sub 2/ emission restriction, and was economically optimal to the consumers was chosen from the results. The chosen solutions are Pareto optimum solutions of a multiobjective problem that concerns both CO/sub 2/ emission and cost to the consumers.

An Automated Impedance Estimation Method in Low-Voltage Distribution Network for Coordinated Voltage Regulation

Internode line impedance values are essential information for achieving coordinated voltage regulation with distributed energy devices. However, in a low-voltage distribution system, these values are difficult to acquire, especially when the devices are installed in an ad hoc manner by individual users. This paper proposes a novel method for automated impedance estimation based on practically available parameters at the terminal nodes. The distributed energy devices measure and transmit the terminal parameters to a host device. Then, the host device estimates the line impedances based on its impedance model and the collected parameters. For practical implementation, the proposed method is built under several assumptions. For example, it is assumed that the phases of terminal voltages are not synchronized owing to communication latency. Instead, only the magnitude value is incorporated during the impedance estimation. The proposed method is verified via a simulation that assumes a realistic environment.

Japan's Pivot to Resilience: How Two Microgrids Fared After the 2011 Earthquake

Japan was an early leader in microgrid research, with the four demonstrations funded by the New Energy and Industrial Technology Development Organization (NEDO) between 2003 and 2008 being particularly influential. In addition, there have been several notable private sector projects, as well as some remote island, dc power, and sustainable community demonstrations. Objectives for the four NEDO projects were primarily to demonstrate the high penetration of local small-scale renewables,local control of diverse resources, islanding, reliability, and heterogeneous power quality (HeQ).

R&D and deployment of residential fuel cell cogeneration systems in Japan

The activities and present state of R&D and deployment of residential fuel cells in Japan are presented. More than 2,000 fuel cell systems using polymer electrolyte membrane fuel cells (PEFC) have been installed to general homes by the end of 2007. The development of residential solid oxide fuel cell (SOFC) systems is also being promoted toward market launch. The activities of Osaka Gas Ltd. are reported as an example of industrial sector. Osaka Gas is an active leader on residential cogeneration systems, and succeeded on residential micro-gas engine and PEM fuel cell cogeneration systems. The stories on the R&D of fuel cell cogeneration systems, especially on the control strategy improvement for energy saving are presented. The future prospective by authors was also addressed.

Independent hybrid renewable energy systems: Example applications around the world

Hybrid renewable energy systems are demonstrated around the world. Some of the systems can be operated in both on-grid and off-grid modes. Some other systems are operated in on-grid mode, but try to minimize the electricity flow as much as possible. Demonstrations in Japan, Hawaii, Norway, and other areas are introduced as examples of the hybrid renewable energy systems.

Energy storage research and development activities in Japan

Energy storage is one of the most important technologies for next generation energy system. Research and development (R&D) from basic to application are being conducted by industries, universities, national laboratories around the world. Japan is also very active on energy storage R&D, especially on Li-ion batteries not only for electric vehicles but also for stationary application. The government is operating, 1) Li-ion battery R&D program for vehicles, 2) innovative battery R&D program that pursues a next generation battery based on a complete new principle, and 3) large scale stationary battery R&D program. The details and perspectives on Japanese R&D activities will be presented.

A network of residential fuel cells and operational strategies: evaluation with a PC simulator and an experimental system

Introduction of fuel cells into residential homes would be a realistic option of near future in present state in Japan. Research and development on polymer electrolyte fuel cell (PEFC) for residential use is at the final stage toward commercial market launch. This paper presents the concept of the interconnection of residential homes with energy networks, and a PC simulator and an experimental system for evaluation of the advantages and disadvantages of the networks, and the result of simulation and experimentation with those evaluation tools. The homes can share their energy equipment virtually by the networks. It provides flexible and efficient operation of the equipment, and reduces partial load operation and start-stop operation which damage the efficiency or the life time of fuel processors. Some operational strategies of the fuel cells were proposed and evaluated with both simulation and experimentation. The evaluation result also revealed that fuel cell systems should be installed to not all homes but some homes within residential areas to realize efficient operation.