Takuya Oda

Energy-Efficient Low Rank Coal Drying Based on Enhanced Vapor Recompression Technology

Vapor recompression is considered a highly energy-efficient technology to recover the heat involved in a process. Unfortunately, in conventional vapor recompression technology, not all of the heat can be recovered effectively. In this study, an enhanced vapor recompression technology enabling more effective heat recovery is proposed, and its ability to dry low rank coal (LRC) is evaluated. We consider the factors of exergy recovery and heat coupling. In addition to conventional vapor recompression, enhanced vapor recompression technology used to dry LRC can recover effectively the sensible heat of dried solid LRC through water recirculation. Moreover, we show that there is an optimum amount of recirculated water for each initial and target moisture content. A temperature–enthalpy diagram reveals that the proposed enhanced vapor recompression technology shows effective heat coupling for each type of heat, which results in less exergy loss so that a marked reduction in energy consumption can be achieved.

Innovative Steam Drying of Empty Fruit Bunch with High Energy Efficiency

Empty fruit bunch (EFB) is one of the solid wastes from crude palm oil mills and has the lowest value for utilization compared to other solid wastes. To achieve an efficient utilization of EFB, drying is considered the first crucial process due to the high moisture content of EFB. In this study, EFB drying based on exergy recovery is proposed to achieve high energy efficiency. A fluidized bed is adopted as the main dryer. The proposed model is evaluated in terms of energy efficiency, especially regarding the influence of target moisture content and fluidization velocity. Up to 92% of the energy involved in the drying process can be recirculated. The total energy consumption for drying decreases as the target moisture content decreases, though there is no significant impact of fluidization velocity to total energy consumption. In addition, the required total length of the heat transfer tubes immersed inside the fluidized bed dryer is calculated because it relates to fluidization performance and economic issues. Lower target moisture content results in a longer heat transfer tube, and higher fluidization velocity leads to a shorter heat transfer tube.

Utilization of EVs and their used batteries in factory load leveling

The market of electric vehicle (EV) is expected to grow positively in the next few decades replacing the current fossil fueled vehicle. Moreover, as EV market grows rapidly, its secondary used battery is predicted to increase accordingly. To support this growth, wider utilization possibilities for both EV and its used battery have been discussed especially their possibility to take part in the electricity market. Among several services, load leveling in certain energy management system is considered to be one of the excellent candidates. This study focuses on the utilization of EVs and their used batteries to support factory energy management system (FEMS) in term of load leveling. For that purpose, a demonstration test bed has been developed and load leveling test has been performed. From the results, it is shown that application of EVs and their used batteries for load leveling in FEMS is considered feasible.

Load Leveling Utilizing Electric Vehicles and their Used Batteries

The increase of electric vehicles (EVs) has led to some challenging problems and opportunities, especially related to electricity issues. The uncontrolled charging and discharging of EVs can reduce the quality of electricity grid due to frequency and voltage instabilities. However, the optimized utilization of EVs also offers high potential for ancillary service including frequency control and storage. The adoption of EVs and used EV batteries is expected to be able to improve the total economic performance of EVs as well as reduce the environmental impact. In this chapter, the utilization of EVs, together with their used batteries, to support the electricity (load leveling) in a smallscale energy management system (EMS) is analyzed and demonstrated. The demon‐ stration bed consists of five EVs, five used EV batteries, and photovoltaic (PV) panels. The EMS forecasts the load of the office building and the possibly generated power from PV panels. In addition, it also calculates the potential of EVs which are available for joining the load leveling program. EMS will control all the charging and discharging behaviors of connected EVs and used EV batteries, therefore the grid load can be maintained to be lower than the calculated peak-cut threshold. It is found that the utilization of EVs to support small-scale EMS through direct contract is feasible, and hence applicable. At the end of the chapter, some suggestions earned from demonstra‐ tion test are also listed for further consideration.

Novel power generation from microalgae: Application of different gasification technologies

Energy harvesting from microalgae based on integrated gasification and combined cycle is proposed and evaluated. Two gasification technologies, i.e. conventional thermal gasification and supercritical water gasification, are employed to convert microalgae to syngas. Supercritical water gasification has advantages on bypassing drying, however the energy to elevate the water to supercritical condition is relatively high. Each model was built on the concept of enhanced process integration technology consisting of exergy recovery and conventional process integration in order to minimize the total exergy destruction throughout the whole integrated processes. High energy efficiency of each integrated processes could be achieved, 57% for supercritical water gasification and 42% for conventional gasification.

Energy policy & New National Energy Strategy in Japan

Energy is the bedrock of our daily lives and industry. Now is the time that industry, government and academia must join together and examine highly independent, fully environmentally considerate and rational energy systems. In this presentation, recent Japanese policy will be introduced focusing on new national energy strategy. Looking at future technology trends, it is probable that, in the case of electricity generation, nuclear power, followed by coal and natural gas, will provide the bulk of the base load, and these will be complemented by highly independent symbiotic and regional energy systems, that will form clusters with appropriate size. In the year 2030, oil will be restricted to transport and chemical use, in other words, ldquonoble userdquo for which it is difficult to find alternatives. In the transport sector, as fuel cell vehicles start to reach full commercialization, it is possible that advances in the capabilities of fuel cells will see plug-in hybrids and electrical vehicles cornering a larger share of the market. From the viewpoint of effective energy, or ldquoexergyrdquo, an arrival of the ldquohydrogen societyrdquo is surely only a matter of time. In this address, having gained a grasp of these issues, first of all the Japanpsilas energy strategy in terms of energy-saving, new energies and nuclear power will be looked, and then some observations about the restructuring of the energy system will be presented focusing on thermoelectric technology.

Advanced Battery-Assisted Quick Charger for Electric Vehicles

Electric vehicles (EVs) have gained considerable attention owing to their excellent characteristics as transportation vehicles and due to their energy storage capacity. Unfortunately, this massive deployment of EVs leads to significantly high electricity demand due to their charging requirements, particularly when they are charged uncoordinatedly. In addition, the concentrated charging of EVs can potentially decrease the quality of electricity, including frequency and voltage, in addition to causing other electrical grid problems. These conditions have motivated the development of technology and policies for minimizing these negative impacts. In this chapter, an advanced quick charging system for EVs that utilizes batteries to support the simultaneous fast charging of EVs has been described, including a description of its performance under different contracted electricity capacities, ambient temperatures (seasons), and high charging demand. In addition, the charging and discharging behaviors of EVs under different ambient temperatures have been explained. Our findings suggest that charging at high ambient temperature (e.g., during summer) allows a significantly higher charging rate than charging performed at low ambient temperature (e.g., during winter). A higher charging rate leads to shorter charging time. Furthermore, the battery-assisted charging system exhibited excellent performance because it enabled optimum quick charging during simultaneous charging in addition to maintaining the contracted electricity of the charger.

Combined hydrogen production and power generation from microalgae

A combined hydrogen production and storage together with power generation from microalgae is proposed based on enhanced process integration technology (EPI). EPI consists of two core technologies: exergy recovery and process integration. Exergy recovery is performed through exergy elevation and heat coupling to minimize the exergy destruction. Furthermore, the unrecoverable energy/heat in a single process in recovered and utilized in other processes through process integration. The proposed integrated system includes a supercritical water gasification, separation, hydrogenation, and combined cycle. Microalga Chlorella vulgaris is used as a sample for modeling and evaluation. The effects of fluidization velocity and gasification pressure to energy efficiency are evaluated. From process modeling and calculation, it is shown that high total energy efficiency (higher than 60%) and electricity generation efficiency (about 40%) of can be achieved.

Integrated Energy-Efficient Hydrogen Production from Low Rank Coal and Its Storage for Transportation

An integrated system for hydrogen production from low rank coal and its storage is developed based on exergy recovery and process integration technologies to achieve high total energy efficiency. The integrated system consists of drying, gasification, chemical looping, and hydrogenation. In term of energy analysis, exergy recovery technology basically recirculates the energy/heat involved in a single process minimizing the exergy destruction in the process. Unfortunately, not all of the energy/heat involved in a single process can be recirculated thoroughly. Hence, a combination with process integration is performed to enhance the minimization of exergy destruction in the overall integrated system. In this study, the energy efficiency is evaluated. The proposed integrated system shows a very high energy efficiency during conversion of low rank coal to hydrogen which is ready for transportation.

Energy-efficient algae utilization based on enhanced process integration

State-of-the-art marine microalgae utilization processes were proposed and their performance with respect to energy consumption was evaluated. Enhanced process integration technology was developed and applied in continuous integrated energy utilization processes of microalgae. The enhanced process integration was developed based on two main principles, first, conventional process integration and, second, a thorough exergy recovery through exergy elevation and effective heat coupling for each type of energy/heat. In this study, the proposed utilization processes include the integration of drying, gasification and combined cycle. The analysis focuses mainly on the application of propose enhanced process integration in microalgae drying. Furthermore, the energy efficiency was analyzed in term of the relation between total required energy and target moisture content of drying. From the results, it is very clear that the proposed processes can reduce the required energy significantly and drying to moisture content of 10 wt% wb seems to be the most energy-efficient. The proposed enhanced process integration could minimize the exergy loss occurred in the whole process.