We calculate the amount of output, employment, energy consumption, and CO₂ emissions induced by constructing and operating a power plant fueled by unused woody biomass. To do this, we use an input-output table developed to analyze the effects of introducing renewable energy sources. The results show that the power plant can increase the output of and employment in the forestry industry and can reduce economy-wide CO₂ emissions. Because the income of the forestry industry would increase, operating such a power plant may result in preservation of nearby forests. We also estimate the amount of public benefit obtained from preserving that area.

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This paper focuses on controlling a real power system which includes 15 kW photovoltaic power source combined with 15 kW - 7.5 kWh lithium - ion battery and 10 kW proton exchange membrane fuel cell. A control method needs to be developed to ensure the power balance between the supply from the intermittent PV power and the demand at any instant. In this study, a power management unit associated with Kalman filter prediction and based on experimental dynamic characteristics of system components has been designed. The performance of system with implemented power management strategy for several typical days is evaluated through simulation. The simulation results show that this new control method is reliable in load satisfaction in a long term as well as in a short term. In addition, the proposed method, compared with conventional power management strategy, shows the benefit of using less hydrogen and therefore, higher efficiency in the simulation time.

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“Straight Vegetable Oil (SVO)” method means the direct use of vegetable oil as car fuel through installation of a heater unit in the car to decrease vegetable oil viscosity. In this study, the authors carried out performance tests on the direct use of waste cooking oil using a car with a heater unit. Moreover, the authors carried out long run driving on road tests in 5 years using a public car of Minami-Aizu town in Fukushima prefecture and analyzed the case of troubles and clarified the availability and problems of SVO vehicles. As a result, the car with a heater unit shows similar performance in both cases using vegetable oil or diesel fuel as fuel. The tested SVO vehicle of Minami-Aizu town could be driven 38,127 km mainly by waste vegetable oil with a total driving distance of 52,293 km in long run driving tests in 5 years, and decreased about 3813.5 L of light oil which corresponds to 9.99 t of CO₂.

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We evaluated the global technical potential of energy crop production up to the year 2100, maintaining consistency with agricultural land use change under three different socioeconomic development and climate change scenarios. Our evaluation shows that the energy potential will increase from 160 EJ yr^-1 in 2000 to 180-200 EJ yr^-1 by 2050, and to 220-270 EJ yr^-1 by 2100, reflecting the increase in the potential land area for energy crops. The upper limits of the aforementioned potential correspond to the scenario with low population growth and high economic growth, while the lower limits correspond to the scenarios with moderate economic and population growth. It was clearly demonstrated that differences of socioeconomic development substantially impact the evaluation results, while differences in the level of global warming have little impact on the results. Furthermore, it is shown that land having relatively high crop yields and high land accessibility will be limited and concentrated in some developing regions such as Africa and Latin America.

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Marine biomass such as seaweed and fishery waste is a potential energy source although it has not yet been practically utilized. This study focuses on anaerobic digestion for the utilization of various organic wastes as energy resources. We introduce marine biomass utilization system, which consists of biomass transportation, anaerobic digestion, and energy conversion, and propose three scenarios varying with waste biomass supplier. The purpose of this paper is to understand digestion characteristics of seaweed, fishery and vegetable waste, and tamarind, which is raw material for the chemical product and the residue in the production process, through batch-processing experiments. Also we investigate feasibility from the economic and environmental viewpoints. The results indicate that each biomass has each digestion characteristics and especially seaweed, fishery, and tamarind have high carbon recovery rate. Among three scenarios, the case including tamarind is the most feasible. Anaerobic digestion can replace energy and products derived from fossil fuels as more environmentally friendly alternatives, however, it has big obstacle in the economically feasible operation.

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Large scale utilization of microalgae to produce biodiesel will boost large amounts of fertilizer and water consumption in upstream stage and needs excessive energy in the downstream process. To overcome these issues, the integrated energy plantation has been introduced as a suitable cultivation system, including the possibility to utilize its effluent. As a free and rich nutrient source for microalgae growth, POME was carefully evaluated in order to find out more energy return in upstream stage. In the downstream stage model, a wet lipid process pathway was chosen as the current best available method. Consequently, reducing energy consumption for the biodiesel production cycle was achieved and the energy profit ratio reached up to 2.6. Energy demand was lessened by a combination of outputs from one system, and served as inputs to another, from the integration of POME treatment, biomass power plant, biogas production, microalgae cultivation, and co-products utilization. Therefore, the energy and material balances could significantly outperform those from the single system.

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Various types of utility-interactive photovoltaic power generations including domestic applications have been reported and accepted widely. Some papers about power converters that interface between photovoltaic arrays and ac utility system have been also reported. The actual application of such solar panels is almost installed on top of the roof of the detached house. However, some residents living in the apartment house are having a fairly strong desire to contribute for energy saving using natural energy generation. In this paper, in order to give a reply, a simple and concise photovoltaic power conditioner installed in apartment house having verandas will be reported. Considering fairly reduced power and narrow space of installation, the system constructions should be simple and concise. The devised circuit which gratifies their wishes is proposed. These solar panels can be easily connected like usual home appliances having attached plug for connection. For reverse power flows and increasing harmonics, their protection circuits are installed in the input power line. System circuit and their sophisticated construction will be presented and discussed.

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A system for growing, harvesting, and utilizing willow trees aimed at short rotation forestry (SRF) was designed in northern Japan, and the system was evaluated from the viewpoints of cost economy and greenhouse gas (GHG) emission based on a life cycle assessment (LCA) method. The willows were assumed to be grown intensively in 200 ha of idle land in the test area, harvested using a sugarcane harvester, and utilized for heat energy through the burning of wood chips directly in a biomass boiler. As a result, the cost of willow was 180.64 US$/dry-t, which was more than the cost of forest biomass such as logging residues and thinned trees, while willow chips were less expensive than heavy oil in terms of their price per calorific value. On the other hand, the GHG emission of willow was 6.633 kgCO₂eq/GJ, less than one-tenth that of heavy oil. Therefore, it is suggested that substituting willow chips for heavy oil as a heating fuel could be economical and could help reduce regional GHG emissions.

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This study estimated the economic effect of utilizing woody biomass as a raw material for high value-added (HVA) material products such as master batch of cellulose Nanofiber (CNF-MB) and high standard Chip-dust (HSD) in Maniwa, Japan. In order to analyze the economic effects, two scenarios were described and compared: the BAU scenario and the HVA scenario. The results show that utilizing woody biomass for manufacturing material products can increase the net benefits to businesses as well as stimulate the economic ripple effect and job creation in a local region such as Maniwa. Moreover, the effects of HVA products can be greater than those for the four kinds of existing products. These results could help clarify the effectiveness of utilizing woody biomass in material products as a method to promote woody biomass business and regional development.

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Biogas, a renewable and carbon-neutral form of energy, could be a very good substituent of fossil fuels which are depleting very fast. Here we report the digestibilities of cafeteria waste (CW), vegetable waste (VW) and fruit waste (FW) with variable mixing ratios. The result showed that anaerobic co-digestion of CW:FW (0.50:0.50), CW:VW (0.75:0.25) and VW:FW (0.50:0.50) produced the highest cumulative biogas 836, 811 and 756 mL/g-VS, respectively after 15 d. The highest average biogas production observed for the mixing ratio CW:FW of 0.75:0.25, 0.50:0.50, and 0.25:0.75 were 50.73, 55.73, and 50.66 mL/ (g-VS d), respectively. It was observed that the highest average methane concentration were 59.1%, 58.3%, and 56.7% for the mixing ratio CW:FW of 50:50, CW:VW 50:50, and VW:FW 25:75, respectively. These results offered simple way to produce biomethane.

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バイオマスを低温ガス化して得られた実バイオガスを燃料として，火花点火ガス機関発電システムを運転したときの性能と燃焼特性を明らかにした。これまでの研究に対して，計測方法と変動の問題を再検討するとともに，天然ガス機関として実用されている機関を新たに用い，結果の信頼性と普遍性を検証した。ガス化に用いたバイオマス資源は木質ペレットであり，生成されたガスは水素やメタン，一酸化炭素といった燃料成分を含むとともに，二酸化炭素や窒素といった希釈ガス成分を含む。実バイオガスでの運転では，天然ガスよりサイクル変動が低く，正味平均有効圧力が0.4 MPa 以下であるにもかかわらず，最大の正味熱効率は30％を超えるなど，実バイオガスが希薄でかつ希釈した燃焼に適していることが明らかになるとともに，従来得られている結果が定量的にも確認された。

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