We developed an econometric-type energy demand and supply model based on detailed energy balance tables, and presented a long-term energy scenario towards a low carbon society in 2050 for Asia and the world.
In Reference Scenario, which yields normative future evolution of energy demand and supply, the world primary energy demand and CO₂ emissions in 2050 will represent 1.8-fold and 1.7-fold increase respectively from those in 2007, which shows this is not a sustainable scenario from the viewpoint of both environment and energy security.
In Technologically Advanced Scenario, which assumes that all the countries of the world take technological advanced measures and that accelerated R&D encourages global deployment of advanced technologies, CO₂ emissions in 2050 will decrease by 16% from the level of 2005. Even in this scenario, the CO₂ reduction is far less than that required to “halve CO₂ emission by 2050”, therefore we need to evaluate further possibility of CO₂ reduction, through investigating additional technological options.

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More reduction in energy consumption is requested for the industry section because a large quantity of waste water at low temperatures is released in the industrial processes. It has potency and possibility for contribution in the energy saving if the waste water can be regenerated to be steam again. To recover waste heat at a low temperature from hot water, adsorption heat pump system can be used as of its advantages. Though most of existing heat pump is indirect heat exchange type, it has some problems such as low heat exchange rates and high capacities of heat exchanger. In this study, the direct heat exchange type which took out heat by contacting directly zeolite and water is proposed. The adsorption heat pump using zeolite-water is theoretically investigated based on adsorption isobar curves. As a result, the ratio of the amount of recovered steam of 140℃ to input waste water of 80℃ is more than 0.55 when adsorption process is only considered. On the other hand, the ratio is 0.038 when desorption process is also considered as heat source. From these calculations, the heat pump system has potential to reduce the energy of 1.4 million ton of crude oil especially for the field of ironworks.

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This paper describes several benefits of the integration of designed optimal municipal solid waste (MSW) utilization system considering energy recovery options and present energy system. A linear programming model has been developed in order to analyse proposed municipal solid waste system, taking into account the 3E's (energy, economic, and environment) aspects. The objective function of the model is to minimize the net cost of the system, under several constraints. A case study in St.Petersburg city, Russia, has been carried out for evaluation of proposed the MSW system. The results show that the introduction of an optimal MSW utilization system has energy, environmental and economic benefits compared with the present system. The proposed integrated system can produce 1,900 GWh/year of heat or 542 GWh/year of electricity in average, which can be supplied to the existing energy system. In addition, the system can reduce the amount of landfilled waste from 89% to 20%, and reduce total system’s CO₂ emission by more than 70%.

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The present study evaluated the optimized operation management of a cold air power system at a large-scale medical facility during the summer, when the air-conditioning cold load reaches the annual maximum. The evaluation was conducted with respect to energy costs, CO₂ emissions and robustness of the energy-supply system. Since there are a large number of possible solutions as to which machines and which refrigeration levels should be operated, a genetic algorithm (GA) was used to obtain approximate, applicable solutions stochastically, to determine a daily plan of operation for the refrigeration system in a timely manner. According to the operation management plan obtained from the GA, over 10% of the energy costs and the CO₂ emissions can be reduced by improved operation. The stability of the cold air power system when a large-sized photovoltaic system is installed or when one of the refrigeration units breaks down can also be evaluated by using the GA. In a medical faculty we taken up, the estimated reduction in CO₂ by adopting the photovoltaic system was calculated to be about 16% compared to the current operation management plan. And also the stability of present energy-supply system was validated except for when the vapor-absorption-type refrigerator was down.

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We have categorized various energy-saving practices carried out in residential buildings, and quantified their advantages and disadvantages. The amount of energy saved, amount of CO₂ reduced, additional time consumed by implementing the practice, and decrease in the comfort level for each energy-saving practice were calculated. We have proposed a method that helps each customer to select some energy-saving practices reasonably through an analytic hierarchy process (AHP), which is a decision-making technique, and investigated user’s attitude to the advantages and disadvantages of energy-saving practices by the web-survey. By using this model, residents may be able to identify reasonable energy-saving practices that meet their expectations and know the energy-saving potential that can be achieved when people carry out energy-saving practices.

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The aim is to clarify whether currently available electric vehicles (EVs) could feasibly match the demand of using gasoline-powered passenger cars with respect to the actual travel activity data in Tsukuba city. We examined 3 types of EVs concerning to vehicle size and battery capacity, and calculated the energy consumption to move a vehicle based on actual speed patterns. Auxiliary energy consumption such as air-conditioner or heater was added to the energy. When the energy consumed during a day did not exceed the initially available energy of the battery, we determined that the EV could replace a gasoline-powered vehicle on that day. Our calculations showed that an EV with a 9 kWh battery could completely replace only 1 of the 18 cars, and a 16 or 24 kWh battery EV could only 3 more vehicles. However, we found that an EV with a 16 or 24 kWh battery could replace 17 of the 18 cars in some cases.

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