Search

• Decoupling of GDP from all energy sources under multiple principles are examined. • World economy achieved weak energy decoupling in most years during 2000–2011. • World economy coupled with coal use and tended to couple with cleaner energy use. • None of studied economies achieved long-term GDP-embodied energy decoupling. • Decoupling delusions occurred when only considering direct and total energy use. Decoupling indicators are widely used to understand links between economic growth and energy use. However, traditional decoupling analyses mostly focus on domestic energy consumption (i.e., the production-based principle) and neglect off-site energy use across global supply chains to satisfy an economy's final consumption (i.e., the consumption-based principle). Moreover, analyses for total primary energy conceal an economy's preference for different energy sources. Therefore, this paper evaluates decoupling states of GDP from all types of primary energy use under consumption-based principle, for world economy and eight typical economies during 2000–2011. Regarding total primary energy, world economy witnessed weak decoupling in most years, and most economies studied (e.g., USA, Japan and China) achieved decoupling initially but performed negative decoupling finally. For EU, USA, Japan, Russia and India, production-based decoupling performances were generally better than consumption-based ones. Decoupling phenomena detected under production-based principle even became coupling or negative decoupling under consumption-based principle in some cases. As for each energy source, world economy decoupled from oil use, but still coupled with coal use, and gradually showed a trend to couple with natural gas and renewables use. Different energy sources showed distinct decoupling degrees from GDP, affected by individual embodied energy requirement structure. This paper uncovers potential energy decoupling delusions to deepen the understanding of relationships between energy use and economic growth. [ABSTRACT FROM AUTHOR]

• Operating time of SMEs is estimated using a SOM and hourly demand data. • The estimated operating time is used for hourly AC demand disaggregation. • The average errors of yearly AC demand estimation are better than 10%. • Hourly disaggregation highlights season and time period of AC demand peaks. Despite the growing penetration of smart meters and energy management systems in recent years, few tools have been proposed for energy demand data analysis and visualization to promote energy conservation in small- and medium-sized enterprises (SMEs). In this paper, we propose a new method consisting of operating time estimation and simplified disaggregation based only on the SME's hourly electricity demand data and actual outdoor temperature data. The method first estimates the operating time using a self-organizing map, which categorizes the hourly data as operating, half-operating, or non-operating time and eliminates manual parameter adjustment that requires user trial and error. Then, using the estimated operating time, our simplified disaggregation method estimates hourly air conditioning (AC) demand considering the variation in each office's temperature at which air conditioners are switched on. The method was evaluated using a public business energy management system dataset from Japan, and the average errors of yearly AC demand estimation were better than 10%. The outputs of the proposed method may provide information that is more relevant, reliable, and specific to each customer and efficiently promote energy conservation measures in SMEs. [ABSTRACT FROM AUTHOR]

This paper aims to estimate the costs and CO 2 emissions of wood biomass co-firing in the Tohoku region of Japan. A woody biomass supply system is designed, which comprises of four processes: collection, resource transportation, preprocessing, and fuel transportation. Preprocessing is further divided into two processes: drying and fuel production. Sawmill residue, construction waste, forest residue, thinning residue, and fruit-tree pruning residue are treated as raw materials. Wood chips, pellets, and torrefied pellets (known as black pellets) are regarded as bio-fuels. The raw-material and bio-fuel transportation pathways are optimized using a geographical information system (GIS). In the Tohoku area, the availability of raw-material is 3.6 PJ/y, and the results indicate that the preprocessing plant locations should be widely distributed in that region, because the resource transportation costs have a significantly greater influence on the costs and emissions than the scale effect of the preprocessing facilities. The chip production case exhibits the smallest energy consumption of 3.8 GJ/t, the lowest supply cost of 1558 JPY/GJ, and the largest CO 2 reduction of 252 × 10 3 t CO 2 /y, whereas the pellet production case exhibits a supply cost and CO 2 reduction of 1643 JPY/GJ and 229 × 10 3 t CO 2 /y, respectively. The energy consumption, energy waste, and cost of torrefaction are greater than the reductions in the transportation energy and cost due to wider distribution of the preprocessing plants; thus, the black pellet case has a larger supply cost than the chip and pellet cases. [ABSTRACT FROM AUTHOR]

Manufacturing accounts for 37% of the global energy demand. Few researchers have conducted a holistic energy assessment of factories where energy beyond production equipment is accounted for, and environmental impact assessments of machine tool manufacturing are even more limited. All the while, factories need to understand where energy is used, how to allocate it to their products, and where savings lie. This paper quantifies the energy consumption and greenhouse gas emissions of a machine tool manufacturer located in Iga, Japan. Six plants within the factory are investigated whose primary operations range from precision machining to product assembly. Furthermore, a model of the energy consumption of each plant's HVAC system is developed and used to evaluate the environmental impacts and operating costs at alternative sites in China, Germany, and the US. Location was found to have a significant influence on the environmental impacts and resulted in changes in the annual energy consumption relative to the Iga baseline that ranged from −10% to 8%. Additionally, opportunities for improvement were identified by comparing the energy intensities of the equipment within the plants to industrial averages. Since the plants in this study use widespread manufacturing processes and varied climates were investigated, the methods and strategies that were developed can be extended to other discrete manufacturing facilities to identify opportunities for cleaner production. [ABSTRACT FROM AUTHOR]

This paper presents a novel review and laboratory test results of four standard test methods for determining the energy consumption of microprocessor controlled gas tankless water heaters. The test standards examined are from Australia, Europe, Japan and North America. The European test standard is found to be technically the most comprehensive in measuring all aspects of energy consumption for these types of appliances. Four water heaters, both conventional and condensing type, ranging in capacity from 28 to 55kW are tested to each of the test standards. The European and North American tests deliver similar results. Those to the Australian standard yield higher energy use while the Japanese method produces the lowest consumption. The relative difference in energy use between water heater models tested to any single standard is consistent, with the exception that the Australian test appears to favour the smaller water heater. Therefore, while consumers cannot use standard test results to calculate their actual running costs, in general, any of the standards will reasonably predict relative running cost differences between models if used as part of the product selection process. While the correlation between the standards varies according to the capacity of the water heater, a simple approximation is developed to convert from the efficiency measured by one standard to another. [ABSTRACT FROM AUTHOR]

Existing optimal control systems for vehicles that consider the effect of road slopes use a cost function with fixed weights related to speed deviation, regardless of driving states on slopes. As a result, gravitational potential energy is not efficiently exploited and braking at down-slopes (which wastes energy) becomes unavoidable. Thus, there is still significant scope to improve fuel saving behavior on slopes. To address this opportunity, in this paper, we present a dynamic eco-driving system (EDS) for a (host) vehicle based on model predictive control (MPC) with fuzzy-tuned weights, which helps efficiently utilize the gravitational potential energy. In the proposed EDS, we formulate a nonlinear optimization problem with an appropriate prediction horizon and an objective function based on the factors affecting vehicle fuel consumption. The objective function's weight is tuned via fuzzy inference techniques using information of the vehicle's instantaneous velocity and the road slope angle. By considering the vehicle longitudinal dynamics, preceding vehicle's state, and road slope information (obtained from the digital road map), the optimization generates velocity trajectories for the host vehicle that minimizes fuel consumption and CO 2 emission. We also investigate the traffic flow performance of following vehicles (behind the host vehicle) in dense traffic; this was not considered in existing works on hilly roads. The effectiveness of the proposed EDS is evaluated using microscopic traffic simulations on a real road stretch in Fukuoka City, Japan, and the results demonstrate that the fuzzy-tuned MPC EDS significantly reduces fuel consumption and CO 2 emission of the host vehicle compared to the traditional driving (human-based) system (TDS) for the same travel time. In dense traffic, the fuel consumption and CO 2 emission of following vehicles are noticeably reduced. • A fast fuzzy-tuned MPC framework is developed for eco-driving on hilly roads. • A dynamically tunable cost function is introduced to optimize the use of gravity. • The framework is tested in dense traffic using data of a road in Fukuoka, Japan. • The controlled and following cars show improved fuel consumption and CO 2 emission. [ABSTRACT FROM AUTHOR]

• GHG reduction target should be planned by aggregating effects of concrete measures. • A bottom-up energy use simulation can be used as a reliable policymaking tool. • An operation-based approach should be adopted for policymaking. • Technology distribution is important since the effects differ by household type. • Distribution of water heaters and heating systems must be considered together. The national policy in Japan for reducing greenhouse gas (GHG) emissions in the residential sector by 2030 is evaluated using a bottom-up-type simulation model called the Total Residential End-use Energy Simulation (TREES) model. According to the Japanese Plan for Global Warming Countermeasures (PGWC), the target GHG reduction in the residential sector is expected to be realized through the aggregated effect of various mitigation measures. In evaluating the impact of these measures, the following three factors must be considered: occupant behavior, differences in the effect among households, and secondary impacts. In this paper, to discuss the required specifications for supporting the policies related to GHG reduction, these factors are examined via the TREES model, considering the differences in the energy use among households due to occupant behavior, appliance/equipment ownership, and building energy efficiency. The simulation results of the end-use energy in the Japanese residential sector in 2013 show good agreement with available statistical values. The results of the TREES model applied to evaluate the proposed countermeasures suggest that 1) The Japanese government may be overestimating the effect of high-efficiency lighting installations, 2) The reduction in the total energy use varies by a factor of two depending on the combination of high-efficiency water heaters and household characteristics, 3) The relationship between the types of water heater and space heating system influences the effect of high-efficiency water heater installations, and 4) Energy demand reduction affects the electricity load curve and CO 2 emission intensity of the electricity grid. [ABSTRACT FROM AUTHOR]

• Environmental and economic performances of multi energy system(MES) was evaluated. • The operation models of MES cause the difference of environmental performance. • System environmental performance also affected by the CO 2 emission coefficient. • The price of equipment and energy mainly affect the economic performance of MES. Due to the improvement of people's living standards, uptake of multi-functional household appliances, electricity consumption accounts for a rising ratio in the proportion of primary energy usage. Currently, electricity accounts for more than 50% of primary energy usage and city gas is about 21% of total. The aim of this research focus on improving the efficiency of household energy usage and optimizing the economy of residential energy systems. This paper classified the detail electricity consumption and generation for a Japan typical household with Hybrid Fuel cell and Photovoltaic System (HFPS) based on the history monitored data. Then a simulation model of the Hybrid Heat pump and Photovoltaic System (HHPS) was designed under the same user load for analyzing the energy consumption. Finally, the economy of the two systems is compared and optimized by considering the carbon tax, equipment price and energy price fluctuation. In general, by comparing the environmental and economic performances of both two systems, the results showed that HFPS has a better environmental performance than HHPS, but HHPS presented an economic advantage over HFPS. In addition, with the change of equipment price and the development trend of energy price in the future, the economic performance of HFPS is gradually improved, which is better than HHPS and has more development prospects. The results of this work provide policy guidance for the future Japanese government's promotion of residential fuel cell systems, while choosing the optimal path between user energy characteristics and power contract scheme. [ABSTRACT FROM AUTHOR]