• Energy Research
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Abstract Based on an extensive dataset containing aggregated hourly energy consumption readings of residents during March 2011 and October 2012 in South Ontario, Canada, this paper estimates the energy consumption of circulating pumps of residential swimming pools (CPRSP) non-intrusively, and quantifies the impact of CPRSP on the power system. The main challenges are that, first, widely used non-intrusive appliance load monitoring (NIALM) methods are not applicable to this work, due to the low sampling rate and the lack of the energy consumption pattern of CPRSP; second, temperature-based building energy disaggregation methods are not suitable for this work, as they highly depend on the accurate base load estimation and predefined parameters. To overcome these issues, in this paper, first it is found that, during the pool season, for homes with and without swimming pools, the ratio between their base loads is approximately equal to the ratio between their temperature-dependent energy consumptions, then a novel weighted difference change-point (WDCP) model has been proposed. The advantages of the WDCP model are that, on one hand, it doesn’t depend on the base load estimation and predefined parameters; on the other hand, it has no requirement on the data sampling rate and the prior information of energy consumption patterns of CPRSP. Based on the WDCP model it is shown that, the average hourly energy consumption of CPRSP is 0.7425 kW, and the minimum and the maximum hourly energy consumptions are 0.5274 kW at 9:00 and 0.9612 kW at 17:00, respectively. At the peak hour 19:00, July 21, 2011, CPRSP contributes 20.36% energy consumption of homes with swimming pools, as well as 8.48% peak load of all neighborhoods. As a result, the peak load could be reduced by 8.48% if all CPRSP are stopped during the peak hour.

Relying on real options theory, we employ a multistage decision model to analyze the effect of delaying the introduction of emission trading systems (ETS) on power plant investments in carbon capture and storage (CCS) retrofits, on plant operation, and on carbon dioxide (CO2) abatement. Unlike previous studies, we assume that the investment decision is made before the ETS is in place, and we allow CCS operating flexibility for new power plant investments. Thus, the plant may be run in CCS-off mode if carbon prices are low. We employ Monte Carlo simulation methods to account for uncertainties in the prices of CO2 certificates, other inputs, and output prices, relying on a realistic parameterization for a supercritical pulverized coal plant in China. We find that CCS operating flexibility lowers the critical carbon price needed to support CCS investment because it renders CCS investment less irreversible. For a low carbon price path, operating flexibility also implies that delaying the introduction of an ETS hardly affects plant CO2 abatement since the plant operator is better off purchasing emission certificates rather than operating the plant in CCS mode. Interestingly, for low carbon prices we find a U-shaped relation between the length of the delay and the economic value of the plant. Thus, delaying the introduction of an ETS may make investors worse off.

Abstract Green electricity is an effective approach to mitigate greenhouse gas emissions without damaging economic development. One effective measure to boost its development is to increase the awareness of residents about sustainable development and to increase their willingness to pay (WTP). This study applies a contingent valuation method to investigate the WTP of residents in Tianjin, China for green electricity. It uses a logit model to test whether the respondents have WTP. In addition to the factors affecting the respondents’ viewpoints frequently discussed in previous studies, this paper has also considered the influence of high prevalence of respiratory disease. Furthermore, it employs a multiple regression model to identify the factors that significantly affected the WTP. According to a sample of 468 respondents, most residents have positive WTP with an average value of CNY 32.63 per month. The main driving factors for a positive WTP are knowledge of renewable energy, belief towards the government, behavior, education, history of respiratory disease and others. The factors affecting the value of WTP include income, belief, disease, gender and age, and the first three factors often have positive influences while the last one has negative impact. Furthermore, males tend to have a higher WTP than females.

Methane accounts for 20% of the global warming caused by greenhouse gases, and wastewater is a major anthropogenic source of methane. Based on the Intergovernmental Panel on Climate Change greenhouse gas inventory guidelines and current research findings, we calculated the amount of methane emissions from 2000 to 2014 that originated from wastewater from different provinces in China. Methane emissions from wastewater increased from 1349.01 to 3430.03 Gg from 2000 to 2014, and the mean annual increase was 167.69 Gg. The methane emissions from industrial wastewater treated by wastewater treatment plants (EIt) accounted for the highest proportion of emissions. We also estimated the future trend of industrial wastewater methane emissions using the artificial neural network model. A comparison of the emissions for the years 2020, 2010, and 2000 showed an increasing trend in methane emissions in China and a spatial transition of industrial wastewater emissions from eastern and southern regions to central and southwestern regions and from coastal regions to inland regions. These changes were caused by changes in economics, demographics, and relevant policies.

This paper characterizes the solar energy literature from 1992 to 2011 using bibliometric techniques based on databases of the Science Citation Index and the Social Science Citation Index. Journal articles were the most frequently used document type representing 86.4% (6670) of the records. The pace of publishing in this field increased exponentially over these two decades, with the US accounting for the highest h-index (87) and the most publications (1273), followed by China and India. The US also plays a central role in the collaboration network among the 20 most productive countries, while China and India do not because of their more limited cross-national authorships. The Indian Institute of Technology was the organization with the most records (126), but it has few multinational co-authored articles. In contrast, the Paul Scherrer Institute in Switzerland is central to the collaboration network. The largest number of retrieved journal articles was in the area of energy applications (1059 articles) followed by light absorbing materials (983) and solar cells (420). Energy applications mainly address hydrogen, desalination, air conditioning, drying, heat pumps, biomass, and water splitting, while the light absorbing material mainly cover nano materials, TiO2, semiconductors, thin films, phase change material and so on. This analysis not only identifies global hotspots in solar energy research, but may also influence researchers' selection of future studies and publications.

Abstract The alternative energy plays a crucial role in the sustainable energy development. The alternative energy related literature had attracted a growing attention with the research outputs expanding substantially. Based on the Science Citation Index-Expanded (SCI-E) and the Social Sciences Citation Index (SSCI), a bibliometric analysis of the research output was carried out to depict existing research activities on alternative energy and future directions. The article was the main type of publications with the English as the dominate language to explain their results. With the publications increasing rapidly since 2008, the researches mostly focused on the fields of Energy & Fuels and Environmental Sciences. Energy Policy was the journal that published the largest number of research articles on the alternative energy. The bioenergy and solar energy were popular items in the commonly used 20 journals. Among the countries, the USA was leading on alternative energy related research, publishing the largest number of articles (TP=2368) and being the most influent ( h -index=90). The USA played a key role in the academic collaborations with China, UK, Canada, Germany, Italy, South Korea and Spain. The National Renewable Energy Lab (the USA) contributed most in the alternative energy field and more specially, the School of Electrical & Computer Engineering (TP=36) was the most productive subordinate in the National Technology University of Athens. It was interesting to note that more attention was paid to solar or wind energy during the first 5 or 10 years, then turned to bioenergy subsequently except for Spain, Canada and Australia. In addition, bioenergy received the most attention in the 7 types of alternative energy. The forest/wood biomass, energy crops and switchgrass were the main bioenergy resources and fermentation was the commonly used conversion technology. The production of biogas, biodiesel and bioethanol was most popular in the bioenergy related studies. Wind energy and solar energy related researches were mainly on the energy utilization approaches such as the wind generation, wind farm, photovoltaic and solar thermal. The conversion devices such as the wind turbine and solar cell were paid most attention in order to improve the production efficiency. The most cited article, published in Desalination in 2009 with 1562 citations until 2013, was about wind power utilization in the reverse osmosis desalination plant.

The power output and the efficiency of a thermophotovoltaic (TPV) system are determined by the radiation from a heat source, TPV cells, system parasitic losses, cell cooling subsystems, etc. The cells are core devices of a system, and the performance of the cells can be characterized by a number of parameters, including open circuit voltage (Voc), short circuit current density (Isc), and maximum output power density (Pm). The cell temperature has a great effect on these parameters. Although several papers have reported the dependence of these parameters on the cell temperature, few studies experimentally examined the temperature-dependent performance of the TPV cells or comparatively analyzed them. In this study, we investigated how the fundamental parameters of GaSb, Ge, and InGaAsSb cells varied with their operating temperatures using a home-built TPV prototype. The measured data indicate that the cell temperature significantly affects the performance of the TPV cells. Variations of these parameters with the cell temperature are different for various TPV cells. The Voc and Pm of the GaSb, Ge, and InGaAsSb cells decreased linearly with increasing cell temperature, while the Isc increased slightly. The normalized value of the temperature coefficient for the Pm of the GaSb was lower than those for the Ge and InGaAsSb cells, which indicated that the GaSb cells were relatively less sensitive to cell temperature. The results provided in this study are useful to improve cell performance and design TPV systems.

Abstract A scientific evaluation of the energy efficiency and CO2 emission performance of the thermal power industry could not only provide valuable information for reducing energy consumption and carbon emissions but also serve as a tool to estimate the effectiveness of relevant policy reforms. Considering the opposite effects of energy conservation and carbon emission reduction on generation cost, this study respectively measures the energy and CO2 emission performance of the thermal power industries in China’s 30 provincial administrative regions during the period 2005–2012 from both static and dynamic perspectives. We implement the bootstrap method for the directional distance function to correct the possible estimate bias and test the significance of productivity changes where the weak disposability of undesirable outputs is also integrated. The empirical analysis leads to the following conclusions. The bootstrapping results could provide us with much valuable information because the initial estimates might result from sampling noise rather than reveal the real variations. In addition, some differences do exist between the energy and CO2 emission performance of China’s thermal power industry. Furthermore, technological progress is the main driving force for energy and CO2 emission productivity improvement and it works better for the former.