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Abstract In this study, we develop indices for the overall technical efficiency (OTE) and energy-saving target ratio (ESTR) using data envelopment analysis (DEA) to calculate the relative efficiency and energy-saving potential of 30 provinces in China from 1997 to 2014. The results are as follows: (1) the OTE of China is 79.187%, indicating that there is 20.813% potential for improvement. The OTE exhibits decreasing efficiency values from the coastal areas to the inland areas and has clear geographical relationships. The average values of OTE in the east, midland and west are 0.932, 0.694 and 0.703. Theoretically, the total energy savings of CE, HE, ME and BE are 11080.60PJ, 5124.71PJ, 4729.24PJ and 6797.39PJ. (2) Regarding CE, HE, ME and BE, the provinces with the highest comprehensive ranks are Henan, Shanxi, Shaanxi, and Gansu, which simultaneously have the greatest energy-saving potentials and energy-saving targets. (3) The HE has the largest average ESTR of 38.357% and the values for BE, CE, and ME are 25.759%, 23.874%, and 22.143%, respectively. The CE category is the greatest in total energy savings (40.171%), which is followed by BE (24.150%), HE (18.384%), and ME (17.293%).

Abstract We will consider cumulative socioeconomic impacts in environmental impact assessment and mitigation processes. Cumulative impacts from several simultaneous projects are greater than aggregate impacts for projects built in isolation. Impacts of energy facilities provide a baseline for potential cumulative impacts in a number of regions. Case studies illustrate the importance of cumulative impacts, as well as their uneven treatment in the environmental impact statement (EIS) process. Important institutional, legal, and practical considerations associated with cumulative impacts are analyzed, and descriptions are offered of how cumulative impact assessments can be used as tools in decision-making.

Abstract Building energy consumption is vulnerable to climate change due to the direct relationship between outside temperature and space cooling/heating. This work quantifies how the relationship between climate change and building energy consumption varies across a range of building types at different spatiotemporal scales based on estimates in 925 U.S. locations. Large increases in building energy consumption are found in the summer (e.g., 39% increase in August for the secondary school building), especially during the daytime (e.g., >100% increase for the warehouse building, 5–6 p.m.), while decreases are found in the winter. At the spatial scale of climate-zones, annual energy consumption changes range from −17% to +21%, while at the local scale, changes range from −20% to +24%. Buildings in the warm-humid (Southeast) climate zones show larger changes than those in other regions. The variation of impact within climate zones can be larger than the variation between climate zones, suggesting a potential bias when estimating climate-zone scale changes with a small number of representative locations. The large variations found in the relationship between climate change and building energy consumption highlight the importance of assessing climate change impacts at local scales, and the need for adaptation/mitigation strategies tailored to different building types.

Abstract Intensive energy consumption and high pollutant emission have always been the obstacles for achieving the sustainable development of the iron and steel (I&S) industry. The complex material flows, energy flows and emission flow of I&S industry require better assessment to implement comprehensive governance and impact analysis. The 48-month data of a typical I&S enterprise is used for evaluating intensities and analyzing influencing factors from the perspective of material, exergy and emission networks. The results show that the exergy intensity and carbon emission intensity of the whole site including main processes and auxiliary processes are 23.804 GJ/t-CS and 1642.7 kg/t-CS, respectively. In particular, auxiliary process plays a critical role, whose exergy loss accounts for about 28.85% of the total. The terms of energy structure, technology capacity, product structure and environmental conditions are considered to analyze on the influencing factors of the case, and then providing relevant suggestions. On the whole, integration assessment of material-exergy-emission networks of I&S industry is necessary and helpful to find their changes and migration, and to further implement energy management and emission reduction.

Abstract Global environmental change is driven by food production. Biogas from food waste is a better source of clean energy. Ghana’s energy strategy targets a 10% increase in renewable energy and modern biomass in the national electricity generation mix. Studies on the assessment of electricity generation potential and economic feasibility of biogas to electricity projects in Ghana’s major cities are scarcely available. This study assesses the electricity generation potential of biogas from food waste through anaerobic digestion technology. The municipal solid waste generation potential of Accra and Kumasi was estimated from 2020 to 2039. The potential theoretical methane yield from food waste was calculated using Buswell’s equation. The study analyzed anaerobic digestion projects’ economic feasibility using the total life cycle cost, net present value, investment payback period, levelized cost of energy, and internal rate of return methods. A sensitivity analysis based on two scenarios (optimistic and pessimistic) was performed to analyze the influence of changes in the composition of food waste, per capita waste generation rate, population growth rate, per capita GDP growth rate, discount rate, capacity factor, electricity generation efficiency, waste collection efficiency, and methane production potential on the economic feasibility of the projects. The main findings indicate that the amount of waste generation in Accra during the project life cycle is 899,000 t/y to 3,359,000 t/y, while that of Kumasi is 915,000 t/y to 3,159,000 t/y. The power generation potential of the project in Accra ranges from 80.43 to 300.49 GWh/y, and in Kumasi ranges from 60.63 to 209.31 GWh/y. Economically, the project is feasible in Accra and Kumasi. The net present value of the project in Accra and Kumasi is $217,800,000 and $156,100,000. The sensitivity analysis shows that the project is infeasible in all the cities with a discount rate exceeding 20%. When the discount rate exceeds 20%, the project becomes highly infeasible in Accra compared to Kumasi. This study will offer itself as scientific guidance for investment in biogas to electricity projects in Ghana’s cities.

Abstract Average energy consumption per U.S. household has fallen by just under 20% in the last ten years. Much of this drop occurred after 1979, when gas and electricity prices as well as oil prices rose in real terms. The response of households to higher prices has involved physical modifications on and in the home and changes in behavior. Many actions have been taken by households, but the most important single factor has been a significant reduction in indoor temperatures. The greater energy efficiency of new homes and appliances has also helped to depress residential energy demand, although improvements have levelled off in the last few years. There are signs that the momentum of energy conservation is less now than it was 2 years ago, but it appears that energy prices will be high enough to discourage households from returning to former energy-using practices. Along with the continued replacement of homes and appliances with more efficient models, and other factors such as the migration to wanner regions and the movement to more apartments and smaller homes, this will probably keep U.S. residential energy consumption at about its present level through the 1980s.

Abstract To understand the relationship between green building energy performance and regional commercial estates, this study analysed Australia’s Commercial Building Disclosure (CBD) program database. This database discloses the annual energy use intensity (EUI) and the corresponding energy rating (1–6 stars) of 2460 National Australian Built Environment Rating System (NABERS) certified office buildings. The study selected for analysis Australia’s six largest cities and then used panel data regression, where commercial estate factors (total stock of office buildings, vacancy rate, average gross face rent, and government incentives such as financial support) served as independent variables and the EUI was the dependent variable. The p-values of all the models are below 0.05, indicating that the results are statistically significant. Results showed the commercial real estate factors were significantly related to the EUI for buildings with a rating of 1 star and above. The correlation between EUI and commercial real estate factors became less strong with the rating level increasing. The effect of ‘green building’ branding makes the office buildings more attractive with regard to tenancy and their energy performance more reflective of the variation in the commercial real estate market. This study is a frontrunner in contextualising green building energy performance and ratings in the context of regional commercial estate, and the regression models employed in the study could be used to define regional baselines for energy ratings in future studies.

Abstract With the encouragement of LNG (liquefied natural gas) application in China, CCHP (combined cooling heating and power) system fueled by natural gas has been receiving increasing attention. This paper presents optimization of CCHP system on their design and operation from energetic analysis, economic operation and environment effect viewpoints. CCHP system for hotels, offices and residential buildings in Dalian (China) is given to ascertain the effectiveness of the model. Weighting method and fuzzy optimum selection theory are employed to evaluate the integrated performances of CCHP systems with various operation strategies. Results show that: (1) Hotels have the greatest contribution (42.28%) to the energy savings based on energetic analysis sub-model because of their relatively stable electricity loads. (2) CCHP systems reduce the annual total costs for all operation cases compared with the reference system for hotels and offices. However, CCHP system achieves no economic merits for residential buildings. (3) The applications of the CCHP system decrease pollutant emissions in all operation cases for the studied buildings. (4) CCHP system driven by gas engine has better performance than driven by gas turbine. Coupled with renewable energy sources and with thermal storage tank are mostly optimum operation cases from energetic, economic and environment criteria.

This study investigated the impact of varying natural gas composition on the exhaust emissions from a waste hauler equipped with a 2002 Cummins 8.3L, C Gas Plus, lean burn, spark ignited natural gas engine and an oxidation catalyst while operated on the William H. Martin Refuse Truck Cycle on a chassis dynamometer. The vehicle was tested on seven different fuel gas blends with varying compositions of light hydrocarbon species and inerts, resulting in different properties in terms of methane number and Wobbe number. The higher hydrocarbons gases exhibited higher fuel economy and CO2 (carbon dioxide) emissions. NOx (Nitrogen oxides) emissions were also impacted by fuel composition, and increased for gases with higher levels of heavier hydrocarbons. THC (Total hydrocarbons), CH4 (methane), CO (carbon monoxide), PM (particulate matter), and particle number emissions all showed some reductions for the gases with higher hydrocarbons, higher Wobbe numbers, and higher energy content. Formaldehyde and acetaldehyde were the most dominant aldehydes in the tailpipe, and decreased with the low methane number and high Wobbe number gases. Ammonia emissions did not show consistent fuel trends, however, ammonia emission levels were higher for the higher speed and load phase of the cycle.