Do vehicle efficiency improvements lead to energy savings? The rebound effect in Great Britain

Fuel efficiency improvements in vehicles reduce the cost of travel, which could stimulate drivers to travel further limiting energy savings. Estimates of this effect, known as the rebound effect, have varied widely, partly due to data constraints and a reliance upon highly aggregated government statistics. This paper instead uses a dataset of over 275 million vehicle roadworthiness tests. The high level of detail in our dataset can reveal, for the first time, how the response to changes in travel costs may differ across types of vehicles and socio-economic areas in Great Britain.We find that the rebound effect in Great Britain is just 4.6%, meaning efficiency improvements are unlikely to stimulate increased mileage in the short-run. We find that larger, less fuel efficient vehicles are more responsive to fuel price changes than smaller vehicles and that drivers in urban areas are more responsive to fuel price changes than drivers in rural areas. Our findings shed light on the effects that policies such as fuel taxation and fuel economy standards may have on vehicle mileage. This has implications for both CO₂ emissions savings and social equity.     

基于综合权重法的河北省水资源脆弱性评价及影响因素分析

基于水资源数量、水资源质量和水资源时空不均衡性(洪灾和旱灾)三个维度,从水量、水质、旱灾、洪灾四个方面构建河北省水资源脆弱性评价指标体系,采用层次分析法(AHP)-熵权法确定评价指标综合权重,并运用综合指数评估法评价河北省2001~2016年水资源脆弱性。同时,运用相关分析、因子分析和回归分析法探究水资源脆弱性变化的主要影响因素。结果表明,2001~2016年间,河北省水资源脆弱性主要集中于中强等级,随时间变化水资源脆弱性呈减缓趋势;旱灾脆弱性为河北省水资源脆弱性主导因素,水资源脆弱性与人口密度、国民生产总值、人均用水量、灌溉用水量呈高度正相关。     

Identification of vulnerable lines in power grids with wind power integration based on a weighted entropy analysis method

Vulnerable overhead electricity lines are a cause of serious risk to power distribution grids as damage can be the cause of large scale blackouts and cascading failures. With the integration of large scale wind power into generating capacity, both the topology structure and the distribution characteristics of power flow in distribution grid have undergone various changes that have increased line vulnerability. A novel approach to identify vulnerable lines based on the weighted entropy analysis method is proposed in this paper. In this approach, an assessment index, named the incremental power flow entropy, is first developed, which is used to describe influences caused by variation of the lines' capability of carrying power flow transfers on the vulnerability of the lines themselves at the same aggregation level. A second assessment index, named structural importance, describes the structural changes of a power grid that are caused by the integration of wind-generated electric power. The two assessment indices then are merged into one index by using the entropy weight analysis method, which can assess the vulnerability of the lines from the two aspects of power flow transmission and structural links. Vulnerability analysis under different situations, such as with and without the integration of the wind farm, and sharp fluctuations in wind speed at the wind farm, were carried out on an IEEE 39-bus system integrated with a 75 MW wind farm. Simulation results verified that the proposed assessment index not only can identify the vulnerable lines in a power grid with wind farm integration but also accurately reflected the vulnerability of the internal lines of the wind farm itself.     

Comparison of homogeneous and heterogeneous thorium fuel blocks with four drivers in advanced high temperature reactors

Thorium is an attractive potential fuel owing to its abundance and unique thermal, neutronic, and chemical properties. One way to utilize thorium in block-type advanced high temperature reactors (AHTRs) is to homogenously mix the driver fuel (eg, U-233) with thorium in every fuel kernel of the tristructural-isotropic particles in a fuel block, which is the mixed oxide fuel (MOX) concept. Application of the seed and blanket (S&B) concept, that is, driver fuel in the seed region of a fuel block and thorium in the blanket region, is also another method to utilize thorium. To investigate the differences in the utilization of thorium using the MOX and S&B concepts in AHTRs, their multiplication factors (k_∞), discharge burnups, conversion ratios, and reactivity temperature coefficients are compared. The investigated drivers include U-233 (U3), weapons-grade uranium (WU), weapons-grade plutonium (WPu), and reactor-grade plutonium (RPu). The results demonstrate that the MOX block with plutonium drivers has a higher discharge burnup in comparison with the S&B block. When the heavy metal mass is 6 kg and the initial mass of the fissile materials is 0.65 kg per block, the MOX block achieves 27% higher discharge burnup than the S&B block with the RPu driver. In contrast, the S&B block achieves higher discharge burnup in the case of uranium drivers (U3 and WU). The MOX block achieves a higher conversion ratio for all the drivers. Furthermore, the MOX block achieves a stronger negative moderator temperature coefficient of reactivity than the S&B block for all the driver fuels.     

An evaluation of the life cycle cost of rapeseed oil as a straight vegetable oil fuel to replace petroleum diesel in agriculture

The use of straight vegetable oil (SVO) as biofuel has been recognized as a valid substitute of diesel fuel in the agricultural sector under specific circumstances. Its direct use reduces most of the chemical processes involved when converting it into biodiesel, thus lowering harmful emissions. This study presents the economic analysis of a self-supply farming model that uses rapeseed as its fuel base. This model addresses agricultural environmental concerns and can even minimize dependence on the fluctuating costs of diesel fuel. The use of SVO in agriculture can help reduce farmers’ vulnerability to fossil fuel prices. The economic evaluation of the model proposed in this study shows clear economic benefits of introducing rapeseed to the traditional crop rotation of wheat and barley. The key factors analyzed in this model are diesel fuel price, diesel fuel grants and crop aids. The current situation in Spain favors the use of diesel fuel in agriculture rather than rapeseed SVO due to an 8% profit difference. However, results show that changes in key factors slightly affect the profit margin, calculating a difference of only 3.7% for particular factor combinations. Combined environmental-friendly agriculture supporting policies are necessary to cover this slight profit difference to promote this biofuel.     

While visitors conserve,residents splurge: Patterns and changes in energy consumption, 1997-2007

This study analyzes changes in energy consumption in Hawai‘i between 1997 and 2007 using input-output analysis. Residents increase their energy use by 33% in electricity and 18% in fuel, largely due to direct consumption. In contrast, visitors contract energy demand by 9% and 4% in electricity and fuel, respectively. The findings are robust at per-capita levels. Key drivers are the significant drops in energy intensity of primarily three industries: air transportation, hotels, and restaurants. Further analysis decomposes the change to evaluate the underlying factors.     

Fuel demand on UK roads and dieselisation of fuel economy

Because of high oil prices, and climate change policy, governments are now seeking ways to improve new car fuel economy thus contributing to air quality and energy security. One strategy is to increase dieselisation rates of the vehicle fleet. Recent trends in fuel economy show improvement since 1995, however, efforts need to go further if the EU Voluntary Agreement targets on CO₂ (a greenhouse gas emission standard) are to be achieved. Trends show diesel car sales have accelerated rapidly and that the advantage of new car fuel economy of diesel cars over gasoline ones is narrowing posing a new challenge. We estimate the demand for new car fuel economy in the UK. In the long-run consumers buy fuel economy, but not in the short-run. We found that long-term income and price changes were the main drivers to achieve improvements particularly for diesel cars and that there is no break in the trend of fuel economy induced by the agreement adopted in the 1990s. Policy should target more closely both consumer choice of, and use of, diesel cars.     

Trends of energy efficiency in Finnish road freight transport 1995–2009 and forecast to 2016

A framework for modeling and analyzing the energy efficiency of road freight transport is presented in this paper. This framework is tested by using the data from the Finnish Goods Transport by Road statistics. The data was enhanced by calculating the fuel consumption for each trip in the data. To calculate this, weight-fuel consumption functions were estimated for each Euro-class vehicles and road type. This is a new method for analyzing the energy efficiency of road freight transport and it could be applied also in other countries gathering freight transport data with continuous company surveys. The analysis show that the energy efficiency of road freight transport in Finland improved during 1995–2002, but has declined since. The major drivers in the development have been the changes in the level of empty running and vehicle fuel efficiency. Extrapolating current statistical trends of factors that influence the energy efficiency show that the target set by the Finnish government for improving energy efficiency by 9% until 2016 will not be achieved. However, the target is possible to be achieved by a combination of small changes to some determinants.     

Residential past and future energy consumption: Potential savings and environmental impact

In order to identify main drivers behind changes in electricity and fuel consumptions in the household sector in Jordan, two empirical models are developed based on multivariate linear regression analysis. In addition, this paper analyzes and evaluates impacts of introducing some efficient measures, such as high efficiency lightings and solar water heating systems, in the housing stock, on the future fuel and electricity demands and associated reduction in GHG emissions. It was found that fuel unit price, income level, and population are the most important variables that affect demand on electrical power, while population is the most important variable in the case of fuel consumption. Obtained results proved that the multivariate linear regression models can be used adequately to simulate residential electricity and fuel consumptions with very high coefficient of determination. Without employing most effective energy conservation measures, electricity and fuel demands are expected to rise by approximately 100% and 23%, respectively within 10 years time. Consequently, associated GHG emissions resulting from activities within the residential sector are predicted to rise by 59% for the same period. However, if recommended energy management measures are implemented on a gradual basis, electricity and fuel consumptions as well as GHG emissions are forecasted to increase at a lower rate.     

Understanding the build-up of a technological innovation system around hydrogen and fuel cell technologies

This study provides insight into the development of hydrogen and fuel cell technologies in the Netherlands (1980–2007). This is done by applying a Technological Innovation System (TIS) approach. This approach takes the perspective that a technology is shaped by a surrounding network of actors, institutions and technologies. When a technology is in an early stage of development, a TIS has yet to be built up in order to propel technological progress. This build-up process is studied for the hydrogen and fuel cell innovation system in the Netherlands. This is done by systematically studying the dynamics of seven key activities that accelerated (or slowed down) developments around hydrogen and fuel cell technologies. The analysis contributes to a better understanding of these dynamics and of the drivers and barriers that caused them to emerge. The study derives important lessons for practitioners.     

Fuel economy of new passenger cars in Mexico: Trends from 1988 to 2008 and prospects

This paper analyzes trends in fuel economy (kilometers per liter) of new passenger vehicles in Mexico over a period of 20 years from 1988 to 2008. Results show that in this period, fuel economy of the new passenger vehicle fleet, including multipurpose vehicles (a category similar to sport utility vehicles, SUVs), increased by only 6.3%. A simple Laspeyres index analysis was developed to evaluate both the impact of changes in vehicle sales structure by category and the changes in fuel economy. Results show that increased sales of heavier, multipurpose vehicles in place of subcompact and compact vehicles, impacted negatively on the fleet average fuel economy. If the structure of sales had continued in the same proportions across all categories as in 1988, fuel economy would have increased by 11.0%, instead of the actual 6.3%. This result coincides with trends in other countries. The paper also presents different scenarios of passenger car fuel economy for the year 2020, and its implications for gasoline consumption and CO₂ emissions. The results may influence the new passenger vehicle fuel economy standard that is currently under discussion in Mexico.     

Evidence of asymmetric behavioral responses to changes in gasoline prices and taxes for different fuel types

Using monthly data from the Spanish gasoline retail market we explore asymmetries in consumers’ behavioral responses to changes in gasoline prices and taxes. In particular, we are interested in investigating whether an increase in gasoline taxes has a more negative impact on the demand than a –similar in magnitude– increase in the “pre-tax” price of gasoline for different fuel types. We estimate fuel consumers’ responses using a rich set of robust panel data models considering potential dynamic effects and endogeneity problems. We find evidence to confirm the existence of asymmetric responses for the demand of unleaded fuels and agricultural diesel fuel. However we cannot support this statement for the regular diesel case: for this fuel both the tax-exclusive price and the tax elasticities are roughly the same. This result agrees with the fact that “diesel drivers” tend to be better informed about changes in both fuel prices and taxes. Some implications in terms of fiscal policy and pollution and climate change policy are also discussed.     

A comparative study of dynamic changes in CO2 emission performance of fossil fuel power plants in China and Korea

This paper aims to conduct a comparative study of the changes in CO₂ emission performance of state-owned fossil fuel power plants between China and Korea. For this purpose, we combine the concept of the metafrontier Malmquist productivity index and the non-radial directional distance function to develop a new index called the non-radial metafrontier Malmquist CO₂ emission performance index (NMMCPI). This new methodology allows for the incorporation of technological heterogeneities and slack variables into the previously introduced Malmquist CO₂ emission performance index (MCPI). The NMMCPI can be derived by solving several non-radial data envelopment analysis (DEA) models. The NMMCPI can be decomposed into an efficiency change (EC) index, a best-practice gap change (BPC) index, and a technology gap change (TGC) index. By fixing the non-energy inputs, we measure the pure CO₂ emission performance change. Based on the proposed indices, the comparative study between Chinese and Korean fossil fuel power industries is conducted for the 2005–2010 period. Empirical results indicate significant differences in terms of various decomposed CO₂ emission performance changes between China and Korea. Korean power plants demonstrate improvements in innovation, while Chinese power plants demonstrate a higher ability for technological leadership. Some related policy implications are also proposed based on the empirical results.     

Fuel consumption rates of passenger cars in China: Labels versus real-world

Recently, China has implemented many policy measures to control the oil demand of on-road vehicles. In 2010, China started to report the fuel consumption rates of light-duty vehicles tested in laboratory and to require new vehicles to show the rates on window labels. In this study, we examined the differences between the test and real-world fuel consumption of Chinese passenger cars by using the data reported by real-world drivers on the internet voluntarily. The sales-weighted average fuel consumption of new cars in China in 2009 was 7.80 L/100 km in laboratory and 9.02 L/100 km in real-world, representing a difference of 15.5%. For the 153 individual car models examined, the real-world fuel consumption rates were −8 to 60% different from the test values. The simulation results of the International Vehicle Emission model show that the real-world driving cycles in 22 selected Chinese cities could result in −8 to 34% of changes in fuel consumption compared to the laboratory driving cycle. Further government effort on fuel consumption estimates adjustment, local driving cycle development, and real-world data accumulation through communication with the public is needed to improve the accuracy of the labeling policy.     

Hydrogen fuel cell electric vehicle performance and user-response assessment: Results of an extended driver study

This study examined driver acceptance and performance of hydrogen fuel cell electric vehicles as tested in real-world conditions over a two-year period. The study sample was a volunteer group of “n = 54” drivers who drove the vehicle for a month-long trial period. Each driver took ‘before’ and ‘after’ surveys regarding their driving experience. Drivers drove an average of 1400 miles per month, and either witnessed and/or performed vehicle refueling 3–10 times during their test period.Key findings from the study include that: 1) 80% of study participant drivers found that the fuel cell vehicle (FCV) performance “exceeded” or “greatly exceeded” their expectations; 2) 98% of study participant drivers view hydrogen as a fuel for vehicles as being “as safe” or “safer” than gasoline as a fuel for vehicles; and 3) 94% of participants view the process of fueling a vehicle with hydrogen to be “as safe” or “safer” than gasoline fueling. Other findings include that 85% of study participants who performed their own fueling described hydrogen fueling to be “somewhat” or “very” simple. Of the participants, 62% percent had to forgo at least one trip due to lack of hydrogen fuel, although vehicle range was rated by 75% of participants as entirely or mostly adequate. If fueling infrastructure availability was not an issue, and fuel cost per-mile was at parity with gasoline, 75% of participants would be willing to pay $40,000 or less for an FCV.     

Substitution possibilities and determinants of energy intensity for China

This paper measures technological change, factor demand and inter-factor and inter-fuel substitutability measures for China. We use individual fuel price data and a two-stage approach to estimate total factor cost functions and fuel share equations. Both inter-factor and inter-fuel substitution elasticities are calculated and the change in energy intensity is decomposed into its driving forces. The results suggest that energy is substitutable for capital regionally and for labor nationally. Capital substitutes for energy more easily than labor does. Energy intensity changes vary by region but the major drivers seem to be “budget effect” and the adoption of energy-intensive technologies, which might be embodied in high-level energy-using exports and sectors, capital investment and even old technique and equipment imports. Whether the trend in rising energy intensity continues will be significant for China and the rest of the world.     

基于模糊集对评价法的广西各城市洪涝易损性分析

针对城市洪涝易损性评价具有不确定性的问题,引入模糊集对评价法,选择5个评价指标建立城市洪涝易损性评价指标体系,考虑等级标准边界的模糊性和各指标的不同作用,通过联系度和权重计算,对广西壮族自治区14个城市洪涝易损性进行定量评估分析。结果表明,广西壮族自治区14个评价城市中有2个城市洪涝易损性为较低度易损性,7个城市为中度易损性,3个城市为较高度易损性,2个城市为高度易损性,研究结果可为广西壮族自治区各城市洪涝灾害防治提供决策依据。     

Global climate change implications for coastal and offshore oil and gas development

The discussion and debate about climate change and oil and gas resource development has generally focused on how fossil fuel use affects the Earth's climate. This paper explores how the changing climate is likely to affect oil and gas operations in low-lying coastal areas and the outer continental shelf. Oil and gas production in these regions comprises a large sector of the economies of many energy producing nations. Six key climate change drivers in coastal and marine regions are characterized with respect to oil and gas development: changes in carbon dioxide levels and ocean acidity, air and water temperature, precipitation patterns, the rate of sea level rise, storm intensity, and wave regime. These key drivers have the potential to independently and cumulatively affect coastal and offshore oil and gas exploration, production, and transportation, and several impacts of climate change have already been observed in North America.     

The validity of the index of vulnerable homes: evidence from consumers vulnerable to energy poverty in the UK

ABSTRACT

Energy poverty is a multidimensional issue, and this means that it is difficult to understand the different levels of vulnerability to this phenomenon and its relationship with households’ quality of life. This paper presents the validation of an innovative index for the analysis of vulnerability to energy poverty according to monetary, energy, and thermal comfort factors: The Index of Vulnerable Homes (IVH). The IVH goes beyond the use of single self-reported indicators of thermal comfort, and instead uses the adaptive thermal-comfort model defined in the normative UNE EN 15251:2007 to assess thermal comfort in relation to energy poverty. Furthermore, it has the potential to evaluate the societal impacts of current energy poverty policies by providing the economic analysis of different situations of vulnerability. The IVH is validated by comparing its results to those obtained from a survey conducted in a small-scale study undertaken in Salford, UK. To this end, evidence from households living in terraced houses built before 1980 is used to analyze health status in terms of vulnerability to energy poverty vulnerability according to their monetary situation and the characteristics of the dwelling. In the end, the results show good agreement between both the IVH’s assessment and households’ evidence, leading to consider the IVH as a suitable approach to understanding different levels of vulnerability to energy poverty.     

U.S. manufacturing aggregate energy intensity decomposition: The application of multivariate regression analysis

This paper introduces the use of a multivariate regression analysis to explain factors that impact aggregate energy intensity. This kind of study is useful to evaluate the past and predicts the future trends for energy‐policy evaluation. Historical aggregate fuel and electricity intensities of the entire U.S. manufacturing sector (Standard Industrial Classification, SIC, codes of 20–39) over the 1977–1998 period are used to develop the proposed multivariate regression model. The proposed model allows identifying the structural effect of aggregate energy intensity changes without relying on detailed disaggregated energy data. Its results are validated by comparison with those from conventional decomposition techniques based on economic index numbers. For illustration, the historical aggregate fuel intensity of the U.S. primary metal industry (SIC 33) is used as an example of a situation for which economic index numbers fail to decompose the historical aggregate energy intensity since the disaggregated energy data are unavailable, while the multivariate regression analysis can still be applied. Empirical results show that a structural shift contributes to decreases of about 28, 41 and 19% of total declines of U.S. manufacturing aggregate fuel, U.S. manufacturing aggregate electricity, and U.S. primary metal industry aggregate fuel intensities, respectively, for the 1977–1998 period. The method based on multivariate regression models estimates the time series structural effects within deviation averages of 8.5 and 7.0% of the time series structural effect estimates based on the economic index numbers for the U.S. manufacturing aggregate fuel and electricity intensities, respectively, even though the multivariate regression model does not require disaggregated energy data. Copyright © 2007 John Wiley & Sons, Ltd.