城市在用CNG汽车排放研究

通过车载实验,怠速法检测、简易工况法检测数据评价分析等方法,研究了重庆市在用CNG车辆排放情况,比较了CNG车与同类型汽油、柴油车尾气污染物排放情况。研究发现,目前CNG在用车并非绝对的环保汽车,其中在NOx的排放上,CNG车排放高于同类型汽油、柴油车0．03—14倍;在CO、THC的排放上,不同测试工况下CNG汽车表...     

The welfare effects of fuel conservation policies in a dual-fuel car market: Evidence from India

We estimate a model of vehicle choice and kilometers driven to analyze the long-run impacts of fuel conservation policies in the Indian car market. We simulate the effects of petrol and diesel fuel taxes and a diesel car tax, taking into account their interactions with the pre-existing petrol fuel tax and car sales taxes. At levels sufficient to reduce total fuel consumption by 7%, the increased diesel and petrol fuel taxes both yield deadweight losses (net of externalities) of about 4 (2010) Rs./L. However, at levels sufficient to reduce total fuel consumption by 2%, the increased petrol fuel tax results in a deadweight loss per liter of fuel conserved that is greater than that caused by the diesel fuel tax. This reflects both the high pre-existing tax on petrol fuel and the high own-price elasticities of fuel demand in India. A tax on diesel cars that results in the same diesel market share as the large diesel fuel tax actually has a negative deadweight loss per liter of fuel conserved. The welfare effects of all three policy instruments are positive, once the external benefits of reducing fuel consumption are added to the excess burden of taxation.     

Fuel prices and new vehicle fuel economy—Comparing the United States and Western Europe

Several recent papers have documented an effect of fuel prices on new vehicle fuel economy in the United States. This paper estimates the effect of fuel prices on average new vehicle fuel economy for the eight largest European markets. The analysis spans the years 2002–2007 and uses detailed vehicle registration and specification data to control for policies, consumer preferences, and other potentially confounding factors. We find fuel prices to have a statistically significant effect on average new vehicle fuel economy in Europe. The effect estimated for Europe is much smaller than comparable estimates for the United States.     

Fuel breaks affect nonnative species abundance in Californian plant communities.

We evaluated the abundance of nonnative plants on fuel breaks and in adjacent untreated areas to determine if fuel treatments promote the invasion of nonnative plant species. Understanding the relationship between fuel treatments and nonnative plants is becoming increasingly important as federal and state agencies are currently implementing large fuel treatment programs throughout the United States to reduce the threat of wildland fire. Our study included 24 fuel breaks located across the State of California. We found that nonnative plant abundance was over 200% higher on fuel breaks than in adjacent wildland areas. Relative nonnative cover was greater on fuel breaks constructed by bulldozers (28%) than on fuel breaks constructed by other methods (7%). Canopy cover, litter cover, and duff depth also were significantly lower on fuel breaks constructed by bulldozers, and these fuel breaks had significantly more exposed bare ground than other types of fuel breaks. There was a significant decline in relative nonnative cover with increasing distance from the fuel break, particularly in areas that had experienced more numerous fires during the past 50 years, and in areas that had been grazed. These data suggest that fuel breaks could provide establishment sites for nonnative plants, and that nonnatives may invade surrounding areas, especially after disturbances such as fire or grazing. Fuel break construction and maintenance methods that leave some overstory canopy and minimize exposure of bare ground may be less likely to promote nonnative plants.     

Carbon abatement in the fuel market with biofuels: Implications for second best policies

A carbon tax on fuel would penalize carbon intensive fuels like gasoline and shift fuel consumption to less carbon intensive alternatives like biofuels. Since biofuel production competes for land with agricultural production, a carbon tax could increase land rents and raise food prices. This paper analyzes the welfare effect of a carbon tax on fuel consisting of gasoline and biofuel in the presence of a labor tax, with and without a biofuel subsidy. The market impacts of a carbon tax are also compared with that of a subsidy. Findings show that if a carbon tax increases biofuel demand, the tax interaction effect due to higher fuel prices is exacerbated by higher land rent and food prices and greater erosion of the carbon tax base. Thus, the second best optimal carbon tax for fuel is lower with biofuel in the fuel mix, especially if biofuel is subsidized.     

Fuel loss and flexible fuel deposition rates in a long-distance migrant

Most migrating birds alternate flight bouts with stopovers, during which they rest and replenish the fuel used during flight (refueling). The rate of refueling (fuel deposition rate, FDR) affects stopover duration, and hence is an important determinant of the overall time required for migration. Although environmental and endogenous factors affect FDR, the urge to refuel depends on the anticipated distance to be travelled and possibly also on the amount of fuel used during the flight preceding stopover. Combining a field study with a fasting–refueling experiment on long-term captive songbirds, we tested whether the extent of fuel loss prior to refueling indeed affects FDR. In the field study, we took a comparative approach and determined FDR in two subspecies of northern wheatear (Oenanthe oenanthe) that differ greatly in the distance flown, and thus the extent of fuel used to reach our study (stopover) site. As both winter in western sub-Sahelian Africa, they face the same remaining migration distance. We found that FDR was higher in the subspecies that uses more fuel to get to our study site. Solidifying this result, in the experiment on captive northern wheatears, we found that the extent of fuel loss as a consequence of fasting explained most of the variation in subsequent FDR. The observation that experimental birds losing little fuel did not maximize their FDR suggests there are costs to rapid refueling. Our study shows that FDR is shaped not just by current environmental and endogenous conditions but also by fuel loss prior to refueling.     

Real-world fuel consumption of light-duty passenger vehicles using on-board diagnostic (OBD) systems

• Fuel consumption (FC) from LDPVs is measured using on-board diagnostic method (OBD). • The FC of the OBD is 7.1% lower than that of the carbon balance results. • The discrepancy between the approved FC and real-world FC is 13%±18%. • There is a strong relationship (R²=0.984) between the average speed and relative FC. An increasing discrepancy between real-world and type-approval fuel consumption for light-duty passenger vehicles (LDPVs) has been reported by several studies. Normally, real-world fuel consumption is measured primarily by a portable emission measurement system. The on-board diagnostic (OBD) approach, which is flexible and offers high-resolution data collection, is a promising fuel consumption monitoring method. Three LDPVs were tested with a laboratory dynamometer based on a type-approval cycle, the New European Driving Cycle (NEDC). Fuel consumption was measured by the OBD and constant-volume sampling system (CVS, a regulatory method) to verify the accuracy of the OBD values. The results of the OBD method and the regulatory carbon balance method exhibited a strong linear correlation (e.g., R² = 0.906-0.977). Compared with the carbon balance results, the fuel consumption results using the OBD were 7.1%±4.3% lower on average. Furthermore, the real-world fuel consumption of six LDPVs was tested in Beijing using the OBD. The results showed that the normalized NEDC real-world fuel consumption of the tested vehicles was 13%±17% higher than the type-approval-based fuel consumption. Because the OBD values are lower than the actual fuel consumption, using a carbon balance method may result in a larger discrepancy between real-word and type-approval fuel consumption. By means of the operating mode binning and micro trip methods, a strong relationship (R² = 0.984) was established between the average speed and relative fuel consumption. For congested roads (average vehicle speed less than 25 km/h), the fuel consumption of LDPVs is highly sensitive to changes in average speed.     

Obligatory barrier crossing and adaptive fuel management in migratory birds: the case of the Atlantic crossing in Northern Wheatears (<Emphasis Type="Italic">Oenanthe oenanthe</Emphasis>)

Behaviour on migration was often suggested to be selected for time-minimising strategies. Current optimality models predict that optimal fuel loads at departure from stopover sites should increase with increasing fuel deposition rates. We modified such models for the special case of the east Atlantic crossing of the Northern Wheatear (Oenanthe oenanthe). From optimality theory, we predict that optimal time-minimising behaviour in front of such a barrier should result in a positive correlation between fuel deposition rates and departure fuel loads only above a certain threshold, which is the minimum fuel load (f _min) required for the barrier crossing. Using a robust range equation, we calculated the minimum fuel loads for different barrier crossings and predict that time-minimising wheatears should deposit a minimum of 24% fuel in relation to lean body mass (m ₀ ) for the sea crossing between Iceland and Scotland. Fuel loads of departing birds in autumn in Iceland reached this value only marginally but showed positive correlation between fuel deposition rate (FDR) and departure fuel load (DFL). Birds at Fair Isle (Scotland) in spring, which were heading towards Iceland or Greenland, were significantly heavier and even showed signs of overloading with fuel loads up to 50% of lean body mass. Departure decisions of Icelandic birds correlated significantly with favourable wind situations when assuming a migration direction towards Spain; however, the low departure fuel loads contradict a direct non-stop flight.     

Umweltschäden durch Heizöl nach Hochwasserereignissen

Background Due to high safety measures in production, transport and storage of fuel oil it rarely occurs, that fuel oil will be released in the environment. One exception of this experience was the fuel oil releases of private fuel oil tanks during the “century flood” 2002 in Germany. By order of IWO (Institut für wirtschaftliche Oelheizung e.?V.), the authors investigated the environmental behaviour of fuel oil after flood incidents. Aim Due to the fast spreading of the fuel oil on water surfaces and the contamination of huge areas one expects large environmental harm. For appraisal the behaviour of fuel oil in water and soil must be studied in detail as well as the effect on high and low developed animals and plants, on water organisms and on the flora and fauna of soil. From the valuation of the environmental harm official measures and measures of precaution and safety by manufacturer and user of private fuel oil installations can be derived. Main features For considering the various aspects the authors studied the extensive analyses of the special measuring programme of Saxony-Anhalt, used interviews of concerned persons (private persons and officials), aerial photos, extensive study of literature including eco-toxicological investigations, experiences of more than 70-years applications of fuel oil in plant protection and practical experiences at large field redevelopment of oil damages following averages and accidents. The authors valuated on the base of results of analyses and on own calculations. Results The release of fuel oil in the air is no particular problem because about 40?% of the oil fast evaporate and will be decomposed to carbon dioxide and water. In addition to the evaporation a characteristic behaviour is fast spreading of the fuel oil on the water surface to very thin layers. For a typical coloured oil layer e.?g. one cubic meter of oil is spread on a water surface of about 3?km², this corresponds to 3?ml/m² surface and contaminates the soil after drying up with about 3?µg/kg soil some orders less than the natural content of hydrocarbons in soil. Because of the absorption capacity of soil and the microbial decomposition by everywhere existing hydrocarbons decomposing micro-organisms the oil infiltrates only a few centimetre and will be decomposed in a few months, so that ground water detriments not arise practically. By measurements a few months after fuel oil release in the flood 2002 oil components in the soil could not be detected. Discussion Acute injuries of micro-flora and -fauna in soil and water by fuel oil cannot be excluded from the first. Thus the limiting values of injuries for some water organisms are below 1?mg/l. According to the special measuring programme at the flood 2002 in Saxony-Anhalt however the measured values were mostly wide below of this limit. In detail the spreading and evaporation of fuel oil on water surfaces, the propagation and decomposition of fuel oil in soil will be described. A quantitative valuation of fuel oil distribution in a real flood incident will be given. Conclusions Particular measures of redevelopment of soil for fuel oil release after flood incidents are not necessary normally. Even at the redevelopment after transport damages or at devastated sites with essential higher oil contaminations of soil in comparison to fuel oil release after flood incidents high decomposition rates are obtained by normal soil improving measures supporting the natural micro-organisms in reducing the hydrocarbon concentration for 70–90?% after a few months. Perspectives With the described results a realistic valuation of the environmental harm of fuel oil release after flood incidents could be given. From this qualified measures can be derived for official decisions and precautionary and reliable activities at fuel oil installations of flood endangered areas.     

Market equilibrium and welfare effects of a fuel tax in China: The impact of consumers' response through driving patterns

We investigate the market equilibrium and welfare effects of a fuel tax in China relative to an alternative policy instrument that rations the number of new automobile sales through auctioned quotas. Unlike those of previous studies, our modeling approach incorporates both household car purchase and utilization decisions, the latter of which have been ignored in previous studies on China's fuel tax. Ignoring this margin of choice will underestimate the fuel tax's ability to mitigate externalities. Using detailed household-level panel data and a fixed effects econometric specification, we estimate the fuel price elasticity of vehicle miles traveled is −0.59 on average. The results of the counterfactual analysis suggest that a 51% increase in tax-inclusive gasoline prices will reduce car sales by 24.9% but increase social welfare to a degree that depends on vehicles' lifetime. We find that compared to auctioned quotas, the fuel tax results in greater car sales but higher social welfare.     

燃用甲醇燃料的发动机尾气排放

本文主要报导了在二冲程、四冲程汽油机及柴油机上燃用甲醇-汽油混合燃料、M_(100)甲醇燃料的发动机尾气排放方面所做的研究,并与燃用汽油、柴油的尾气排放进行了对照。结果表明,无论是甲醇-汽油混合燃料,还是M_(100)甲醇燃料尾气排放,都较汽油、柴油尾气排放的常规污染物,均有不同程度的减少。因此,应用甲醇燃料对改善环境是有益的。     

A comparative study of particle size distribution from two oxygenated fuels and diesel fuel

Oxygenated fuels are known to reduce particulate matter (PM) emissions from diesel engines. In this study, 100% soy methyl ester (SME) biodiesel fuel (B100) and a blend of 10% acetal denoted by A-diesel with diesel fuel were tested as oxygenated fuels. Particle size and number distributions from a diesel engine fueled with oxygenated fuels and base diesel fuel were measured using an Electrical Low Pressure Impactor (ELPI). Measurements were made at ten steady-state operational modes of various loads at two engine speeds. It was found that the geometric mean diameters of particles from SME and Adiesel were lower than that from base diesel fuel. Compared to diesel fuel, SME emitted more ultra-fine particles at rated speed while emitting less ultra-fine particles at maximum speed. Ultra-fine particle number concentrations of A-diesel were much higher than those of base diesel fuel at most test modes.     

Efficient adsorption of thiophene from model fuel by pyrolysed rice husks: factors of influence

Rice husks pyrolysed at different temperatures in the range of 250–700°C were investigated as adsorbents for thiophene removal from a model fuel. The adsorption ability of the samples was evaluated under both static and dynamic conditions. It was found that pyrolysed rice husks without any pretreatment are a promising adsorbent for the removal of sulphur-containing molecules from the model fuel. Removal of 92% of the sulphur from the fuel was achieved. The adsorption capacity of the pyrolysed rice husks correlates with their textural and chemical characteristics which strongly depend on the pyrolysis temperature. The adsorption of thiophene is influenced by the initial sulphur concentration level, the fractional composition of the adsorbent, the temperature and the adsorbent/fuel volume ratio. The adsorption capacity of the pyrolysed rice husks is higher under static than under dynamic conditions.     

Modeling the influence of precipitation and nitrogen deposition on forest understory fuel connectivity in Sierra Nevada mixed-conifer forest

Climate change models for California's Sierra Nevada predict greater inter-annual variability in precipitation over the next 50 years. These increases in precipitation variability coupled with increases in nitrogen deposition from fossil fuel consumption are likely to result in increased productivity levels and significant increases in forest understory fuel loads. Higher understory plant biomass contributes to fuel connectivity and may increase future fire size and severity in the Sierra Nevada. The objective of this research was to develop and test a model to determine how changing precipitation and nitrogen deposition levels affect shrub and herb biomass production, and to determine how often prescribed fire would be needed to counter increasing fuel loads. Model outputs indicate that under an increasing precipitation scenario significant increases in shrub and herb biomass occur that can be counteracted by decreasing the fire return interval to 10 years. Under a scenario with greater inter-annual variability in precipitation and increased nitrogen deposition, implementing fire treatments at an interval equivalent to the historical range of 15–30 years maintains understory vegetation fuel loads at levels comparable to the control.     

Fuel Economy and Motor Vehicle Emissions

The conventional wisdom is that there is no relationship between fuel economy and motor vehicle emissions, at least for new cars. The requirement that all vehicles meet a common emission standard in terms of grams per mile effectively breaks whatever link there might have been between fuel economy and emissions in uncontrolled (preregulatory) vehicles. As cars age, however, the emission control equipment tends to break down, providing reason to think that the conventional wisdom might do the same. This paper reports on an empirical examination of this proposition, by linking EPA fuel economy certification data to a large database of motor vehicle emission measurements collected by remote sensing. It is found that better fuel economy is strongly associated with lower emissions of CO and HC and that the effect gets stronger as vehicles age.     

Incomplete International Cooperation to Reduce CO2 Emissions: The Case of Price Discrimination

This paper analyzes the effect of introducing a fuel tax in some countries, but not all, when the world fuel market is monopolistic. Based on the observation that price discrimination becomes possible in these circumstances, it is shown that the fuel price in countries not levying the tax may increase, in contrast to common views.     

A model of surface fire,climate and forest pattern in the Sierra Nevada,California

A spatially explicit forest gap model was developed for the Sierra Nevada, California, and is the first of its kind because it integrates climate, fire and forest pattern. The model simulates a forest stand as a grid of 15×15 m forest plots and simulates the growth of individual trees within each plot. Fuel inputs are generated from each individual tree according to tree size and species. Fuel moisture varies both temporally and spatially with the local site water balance and forest condition, thus linking climate with the fire regime. Fires occur as a function of the simulated fuel loads and fuel moisture, and the burnable area is simulated as a result of the spatially heterogeneous fuel bed conditions. We demonstrate the model’s ability to couple the fire regime to both climate and forest pattern. In addition, we use the model to investigate the importance of climate and forest pattern as controls on the fire regime. Comparison of model results with independent data indicate that the model performs well in several areas. Patterns of fuel accumulation, climatic control of fire frequency and the influence of fuel loads on the spatial extent of fires in the model are particularly well-supported by data. This model can be used to examine the complex interactions among climate, fire and forest pattern across a wide range of environmental conditions and vegetation types. Our results suggest that, in the Sierra Nevada, fuel moisture can exert an important control on fire frequency and this control is especially pronounced at sites where most of the annual precipitation is in the form of snow. Fuel loads, on the other hand, may limit the spatial extent of fire, especially at elevations below 1500 m. Above this elevation, fuel moisture may play an increasingly important role in limiting the area burned.     

Autumn migratory fuelling: a response to simulated magnetic displacements in juvenile wheatears, Oenanthe oenanthe

Recent experiments exposing migratory birds to altered magnetic fields simulating geographical displacements have shown that the geomagnetic field acts as an external cue affecting migratory fuelling behaviour. This is the first study investigating fuel deposition in relation to geomagnetic cues in long-distance migrants using the western passage of the Mediterranean region. Juvenile wheatears (Oenanthe oenanthe) were exposed to a magnetically simulated autumn migration from southern Sweden to West Africa. Birds displaced parallel to the west of their natural migration route, simulating an unnatural flight over the Atlantic Ocean, increased their fuel deposition compared to birds experiencing a simulated migration along the natural route. These birds, on the other hand, showed relatively low fuel loads in agreement with earlier data on wheatears trapped during stopover. The experimental displacement to the west, corresponding to novel sites in the Atlantic Ocean, led to a simulated longer distance to the wintering area, probably explaining the observed larger fuel loads. Our data verify previous results suggesting that migratory birds use geomagnetic cues for fuelling decisions and, for the first time, show that birds, on their first migration, can use geomagnetic cues to compensate for a displacement outside their normal migratory route, by adjusting fuel deposition.     

Small-scale fuel variation alters fire intensity and shrub abundance in a pine savanna

Small-scale variation in fire intensity and effects may be an important source of environmental heterogeneity in frequently burned plant communities. We hypothesized that variation in fire intensity resulting from local differences in fuel loads produces heterogeneity in pine savanna ground cover by altering shrub abundance. To test this hypothesis, we experimentally manipulated prefire fuel loads to mimic naturally occurring fuel-load heterogeneity associated with branch falls, needle fall near large pines, and animal disturbances in a frequently burned longleaf pine (Pinus palustris) savanna in Louisiana, USA. We applied one of four fuel treatments (unaltered control, fine-fuel removal, fine-fuel addition, wood addition) to each of 540 (1-m2) quadrats prior to growing-season prescribed fires in each of two years (1999 and 2001). In both years fuel addition increased (and fuel removal decreased) fuel consumption and maximum fire temperatures relative to unaltered controls. Fuel addition, particularly wood, increased damage to shrubs, increased shrub mortality, and decreased resprout density relative to controls. We propose that local variation in fire intensity may contribute to maintenance of high species diversity in pine savannas by reducing shrub abundance and creating openings in an otherwise continuous ground cover.