Long-term implications of alternative light-duty vehicle technologies for global greenhouse gas emissions and primary energy demands

This study assesses global light-duty vehicle (LDV) transport in the upcoming century, and the implications of vehicle technology advancement and fuel-switching on greenhouse gas emissions and primary energy demands. Five different vehicle technology scenarios are analyzed with and without a CO₂ emissions mitigation policy using the GCAM integrated assessment model: a reference internal combustion engine vehicle scenario, an advanced internal combustion engine vehicle scenario, and three alternative fuel vehicle scenarios in which all LDVs are switched to natural gas, electricity, or hydrogen by 2050. The emissions mitigation policy is a global CO₂ emissions price pathway that achieves 450 ppmv CO₂ at the end of the century with reference vehicle technologies. The scenarios demonstrate considerable emissions mitigation potential from LDV technology; with and without emissions pricing, global CO₂ concentrations in 2095 are reduced about 10 ppmv by advanced ICEV technologies and natural gas vehicles, and 25 ppmv by electric or hydrogen vehicles. All technological advances in vehicles are important for reducing the oil demands of LDV transport and their corresponding CO₂ emissions. Among advanced and alternative vehicle technologies, electricity- and hydrogen-powered vehicles are especially valuable for reducing whole-system emissions and total primary energy.     

Plug-in hybrid fuel cell vehicles market penetration scenarios

The main objective of this research is to analyze the impact of the market share increase of hydrogen based road vehicles in terms of energy consumption and CO₂, on today's Portuguese light-duty fleet. Actual yearly values of energy consumption and emissions were estimated using COPERT software: 167112 TJ of fossil fuel energy, 12213 kton of CO₂ emission and 141 kton of CO, 20 kton of HC, 46 kton of NO_x and 3 kton of PM. These values represent 20–40% of countries total emissions. Additionally to base fleet, three scenarios of introduction of 10–30% fuel cell vehicles including plug-in hybrids configurations were analysed. Considering the scenarios of increasing hydrogen based vehicles penetration, up to 10% life cycle energy consumption reduction can be obtained if hydrogen from centralized natural gas reforming is considered. Full life cycle CO₂ emissions can also be reduced up to 20% in these scenarios, while local pollutants reach up to 85% reductions. For the purpose of estimating road vehicle technologies energy consumption and CO₂ emissions in a full life cycle perspective, fuel cell, conventional full hybrids and hybrid plug-in technologies were considered with diesel, gasoline, hydrogen and biofuel blends. Energy consumption values were estimated in a real road driving cycle and with ADVISOR software. Materials cradle-to-grave life cycle was estimated using GREET database adapted to Europe electric mix. The main conclusions on CO₂ full life cycle analysis is that light-duty vehicles using fuel cell propulsion technology are highly dependent on hydrogen production pathway. The worst scenario for the current Portuguese and European electric mix is hydrogen produced from on-site electrolysis (in the refuelling stations). In this case full life cycle CO₂ is 270 g/km against 190 g/km for conventional Diesel vehicle, for a typical 150,000 km useful life.     

How private car purchasing trends offset efficiency gains and the successful energy policy response

In 2006, energy-related CO₂ emissions from transport energy in Ireland were 168% above 1990 levels. Private cars were responsible for approx 45% of transport energy demand in 2006 (excluding fuel tourism). The average annual growth of new cars between 1990 and 2006 was 5.2%. This paper focuses on these new cars entering the private car fleet, in particular the purchasing trend towards larger size cars. This has considerably offset the improvements in the technical efficiency of individual car models. The analysis was carried out on the detailed data of each individual new vehicle entering the fleet in 2000–2006. The average CO₂ emissions per kilometre for new petrol cars entering the Irish fleet grew from 166 to 168 g CO₂/km from 2000 to 2005 and reduced to 164 in 2006. For diesel cars the average reduced from 166 in 2000 to 161 in 2006. The paper also discusses how a recent change in vehicle registration taxation and annual motor tax had a significant impact purchasing trends by supporting lower emission vehicles. Cars with emissions up to 155 g CO₂/km represented 41% of new private cars sold in Ireland in 2007 compared with 84% during the period July–November 2008.     

Food transport refrigeration – Approaches to reduce energy consumption and environmental impacts of road transport

Food transport refrigeration is a critical link in the food chain not only in terms of maintaining the temperature integrity of the transported products but also its impact on energy consumption and CO₂ emissions. This paper provides a review of (a) current approaches in road food transport refrigeration, (b) estimates of their environmental impacts, and (c) research on the development and application of alternative technologies to vapour compression refrigeration systems that have the potential to reduce the overall energy consumption and environmental impacts. The review and analysis indicate that greenhouse gas emissions from conventional diesel engine driven vapour compression refrigeration systems commonly employed in food transport refrigeration can be as high as 40% of the greenhouse gas emissions from the vehicle’s engine. For articulated vehicles over 33 ton, which are responsible for over 80% of refrigerated food transportation in the UK, the reject heat available form the engine is sufficient to drive sorption refrigeration systems and satisfy most of the refrigeration requirements of the vehicle. Other promising technologies that can lead to a reduction in CO₂ emissions are air cycle refrigeration and hybrid systems in which conventional refrigeration technologies are integrated with thermal energy storage. For these systems, however, to effectively compete with diesel driven vapour compression systems, further research and development work is needed to improve their efficiency and reduce their weight.     

Modeling the CO2 emissions from battery electric vehicles given the power generation mixes of different countries

With the number of vehicles on the world’s roads expected to grow to 2.9 billion by 2050, steps must be taken to reduce the CO₂ emissions from transport. Battery electric vehicles (BEVs) can help achieve this. This study aimed to determine the CO₂ emissions stemming from BEV operation in different countries and to compare those CO₂ emissions to the emissions from similar vehicles based on internal combustion engines (ICEs). This study selected four ICE-based vehicles, and modeled BEVs based on the specifications of each of these vehicles. The modeled BEVs were run through a simulation to determine their energy consumption. Their energy consumption was combined with data on the CO₂ intensity of the power generation mix in different countries to reveal the emissions resulting from BEV operation. The CO₂ emissions from the BEVs were compared to the CO₂ emissions for their ICE-based counterparts. Amongst the results, it was shown that for China and India, and other countries with a similarly high CO₂ intensity, unless power generation becomes dramatically less CO₂ intensive, BEVs will not be able to deliver a meaningful decrease in CO₂ emissions and an increase in the penetration of BEVs could actually lead to higher CO₂ emissions.     

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.     

Oil consumption and CO2 emissions in China's road transport: current status,future trends,and policy implications

With the rapid economic growth in China, the Chinese road transport system is becoming one of the largest and most rapidly growing oil consumers in China. This paper attempts to present the current status and forecast the future trends of oil demand and CO₂ emissions from the Chinese road transport sector and to explore possible policy measures to contain the explosive growth of Chinese transport oil consumption. A bottom-up model was developed to estimate the historical oil consumption and CO₂ emissions from China's road transport sector between 1997 and 2002 and to forecast future trends in oil consumption and CO₂ emissions up to 2030. To explore the importance of policy options of containing the dramatic growth in Chinese transport oil demand, three scenarios regarding motor vehicle fuel economy improvements were designed in predicting future oil use and CO₂ emissions. We conclude that China's road transportation will gradually become the largest oil consumer in China in the next two decades but that improvements in vehicle fuel economy have potentially large oil-saving benefits. In particular, if no control measures are implemented, the annual oil demand by China's road vehicles will reach 363 million tons by 2030. On the other hand, under the low- and high-fuel economy improvement scenarios, 55 and 85 million tons of oil will be saved in 2030, respectively. The scenario analysis suggests that China needs to implement vehicle fuel economy improvement measures immediately in order to contain the dramatic growth in transport oil consumption. The imminent implementation is required because (1) China is now in a period of very rapid growth in motor vehicle sales; (2) Chinese vehicles currently in the market are relatively inefficient; and (3) the turnover of a fleet of inefficient motor vehicles will take a long time.     

Life cycle inventory study on magnesium alloy substitution in vehicles

Magnesium (Mg) alloys are suitable materials for weight reduction in vehicles because of their low density of 1.7 g/cm³ and high specific strength. The effect of Mg substitution for conventional steel parts in a vehicle on total energy consumption and CO₂ emissions was evaluated through life cycle inventory calculation. The Mg substitution reduces the total energy consumption by weight reduction, although the production energy of a Mg-substituted vehicle is higher than those of conventional and Al-substituted vehicles. The Mg substitution can save more life cycle energy consumption than the Al substitution. Recycling of Mg parts is indispensable for efficient CO₂ reduction, because the CO₂ emissions during new ingot production of Mg are much higher than those of conventional steel and Al. Strengthening of the Mg parts also can reduce the total energy consumption and CO₂ emissions. If the main body and hood are made of Mg alloy and the ratio of recycled ingot is sufficiently high, the life cycle energy consumption and CO₂ emissions will be markedly reduced.     

Dazzled by diesel? The impact on carbon dioxide emissions of the shift to diesels in Europe through 2009

This paper identifies trends in new gasoline and diesel passenger car characteristics in the European Union between 1995 and 2009. By 2009 diesels had captured over 55% of the new vehicle market. While the diesel version of a given car model may have as much as 35% lower fuel use/km and 25% lower CO₂ emissions than its gasoline equivalent, diesel buyers have chosen increasingly large and more powerful cars than the gasoline market. As a result, new diesels bought in 2009 had only 2% lower average CO₂ emissions than new gasoline cars, a smaller advantage than in 1995. A Laspeyres decomposition investigates which factors were important contributors to the observed emission reductions and which factors offset savings in other areas. More than 95% of the reduction in CO₂ emissions per km from new vehicles arose because both diesel and gasoline new vehicle emissions/km fell, and only 5% arose because of the shift from gasoline to diesel technology. Increases in vehicle mass and power for both gasoline and diesel absorbed much of the technological efficiency improvements offered by both technologies. We also observe changes in the gasoline and diesel fleets in eight EU countries and find changes in fuel and emissions intensities consistent with the changes in new vehicles reported. While diesel cars continue to be driven far farther than gasoline cars, we attribute only some of this difference to a “rebound effect”. We conclude that while diesel technology has permitted significant fuel savings, the switch from gasoline to diesel in the new vehicle market contributed little itself to the observed reductions in CO₂ emissions from new vehicles.     

Analysis of the vehicle mix in the passenger-car sector in Japan for CO2 emissions reduction by a MARKAL model

Carbon dioxide (CO₂) emissions from the passenger-car sector in Japan are increasing rapidly and should be reduced cost-effectively in order to stabilize energy-related CO₂ emissions in Japan. The purpose of the present paper is to clarify the most cost-effective mix of vehicles for reducing CO₂ emissions and to estimate the subsidy that is necessary to achieve this vehicle mix. For this analysis, the energy system of Japan from 1988 to 2032 is modeled using a MARKAL model. The most cost-effective mix of vehicles is estimated by minimizing the total energy system cost under the constraint of an 8% energy-related CO₂ emissions reduction nationally by 2030 from the CO₂ emissions of 1990. Based on the results of the analysis, hybrid vehicles are the only type of clean-energy vehicle, and their share of the passenger car sector in 2030 will be 62%. By assuming the subsidization of hybrid vehicles, the same vehicle mix can be achieved without constraining CO₂ emissions. The peak of the total subsidy estimated to be necessary is 1.225 billion US$/year in 2020, but the annual revenue of the assumed 31 US$/t-C carbon tax from the passenger car sector is sufficient to finance the estimated subsidy. This suggests that we should support the dissemination of hybrid vehicles through subsidization based on carbon tax.     

Cost and CO2 aspects of future vehicle options in Europe under new energy policy scenarios

New electrified vehicle concepts are about to enter the market in Europe. The expected gains in environmental performance for these new vehicle types are associated with higher technology costs. In parallel, the fuel efficiency of internal combustion engine vehicles and hybrids is continuously improved, which in turn advances their environmental performance but also leads to additional technology costs versus today’s vehicles. The present study compares the well-to-wheel CO₂ emissions, costs and CO₂ abatement costs of generic European cars, including a gasoline vehicle, diesel vehicle, gasoline hybrid, diesel hybrid, plug in hybrid and battery electric vehicle. The predictive comparison is done for the snapshots 2010, 2020 and 2030 under a new energy policy scenario for Europe. The results of the study show clearly that the electrification of vehicles offer significant possibilities to reduce specific CO₂ emissions in road transport, when supported by adequate policies to decarbonise the electricity generation. Additional technology costs for electrified vehicle types are an issue in the beginning, but can go down to enable payback periods of less than 5 years and very competitive CO₂ abatement costs, provided that market barriers can be overcome through targeted policy support that mainly addresses their initial cost penalty.     

Estimating road transport fuel consumption in Ecuador

Road transport is one of the sectors with highest energy consumptions in the planet, with large dependence of fossil fuels, and contribution for global greenhouse gas emissions. Although, Latin America is not a high-energy consumer, its share in global consumption is expected to grow, especially in the transportation sector. This make essential for developing countries the adoption of better policies to identify the vehicle groups with largest fuel demands. The present study describes the VKT technique to disaggregate road transport energy consumption by vehicle type, applied to the road transportation system of Ecuador. It also describes the procedures performed to estimate the variables required to run the model, and some of the practical applications that be used to create public policies. Results show as the biggest fuel consumers the heavy-duty freight cargo, followed by light duty vehicles. The estimation of greenhouse gas emissions evidence that road transport released 14.3 million tons of CO₂ in 2012. When fuel consumption is compared by it costs, it can be confirmed that Ecuadorean Government covered, through subsidies, for 68% of the annual fuel costs of national road transport, demonstrating the importance of restructuring these expenditures in order to achieve an efficient road transport system.     

Modelling the impacts of a carbon emission-differentiated vehicle tax system on CO2 emissions intensity from new vehicle purchases in Ireland

The increasing awareness of the effects of climate change on the environment and the economic pressure on oil supply has focused international attention on reducing CO₂ emissions and energy usage across all sectors. In order to meet their Kyoto protocol commitments and in line with European Union policy, the Irish government has introduced a carbon-based tax system for new vehicles purchased from the 1st of July 2008. This new legislation aims to reduce carbon emissions in the transport sector, a sector which is responsible for a significant proportion of both. This paper presents the results of the development, calibration, and application of a car choice model which predicts the changes in CO₂ emissions intensity from new vehicle purchases as a result of the changes in vehicle tax policy and fuel price in Ireland. The model also predicts the impact of such changes on tax revenue for the Irish government and the changes in the split between the number of diesel and petrol vehicles purchased. The investigation found that the introduction of these new carbon-based taxes in Ireland will result in a reduction of 3.6–3.8% in CO₂ emissions intensity and a reduction in annual tax revenue of €191 M.     

Electric and plug-in hybrid vehicles influence on CO2 and water vapour emissions

The main objective of this research is to quantify the impact of introducing electric vehicles and plug-in hybrid vehicles, including fuel cell on conventional fleets. The impact is estimated in terms of local pollutants, HC, CO, NO_x, PM, and in terms of CO₂ and water vapour global emissions. The specific fleet of Portugal, roughly 6 million light-duty vehicles (30% diesel, 70% gasoline) is considered, and the mobility indicator of the fleet, 90 thousand million p × km, is kept constant throughout the analysis. Probability density functions for energy consumption and emissions are derived for conventional, electric and plug-in hybrid vehicles, in charge depleting and charge sustaining modes. The Monte Carlo method is used to obtain average distribution estimates for discounting values of “old vehicles” that are removed from the fleet, and to add average distribution estimates for the “new vehicles” entering the fleet. Considering the actual Portuguese fleet as the reference case, local pollutant emissions decrease by a factor of 10-53%, for 50% fleet replacement. A potential 23% decrease of CO₂ is foreseen, and a potential 31% increase of H₂O emissions is forecasted. Life cycle water vapour emissions tend to rise and are, typically, 2-4 times higher than CO₂ values at the upstream stage, due to its release in the cooling towers of thermal power plants. It is interesting to note that considering 1 MJ of energy required at vehicle wheels, in an overall life cycle context, both fuel cell and electric modes have nearly twice as much H₂O emissions than internal combustion vehicles. CO₂ emissions tend to decrease with electric drive vehicles penetration due to the higher fleet life cycle efficiency.     

Light vehicle energy efficiency programs and their impact on Brazilian CO2 emissions

This paper analyses the impact of an energy efficiency program for light vehicles in Brazil on emissions of carbon dioxide (CO₂), the main greenhouse gas in the atmosphere. Several energy efficiency programs for light vehicles around the world are reviewed. The cases of Japan and Europe were selected for presentation here given their status as current and future world leaders in the control of passenger vehicle fuel consumption. The launching of the National Climate Change Plan and the pressure on the Brazilian car industry due to the world financial crisis make it a good time for the Brazilian government to implement such a program, and its various benefits are highlighted in this study. Three scenarios are established for Brazil covering the 2000–2030 period: the first with no efficiency goals, the second with the Japanese goals applied with a 10 years delay, and the third, with the Japanese goals applied with no delay. The consequences of a vehicular efficiency program and its middle and long-term effects on the consumption of energy and the CO₂ emissions are quantified and discussed. The simulation results indicate that efficiency goals may make an important contribution to reducing vehicular emissions and fuel consumption in Brazil, compared to a baseline scenario.     

Assessment of transport fuel taxation strategies through integration of road transport in an energy system model—the case of Sweden

Road transport is responsible for a large and growing share of CO₂ emissions in most countries. A number of new fuel‐efficient vehicle technologies and renewable transport fuels are possible alternatives to conventional options but their deployment relies strongly on different policy measures. Even though a future higher use of transport biofuels and electric vehicles is likely to increase the interaction between the transportation sector and the stationary energy system (heat, power, etc.), these systems are often analysed separately. In this study, a transport module is developed and integrated into the MARKAL_Nordic energy system model. The transport module describes a range of vehicle technologies and fuel options as well as different paths for conversion of primary energy resources into transport fuels. The integrated model is utilized to analyse the impact of transport fuel tax designs on future cost‐effective fuel and technology choices in the Swedish transportation sector, as well as the consequences of these choices on system costs and CO₂ emissions. The model, which is driven by cost‐minimization, is run to 2050 with various assumptions regarding transport fuel tax levels and tax schemes. The results stress the importance of fuel taxes to accelerate the introduction of fuel‐efficient vehicle technologies such as hybrids and plug‐in hybrids. Tax exemptions can make biofuels an economically favourable choice for vehicle users. However, due to limitations in biomass supply, a too strong policy‐focus on transport biofuels can lead to high system costs in relation to the CO₂ abatement achieved. The modelling performed indicates that the effects caused by linkages between the transportation sector and the stationary energy system can be significant and integrated approaches are thus highly relevant. Copyright © 2011 John Wiley & Sons, Ltd.     

Modeling energy consumption and CO2 emissions at the urban scale: Methodological challenges and insights from the United States

Local policy makers could benefit from a national, high-resolution inventory of energy consumption and related carbon dioxide (CO₂) emissions based on the Vulcan data product, which plots emissions on a 100 km² grid. We evaluate the ability of Vulcan to measure energy consumption in urban areas, a scale of analysis required to support goals established as part of local energy, climate or sustainability initiatives. We highlight the methodological challenges of this type of analytical exercise and review alternative approaches. We find that between 37% and 86% of direct fuel consumption in buildings and industry and between 37% and 77% of on-road gasoline and diesel consumption occurs in urban areas, depending on how these areas are defined. We suggest that a county-based definition of urban is preferable to other common definitions since counties are the smallest political unit for which energy data are collected. Urban counties, account for 37% of direct energy consumption, or 50% if mixed urban counties are included. A county-based definition can also improve estimates of per-capita consumption.     

Diesel vehicles and sustainable mobility in the U.S.

Concerns regarding global warming and energy security have increased the importance of decreasing emissions of CO₂ from vehicles. Diesel vehicles have higher fuel economy and lower CO₂ emissions than their gasoline counterparts. On a well-to-wheels per vehicle per km basis it has been estimated that diesel light-duty vehicles in 2015 will emit 14–27% less CO₂ than their gasoline counterparts. We estimate here that on a gCO₂/kWh at peak torque, diesel medium-duty vehicles currently have an approximately 10% CO₂ advantage over their gasoline counterparts. At light and moderate loads the CO₂ advantage for medium-duty diesels with SCR after-treatment will be greater than 10% (reflecting pumping losses when gasoline engines are operated at low and moderate loads). Emission of NO_x, HCs, and PM from diesel (and gasoline) vehicles has decreased substantially over the past decade and further reductions are anticipated in the future. In addition to the heavy-duty segment, which diesels currently dominate, modern diesel engines are likely to continue to play an important role in the medium-duty segment, and perhaps also in the light-duty segment in a transition to more sustainable mobility.     

CO2 benefit from the increasing percentage of diesel passenger cars. Case of Ireland

The decrease of CO₂ emissions is one way to minimize climate changes. An efficient way to decrease these emissions is the replacement of gasoline passenger cars (PCs) by diesel ones, which emit less CO₂. Most of the member countries of the European Union (EU) have high percentages of new diesel PC registrations; however, this percentage remains less than 17% in Ireland. The benefit on CO₂ emitted from new PCs is studied in the case of an increased diesel penetration in Ireland, after several scenarios using the current and estimated future PC sales and estimated fuel consumption. The results show that, in the case of new PCs, a CO₂ benefit of more than 2.9% can be achieved, if a diesel penetration higher than 30% occurs in the case of the current fleet. If this penetration reaches 50%, this benefit will be higher than 7.4%. Future total CO₂ emissions from new PCs can be partially controlled by the introduction of diesel PC or the replacement of heavy PCs by lighter ones. Future fuel consumption of gasoline and diesel PCs and the percentage of diesel penetration are the key factors for this control.     

Hydrogen perspectives in Italy: Analysis of possible deployment scenarios

The paper analyses Italian hydrogen scenarios to meet climate change, environmental and energy security issues. An Italy-Markal model was used to analyse the national energy–environment up to 2050. About 40 specific hydrogen technologies were considered, reproducing the main chains of production, transport and consumption, with a focus on transport applications. The analysis is based on the Baseline and Alternative scenario results, where hydrogen reaches a significant share. The two scenarios constitute the starting points to analyse the hydrogen potential among the possible energy policy options. The energy demand in the Baseline scenario reaches values around 240 Mtoe at 2030, with an average annual growth of 0.9%. The Alternative scenario reduces consumption down to 220 Mtoe and stabilizes the _CO2${\mathrm{CO}}_2$ emissions. The Alternative scenario expects a rapid increase of hydrogen vehicles in 2030, up to 2.5 million, corresponding to 1 Mtoe of hydrogen consumption. A sensitivity analysis shows that the results are rather robust.