Fuel and vehicle technology choices for passenger vehicles in achieving stringent CO2 targets: connections between transportation and other energy sectors

Identification of Key Factors to Reduce Transport-Related Air Pollutants and CO2 Emissions in Asia

Asian countries are major contributors to global air pollution and greenhouse gas emissions, with transportation demand and emissions expected to increase. However, few studies have been performed to evaluate policies that could reduce transport-related emissions in the region. This study explores transport-related CO2 and air pollutant emissions in major Asian nations along with the impacts of transport, climate, and emission control policies using the Asia-Pacific Integrated Model (AIM)/Transport model. Our results show that by 2050, CO2 emissions in developing countries will be 1.4–4.7-fold greater than the levels in 2005, while most air pollutant emissions will show large reductions (mean annual reduction rates of 0.2% to 6.1%). Notably, implementation of transport, emission control, and carbon pricing policies would reduce CO2 emissions by up to 33% and other air pollutants by 43% to 72%, depending on the emission species. An emission control policy represents the strongest approach for short-term and mid-term reduction of air pollutants. A carbon pricing policy would lead to a direct reduction in CO2 emissions; more importantly, air pollutant emissions would also be effectively reduced. Shifting to public transportation in developing countries can also greatly influence emissions reductions. An increase in traffic speed shows relatively small effects, but can be meaningful in Japan.

The Potential Role of Ammonia as Marine Fuel—Based on Energy Systems Modeling and Multi-Criteria Decision Analysis

To reduce the climate impact of shipping, the introduction of alternative fuels is required. There is a range of different marine fuel options but ammonia, a potential zero carbon fuel, has recently received a lot of attention. The purpose of this paper is to assess the prospects for ammonia as a future fuel for the shipping sector in relation to other marine fuels. The assessment is based on a synthesis of knowledge in combination with: (i) energy systems modeling including the cost-effectiveness of ammonia as marine fuel in relation to other fuels for reaching global climate targets; and (ii) a multi-criteria decision analysis (MCDA) approach ranking marine fuel options while considering estimated fuel performance and the importance of criteria based on maritime stakeholder preferences. In the long-term and to reach global GHG reduction, the energy systems modeled indicate that the use of hydrogen represents a more cost-effective marine fuel option than ammonia. However, in the MCDA covering more aspects, we find that ammonia may be almost as interesting for shipping related stakeholders as hydrogen and various biomass-based fuels. Ammonia may to some extent be an interesting future marine fuel option, but many issues remain to be solved before large-scale introduction.

What Future for Electrofuels in Transport? Analysis of Cost Competitiveness in Global Climate Mitigation

The transport sector is often seen as the most difficult sector to decarbonize. In recent years, so-called electrofuels have been proposed as one option for reducing emissions. Electrofuels-here defined as fuels made from electricity, water, and carbon dioxide-can potentially help manage variations in electricity production, reduce the need for biofuels in the transportation sector while utilizing current infrastructure, and be of use in sectors where fuel switching is difficult, such as shipping. We investigate the cost-effectiveness of electrofuels from an energy system perspective under a climate mitigation constraint (either 450 or 550 ppm of CO₂ in 2100), and we find the following: (i) Electrofuels are unlikely to become cost-effective unless options for storing carbon are very limited; in the most favorable case modeled-an energy system without carbon storage and with the more stringent constraint on carbon dioxide emissions-they provide approximately 30 EJ globally in 2070 or approximately 15% of the energy demand from transport. (ii) The cost of the electrolyzer and increased availability of variable renewables appear not to be key factors in whether electrofuels enter the transport system, in contrast to findings in previous studies.

Cost-effective choices of marine fuels in a carbon-constrained world: results from a global energy model

The regionalized Global Energy Transition model has been modified to include a more detailed shipping sector in order to assess what marine fuels and propulsion technologies might be cost-effective by 2050 when achieving an atmospheric CO2 concentration of 400 or 500 ppm by the year 2100. The robustness of the results was examined in a Monte Carlo analysis, varying uncertain parameters and technology options, including the amount of primary energy resources, the availability of carbon capture and storage (CCS) technologies, and costs of different technologies and fuels. The four main findings are (i) it is cost-effective to start the phase out of fuel oil from the shipping sector in the next decade; (ii) natural gas-based fuels (liquefied natural gas and methanol) are the most probable substitutes during the study period; (iii) availability of CCS, the CO2 target, the liquefied natural gas tank cost and potential oil resources affect marine fuel choices significantly; and (iv) biofuels rarely play a major role in the shipping sector, due to limited supply and competition for bioenergy from other energy sectors.

Light-duty vehicle CO2 targets consistent with 450 ppm CO2 stabilization

We present a global analysis of CO2 emission reductions from the light-duty vehicle (LDV) fleet consistent with stabilization of atmospheric CO2 concentration at 450 ppm. The CO2 emission reductions are described by g CO2/km emission targets for average new light-duty vehicles on a tank-to-wheel basis between 2010 and 2050 that we call CO2 glide paths. The analysis accounts for growth of the vehicle fleet, changing patterns in driving distance, regional availability of biofuels, and the changing composition of fossil fuels. New light-duty vehicle fuel economy and CO2 regulations in the U.S. through 2025 and in the EU through 2020 are broadly consistent with the CO2 glide paths. The glide path is at the upper end of the discussed 2025 EU range of 68-78 g CO2/km. The proposed China regulation for 2020 is more stringent than the glide path, while the 2017 Brazil regulation is less stringent. Existing regulations through 2025 are broadly consistent with the light-duty vehicle sector contributing to stabilizing CO2 at approximately 450 ppm. The glide paths provide long-term guidance for LDV powertrain/fuel development.

Peak oil demand: the role of fuel efficiency and alternative fuels in a global oil production decline

Some argue that peak conventional oil production is imminent due to physical resource scarcity. We examine the alternative possibility of reduced oil use due to improved efficiency and oil substitution. Our model uses historical relationships to project future demand for (a) transport services, (b) all liquid fuels, and (c) substitution with alternative energy carriers, including electricity. Results show great increases in passenger and freight transport activity, but less reliance on oil. Demand for liquids inputs to refineries declines significantly after 2070. By 2100 transport energy demand rises >1000% in Asia, while flattening in North America (+23%) and Europe (-20%). Conventional oil demand declines after 2035, and cumulative oil production is 1900 Gbbl from 2010 to 2100 (close to the U.S. Geological Survey median estimate of remaining oil, which only includes projected discoveries through 2025). These results suggest that effort is better spent to determine and influence the trajectory of oil substitution and efficiency improvement rather than to focus on oil resource scarcity. The results also imply that policy makers should not rely on liquid fossil fuel scarcity to constrain damage from climate change. However, there is an unpredictable range of emissions impacts depending on which mix of substitutes for conventional oil gains dominance-oil sands, electricity, coal-to-liquids, or others.

Global scenarios of air pollutant emissions from road transport through to 2050

This paper presents global scenarios of sulphur dioxide (SO(2)), nitrogen oxides (NO(x)), and particulate matter (PM) emissions from road transport through to 2050, taking into account the potential impacts of: (1) the timing of air pollutant emission regulation implementation in developing countries; (2) global CO(2) mitigation policy implementation; and (3) vehicle cost assumptions, on study results. This is done by using a global energy system model treating the transport sector in detail. The major conclusions are the following. First, as long as non-developed countries adopt the same vehicle emission standards as in developed countries within a 30-year lag, global emissions of SO(2), NO(x), and PM from road vehicles decrease substantially over time. Second, light-duty vehicles and heavy-duty trucks make a large and increasing contribution to future global emissions of SO(2), NO(x), and PM from road vehicles. Third, the timing of air pollutant emission regulation implementation in developing countries has a large impact on future global emissions of SO(2), NO(x), and PM from road vehicles, whereas there is a possibility that global CO(2) mitigation policy implementation has a comparatively small impact on them.

Nationwide shift in CO concentration levels in urban areas of Korea after 2000

Concentrations of carbon monoxide (CO) in urban and rural air were analyzed from 16 urban roadside locations in the 7 major cities along with 5 background areas in Korea during an 11-year period (1998-2008). Because of noticeable changes in CO levels after 2000, temporal evaluation of its roadside data was carried out by grouping them into period I (1998-2000) and II (2001-2008). The mean CO values for all 16 roadside stations between the two study periods I and II were significantly different from each other (1.67 ± 0.31 ppm (I) vs. 0.95 ± 0.17 ppm (II)). This interperiod reduction in CO levels fell, if compared between different stations, in the range of 8.62-59.94% (mean = 39.8 ± 14.7%). The statistical analysis confirms that CO concentrations decreased very rapidly with the annual reduction rate of 0.093 ppm year(-1) (9.8% year(-1)). In contrast, in background areas such distinctions are no longer valid between the two periods. A line of evidence collected in this study thus suggests that the implementation of legal and technical support (e.g., upgrading of fuel quality and the natural gas vehicle supply program) should have been the effective driving forces leading to the gradual reduction in CO levels in roadside locations (10 out of 16 stations) on the peninsula.

Low-CO(2) electricity and hydrogen: a help or hindrance for electric and hydrogen vehicles?

The title question was addressed using an energy model that accounts for projected global energy use in all sectors (transportation, heat, and power) of the global economy. Global CO(2) emissions were constrained to achieve stabilization at 400-550 ppm by 2100 at the lowest total system cost (equivalent to perfect CO(2) cap-and-trade regime). For future scenarios where vehicle technology costs were sufficiently competitive to advantage either hydrogen or electric vehicles, increased availability of low-cost, low-CO(2) electricity/hydrogen delayed (but did not prevent) the use of electric/hydrogen-powered vehicles in the model. This occurs when low-CO(2) electricity/hydrogen provides more cost-effective CO(2) mitigation opportunities in the heat and power energy sectors than in transportation. Connections between the sectors leading to this counterintuitive result need consideration in policy and technology planning.

Reducing motor vehicle greenhouse gas emissions in a non-California state: a case study of Minnesota

Approaches for reducing greenhouse gas (GHG) emissions from motor vehicles include more-efficient vehicles, lower-carbon fuels, and reducing vehicle-kilometers traveled (VKT). Many U.S. states are considering steps to reduce emissions through actions in one or more of these areas. We model several technology and policy options for reducing GHGs from motor vehicles in Minnesota. Considerable analysis of transportation GHGs has been done for California, which has a large population and vehicle fleet and can enact unique emissions regulations; Minnesota represents a more typical state with respect to many demographic and transportation parameters. We conclude that Minnesota has a viable approach to meeting its stated GHG reduction targets (15% by 2015 and 30% by 2025, relative to year 2005) only if advancements are made in all three areas-vehicle efficiency, carbon content of fuels, and VKT. If policies focus on only one or two areas, potential improvements may be negated by backsliding in another area (e.g., increasing VKT offsetting improvements in vehicle efficiency).