EU climate policy aims to limit the global mean temperature increase from anthropogenic climate change to below 2 °C. EC analysis indicates that achieving this goal would require cuts of 80−95% in EU GHG emissions with respect to year-1990 levels by 2050. As deeper cuts are likely to be made in other sectors, this requires a cut of at least 60% in transportation GHG emissions, most notably CO₂, by midcentury. The EU has also made a commitment to reduce emissions in sectors outside the EU ETS, including transportation, by 10% on year-2005 levels by 2020.

Past research concludes that achieving these goals through technological measures alone is difficult...Many transportation technologies currently in development show promise in significantly reducing energy use and CO₂ emissions before 2050. A detailed survey of these technologies, their likely future techno-economic characteristics, and the uncertainty involved was carried out by the Technology Opportunities and Strategies toward Climate-friendly Transport (TOSCA) project. The TOSCA data covering all major transportation modes and its explicit treatment of uncertainty suggests a new study is justified which looks at what range of reductions in emissions is possible over different scenarios and uncertain input values. This is the subject of this paper.

—Dray et al.

Dray, from the University of Cambridge, Andreas Schäfer from Stanford, and Moshe E. Ben-Akiva from MIT combined TOSCA’s techno-economic characteristics of transportation technology with existing European transport modeling capabilities. They estimated the number of new vehicles required and the adoption of new technologies and fuels based on their availability and cost effectiveness under projected scenario variables such as fuel price. This step was iterated with an estimation of demand changes. Existing fleet and vehicle withdrawal were estimated using fleet data by vehicle location and age, and vehicle age-dependent retirement curves. They then estimated emissions based on fleet composition.

They assessed purchaser technology choice for new vehicles on a cost-effectiveness basis using net present value (NPV) as a decision criterion, with parameters chosen to take account of factors such as consumer myopia with regard to fuel cost savings.

Because the future development of socioeconomic variables, oil price, and the carbon intensity of electricity are outside the transportation sector and uncertain, the team used a set of three scenarios for plausible ranges for their future development.

• “Baseline” scenario continues past trends;
• “Challenging” scenario assumes rapid transportation demand and emissions growth; and
• “Favorable” scenario assumes slow transportation demand and emissions growth.

The team first ran all three scenarios with no new policies—although including major near-future confirmed policies, such as the inclusion of aviation in the EU ETS—applied to set a baseline. For these No New Policies (NNP) cases, they found:

• Emissions trajectories vary by mode and geographical scope, but in nearly all cases are projected to increase from present-day values by 2050.

• The biggest increase comes from intercontinental aviation emissions.

• Adoption of new technologies is small because of R&D limitations and the high costs associated with some available technologies.

• Technologies widely adopted in the fleet in all scenarios include heavy truck driving resistance reduction, the composite-material intensive evolutionary narrow-body replacement aircraft, and space-efficient trains.

• Carbon accounting practices have a strong impact on total emissions.

• In the “Challenging” scenario including intercontinental transport, emissions more than double by 2050.

• CO₂ emissions decrease through 2050 by about 10% relative to 2010 in the “Favorable” scenario with only intra-EU27 traffic.

They then posited a range of new policies to demonstrate a range of possible fleet outcomes:

• R&D only. This option is assumed to make available all technologies with “substantial” (EU-wide) R&D requirements.

• R&D as above plus carbon tax applied from 2015, and increased over 10 years to a maximum value of €100/t (US$131) CO₂.

• R&D plus electric vehicle subsidy. R&D as above, plus a €3,000/vehicle (US$3,900) purchase subsidy is available for plug-in hybrid and battery electric vehicles.

• R&D plus fuel cell electric vehicle subsidy. R&D as above, plus a €3000/vehicle purchase subsidy for fuel cell electric vehicles.

Combining these new policy options with the scenarios resulted in:

• In the R&D only case, year 2050 emissions are reduced by 8−10% (depending on scenario) from NNP values, primarily due to the use of alternative fuels from wood feedstocks. Although alternative passenger car technologies are available, their adoption is very limited.

• With R&D plus a €100/t CO₂ carbon tax, lifecycle CO₂ emissions reduction doubles to 16−19% compared to the NNP case. This results mainly from increased use of alternative fuels and demand reduction from increased journey costs; passenger car alternative technology uptake remains low.

• he two subsidy cases result in reductions of year-2050 emissions by slightly lower levels, i.e. 14−17% (plug-in hybrid electric vehicles) and 12−17% (fuel cell electric vehicles) and alternative technology fleet penetration of 40−55%. While the carbon tax reduces transportation demand and induces extra biofuel use, the vehicle subsidies cause much greater technology penetration for passenger cars, and a demand increase for passenger cars due to reduced journey costs.

• Subsidy support would require up to 0.8% of EU27 GDP, whereas the carbon taxation policy would increase government revenues by a similar amount.

• Although the sample policies would reduce absolute emission levels from present-day values for the “Favorable” scenario by up to 10%, none approaches meeting the targets.

They then examined the maximum emissions reduction achievable through transportation technologies alone. This case assumes sufficient subsidy for widespread adoption of the lowest-emission vehicle, fuel, and capacity technology combination in each category. In addition to R&D and infrastructure support, government spending of at least 2% of EU27 GDP would be required in subsidies and to compensate for lost fuel tax revenue.

The resulting CO₂ emissions differed strongly depending on scenario and geographical scope; further with a very broad range of new technologies in operation, the outcomes are also more uncertain, the team noted. An emissions decrease of 60% or greater was achievable by 2050 only for direct intra-EU27 transport CO₂ emissions in the “Baseline” and “Favorable” scenarios, and is never achieved in the “Challenging” scenario.

Exploiting the full potential of currently projected technology and fuel opportunities requires policy intervention. Many critical technologies and fuels will need EU-wide R&D investments in order to be produced at commercial scale. High carbon prices, stringent regulation, or other significant policy intervention will likely be needed to induce market penetration of breakthrough passenger car and aircraft technologies. Realizing these opportunities requires society to prioritize climate change mitigation, as such interventions may lead to additional public expenditures, higher prices, and decreased mobility. Even then, technological measures alone cannot produce large enough emissions reductions to meet EU climate goals. The question then is better understanding the potential for behavioral measures to mitigate transport sector GHG emissions.

—Dray et al.

Resources

• Lynnette M. Dray, Andreas Schäfer, and Moshe E. Ben-Akiva (2012) Technology Limits for Reducing EU Transport Sector CO₂ Emissions. Environmental Science & Technology doi: 10.1021/es204301z