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| Decomposition of greenhouse gas emission in transportation (A), relevant actors (B), and corresponding policy instruments (C). Creutzig et al. Click to enlarge. |
Vehicle regulations (e.g., volume and GHG-based fuel standards) to achieve reductions in greenhouse gas emissions from on-road transportation need to evolve towards energy-intensity-based fuel standards (e.g., MJ/km) and complementary regulation of fuel carbon intensity (e.g., price-based policies and a cap on total emissions) to regulate coherently alternative fuel vehicles such as electric cars, according to a new study by a team from the Technische Universit¨t Berlin published in the journal Energy Policy.
A detailed examination of fuel pathways shows that alternative vehicles and fuels foster a shift in focus from tailpipe emissions to upstream emissions, the authors note. Correspondingly, because of a number of different possible fuel pathways, lifecycle emissions of vehicle usage partially decouple from fuel efficiency. Decomposing transport’s GHG emissions into three factors—carbon intensity, energy intensity and demand, allows for conceptualizing the match between policy instruments, actors, and level of regulation, the team concludes.
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| Overview on efficiency losses and lifecycle emissions of fuel supply chains. Numbers and references are given in Creutzig et al. (2010). Click to enlarge. |
…with diversified fuel supply chains and alternatives to the internal combustion engine, existing policy instruments need to further evolve to ensure
efficiency in terms of setting harmonized incentives across different technologies and fuel chains, and effectiveness in achieving emission reduction objectives.
In this article, we elucidate
that most GHG emissions of ICE vehicles and fuels occur at
tank-to-wheel (downstream), but emissions of alternative fuels
tend to occur at well-to-tank (upstream). Emissions in the
transport sector can be decomposed into carbon intensity, energy
intensity and travel demand. Regulation aimed at curing market
failures needs to address each decomposition factor to appropriately
target and incentivize the corresponding actors to reduce
their emissions factor.
…Altogether, a quantity and price instrument can address the
drawbacks of existing regulation. In principle, both emissions
trading and GHG taxes can be used to achieve effectiveness and
efficiency as both instruments directly tackle greenhouse gas
emissions. Thus, both simultaneously address all driving factors
for road transport emissions with one harmonized instrument.—Creutzig et al.
Transportation consumes more than half of the oil used world-wide, and contributes roughly 25% of energy-related CO2 emissions. If emissions from feedstock and fuel production
are included, the transport sector is responsible for close to 27% of
global greenhouse gas (GHG) emissions, the team notes.
| “…distance should always be in the denominator to reduce misconceptions over fuel savings.” |
| —Creutzig et al. |
Irrespective of the exact trajectory of their growth in the market, the growing presence and variety of alternative vehicles will imply a long-term shift in the energy used for vehicle propulsion. The fuels market may become more diverse, and supply chains of some of these
new fuel technologies will be more complicated. Rather than the historical dominance of conventional gasoline or diesel, the emerging transportation market will see electricity, and potentially hydrogen, but also non-conventional fossil fuels, such as Canadian tar sands, and biofuels.
As the resource base of transportation
fuels diversifies, GHG emissions partially decouple from the end-of-pipe energy content of fuels. In fact, both varying feedstock and
varying production process will increasingly determine the overall
carbon footprint of road transportation. From a climate
perspective, only the lifecycle emissions of these fuels matter.
However, in the current EU and Californian policy framework,
cars are regulated with respect to GHG emissions per distance
(CO2e/km)—in the case of electric, hydrogen, and biofuel-powered
cars, this emissions metric may not accurately reflect the
global warming impact of fuels used, if the regulatory emissions
accounting generalizes across feedstocks and production processes
for each final fuel.
Furthermore, sometimes the more environmentally benign fuels are more tightly regulated with respect to GHG emissions than the more harmful fuel. For
example, in the European ETS, GHG emissions of electric rail are
part of a cap-and-trade scheme whereas conventional transport
fuels are not covered by climate policies…providing a level playing field for all fuels is important for achieving efficient and effective abatement in the transport
sector.—Creutzig et al.
Resources
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Creutzig, F., et al. (2011) Climate policies for road transport revisited (I): Evaluation of the current framework. Energy Policy doi: 10.1016/j.enpol.2011.01.062