Mobility is becoming more and more important in today's life. This is reflected by European citizens continuously increasing their travel demand or by the employment opportunities generated by transport, for example the 7.5 million people employed in the transport service sector of the EU-25. The downside of this development becomes obvious when looking at the growing proportion of transport emissions against total human greenhouse gas emissions, which is almost 30% today, and the almost total dependence of transport on fossil fuels as an energy source.
Given this framework, the requirement for changes in the transport system became obvious. Both behavioural and technological changes will be necessary to alter the harmful trends and make transport sustainable, delivering support to social development and providing fairness, economic growth and environmental stability.
A major step in making the transport system more sustainable would be a shift towards alternative fuels like biofuels or hydrogen generated from various sources. This requires a symbiotic transition of the transport-energy system towards the supply and use of such alternative fuels. Scenarios for such a matched transition process were developed and assessed by the TRIAS project. The focus of TRIAS was to provide an integrated and quantitative assessment of the transport-energy system adaptations and their economic, social and environmental impacts.
The strategic objectives of TRIAS were four-fold:
- Develop and test strategies to reduce greenhouse gas emissions and noxious emissions from transport based on the trilogy ('trias') of transport, technology and energy scenarios. In particular, the introduction of biofuels and hydrogen as energy carriers for transport are analysed.
- Base the assessment on an integrated model-based approach looking at environmental, economic and social impacts (sustainability impact assessment). The use of integrated models enables quantifying the impacts of scenarios, deriving new sustainability indicators from the quantitative model variables and creating consistent scenarios where all the numbers fit together avoiding contradictions within a scenario. The four models applied are POLES (world-energy system), ASTRA (economy-transport-environment interaction), VACLAV (transport network impacts), Regio-SUSTAIN (regional environmental impacts).
- Provide an open field for both external scenarios and scenarios developed within TRIAS, by reviewing the scenario literature and providing interaction with stakeholders concerning scenario design.
- Consider the life-cycle implications of all strategies investigated. For example, the use of biofuels or hydrogen has underlying restrictions on the available land to produce biomass, so that for each technology path tested its full life cycle has to be considered.
The TRIAS project commenced with an analysis of available scenarios from existing studies. Based on this knowledge the TRIAS scenarios were developed and these were analysed in a final step.
A second starting point was the development of a technology database that provided the techno-economic data for alternative technologies related to biofuel and hydrogen use for transport. These data were required to update the applied models so that they disposed over the capabilities to simulate the technology diffusion and transition as part of the scenarios.
The four models, POLES, ASTRA, VACLAV and Regio-SUSTAIN, were upgraded to:
- Incorporate the new technologies;
- Extend their assessment capabilities;
- Provide linkages between the models. Models then calculated scenarios until the year 2030, with an outlook until 2050 by POLES and ASTRA.
The scenario results were provided on a detailed level consisting of both the single indicators of the various models (e.g. presenting results, for either a country or region, at a sectoral level) and the aggregate indicators relevant to describe sustainability of the scenarios.
The project results achieved were an update of the POLES, ASTRA, VACLAV and Regio-SUSTAIN models with new model elements required for the specific scenario analysis in TRIAS e.g. extending to the time horizon 2050, adding new technologies to the vehicle fleets, modelling of biofuels for the energy and transport markets as well as the new development of the BIOFUEL model. In particular, the ASTRA model made a large step ahead, as during the course of the project it was agreed to actually modularise the software and to develop a tool that would merge it back to the integrated System Dynamics model that incorporates the most important feedbacks between transport, energy, technology and the economy. A further achievement was the improved linkage between ASTRA and POLES that enabled fast running of scenarios in an iterative manner and achieving convergence between the two models.
In the shorter term, setting CO2 emission limits provided economic stimulus as well as reducing CO2 emissions. This can be reinforced by fostering biofuels. The type of biofuels must be carefully selected according to sustainability criteria and to limit the use of biofuels, because (1) overemphasized use of biofuels could lead to strong conflicts between the use of biomass for food and the use for energy, which seems not to be reasonable considering (2) that the impacts on economy and CO2 emissions of the biofuels policies remain limited. In the longer term, hydrogen seems to be a suitable option to foster economic growth and to significantly reduce CO2 emissions and other environmental impacts of transport. However, this presupposes that other countries follow the same but delayed trend towards transport infrastructure based on hydrogen and, therefore, hydrogen cars would become a more successful export good than today's European cars. Furthermore, it assumes that this hydrogen is mainly produced from renewable sources.
Applying the improved models and using the newly established linkages between the models the eight policy scenarios was tested and compared with the baseline scenario. The main conclusion is that all scenarios showed both a positive impact on the economy, though in most of the scenarios the improvement remained quite limited, and a reduction of emissions and resource use. The two most effective scenarios were the first mover scenario for hydrogen and the introduction of CO2 emission limits, because the main driver for making scenarios positive were the
While the model outcomes are consistent among each other, some important constraints should be taken into account:
- The policies analysed in TRIAS are conservative. In particular, meeting ambitious CO2 emissions reduction targets until 2050 require policies to be designed more ambitiously than those considered in the project.
- In TRIAS, only changes of policy instruments designed for affecting the transport sector are reflected. This allows estimation of the impacts of transport policies but might be considered as incomplete as e.g. setting CO2 emission limits in the transport sector is likely to be only one element of an overall CO2 emission reduction strategy, and pushing biofuels shall be seen in the context of increasing the share of renewable energy sources in overall energy demand.
- The technology screening of TRIAS does not account for the fast development of batteries, in the two years (2005-2006). This was not considered in the TRIAS scenarios. Thus battery electric vehicles may play a more important role than in the TRIAS scenarios.
- Finally, some systemic effects could not be modelled with the available toolset. For example, no competition was assumed to take place between biofuel and hydrogen fuel production from biomass, even though this may occur through e.g. gasification of biomass. Other model-inherent parameters of the BIOFUEL model, such as the feedstock price elasticities describing the feedback of an increased biofuel demand on feedstock prices are calibrated on historic data with limited biofuel volumes. With biofuels gaining importance and the demand of crops for energy purposes attaining a high share of overall crop production, those elasticities might need to be modified. Similarly, the model does not allow for a comprehensive assessment of the origins and quantities of imported biofuels, resulting in uncertainties about the overall related GHG emissions.
TRIAS found that the policies applied steer EU development in the desired direction. However, implementing them in a moderate way as in TRIAS would not be sufficient to achieve European policy targets such as achieving a significant reduction of transport CO2 emissions or increasing security of energy supply. This requires more ambitious and stringent policies e.g. in terms of higher carbon taxes than in TRIAS, comprehensive carbon taxation of all fuels or more focused subsidy of new vehicle technologies at market entry. The TRIAS sensitivity analysis revealed that such policies would pay-off for Europe, in particular when oil prices are sustained at high levels.