Enhancing Integrated Energy and Transport Modelling for the Scandinavian Region

Abstract

Transportation has always been an essential activity for human society, but, is also responsible for several externalities. Today the transport sector accounts for almost one-third of final energy demand and for approximately one-third of global energy-related CO2 emissions. Changing the current transport paradigm is crucial to meet global environmental goals such as the Paris Agreement, though this requires a broad set of technological and behavioural measures summarized in the International Energy Agency (IEA) slogan Avoid, Shift, improve. Nordic countries are pioneers in deploying sustainable energy technologies, as witnessed by the wide penetration of renewables in the power and heat sectors. However, the transport sector lags behind, representing the largest source of Nordic greenhouse-gas (GHG) emissions and accounting for 40% of total CO2 emissions, a higher share compared to the global average. A low-carbon transition of the Nordic transport sector has slowly started. Indeed, the Nordic region represents the third largest electric car market by volume of sales in the world. However, further mitigation measures and a solid decarbonisation strategy encompassing all the sub-sectors (including navigation and aviation) are needed. Relying on a rich and diversified portfolio of renewable energy sources and expertise, Nordic countries could benefit by outlining a common mitigation strategy by embracing a larger variety of sustainable solutions and possible synergies. Energy system models have been applied for more than three decades to investigate sustainable pathways to meet energy and environmental goals for specific sectors or even for the whole energy systems. In particular, bottom-up (BU) optimization energy-economy-environmental-engineering (E4) models provide a thorough technological description besides considering cross-sectorial and cross-regional dynamics and synergies. Though, these models are generally weak in representing human behaviour, an important aspect in transport decision making. This PhD thesis builds on the research field of energy systems analysis to enhance integrated energy and transport modelling aimed at robust planning for the decarbonisation of the Scandinavian transport sector. A systematic critical review of studies applying energy system analysis for integrated energy and transport scenarios for the Nordic region lays the basis for this work. Research gaps and potential modelling improvements are identified in light of recent findings in transport research and considering the future challenges that the sustainable transition of the transport sector is likely to face. Such limitations are tackled by this PhD thesis through two main scientific contributions. The first contribution addresses a weakness of BU optimization E4 models: the poor representation of transport modal competition. A novel methodology enabling transport modal shift through the application of substitution elasticities is developed to tackle this gap. For the passenger sub-sector, this represents an attempt to enhance the weak capability of BU optimization E4 models to depict transport behavioural dimensions. The methodology is tested and applied for a real case study to investigate the role of modal shift in decarbonising the future Scandinavian transport sector under an increasing CO2 tax. Transport modal shift, towards the more efficient and less carbon-intense modes (e.g. rail), results a cost-effective measure to reduce cumulative CO2 emissions. The presented methodology facilitates more comprehensive analyses by enabling a wider range of applications compared to traditional approaches. For instance, the Shift pillar at the base of the IEA decarbonisation strategy can be integrated directly in the analysis. In addition, endogenous modal shift is enabled for both passengers and freight, representing further progress compared to previous attempts in BU optimization E4 models, which focus mainly on passengers. The second contribution to tackle the gaps identified is the development of an open-source energy system model (TIMES-Nordic) depicting the full Scandinavian energy system. TIMES-Nordic structure is designed to overcome most of the modelling limitations identified in the reviewed literature. Besides including elastic modal shift, the model is enriched by breakthrough energy and transport technologies and innovative fuel chains. The full energy system of each country is modelled separately, allowing the investigation of sustainable pathways for the whole Scandinavian region while enabling the identification of specific national strategies. All sectors composing the national energy systems are included, enabling resource competition and technological synergies to be identified across sectors. All transport sub-sectors (including international aviation and navigation) are modelled to provide a complete outlook for emission reduction strategies. Concluding, this PhD thesis provides tools (open-source) and methodologies that can support fellow researchers and modellers interested in the decarbonisation of the Scandinavian transport sector. Concerning suggestions for further research, substitution elasticities could be tested to describe other phenomena than transport modal shift, while TIMESNordic can be further developed to address the remaining modelling gaps.