Aviation and maritime shipping are hard-to-abate transport sectors that are heavily dependent on fossil fuels. They jointly account for nearly 10 % of global greenhouse gas emissions, while infrastructure and investments are locked into high-carbon pathways for decades. Fuels and technologies to decarbonize include advanced biofuels, electrofuels, hydrogen and electric propulsion. This research aims to analyse the decarbonization strategies for maritime shipping and aviation from a comparative perspective, and analyzing the role of different actors for disruption to break through carbon lock-in and path dependency. The research uses Sweden as a case study and applies qualitative methods, including expert interviews, focus group discussions and site visits. Our research finds that aviation and maritime shipping are slowly changing, albeit with different dynamics. Both sectors show that incumbent regime actors play a major role in shaping transition pathways and disrupting the (quasi)equilibrium, while niche innovation is often developed together by incumbents and niche players.

The maritime shipping industry accounts for 3 % of global greenhouse gas emissions and delivers 90 % of globally traded goods. Maritime shipping is heavily reliant on fossil fuels. There is increasing policy pressure to cut emissions to achieve the Paris Agreement and to meet decarbonization targets. This paper aims to analyze sector coupling for decarbonization and sustainable energy transitions in maritime shipping, exploring the interlinkages between the transport, energy, industry, agriculture and forestry sectors. First, this paper analyses the opportunities and barriers for sector coupling between the maritime shipping sector and other industries. Second, this paper adds new knowledge on the wider implications of sustainable energy transitions and decarbonization for the maritime shipping sector, the role of various stakeholders in supporting or impeding sustainable energy transitions, policy issues at the international, regional and national level and the links to sector coupling. This research uses a mixed methods approach, applying both qualitative research including interviews and quantitative energy modeling. The research thereby links theories from sustainability transitions with techno-economic modeling approaches. Our research finds that the sector couplings between the transport, energy, industry, agriculture and forestry sectors are of growing importance as maritime shipping is transitioning towards decarbonized and renewable marine fuels. At the same time there is competition for scarce natural resources with other sectors, including aviation and road transport. Socio-technical aspects, particularly of financial and political nature, are key factors that determine the speed and direction of the transition, yet they remain under-explored.

The role of electric vehicles (EVs) in more sustainable cities is widely recognized, with their adoption increasing rapidly. Most governments have targets for continued EV adoption rate growth, and some plan to ban fossil-fuelled vehicles altogether. Yet, in most countries, including Brazil, the proportion of EVs among new vehicles sold remains low. EV adoption poses multiple technological, economic and social challenges that require targeted policy mechanisms. This study assesses policy measures to expedite EV adoption for road transport decarbonisation and sheds light on the critical role of EVs in sustainable urban development. We explore electric mobility challenges in urban areas, focusing on the case of Curitiba City in Brazil. We investigate existing challenges and barriers to policy implementation in Curitiba and successful interventions in cities worldwide to identify suitable policies for Curitiba. The study uses in-depth interviews with relevant stakeholders to examine policy tools, including financial, legal, knowledge-based, and societal instruments. The study recommends complementary instruments and measures to accelerate their adoption in Curitiba. Overall, the study's results, which identify criteria for policy design and implementation towards complete transport decarbonisation, should be valuable for decision-making in transport and mobility planning.

This article investigates the potential of renewable and low-carbon fuel production for the maritime shipping sector, using Sweden as a case in focus. Techno-economic modelling and socio-technical transition studies are combined to explore the conditions, opportunities and barriers to decarbonising the maritime shipping industry. A set of scenarios have been developed considering demand assumptions and potential instruments such as carbon price, energy tax, and blending mandate. The study finds that there are opportunities for decarbonising the maritime shipping industry by using renewable marine fuels such as advanced biofuels (e.g., biomethanol), electrofuels (e.g., e-methanol) and hydrogen. Sweden has tremendous resource potential for bio-based and hydrogen-based renewable liquid fuel production. In the evaluated system boundary, biomethanol presents the cheapest technology option while e-ammonia is the most expensive one. Green electricity plays an important role in the decarbonisation of the maritime sector. The results of the supply chain optimisation identify the location sites and technology in Sweden as well as the trade flows to bring the fuels to where the bunker facilities are potentially located. Biomethanol and hydrogen-based marine fuels are cost-effective at a carbon price beyond 100 €/tCO2 and 200 €/tCO2 respectively. Linking back to the socio-technical transition pathways, the study finds that some shipping companies are in the process of transitioning towards using renewable marine fuels, thereby enabling niche innovations to break through the carbon lock-in and eventually alter the socio-technical regime, while other shipping companies are more resistant. Overall, there is increasing pressure from (inter)national energy and climate policy-making to decarbonise the maritime shipping industry.

The global Sustainable Development Goals (SDGs) are now converging to address the economic, social and environmental dimensions. Bioenergy can play a significant role in achieving the agreed SDGs on climate change, thereby advancing climate goals, food security, better land use, and sustainable energy for all. Bioenergy is essential in the past, present and future energy systems. At least 10% of global energy supply comes from bioenergy source, of which two-thirds is used in developing countries for cooking and heating. Compared to other renewable energy sources, bioenergy is the most problematic area due the multitude of biomass feedstock, technology pathways, and end products which encompass the biomass to energy conversion. The use of biomass for bioenergy is expected to increase driven by several SDGs (goals: 2, 7, 8, 9, 11, 12, 13, 15), but bioenergy also act as sustainability safeguards. By exploring bioenergy in a context of multi-sectoral objectives and synergies, pathways can be found to promote the transition to sustainable modern bioenergy. This paper explores pathways to enhance resource efficiency, particularly for bioenergy production in the palm oil industry in Indonesia for meeting the SDGs. 

The Indonesian power sector faces the combined challenge to (i) satisfy growing electricity demand at an affordable cost and (ii) comply with the decarbonization targets committed under the Paris Agreement. In this study, we investigate cost-optimal pathways for the development of the power sector in line with climate targets. We used the Low Emissions Analysis Platform (LEAP) software tool to build a power-system expansion model for Sumatra and simulated four scenarios representing a business as usual development, the current development plans, and two mitigation pathways in line with the national climate targets. Particular focus is put on bioenergy, an energy source that has been often overlooked in previous studies and plans. The results show that, although the national plans consider mitigation actions, they do not reduce coal dependency. Besides, current development plans are not cost-effective and have high marginal abatement costs for emissions reduction. The two mitigation scenarios achieve better environmental results at lower system costs. Our results show that bioenergy deployment can contribute significantly to achieving the greenhouse gas (GHG) targets of 19% and 24% pledged by the Indonesian government. More efficient use of modern renewables and natural gas can reduce Sumatra's dependence on coal resources.

The aviation industry contributes to more than 2% of global human-induced CO2-emissions, and it is expected to increase to 3% by 2050 as demand for aviation grows. As the industry is still dependent on conventional jet fuel, an essential component for a carbon-neutral growth is low-carbon, sustainable aviation fuels, for example alternative drop-in fuels with biobased components. An optimization model was developed for the case of Sweden to examine the impacts of carbon price, blending mandates and penalty fee (for not reaching the blending mandate) on the production of renewable jet fuel (RJF). The model included biomass gasification-based Fischer–Tropsch (FT) jet fuel, Power-to-Liquid (PTL) jet fuel through the FT route and Hydrothermal liquefaction (HTL)-based jet fuel. Thus, this study aims at answering how combining different policies for the aviation sector can support the production of RJF in Sweden while reducing greenhouse gas (GHG) emissions. The results demonstrate the importance of implementing policy instruments to promote the production of RJF in Sweden. The blending mandate is an effective policy to both promote RJF production while reducing emissions. The current level of the penalty fee is not sufficient to support the fuel switch to RJF. A higher blending mandate and carbon price will accelerate the transition towards renewable and sustainable fuels for the aviation industry.

Biorefineries provide opportunities to improve the economic, environmental, and social performance of bio-based production systems. Prudent planning of plant configuration and localization is however of great merit to obtain maximum benefits from biorefineries. This study investigates optimal deployment of palm oil-based biorefineries on the two major islands of Indonesia, Sumatra and Kalimantan. In addition, the results of the optimal bioenergy (bioelectricity, biodiesel, ethanol) production are used to calculate the potential contribution of the palm oil industry according to the national bioenergy targets from 2020 to 2030. This work also offers a new perspective of analyzing the role of bioenergy in the palm oil industry in relation to meeting the bioenergy targets through the development of spatially explicit optimization model, BeWhere Indonesia. Results show that the palm oil-based biorefineries in Sumatra and Kalimantan can produce 1–1.25 GW of electricity, 4.6–12.5 bL of biodiesel, and 2.8–4.8 bL of ethanol in 2030. Significant efforts in terms of mobilization of resources and economic instruments are required to harness the full potential offered by the palm oil-based biorefineries. This study provides an important insight on how palm oil biorefineries can be developed for their enhanced roles in meeting global sustainability efforts.

This paper investigates the consequences of divergence in policy assumptions in energy planning for preparing national low-carbon pathways and enhancement of Nationally Determined Contributions (NDCs) in Indonesia, Thailand and Vietnam. We present an assessment of the resulting forecasts based on a multimethod exploratory study. Our analysis contributes to an ongoing debate on the policy coherence and integration in the energy sector and climate action strategies. Our results indicate how data availability, ownership and transparency, as well as institutional factors inbuilt in national energy planning impact policy implementation and climate action. This analysis can provide valuable insights for policy-makers working with enhancing NDCs to ensure the updated NDC is actionable.