The IMO Net-Zero Framework promotes adoption of low climate impact marine fuel through combination of pricing mechanism and fuel standard; however, fuel choice depends on competition for clean energy across sectors. Policies must consider life cycle perspective to avoid shifting impacts to the fuel supply chain and address wider environmental impacts, including land use and mineral resource depletion.

Low-carbon transition is a focus in current energy debates. Given current reliance on liquid fuels, this transition raises uncertainties regarding their future role. This study investigates liquid fuels' future role by complementing a global Energy Systems Optimization Model (ESOM) with stakeholders' engagement from a Swedish local energy port cluster. Stakeholders' participation followed a three-phase process: semi-structured interviews and two workshops. The model examined how liquid fuels may evolve from 2020 to 2070 across different socio-economic narratives. While stakeholders acknowledged their commitment to contribute to a low-carbon energy transition, they expressed uncertainty about the future role of today's infrastructure. Nonetheless, stakeholders anticipated continued demand for liquid fuels, confirmed by local low-carbon initiatives, presented as market and policy-driven. Similarly, model results indicate continued demand for liquid fuels, particularly in hard-to-abate sectors such as aviation and industrial feedstock. Yet, the cost-effective role of liquid fuels depends on socio-economic scenarios, carbon budget, carbon storage capacity, biomass availability, and interregional trade. Through a single analytical framework, this study contributes to the ESOM community by showing how a dialogue between energy modelers and local actors can be mutually beneficial, i.e., actors can help refine modeling uncertainties, and model results can guide local actors towards low-carbon transitions.

Shipping is a transnational sector competing for energy on a global market and needs effective policies to decarbonize. Here we assess energy transitions under different shipping policies using a sector-coupled global energy system model and connected life-cycle environmental impacts. We find that postponed International Maritime Organization's 'net-zero framework' could increase biofuel use in shipping to 40% by 2050 but might fall short of net-zero targets, which require broader adoption of low-carbon fuels. A combined levy and global fuel standards mechanism accelerates low-carbon fuel adoption, achieving 60% of ammonia penetration as marine fuel. Ammonia emerges as most cost-effective fuel under cross-sectoral competition for several assessed policies, whereas electrification is preferred for vessels with daily bunkering possibilities. To reach global climate targets, ammonia from bioenergy with carbon capture (yielding negative emissions) and e-ammonia are found potentially crucial for shipping. However, this transition risks increasing other environmental impacts, including land use and mineral resource depletion.

A techno-economic assessment and environmental and social sustainability assessments of novel Fischer–Tropsch (FT) biodiesel production from the wet and dry gasification of biomass-based residue streams (bark and black liquor from pulp production) for transport applications are presented. A typical French kraft pulp mill serves as the reference case and large-scale biofuel-production-process integration is explored. Relatively low greenhouse gas emission levels can be obtained for the FT biodiesel (total span: 16–83 g CO2eq/MJ in the assessed EU countries). Actual process configuration and low-carbon electricity are critical for overall performance. The site-specific social assessment indicates an overall positive social effect for local community, value chain actors, and society. Important social aspects include (i) job creation potential, (ii) economic development through job creation and new business opportunities, and (iii) health and safety for workers. For social risks, the country of implementation is important. Heat and electricity use are the key contributors to social impacts. The estimated production cost for biobased crude oil is about 13 €/GJ, and it is 14 €/GJ (0.47 €/L or 50 €/MWh) for the FT biodiesel. However, there are uncertainties, i.e., due to the low technology readiness level of the gasification technologies, especially wet gasification. However, the studied concept may provide substantial GHG reduction compared to fossil diesel at a relatively low cost.

EU recently decided to include shipping, meaning all intra-European shipping and 50% of extra-European voyages, in the EU Emissions Trading System (ETS) beginning in 2024. This article provides an early assessment of the impacts of the EU ETS on the shipping sector's potential reductions in greenhouse gas emissions for different types of ships. It further examines selected mitigation measures and the impact on modals split and costs. The study employs a mixed-methods approach combining quantitative estimates (based on data from the EU monitoring, reporting and verification system) with qualitative data and information from interviews with key actors and from previous literature. This approach aims to provide a comprehensive understanding of the impacts of the EU ETS. The inclusion of shipping in the EU ETS is expected to introduce significant incentives to reduce emissions. We estimate that switching to bio-methanol at an emissions allowance price of euro90-100/tCO2 will be cost-effective for a minor share of shipping segments (representing about 0.5-5% of all ships), whereas at a price above euro150/tCO2 it could be cost-effective for a considerable share (potentially 75%) of ships. In the short term, the costs incurred by the EU ETS will be passed on to transport customers as a surcharge. The increased cost may, unless properly addressed, drive carbon leakage. Meanwhile, a modal shift away from shipping may occur in the roll-on, roll-off (RoRo) and roll-on passenger (RoPax) segments due to direct competition with road and rail transport and the relative ease of shifting to other modes of transport. Integrating shipping into the EU ETS is an important step towards reducing GHG emissions in the sector but also will reduce emissions of NOX, SOX, and PM.CO2 emissions from shipping constitute about 8% of GHG emissions from all sectors in the EU ETS.The need to purchase allowances will increase operating costs, which will initially be passed on to transport customers as a surcharge.Interviews confirm that a modal shift away from shipping to road and rail may occur in the RoRo and RoPax segments.Switching to bio-methanol may be cost-effective mainly for some ships in the RoRo, RoPax and reefer segments at an allowance price below euro100/tCO2, while for most ships (about 85-100% of ships) it will be cost-effective above euro200/tCO2.

AbstractThe Nordics have a huge renewable energy potential, mainly in the form of onshore and offshore wind as well as biomass potentials and can deliver some of the lowest electricity prices in Europe. They could export large amounts of electricity and hydrogen, supplying mainland Europe and abroad. But where and when should wind, PV and green fuel production capacity be built, and what kind of infrastructure is needed? Within the Nordics—who can/will become a net exporter of electricity and green fuels?To avoid sub-optimal solutions, some overall analysis and planning may be needed to secure societal benefits and reduce the overall cost. By comparing plans and visions for the build-out of electrolyser capacity, electricity and gas infrastructure, and wind and solar projects, we discuss consistency (or lack thereof) in the project pipelines. Furthermore, the future role of the Nordics is discussed by comparing scenario analysis from different modelling teams to identify robust conclusions and critical uncertainties.The impact goes beyond SDG 13 (Climate action) and supports e.g., SDG 8 (Decent work and economic growth) by implementing a more sustainable economic system and also offers the opportunity to provide affordable and clean energy (SDG 7).

Identifying an obvious non-fossil fuel solution for all ship types for meeting the greenhouse gas reduction target in shipping is challenging. This paper evaluates the technical viability, environmental impacts, and economic feasibility of different energy carriers for three case vessels of different ship types: a RoPax ferry, a tanker, and a service vessel. The energy carriers examined include battery-electric and three electro-fuels (hydrogen, methanol, and ammonia) which are used in combination with engines and fuel cells. Three methods are used: preliminary ship design feasibility, life cycle assessment, and life cycle costing. The results showed that battery-electric and compressed hydrogen options are not viable for some ships due to insufficient available onboard space for energy storage needed for the vessel's operational range. The global warming reduction potential is shown to depend on the ship type. This reduction potential of assessed options changes also with changes in the carbon intensity of the electricity mix. Life cycle costing results shows that the use of ammonia and methanol in engines has the lowest life cycle cost for all studied case vessels. However, the higher energy conversion losses of these systems make them more vulnerable to fluctuations in the price of electricity. Also, these options have higher environmental impacts on categories like human toxicity, resource use (minerals and metals), and water use. Fuel cells and batteries are not as cost-competitive for the case vessels because of their higher upfront costs and shorter lifetimes. However, these alternatives are less expensive than alternatives with internal combustion engines in the case of higher utilization rates and fuel costs.

To meet climate targets the emissions of greenhouse gases from transport need to be reduced considerably. Electrofuels (e-fuels) produced from low-CO 2 electricity, water, and carbon (or nitrogen) are potential low-climate-impact transportation fuels. The purpose of this review is to provide a technoeconomic assessment of the feasibility and potential of e-fuels for road, ocean, and air transport. The assessment is based on a review of publications discussing e-fuels for one or more transport modes. For each transport mode, (a) e-fuel options are mapped, (b) cost per transport unit (e.g. vehicle km) and carbon abatement costs are estimated and compared to conventional options, (c) prospects and challenges are highlighted, and (d) policy context is described. Carbon abatement costs for e-fuels (considering vehicle cost, fuel production and distribution cost) are estimated to be in the range 110–1250 € tonne −1 CO 2 with e-gasoline and e-diesel at the high end of the range. The investigated combined biofuel and e-fuels production pathways (based on forest residues and waste) are more cost-competitive than the stand-alone e-fuel production pathways, but the global availability of sustainable biomass is limited making these pathways more constrained. While the potential for e-fuels to decarbonize the transport sector has been discussed extensively in the literature, many uncertainties in terms of production costs, vehicle costs and environmental performance remain. It is too early to rule out or strongly promote particular e-fuels for different transport modes. For e-fuels to play a significant role in transportation, their attractiveness relative to other transport options needs to be improved. Incentives will be needed for e-fuels to be cost-effective and increased clarity on how e-fuels are linked to existing policies is needed.

Electrofuels, fuels produced from electricity, water, and carbon or nitrogen, are of interest as substitutes for fossil fuels in all energy and chemical sectors. This paper focuses on electrofuels for transportation, where some can be used in existing vehicle/vessel/aircraft fleets and fueling infrastructure. The aim of this study is to review publications on electrofuels and summarize costs and environmental performance. A special case, denoted as bio-electrofuels, involves hydrogen supplementing existing biomethane production (e.g. anaerobic digestion) to generate additional or different fuels. We use costs, identified in the literature, to calculate harmonized production costs for a range of electrofuels and bio-electrofuels. Results from the harmonized calculations show that bio-electrofuels generally have lower costs than electrofuels produced using captured carbon. Lowest costs are found for liquefied bio-electro-methane, bio-electro-methanol, and bio-electro-dimethyl ether. The highest cost is for electro-jet fuel. All analyzed fuels have the potential for long-term production costs in the range 90–160 € MWh −1 . Dominant factors impacting production costs are electrolyzer and electricity costs, the latter connected to capacity factors (CFs) and cost for hydrogen storage. Electrofuel production costs also depend on regional conditions for renewable electricity generation, which are analyzed in sensitivity analyses using corresponding CFs in four European regions. Results show a production cost range for electro-methanol of 76–118 € MWh −1 depending on scenario and region assuming an electrolyzer CAPEX of 300–450 € kW elec −1 and CFs of 45%–65%. Lowest production costs are found in regions with good conditions for renewable electricity, such as Ireland and western Spain. The choice of system boundary has a large impact on the environmental assessments. The literature is not consistent regarding the environmental impact from different CO 2 sources. The literature, however, points to the fact that renewable energy sources are required to achieve low global warming impact over the electrofuel life cycle.

Future ships need to operate with low or possibly zero greenhouse gas (GHG) emissions while ensuring low influence on other environmental impacts and that the operation is economically feasible. This study conducts a life-cycle evaluation of potential decarbonization solutions involving selected energy carriers (electrolytic hydrogen, electro-ammonia, electro-methanol, and electricity) in different propulsion system setups (engines, fuel cells, and carbon capture technologies) in terms of environmental impact and costs. The results of the study show that the assessed decarbonization options are promising measures to reduce maritime GHG emissions with low-carbon-intensive electricity. The same order of GHG reduction is shown to be possible independent of the propulsion system and energy carrier used onboard. However, the carbon abatement cost ranges from 300 to 550 €/tCO2eq, and there is a trade-off with environmental impacts such as human toxicity (cancer and non-cancer effects) and freshwater ecotoxicity mainly linked with the wind infrastructure used for electricity production. Electro-ammonia in fuel cells is indicated to be effective in terms of the carbon abatement cost followed by the so-called HyMethShip concept. The higher abatement cost of all options compared to current options indicates that major incentives and policy measures are required to promote the introduction of alternative fuel and propulsion systems.

The change to more sustainable fuels in shipping is important and urgent. This chapter describes the main renewable fuel production pathways and potential energy carriers for ships. Furthermore, criteria to consider when evaluating fuels for shipping are also described and some examples of how different fuels perform against the criteria are shown. There are several pathways to more sustainable fuels. For existing ships, mainly renewable fuels that can be used without any extensive retrofit will be needed. Technically, ships running on LNG can shift to renewable liquefied methane, ships running on diesel can shift to hydrotreated vegetable oil or be retrofitted to run on renewable methanol. For newbuilding's there are several technology pathways, and the choice may depend on the type of ship segment and operational pattern. For costal and short sea shipping, battery-electric propulsion is possible while deep sea shipping could use e.g., electro-methanol or renewable hydrogen. A way to reduce the risk of new environmental problems or unforeseen challenges is to consider a broad set of sustainability criteria when producing, assessing, and selecting fuels and propulsion combinations, and when formulating policy and regulations.

To meet future climate targets, shipping, aviation, and road transport need to reduce their carbon dioxide emissions. This partly by the introduction of alternative transportation fuels and a range of fuel options exist. This study provides an initial assessment of cost-effective future fuel choices for shipping, aviation and road transport in Scandinavia considering carbon reduction requirements and the entire energy system. The cost minimizing energy systems model TIMES Nordic covering Sweden, Norway and Denmark is used. For passenger and freight road transport a considerable electrification seems cost-effective. However, biofuels are needed too, not least in shipping and aviation. The findings indicate that biomass-based marine fuels and bio-jet fuels represent cost-effective mitigation measures in the shipping and aviation sector for 2030 and 2050 in all studied scenario cases. Electrofuels in the aviation and shipping sector is to some extent also a cost-effective option but only when carbon capture and storage is not deployed in large-scale. In general, the development of carbon capture and storage for biomass-based technologies and how these negative emissions will be considered in policy making is important for the development also in the transport sector and particularly for the role of biofuels.

Substitution of conventional jet fuel with low-to zero-carbon-emitting alternative aviation fuels is vital for meeting the climate targets for aviation. It is important to understand the technical, environmental, and economic performance of alternative aviation fuels and prospective engine and propulsion technologies for future aircraft. This study reviews alternative fuels and propulsion systems, focusing on costs and technical maturity, and presents conceptual aircraft designs for different aviation fuels. The cost review includes minimum jet fuel selling price (MJFSP) for alternative aviation fuels. Direct operating cost (DOC) is estimated based on the conceptual aircraft designs and the reviewed MJFSP. The DOCs for bio-jet fuel (5.0-9.2 US cent per passengerkilometer (cent/PAX/km)), fossil and renewable liquefied hydrogen (5.9-10.1 and 8.1-23.9 cent/PAX/km, respectively), and electro-methane and electro-jet fuel (5.6-16.7 and 9.2-23.7 cent/PAX/km, respectively) are higher than for conventional jet fuel (3.9-4.8 cent/PAX/km) and liquefied natural gas (4.2-5.2 cent/PAX/km). Overall, DOC of renewable aviation fuels is 15-500 % higher than conventional jet fuels. Among the bio-jet fuels, hydroprocessed esters and fatty acids (23-310 $/GJ) and alcohol-to-jet (4-215 $/GJ) pathways offer the lowest MJFSPs. The implementation of alternative fuels in existing aircraft engines and the design and development of appropriate propulsion systems and aircraft are challenging. The overall cost is a key factor for future implementation. Bio-jet fuel is most promising in the near term while hydrogen and electrofuels in the long term. The level of carbon tax on fossil jet fuels needed for the latter options to be competitive depend on the hydrogen production cost.

The transportation of freight, via aviation, shipping, and heavy-duty trucks, plays a vital role in economic development but also accounts for nearly 10% of global greenhouse gas emissions, which could increase further in light of emerging economies and markets. This Voices asks: how can we catalyze a transition toward net-zero freight?

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.

To reach the International Maritime Organization, IMO, vision of a 50% greenhouse gas (GHG) emission reduction by 2050, there is a need for action. Good decision support is needed for decisions on fuel and energy conversion systems due to the complexity. This paper aims to get an overview of the criteria types included in present assessments of future marine fuels, to evaluate these and to highlight the most important criteria. This is done using a literature review of selected scientific articles and reports and the authors' own insights from assessing marine fuels. There are different views regarding the goal of fuel change, what fuel names to use as well as regarding the criteria to assess, which therefore vary in the literature. Quite a few articles and reports include a comparison of several alternative fuels. To promote a transition to fuels with significant GHG reduction potential, it is crucial to apply a life cycle perspective and to assess fuel options in a multicriteria perspective. The recommended minimum set of criteria to consider when evaluating future marine fuels differ somewhat between fuels that can be used in existing ships and fuels that can be used in new types of propulsion systems.

To reduce the climate impact of shipping, the introduction of alternative fuels is required. There is a range of different marine fuel options but ammonia, a potential zero carbon fuel, has recently received a lot of attention. The purpose of this paper is to assess the prospects for ammonia as a future fuel for the shipping sector in relation to other marine fuels. The assessment is based on a synthesis of knowledge in combination with: (i) energy systems modeling including the cost-effectiveness of ammonia as marine fuel in relation to other fuels for reaching global climate targets; and (ii) a multi-criteria decision analysis (MCDA) approach ranking marine fuel options while considering estimated fuel performance and the importance of criteria based on maritime stakeholder preferences. In the long-term and to reach global GHG reduction, the energy systems modeled indicate that the use of hydrogen represents a more cost-effective marine fuel option than ammonia. However, in the MCDA covering more aspects, we find that ammonia may be almost as interesting for shipping related stakeholders as hydrogen and various biomass-based fuels. Ammonia may to some extent be an interesting future marine fuel option, but many issues remain to be solved before large-scale introduction.