Environmental assessment of present and future marine fuels

Our globalised world is connected by shipping, an industry powered by one of heaviest and dirtiest products of refining: heavy fuel oil. Tougher environmental regulations are now challenging the industry to take action. Ship-owners and operators are faced with the choice of installing exhaust gas cleaning technologies or switching to a different fuel altogether. The primary purpose of this thesis was to assess the environmental performance of present and future marine fuels and to evaluate potential methods and tools for their assessment.Two different system approaches are used in this study: life cycle assessment (LCA) and global energy systems modelling. LCA is a well-established method for assessing the environmental performance of fuels. This type of assessment was complemented with the use of the Global Energy Transition (GET) model to investigate cost-effective fuel choices based on a global stabilisation of CO2 emissions and the global competition for primary energy sources. The GET model includes all energy sectors and considers the interactions among them, but it is limited in scope to CO2 emissions and costs. The LCAs involve a holistic systems perspective that includes the entire life cycle and various types of environmental impacts, but they are limited to analyses of one product or service at a time. These methods provide insights that are both contradictory and complementary.This study concludes that there is substantial potential for reducing the environmental impact of shipping through a change in fuel types and/or the use of exhaust abatement technologies. A switch from heavy fuel oil to any of the alternatives investigated in this study reduces the overall environmental impact of marine fuels. The GET model indicates that it is cost-effective to phase out the use of crude oil-based fuels in the shipping sector and replace these fuels with the use of natural gas-based fuels during the next few decades. Based on the LCA results, the use of biofuels may be one possible way to reduce the impact of shipping on the climate, but biofuels may only be a cost-effective fuel in shipping if the corresponding annual available bioenergy resources are sufficiently large. Three important implications are highlighted: the importance of reducing the NOX emissions from marine engines, the need to regulate the methane slip from gas engines and the fact that a change in fuels may not reduce the impact of shipping on the climate

Electricity as an Energy Carrier in Transport: Cost and Efficiency Comparison of Different Pathways

This study includes a techno-economic assessment of different pathways of using electricity in passenger cars and short sea ships, with a special focus on electrofuels (i.e.fuels produced from electricity, water and CO2) and electric road systems (ERS). For passenger cars electro-diesel is shown to be cost-competitive compare to battery electric vehicles with larger batteries (BEV50kWh) and hydrogen fuel cell vehicles (FCEV), assuming optimistic cost for the electrolyser. ERS is shown to reduce the vehicle cost substantially compare to BEV50kWh and FCEV, but depend on a new large scale infrastructure. For ships it is shown that battery electric vessels with a relatively small battery has the lowest cost. Electro-diesel and hydrogen can compete with the battery options only when ships operate few days per year

Criteria and Decision Support for A Sustainable Choice of Alternative Marine Fuels

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 system

The Potential Role of Ammonia as Marine Fuel-Based on Energy Systems Modeling and Multi-Criteria Decision Analysis

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

Electrofuels: a review of pathways and production costs

Electrofuels are produced from carbon dioxide (CO2) and water using electricity as the primary source of energy. Production costs for the fuel options methane, methanol, dimethyl ether, Fischer-Tropsch (FT) diesel are estimated based on different assumptions. The production costs of these electrofuels, for a best, average and worst case, was found to be in the range of 120-135, 200-230 and 650-770 €2015/MWh fuel respectively where methane had the lowest and FT diesel the highest costs within each range

The environmental performance of a fossil-free ship propulsion system with onboard carbon capture - a life cycle assessment of the HyMethShip concept

The climate impact caused by the shipping industry has increased over the past decades despite attempts to improve the energy efficiency of vessels and lower induced emissions. A tool in reducing climate and other environmental impacts is new low emissions propulsion technologies. These new technologies need to reduce harmful emissions not only in the tailpipe but also over the entire life cycle. This study uses life cycle assessment to investigate the life cycle environmental impact of a propulsion concept currently under development: the HyMethShip concept. The HyMethShip concept combines electro-methanol energy storage, an onboard pre-combustion carbon capture system, and a dual fuel internal combustion engine. The concept aims for an almost closed CO2 loop by installing CO2 capture onboard. The CO2 is unloaded in port and converted into electro-methanol which is used to fuel the ship again. This is made possible by a pre-combustion process converting electro-methanol to hydrogen and CO2. The assessment is conducted from well-to-propeller and focuses on ship operation in the North Sea in 2030. The results indicate that this technology could be an alternative to reduce the climate impact from shipping. The results show a lower impact on acidification, climate change, marine eutrophication, particulate matter, photochemical ozone formation, and terrestrial eutrophication compared to internal combustion engines run on either marine gas oil (0.1% sulphur content), biogenic methanol, fossil methanol, or electro-methanol. Electricity with low climate and environmental impact is likely required to achieve this, and low NOx emissions from combustion processes need to be maintained. A potential trade-off is higher toxicity impacts from the HyMethShip concept compared to most other options, due to metal needs in wind power plants

Reviewing the development of alternative aviation fuels and aircraft propulsion systems

Alternative aviation fuels such as bio-jet fuels, liquid natural gas (LCH4), hydrogen (H2), electro-jet fuels and direct electricity use play an important role in decarbonizing the aviation sector. New aircraft propulsion systems are being developed but low-blending of fuels is possible for some options. It is imperative to understand the technical, environmental and economic performance of the different alternative aviation fuels and the new engine and propulsion technologies for the utilization of these fuels. We have reviewed various literature to map the current status of development on alternative aviation fuels and related aircraft propulsion systems in relation to different perspective such as their cost and technical maturity. There are several challenges related to the design and implementation of the fuels and new propulsion systems. For instance, the volumetric energy content of alternative fuels is lower than the conventional aviation fuels which requires larger fuel storage tanks. Despite the advantageous environmental performance, both the bio-jet and electro-jet fuels are currently not economically competitive. Yet, studies forecast that increased use of alternative aviation fuels is possible after modifications of engines, fuel storage tanks and improvements of the aerodynamics of aircraft and by introducing subsidies and/or carbon taxes on conventional jet fuels

What Future for Electrofuels in Transport? Analysis of Cost Competitiveness in Global Climate Mitigation

The transport sector is often seen as the most difficult sector to decarbonize. In recent years, so-called electrofuels have been proposed as one option for reducing emissions. Electrofuels-here defined as fuels made from electricity, water, and carbon dioxide-can potentially help manage variations in electricity production, reduce the need for biofuels in the transportation sector while utilizing current infrastructure, and be of use in sectors where fuel switching is difficult, such as shipping. We investigate the cost-effectiveness of electrofuels from an energy system perspective under a climate mitigation constraint (either 450 or 550 ppm of CO2 in 2100), and we find the following: (i) Electrofuels are unlikely to become cost-effective unless options for storing carbon are very limited; in the most favorable case modeled-an energy system without carbon storage and with the more stringent constraint on carbon dioxide emissions-they provide approximately 30 EJ globally in 2070 or approximately 15% of the energy demand from transport. (ii) The cost of the electrolyzer and increased availability of variable renewables appear not to be key factors in whether electrofuels enter the transport system, in contrast to findings in previous studies

WHAT FUTURE FOR ELECTROFUELS?

Transport sector is seen as the most difficult sector to decarbonise. In recent years so called electrofuels have been proposed as one option for emissions reduction. Electrofuels – fuels made from electricity and carbon dioxide - can potentially help to manage variations in electricity production and reducethe need for biofuels as well as make use of current infrastructure and can be used in sectors where fuel switch is difficult such as aviation. We investigate the cost-effectiveness of electrofuels under climate mitigation constraint and find that electrofuels are unlikely to become cost-effective unless options for storing carbon are very limited

Life-Cycle Assessment and Costing of Fuels and Propulsion Systems in Future Fossil-Free Shipping

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 (sic)/tCO(2)eq, 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