| 1. |
- Dahal, Karna, 1984, et al.
(författare)
-
Reviewing the development of alternative aviation fuels and aircraft propulsion systems
- 2020
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
| 2. |
- Dahal, Karna, 1984, et al.
(författare)
-
Techno-economic review of alternative fuels and propulsion systems for the aviation sector
- 2021
-
Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 151
-
Forskningsöversikt (refereegranskat)abstract
- 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 passenger-kilometer (¢/PAX/km)), fossil and renewable liquefied hydrogen (5.9–10.1 and 8.1–23.9 ¢/PAX/km, respectively), and electro-methane and electro-jet fuel (5.6–16.7 and 9.2–23.7 ¢/PAX/km, respectively) are higher than for conventional jet fuel (3.9–4.8 ¢/PAX/km) and liquefied natural gas (4.2–5.2 ¢/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.
|
|
| 3. |
- Fridahl, Mathias, 1980-, et al.
(författare)
-
Bioenergy with carbon capture and storage (BECCS): Global potential, investment preferences, and deployment barriers
- 2018
-
Ingår i: Energy Research and Social Science. - : Elsevier BV. - 2214-6296 .- 2214-6326. ; 42, s. 155-165
-
Tidskriftsartikel (refereegranskat)abstract
- Keeping global warming well below 2 °C entails radically transforming global energy production and use. However, one important mitigation option, the use of bioenergy with carbon capture and storage (BECCS), has so far received only limited attention as regards the sociopolitical preconditions for its deployment. Using questionnaire data from UN climate change conferences, this paper explores the influence of expertise, actor type, and origin on respondents’ a) preferences for investing in BECCS, b) views of the role of BECCS as a mitigation technology, globally and domestically, and c) assessment of possible domestic barriers to BECCS deployment. Non-parametric statistical analysis reveals the low priority assigned to investments in BECCS, the anticipated high political and social constraints on deployment, and a gap between its low perceived domestic potential to contribute to mitigation and a slightly higher perceived global potential. The most important foreseen deployment constraints are sociopolitical, which in turn influence the economic feasibility of BECCS. However, these constraints (e.g. lack of policy incentives and social acceptance) are poorly captured in climate scenarios, a mismatch indicating a need for both complemented model scenarios and further research into sociopolitical preconditions for BECCS.
|
|
| 4. |
- Göransson, Lisa, 1982, et al.
(författare)
-
The benefit of collaboration in the North European electricity system transition - System and sector perspectives
- 2019
-
Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 12:24
-
Tidskriftsartikel (refereegranskat)abstract
- This work investigates the connection between electrification of the industry, transport, and heat sector and the integration of wind and solar power in the electricity system. The impact of combining electrification of the steel industry, passenger vehicles, and residential heat supply with flexibility provision is evaluated from a systems and sector perspective. Deploying a parallel computing approach to the capacity expansion problem, the impact of flexibility provision throughout the north European electricity system transition is investigated. It is found that a strategic collaboration between the electricity system, an electrified steel industry, an electrified transport sector in the form of passenger electric vehicles (EVs) and residential heat supply can reduce total system cost by 8% in the north European electricity system compared to if no collaboration is achieved. The flexibility provision by new electricity consumers enables a faster transition from fossil fuels in the European electricity system and reduces thermal generation. From a sector perspective, strategic consumption of electricity for hydrogen production and EV charging and discharging to the grid reduces the number of hours with very high electricity prices resulting in a reduction in annual electricity prices by up to 20%.
|
|
| 5. |
- Hansson, Julia, 1978, et al.
(författare)
-
The Potential Role of Ammonia as Marine Fuel-Based on Energy Systems Modeling and Multi-Criteria Decision Analysis
- 2020
-
Ingår i: Sustainability. - : MDPI AG. - 2071-1050. ; 12:8
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 6. |
- Johansson, Daniel, 1975, et al.
(författare)
-
The role of negative carbon emissions in reaching the Paris climate targets: The impact of target formulation in integrated assessment models
- 2020
-
Ingår i: Environmental Research Letters. - : IOP Publishing. - 1748-9326 .- 1748-9318. ; 15:12
-
Tidskriftsartikel (refereegranskat)abstract
- Global net-negative carbon emissions are prevalent in almost all emission pathways that meet the Paris temperature targets. In this paper, we generate and compare cost-effective emission pathways that satisfy two different types of climate targets. First, the common approach of a radiative forcing target that has to be met by the year 2100 (RF2100), and, second, a temperature ceiling target that has to be met over the entire period, avoiding any overshoot. Across two integrated assessment models (IAMs), we found that the amount of net-negative emissions - when global net emissions fall below zero - depends to a large extent on how the target is represented, i.e. implemented in the model. With a temperature ceiling (no temperature overshoot), net-negative emissions are limited and primarily a consequence of trade-offs with non-CO2 emissions, whereas net-negative emissions are significant for the RF2100 target (temperature overshoot). The difference becomes more pronounced with more stringent climate targets. This has important implications: more stringent near-term emission reductions are needed when a temperature ceiling is implemented compared to when an RF2100 target is implemented. Further, in one IAM, for our base case assumptions, the cost-effective negative carbon emissions (i.e. gross anthropogenic removals) do not depend to any significant extent on how the constraint is implemented, only, largely, on the ultimate stringency of the constraint. Hence, for a given climate target stringency in 2100, the RF2100 target and the temperature ceiling may result in essentially the same amount of negative carbon emissions. Finally, it is important that IAM demonstrate results for diverse ways of implementing a climate target, since the implementation has implications for the level of near-term emissions and the perceived need for net-negative emissions (beyond 2050).
|
|
| 7. |
- Johansson, Viktor, 1991, et al.
(författare)
-
Biomass in the electricity system: A complement to variable renewables or a source of negative emissions?
- 2019
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 168, s. 532-541
-
Tidskriftsartikel (refereegranskat)abstract
- Biomass is often assigned a central role in future energy system scenarios as a carbon sink, making negative greenhouse gas emissions possible through carbon capture and storage of biogenic carbon dioxide from biomass-fuelled power plants. However, biomass could also serve as a strategic complement to variable renewables by supplying electricity during hours of high residual load. In this work, we investigate the role of biomass in electricity systems with net zero or negative emissions of carbon dioxide and with different levels of biomass availability. We show that access to biomass corresponding to ca. 20% of the electricity demand in primary energy terms, is of high value to the electricity system. Biomass for flexibility purposes can be a cost-efficient support to reach a carbon neutral electricity system with the main share of electricity from wind and solar power. Biomass-fired power plants equipped with carbon capture and storage in combination with natural gas combined cycle turbines are identified as being the cost-effective choice to supply the electricity system with flexibility if the availability of biomass within the electricity system is low. In contrast, in the case of excess biomass, flexibility is supplied by biomethane-fired combined cycle turbines or by biomass-fired power plants.
|
|
| 8. |
- Lehtveer, Mariliis, 1983, et al.
(författare)
-
Actuating the European Energy System Transition: Indicators for Translating Energy Systems Modelling Results into Policy-Making
- 2021
-
Ingår i: Frontiers in Energy Research. - : Frontiers Media SA. - 2296-598X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we define indicators, with a focus on the electricity sector, that translate the results of energy systems modelling to quantitative entities that can facilitate assessments of the transitions required to meet stringent climate targets. Such indicators, which are often overlooked in model scenario presentations, can be applied to make the modelling results more accessible and are useful for managing the transition on the policy level, as well as for internal evaluations of modelling results. We propose a set of 13 indicators related to: 1) the resource and material usages in modelled energy system designs; 2) the rates of transition from current to future energy systems; and 3) the energy security in energy system modelling results. To illustrate its value, the proposed set of indicators is applied to energy system scenarios derived from an electricity system investment model for Northern Europe. We show that the proposed indicators are useful for facilitating discussions, raising new questions, and relating the modelling results to Sustainable Development Goals and thus facilitate better policy processes. The indicators presented here should not be seen as a complete set, but rather as examples. Therefore, this paper represents a starting point and a call to other modellers to expand and refine the list of indicators.
|
|
| 9. |
- Lehtveer, Mariliis, 1983, et al.
(författare)
-
BECCS and DACCS as Negative Emission Providers in an Intermittent Electricity System: Why Levelized Cost of Carbon May Be a Misleading Measure for Policy Decisions
- 2021
-
Ingår i: Frontiers in Climate. - : Frontiers Media SA. - 2624-9553. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide removal (CDR) from the atmosphere is likely to be needed to limit global warming to 1.5 or 2°C and thereby for meeting the Paris Agreement. There is a debate which methods are most suitable and cost-effective for this goal and thus deeper understanding of system effects related to CDR are needed for effective governance of these technologies. Bio-Energy with Carbon Capture and Storage (BECCS) and Direct Air Carbon Capture and Storage (DACCS) are two CDR methods, that have a direct relation to the electricity system—BECCS via producing it and DACCS via consuming. In this work, we investigate how BECCS and DACCS interact with an intermittent electricity system to achieve net negative emissions in the sector using an energy system model and two regions with different wind and solar resource conditions. The analysis shows that DACCS has a higher levelized cost of carbon (LCOC) than BECCS, implying that it is less costly to capture CO2 using BECCS under the assumptions made in this study. However, due to a high levelized cost of electricity (LCOE) produced by BECCS, the total system cost is lower using DACCS as negative emission provider as it is more flexible and enables cheaper electricity production from wind and solar PV. We also find that the replacement effect outweighs the flexibility effect. Since variations in solar-based systems are more regular and shorter (daily cycles), one could assume that DACCS is better suited for such systems, whereas our results point in the opposite direction showing that DACCS is more competitive in the wind-based systems. The result is sensitive to the price of biomass and to the amount of negative emissions required from the electricity sector. Our results show that the use of the LCOC as often presented in the literature as a main indicator for choosing between different CDR options might be misleading and that broader system effects need to be considered for well-grounded decisions.
|
|
| 10. |
- Lehtveer, Mariliis, 1983, et al.
(författare)
-
Estonian energy supply strategy assessment for 2035 and its vulnerability to climate driven shocks
- 2016
-
Ingår i: Environmental Progress and Sustainable Energy. - : Wiley. - 1944-7442 .- 1944-7450. ; 35:2, s. 469-478
-
Tidskriftsartikel (refereegranskat)abstract
- Estonia is a relatively small country with a limited supply of indigenous energy resources mainly consisting of oil shale, wood, and peat. Estonia is also the only country in Europe with a dominant electricity production by burning oil shale. Around 90% of the overall electric energy production in Estonia comes from the Narva Power Plants. This presents great challenges and problems due to massive emissions of greenhouse gases into the atmosphere as well as radiological impact on the environment. Therefore, the current energy supply strategy can be considered hazardous and an unpopular choice for future energy system planning. In this article, we analyze the current energy policy as well as inclusion of new strategies to produce electricity for Estonia for a target year of 2035. We use a computer model Model for Supply Strategy Alternatives and their General Environmental Impacts (MESSAGE) to provide optimization and aim in helping the policymakers in the Estonian decision making process. We also add a specific case in the MESSAGE model to examine the ability of the current electricity supply strategy to handle climate related shocks with a special focus on cold weather in two plausible cases; single cold winter and prolonged cold winter. Results indicate that unexpected demand shocks may cause serious losses in gross domestic product (GDP). Therefore, the authors come to the conclusion that extra capacity is highly recommendable for a number of reasons. We also find that nuclear power becomes economically preferable to oil shale with a CO2 tax of Euro20/t. Yet moving toward nuclear or other low CO2 alternatives presents certain challenges. (c) 2015 American Institute of Chemical Engineers Environ Prog, 35: 469-478, 2016
|
|
