| 1. |
- Xylia, Maria
(författare)
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Towards electrified public bus transport : The case of Stockholm
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis addresses the challenge of road transport electrification using a systems approach for the particular context of Stockholm’s public transport system. The objective is to identify the benefits of large-scale bus electrification on energy efficiency and greenhouse gas emissions, as well as the cost and planning considerations required for achieving such a shift. Quantitative and qualitative methods are deployed for answering the research questions, including the development and use of an optimisation model, survey research, and interviews. The results of the optimisation model developed for this thesis show that an optimal system configuration is obtained with a combination of electricity and biodiesel. The high energy efficiency of electric buses would lead to a significant reduction of energy consumption in Stockholm, even if not all bus routes in the network are electrified. Although larger battery capacities could support the electrification of more bus routes, this does not necessarily lead to lower environmental impact. In any case, electricity from renewable sources should be used to maximise emission reductions. The results also show that the annual costs necessary to invest in electric buses can be balanced by lower fuel costs. An effective utilisation of the charging infrastructure is of high priority in order to justify the costs of the required investments. The model results confirm the benefits of creating a dense initial network of charging stations in the inner city’s public transport hubs, which would facilitate the electrification of multiple routes and high infrastructure utilisation at lower costs. The survey and interviews with stakeholders indicate that multiple issues affect the choice of charging technology, not just costs. Compatibility, reliability, bus dwell time, as well as weather conditions and visual impact are some of the additional aspects taken into account. The introduction of electricity tax exemption for electric buses, the expansion of the electric bus premium to include private stakeholders, as well as the expansion of infrastructure investment subsidy programmes are among the policy instruments suggested for assisting a faster introduction of electric buses into Stockholm’s public transport system. Although the focus is on Stockholm, the conclusions of this work can be applicable to other cities in Sweden and around the world, which also face the challenge of making public transport a more sustainable option.
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| 2. |
- Barragán-Beaud, Camila, et al.
(författare)
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Carbon tax or emissions trading? : An analysis of economic and political feasibility of policy mechanisms for greenhouse gas emissions reduction in the Mexican power sector
- 2018
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Ingår i: Energy Policy. - : Elsevier Ltd. - 0301-4215 .- 1873-6777. ; 122, s. 287-299
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Tidskriftsartikel (refereegranskat)abstract
- This study provides a comparative assessment of carbon-pricing instruments for the Mexican electricity sector, contrasting a carbon tax with an emissions trading scheme (ETS). The assessment is performed in terms of economic impacts and political feasibility. Model-based scenarios considering different price and quantity levels are analyzed on Balmorel-MX, a cost optimization bottom-up model of the Mexican electricity system. The political feasibility is evaluated using an online survey and interviews with representatives of relevant stakeholder groups. The assessment suggests that an ETS is the most appropriate instrument for the Mexican case. We recommend to set the cap as 31% abatement in relation to a baseline, which is suggested to be 102 MtCO2 by 2030, given the business-as-usual baseline used as reference by the Mexican government (202 MtCO2) is found to leave cost-effective abatement potential untapped. An emission trading system with such design has higher cost-efficiency and lower distributional effects than a carbon tax at equivalent ambition level (15 USD/tCO2). The political feasibility analysis confirms the assessment, as it is in line with the priorities of the stakeholder groups, allows earmarking carbon revenue and avoids exempting natural gas from carbon pricing.
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| 3. |
- Gorosabel, Oier Lopez de Briñas, et al.
(författare)
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A framework for the assessment of electric bus charging station construction : A case study for Stockholm's inner city
- 2022
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Ingår i: Sustainable cities and society. - : Elsevier BV. - 2210-6707. ; 78
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Tidskriftsartikel (refereegranskat)abstract
- Electromobility has gained momentum in the last years following the efforts to reduce transportation-related emissions. In this context, efficient charging infrastructure is vital to foster the expansion of electric vehicles. This paper presents a standardized framework for micro-scale analysis of potential charging locations for electric buses aiming at easing the analysis process and promoting the expansion of electric buses. The framework is tailor-made for the Municipality of Stockholm and tested in two city-centre public transport hubs, namely Odenplan and Slussen. However, the framework can be used in other locations by implementing minimum changes. Connecting charging stations to the power grid is identified as the main drawback in city-centre locations due to their high impact on the grid. Lack of available capacity at nearby connection points results in long distance connections, reaching up to 1 km in some cases. Such connections impact the overall cost of electrification directly, as they may account for up to 63% of the total cost. Although other issues regarding space availability and operational efficiency also need to be addressed, such as the lack of enough dwell time to charge the batteries, the framework proves the suitability of these inner-city locations as charging points.
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| 4. |
- Muthukumaran, Gowtham, et al.
(författare)
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Decentralized solutions for island states: Enhancing energy resilience through renewable technologies
- 2024
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Ingår i: Energy Strategy Reviews. - : Elsevier BV. - 2211-467X .- 2211-4688. ; 54
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Tidskriftsartikel (refereegranskat)abstract
- Decentralized grid solutions could be a feasible alternative to improve resilience and mitigate cascading effects in island states. Our study explores approaches that reduce the risk of infrastructure failures and promote decentralized utility planning in islands. A novel framework is proposed to conduct a power system resilience assessment by integrating vulnerability assessments and energy system modelling approaches through network analysis. The framework is applied to an island context, where vulnerability to hydroclimatic hazards, geographic isolation, restricted access to energy sources, small population bases inadequate for substantial infrastructure investments, dependence on imported energy, lack of energy source diversification, and fragile ecosystems have exacerbated energy insecurity. As a case study, we have applied the framework to Cuba. We simulate disruptions in vulnerable network nodes in Cuba to determine the municipalities that are most impacted by the simulated cascading failures. We designed and optimized the lowest cost decentralized solutions to increase resilience either by acting as the baseload electricity source or as a complementary backup system to complement in case of a power outage. Then, the resilience of the designed system was assessed using power system resilience metrics. The study results show Regla municipality in Cuba as the most vulnerable hotspot for electricity distribution. Upon the different system comparisons, ancillary systems outperform backup systems in enhancing power system resilience, especially in the context of a disruptive event, supplying up to 53 MWh/day more, although they have higher investment costs. Based on this research, resource planners and policymakers can understand vulnerable node points and prioritize the necessary investments for the preferred system choice to alleviate impacts of energy insecurity on the Island States.
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| 5. |
- Silveira, Semida, et al.
(författare)
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Exploring new pathways to promote the transition towards electrification of Public Transport in urban areas : the case of Stockholm.
- 2016
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- As cities struggle to provide public transport services at competitive costs, they also have a major responsibility to reduce overall greenhouse gas emissions, thus often facing a dilemma between multiple objectives, and short-term versus long-term solutions. Still significant efforts and progress are being made in this direction. The city of Stockholm has already achieved broad penetration of renewables in bus fleets and now aims at 20% electrification in 2030. This paper explores ways to overcome infrastructure and cost barriers and facilitate the transition towards fully renewable pathways in the transport sector. The impacts of externalities such as air pollution and noise exposure are observed in the context of property price dynamics, aiming at finding patterns that can justify electrification pathways for public bus transport in Stockholm. An overlay analysis combining public transport hotspots with empirical data on air and noise pollution in Stockholm inner-inner city area is linked to a property price analysis. This allows an evaluation of relationships between property prices and urban externalities resulting from road transport. The analysis shows that the properties with the highest selling prices for the year 2015 generally fall outside the most polluted traffic and noisy avenues with extensive public transport. An optimum location in terms of price premiums can be observed between the 100-meter and 300-meter band. The results indicate that electrification of public transport may have implications for real estate property values. If captured in a broader urban planning context, barriers to the sustainable transition for transport systems can be partly overcome, particularly when it comes to the high investment costs for infrastructure. Thus municipalities need to consider new planning frameworks to actively capture the multiple dividends of electrification of bus transport, motivating the transition not only in terms of emissions reductions but also towards value creation and total improvement of the urban environment.
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| 6. |
- Torres-Morales, Eileen, et al.
(författare)
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Investigating biochar as a net-negative emissions strategy in Colombia : Potentials, costs, and barriers
- 2023
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Ingår i: Current Research in Environmental Sustainability. - : Elsevier BV. - 2666-0490. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Biochar is identified as a land-based mitigation technology (LMT) and a net-negative emissions technology (NET) with significant potential for mitigating climate change and providing co-benefits. Transforming residual biomass into biochar can potentially avoid CO2 emissions to be rapidly released to the atmosphere. This study aims to assess the sustainability of biochar production in Colombia as a NET. The research consists of five steps, literature review, expert elicitation, estimation of agricultural residues for biochar production, evaluation of biochar's CO2 mitigation potential, and techno-economic analysis of biochar under different biomass availability and technologies scenarios. Our findings indicate that approximately 10% of agricultural residual biomass can be transformed into biochar and reintegrated into the soil. Over a 100-year period, each tonne of biochar in the soil has the potential to avoid emissions of 1 to 2.2 t of CO2eq. Cost-wise, biochar production cost structure depends on the pyrolysis technology used. The cost structure of biochar production depends on the pyrolysis technology used. We find that raw feedstock represents the main cost component, ranging from 64% to 74% of total costs for artisan-made equipment, and 33% to 34% for specialized pyrolysis equipment. Capital investments, fixed costs, and raw feedstock account for the remaining costs. Our results highlight that the net present value (NPV) is most sensitive to biomass transport distance, biomass price and biomass humidity. Our findings can be used internationally for navigating the production, mitigation potentials, costs, and barriers of biochar, and devising deployment and market creation strategies.
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| 7. |
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| 8. |
- Xylia, Maria, et al.
(författare)
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Comparative analysis of charging technologies for electric buses : a meta-synthesis of international experiences
- 2016
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Konferensbidrag (refereegranskat)abstract
- Public transport is crucial for the functionality of urban systems. Globally, much attention is being given lately to reducing transport’s environmental impacts by shifting towards fossil-free fuels, while also improving service availability. In this context, electrification of bus transport is gaining popularity because of the high energy efficiency improvements that can be accrued, together with low emissions and noise reduction compared to conventional buses.Although several studies focus on engine performance and powertrain characteristics of electric buses for individual demonstration projects, there are few studies that analyze the role of bus charging technologies and charging strategies. Gathering and systematically analyzing existing experiences from electric bus demonstration projects around the world is necessary for understanding the benefits and drawbacks of emerging solutions. The aim of this paper is to fill this gap and offer a comparative analysis of various alternatives for electric bus charging. What are the characteristics of each technology and what are the main themes emerging when it comes to implementation? The analysis draws from experiences around the world, which are systematically evaluated under guidelines of meta-synthesis, reviewing existing literature and complementing it with expert knowledge gathered from an electronic survey. The respondents belong to stakeholder groups involved with electric bus demonstration projects, such as public transport authorities, transport service operators, charging technology providers, municipalities, regional authorities, and academia. Particular attention is given to the Nordic region, where several successful initiatives are already in place.The preliminary results show a variety of choices among charging technologies, and it is not uncommon to have different strategies combined in the demonstration projects. The survey responses indicate that stakeholders participate in such projects primarily in order to gain knowledge about the technologies tested, as well as due to the potential environmental benefits from bus transport electrification. Common unexpected issues faced during project implementation include increased costs for infrastructure installation, difficulties in communication between the stakeholders involved, as well as unexpected technology compatibility issues.The decisive factors when choosing charging technologies are related to market-readiness, cost-effectiveness, replicability and operation costs of available technologies, but also the institutional set up that allow for the development of certain options over time. The analysis of the survey results links charging technologies and strategies to their advantages and disadvantages as acquired from experience, and explain the factors behind the choices made.The results are useful in helping to enrich the knowledge basis on transport electrification, shifting from individual empirical findings to a generalized framework for evaluation of technology choices when it comes to charging infrastructure. In this way, we extract knowledge that facilitates choosing the most appropriate charging technology, designing implementation strategies and avoiding pitfalls that have already been encountered elsewhere.
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| 9. |
- Xylia, Maria, et al.
(författare)
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Developing a dynamic optimization model for electric bus charging infrastructure
- 2017
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Ingår i: Transportation Research Procedia. - : Elsevier. - 2352-1465. ; , s. 776-783
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Konferensbidrag (refereegranskat)abstract
- Urban regions account for 64% of global primary energy use and 70% of carbon emissions. For that reason, options to decarbonize urban environments are receiving increasing attention. In this context, public transport shall play a key role in decarbonizing urban road transport. One efficient way to achieve that is shifting towards clean fuels and modern electric buses, an option that is already under implementation in several cities around the world. In this paper, the basis for developing a dynamic optimization model for establishing charging infrastructure for electric buses is presented, using Stockholm, Sweden, as a case study. The model places constraints depending on the bus stop type (end or middle stop) which affects the time available for charging at each particular location. It also identifies the optimal technology type for the buses: conductive or inductive. In addition, the electric buses compete with buses run on biogas or biodiesel. In this paper, we present the results of a cost minimization scenario with constraints placed on the available charging time and power, differentiated between end stops and major public transport hubs. The mean charging time is 7.33 minutes, with a standard deviation of 4.78 minutes for all bus stops. The inner city bus routes require less charging time, which ranges on average at around 3 minutes. The installation of chargers at the locations proposed in the model would require scheduling adjustments and careful planning for the density of charging occasions.
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| 10. |
- Xylia, Maria, et al.
(författare)
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Fossil-free Public Transport : Prescriptive Policy Analysis for the Swedish Bus Fleets
- 2016
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Ingår i: 13th European Energy Market Conference -EEM 2016. IEEE XPlore. - : IEEE conference proceedings. - 9781509012985 - 9781509012978
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Konferensbidrag (refereegranskat)abstract
- Elicitation and processing of the relevant informationis the core of any policy decision-making process. This studypresents a prescriptive policy analysis for the “fossil-free fueldeployment for public transport buses at the national level inSweden”, using a policy-oriented modelling and simulation tool,Sense4us1, that supports systems analysis for policy involving: (i)structuring of policy problems using the labelled causal mappingmethod, (ii) ex-ante impact assessment using scenario-baseddynamic simulation modelling and (iii) ex-ante evaluation of theconsidered policy options based on the simulation results andusing a set of standard criteria for evaluation of EU policyinterventions. The results are most of all useful for designing apolicy pathway for public bus transport that is bothenvironmentally sustainable and economically feasible.Moreover, the process allows involvement of the keystakeholders to reflect various priorities and preferences.
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