Global climate change, which is largely attributed to human activity, is one of the foremost challenges of the 21st century. In recent times, there have been notable alterations in the Earth's climate, resulting in profound impacts on ecosystems and biodiversity. These alterations are caused by greenhouse gas, such as carbon dioxide, methane, and nitrous oxide. Greenhouse gas emissions are caused by practices such as deforestation, industrial operations, and the combustion of fossil fuels in vehicles, vessels, aircraft, and manufacturing facilities. The maritime and aviation industry is currently responsible for approximately 6% of global greenhouse gas emissions. Due to logistical and economic constraints, these industries are heavily reliant on liquid fuels, making direct electrification options unavailable for large parts of these sectors. As a result, these sectors are considered ‘hard to abate’. Understanding the future climate mitigation challenges associated with the maritime and aviation sectors is crucial in shaping effective policy measures, avoiding stranded assets, and preserving the chance to meet Paris Agreement-compatible emission reduction pathways.
This thesis identifies three main challenges and proposes modelling approaches to address them when modelling decarbonization pathways for the aviation and maritime sectors. From these challenges, research gaps have been identified that this PhD thesis aims to fill. Three models have been developed for the thesis: a maritime optimization model, a maritime demand model, and an aviation demand model. The modelling landscape and methodology vary across models, ranging from econometrics and data science to mathematical optimization.
To overcome the challenges and fill in the research gaps, three corresponding modelling approaches have been successfully applied:
1. Developing a holistic decarbonization modelling landscape. This includes life-cycle representations of technology costs and emissions, the upscaling of bottleneck technologies, the availability of sustainable biomass, and consideration of competing demand from other industries, as well as representations of policy levers such as carbon pricing or improvements to fuel efficiency.
2. Developing demand models that interpret the underlying scenario narrative consistently (SSP framework).
3. Improving the representation of technological learning for low-carbon technologies in energy system models.
The findings acquired by applying these three modelling approaches are valuable for energy modellers, climate scientists, and policymakers and offer unique insights into the inherent system dynamics associated with decarbonization of hard-to-abate sectors. Utilizing this modelling landscape reveals that current decarbonization efforts for hard-to-abate sectors are insufficient.
The “Initial IMO Strategy” was adopted in the 72nd session of the Marine Environment Protection Committee (MEPC 72) of the International Maritime Organization (IMO) in April 2018. It has set, among other things, ambitious targets to reduce greenhouse gas (GHG) emissions from ships, and purports to express a strong political will to phase them out as soon as possible. The most ambitious of these targets is to reduce GHG emissions by 2050 at least 50% vis-à-vis 2008 levels, and there is also an intermediate target to reduce CO2 emissions per transport work by 2030 at least 40%, again vis-à-vis 2008 levels. More than three years since the adoption of the Initial IMO Strategy, this chapter takes stock at the status of shipping decarbonisation and attempts to assess prospects for the future. Obstacles towards achieving the IMO targets are identified and discussed.
Havebrugsindustrien i nordiske lande er meget afhængig af drivhussystemer på grund af begrænsningen af det naturlige miljø og de strenge plantekrav for bestemte plantetyper. Kommercielle avlere i disse regioner støder på betydelige udfordringer med at garantere kvaliteten af planterne, mens de minimerer produktionsomkostningerne. På den ene side skal et drivhussystem forbruge en stor mængde energi for at give et tilfredsstillende klima for plantevækst. På den anden side, i de senere år, har energiprisen stigende i Europa ført til en stigning i produktionsomkostningerne for drivhuse, hvilket gør energibesparelse og optimering imperativ. Det er dog udfordrende for avlere at håndtere dette dilemma, fordi drivhusklimakontrol er et meget dynamisk og meget koblet komplekst system. Ved at analysere funktionerne i ikke-linearitet og dynamik i drivhusklimaet kan de eksisterende løsninger ikke korrekt opfylde de praktiske krav i gartneriindustrien.
For at tackle disse problemer foreslås en digital tvilling af drivhusklimakontrol (DT-GCC) rammer i denne forskning for at optimere aktuatorens driftsplan til minimering af energiforbrug og produktionsomkostninger uden at gå på kompromis med produktionskvaliteten. Arkitekturen i DT-GCC-rammen og de anvendte metoder er uddybet modulært, herunder fysisk tvilling af drivhusklimakontrol (PT-GCC) systemforståelse, design af DT-GCC-system, sammenkobling af DTGCC og PT-GCC og integration med andre digitale tvillinger (DTS).
DT-GCC omfatter en virtuel drivhus (VGH) og en multi-objektiv optimeringsbaseret klimakontrol (MOOCC) platform. VGH er den digitale repræsentation af det fysiske drivhus gennem modellering af de faktorer, der kan påvirke drivhusklimaet markant og aktuatorens driftsstrategier. MOOCC er ansvarlig for at definere drivhusklimakontrol som et multi-objektivt optimeringsproblem (MOO) og optimere driftsplanen for kunstigt lys (lysplan) og varmesystem (varmeplan). Desuden er en hierarkisk struktur af DT-GCC designet i henhold til funktionerne og ansvaret for individuelle lag, der gavner den praktiske realisering af DT-GCC med en organiseret arkitektur af design og styring.
Funktionaliteterne i DT-GCC er udviklet i en drivhusklimakontrolplatform, der er navngivet af Dynalight, som er kombineret med en genetisk algoritme (GA) ramme kaldet Controleum. Dynalight definerer et MOO -problem til at abstrahere drivhusklimakontrolsystemet med flere objektive funktioner, og omkostningerne beregnes baseret på modelleringsresultaterne fra VGH. Controleum er ansvarlig for implementeringen af GA for at generere en Pareto Frontier (PF) og endelig løsning af løsning til let plan og varmeplan.
Forskellige scenarier og tilsvarende eksperimenter er designet til at evaluere ydelsen af DT-GCC fra individuelle perspektiver, herunder VGH, MOOCC og DT-integration. Eksperimenterne på VGH verificerer forudsigelsesydelsen for kunstigt neuralt netværk (ANN) metoder på indendørs temperatur, opvarmning af forbrug og netto fotosyntese (PN). Hvad angår de to standaloneeksperimenter, garanterer resultaterne DT-GCCs evne til at kortlægge avlernes beslutningstagning om let plan og varmeplan og verificere MOOCC-ydelsen for at opfylde voksende krav og samtidig reducere energiforbruget og omkostningerne. Endelig, i DT-integrationseksperimenterne med Digital Twin of Production Twin (DT-PF) og Digital Twin of Energy System (DT-ES), afslutter DT-GCC det tilsvarende svar på forudsigelser og optimeringsanmodninger.
In this study, we investigate the barriers and enablers companies face when they seek to establish a fully decarbonized supply chain from the ground up. While recent research on sustainable supply chain management has advanced our understanding of how existing supply chains can become more sustainable, there is less research on fully decarbonized supply chains that are designed carbon neutral to produce carbon neutral products. This research aims to expand that frontier by investigating the case of the emerging supply chain delivering fossil-neutral e- methanol to the shipping industry.
The International Maritime Organization (IMO) has recently adopted short-term measures introducing technical standards for existing ships and a labeling system reflecting their operational carbon intensity. This paper investigates the relevant techno-economic implications from a shipowner's perspective and estimates the effect of six compliance options on six sample containerships. The study applies a new evidence-based bottom-up approach, and the results show that compliance, when possible, is not straightforward and costly. Engine power limitation is the most cost-effective option, but low power limits can lead to substantially increased sailing times (up to 793.92 h/year), which can be prohibitive. The option favors older ships with oversized engines as its effectiveness is mainly determined by the main engine load profile. In general, the effectiveness of the measures is not without limits, particularly concerning older ships and those that have already installed several options. Solutions such as market-based measures and alternative fuels, classed by IMO as medium- and long-term measures, must be considered soon.
The International Maritime Organization (IMO) has recently adopted short-term measures introducing technical standards for existing ships and a labeling system reflecting their operational carbon intensity. This paper investigates the relevant techno-economic implications from a shipowner's perspective and estimates the effect of six compliance options on six sample containerships. The study applies a new evidence-based bottom-up approach, and the results show that compliance, when possible, is not straightforward and costly. Engine power limitation is the most cost-effective option, but low power limits can lead to substantially increased sailing times (up to 793.92 h/year), which can be prohibitive. The option favors older ships with oversized engines as its effectiveness is mainly determined by the main engine load profile. In general, the effectiveness of the measures is not without limits, particularly concerning older ships and those that have already installed several options. Solutions such as market-based measures and alternative fuels, classed by IMO as medium- and long-term measures, must be considered soon.
The pressure on shipping to reduce its carbon footprint is increasing. Various measures are being proposed at the International Maritime Organization (IMO), including MarketBased Measures (MBMs). This paper investigates the potential of a bunker levy in achieving short-term CO2 emissions reductions. The analysis focuses on the tanker market and uses data from the latest IMO GHG studies and a variety of other sources. The connection between fuel prices and freight rates on the one hand and vessel speeds on the other is investigated for the period 2010-2018. A model to find a tanker’s optimal laden and ballast speeds is also developed and applied to a variety of scenarios. Results show that a bunker levy, depending on the scenario, can lead to short-term CO2 emissions reductions of up to 43%. Policy implications are also discussed, particularly vis-à-vis recent IMO and European Union (EU) action on MBMs.
The “Initial IMO Strategy” was adopted in the 72nd session of the Marine Environment Protection Committee (MEPC 72) of the International Maritime Organization (IMO) in April 2018. It has set, among other things, ambitious targets to reduce greenhouse gas (GHG) emissions from ships, and purports to express a strong political will to phase them out as soon as possible. The most ambitious of these targets is to reduce GHG emissions by 2050 at least 50% vis-à-vis 2008 levels, and there is also an intermediate target to reduce CO2 emissions per transport work by 2030 at least 40%, again vis-à-vis 2008 levels (IMO, 2018). In the period after MEPC 72, the focus of the IMO discussion has been on the formulation and eventual adoption of the short-term measures, that is, measures that are to be agreed upon and implemented by 2023. In fact, MEPC 76, held in June 2021, and after a rather difficult discussion, adopted such a short-term measure. MEPC 77 (November 2021) saw the initiation of the discussion on mid-term and long-term measures, which include, among others, market based measures (MBMs) and alternative fuels. The discussion continued at MEPC 78 (June 2022) and is expected to continue at future meetings of MEPC.
The purpose of this paper is to provide an overview and discussion of potential Market Based Measures (MBMs) under the Initial IMO Strategy for the reduction of greenhouse gas (GHG) emissions from ships. In this context, some related developments are also seen as directly relevant, mainly in the context of the possible inclusion of shipping into the EU Emissions Trading System (ETS). A comparative evaluation of maritime MBMs is made using the following criteria: GHG reduction effectiveness, compatibility with existing legal framework, potential implementation timeline, potential impacts on States, administrative burden, practical feasibility, avoidance of split incentives between ship-owner and charterer, and commercial impacts. The paper breaks down potential MBMs into the following classes: Bunker levy/carbon levy MBMs, ETS (global and/or EU ETS) MBMs and other MBM proposals.
The 76th session of the Marine Environment Committee (MEPC 76) of the International Maritime Organization adopted several mandatory measures in June 2021 to reduce carbon emissions from ships. One of the measures is the carbon intensity indicator (CII), which is the carbon emissions per unit transport work for each ship. Several options of CIIs are available and none of them is chosen to be applied yet. We prove that, at least in theory, requiring the attained annual CII of a ship to be less than a reference value, no matter which CII option is applied, may increase its carbon emissions. Therefore, more elaborate models, combined with real data, should be developed to analyze the effectiveness of each CII option and possibly to design a new CII.