The European Commission recently proposed requirements for the production of renewable fuels as these are required to decarbonize the hard-to-electrify parts of the industrial and heavy transport sectors. Power-to-X (P2X) energy hubs enable efficient synergies between energy infrastructures, production facilities, and storage options. In this study, we explore the optimal operation of an energy hub by leveraging the flexibility of P2X, including hydrogen, methanol, and ammonia synthesizers by analyzing potential revenue streams such as the day-ahead and ancillary services markets. We propose EnerHub2X, a mixed-integer linear program that maximizes the hub’s profit based on current market prices, considering the technical constraints of P2X, such as unit commitment and non-linear efficiencies. We investigate a representative Danish energy hub and find that without price incentives, it mainly sells renewable electricity and produces compressed hydrogen. A sufficient amount of renewable ammonia and methanol is only produced by adding a price premium of about 50% (0.16 €/kg) to the conventional fuel prices. To utilize production efficiently, on-site renewable energy sources and P2X must be carefully aligned. We show that renewable power purchase agreements can provide flexibility while complying with the rules set by the European Commission.
Aarhus University, DCE - Danish Centre for Environment and Energy, has prepared an overall assessment of the potential environmental impacts from a major release or spill of ammonia in relation to production and transportation of ammonia in a PtX plant or by shipping in Greenland. Three sites were included in the assessment: Kangerlussuaq (Sdr. Strømfjord), Kangerlussuatsiaq (Evighedsfjorden) and Nuup Kangerlua (Godthåbsfjorden). The overall findings shows that a large, worst-case ammonia spill could cause severe toxic damage to organisms during the passage of the ammonia cloud from within a few km to possibly more than 10 km from the source. This could lead to local loss of animal and plant abundance for some years. However, the ammonia will be quickly diluted and degraded and will not be transferred in the food web, and the mortality will not seriously impact plant and animal populations at a regional scale. There could be a fertilising effect of ammonia on the nutrient-poor terrestrial environment lasting for some years.
We present the results of a numerical model which has been developed for estimating the contribution to the methane slip from different sources in a four-stroke dual-fuel marine engine running on natural gas. The model is a thermodynamic three-zone zero-dimensional full engine cycle model and considers methane slip contributions from short-circuiting, crevices and wall quenching. The model is applied to analyze the methane slip from a four-stroke dual-fuel medium speed marine engine using natural gas as primary fuel. At low loads, wall quenching is found to be the dominant contribution to the methane slip. At full load, the wall quenching contribution is comparable to the level of the short-circuiting and crevice contributions which only vary relatively little with load. At 75% load, the contribution from short-circuiting is highest. In addition, we found that in-cylinder post-oxidation of unburned fuel remaining after the main combustion is negligible.
Hydrogen can be key in the energy system transition. We investigate the role of offshore hydrogen generation in a future integrated energy system. By performing energy system optimisation in a model application of the Northern-central European energy system and the North Sea offshore grid towards 2050, we find that offshore hydrogen generation may likely only play a limited role, and that offshore wind energy has higher value when sent to shore in the form of electricity. Forcing all hydrogen generation offshore would lead to increased energy system costs. Under the assumed scenario conditions, which result in deep decarbonisatiton of the energy system towards 2050, hydrogen generation – both onshore and offshore – follows solar PV generation patterns. Combined with hydrogen storage, this is the most cost-effective solution to satisfy future hydrogen demand. Overall, we find that the role of future offshore hydrogen generation should not simply be derived from minimising costs for the offshore sub-system, but by also considering the economic value that such generation would create for the whole integrated energy system. We find as a no-regret option to enable and promote the integration of offshore wind in onshore energy markets via electrical connections.
For more than a century, conventional marine vessels spatter the atmosphere with CO2 emissions and detrimental particles when operated by diesel motors/generators. Fuel cells have recently emerged as one of the most promising emission-free technologies for the electrification of ship propulsion systems. In fuel cell-based ship electrification, the entire marine power system is viewed as a direct current (DC) microgrid (MG) with constant power loads (CPLs). A challenge of such settings is how to stabilize the voltages and currents of the ship’s grid. In this paper, we propose a new modified backstepping controller to stabilize the MG voltage and currents. Finally, to study the performance and efficiency of our proposal, we run an experiment simulation using dSPACE real-time emulator.
Global warming and, correspondingly, reducing CO2 emissions is one of the most challenging tasks the world faces today. The maritime industry contributed to 2.89% of the global anthropogenic CO2 emissions. To decrease this share, the International Maritime Organization (IMO) defined, among others, the goal to reduce the carbon intensity of international shipping by 40% until 2030. In this context, the short-term measures recently adopted, in the form of a technical standard (Energy Efficiency Existing Ship Index, EEXI) and a rating scheme based on an operational indicator (Carbon Intensity Indicator, CII), mark a crucial step to achieving the mentioned goal. In addition, the EU Commission has recently introduced the FuelEU Maritime Initiative limiting the annual greenhouse gas (GHG) intensity of a ship’s energy use incorporating a reduction occurring in a five-year rhythm between 2025 and 2050. The paper investigates the practical options availed to existing containerships of different sizes and technological vintages for meeting the specific EEXI, CII, and GHG intensity reduction requirements imposed by the regulations. The investigation will be based on the actual technical and operational profiles of six sample ships and will consider a set of possible compliance options including, but not limited to, engine power limitation, waste heat recovery system, variable frequency drives, and virtual arrival. The data used originates from noon reports of existing containerships provided by a European industry leader. The ship-specific CO2 emission reduction potentials required for the impact assessment result from either literature or actual data-based calculations. Financial data is used for investigating the economic impact of the reduction requirements. Conclusions drawn include an operational advantage that pre-EEDI ships enjoy when applying engine power limitation (EPL) for EEXI compliance, the occurrence of payback periods exceeding ship lifetimes, and an estimate of the effect that onshore power supply can have on complying with the FuelEU Maritime Initiative.
The shipping sector's rising greenhouse gas emissions are often considered “hard-to-abate”. Some ship-owners have recently adopted or started to consider the adoption of alternative fuels, but systematic studies of this are still lacking. We address this gap by studying how ship-owners differ in both actual and intended adoption of alternative fuels. We analyze data from a unique survey with 281 ship-owners in Norway, a major ship-owning country and center for maritime technology development, with descriptive statistics and analysis of variance. We find early adopters among large and established ship-owners in offshore, international cargo and domestic passenger shipping segments, which are often subjected to specific contractual demands for alternative fuel adoption. Laggards were typically small and young ship-owners operating in shipping segments where demands for alternative fuel adoption are weak. Our findings also suggest that firms' business strategy and financial and knowledge resources may have relevance for ship-owner's adoption of alternative fuels. Our study has implications for national and international policymaking, highlighting for example how contracting mechanisms can be an effective tool in incentivizing the adoption of alternative fuels.
The maritime sector is a key asset for the world economy, but its environmental impact represents a major concern. The sector is primarily supplied with Heavy Fuel Oil, which results in high pollutant emissions. The sector has set targets for deacrbonisation, and alternative fuels have been identified as a short-to medium-term option. The paper addresses the complexity related to the activities of the maritime industry, and discusses the possible contribution of alternative fuels. A sector segmentation is proposed to define the consumption of each sub-segment, so to compare it with the current alternative fuel availability at European level. The paper shows that costs and GHG savings are fundamental enablers for the uptake of alternative fuels, but other aspects are also crucial: technical maturity, safety regulation, expertise needed, etc. The demand for alternative fuels has to be supported by an existing, reliable infrastructure, and this is not yet the case for many solutions (i.e. electricity, hydrogen or methanol). Various options are already available for maritime sector, but the future mix of fuels used will depend on technology improvements, availability, costs and the real potential for GHG emissions reduction.
This paper investigates the significance of ports in the energy transition (ET) and decarbonisation. Ports, being vital in energy value chains, play a critical role in curbing energy use and emissions. The paper draws from the MAGPIE project, funded by the Horizon 2020 programme, which showcases energy and digital solutions in a real-world setting. The paper focuses on sustainable initiatives in 12 European sea- and inland- ports, analysed through interviews and secondary data. Findings reveal that while many ports discuss ET, few have transformed their plans into significant actions due to technological, regulatory, and financial challenges. Three core themes emerge from the review: ET infrastructure, seagoing ships and hinterland transport, and governance. Ports need more actionable strategies for ET, with port authorities spearheading the adoption of sustainable technologies through collaboration.
The liner shipping industry is undergoing an extensive decarbonization process to reduce its 275 million tons of CO2 emissions as of 2018. In this process, the long-term solution is the introduction of new alternative maritime fuels. The introduction of alternative fuels presents a great set of unknowns. Among these are the strategic concerns regarding sourcing of alternative fuels and, operationally, how the new fuels might affect the network of shipping routes. We propose a problem formulation that integrates fuel supply/demand into the liner shipping network design problem. Here, we present a model to determine the production sites and distribution of new alternative fuels-we consider methanol and ammonia. For the network design problem, we apply an adaptive large neighborhood search combined with a delayed column generation process. In addition, we wish to test the effect of designing a robust network under uncertain demand conditions because of the problem's strategic nature and importance. Therefore, our proposed solution method will have a deterministic and stochastic setup when we apply it to the second-largest multihub instance, WorldSmall, known from LINER-LIB. In the deterministic setting, our proposed solution method finds a new best solution to three instances from LINER-LIB. For the main considered WorldSmall instance, we even noticed a new best solution in all our tested fuel settings. In addition, we note a profit drop of 7.2% between a bunker-powered and pure alternative fuel-powered network. The selected alternative fuel production sites favor a proximity to European ports and have a heavy reliance on wind turbines. The stochastic results clearly showed that the found networks were much more resilient to the demand changes. Neglecting the perspective of uncertain demand leads to highly fluctuating profits.