• Energy Research

Reducing aviation emissions is important as they contribute to air pollution and climate change. Several alternative aviation fuels that may reduce life cycle emissions have been proposed. Comparative life cycle assessments (LCAs) of fuels are useful for inspecting individual fuels, but systemwide analysis remains difficult. Thus, systematic properties like fleet composition, performance, or emissions and changes to them under alternative fuels can only be partially addressed in LCAs. By integrating the geospatial fuel and emission model, AviTeam, with LCA, we can assess the mitigation potential of a fleetwide use of alternative aviation fuels on 210 000 shorter haul flights. In an optimistic case, liquid hydrogen (LH2) and power-to-liquid fuels, when produced with renewable electricity, may reduce emissions by about 950 GgCO2eq when assessed with the GWP100 metric and including non-CO2 impacts for all flights considered. Mitigation potentials range from 44% on shorter flights to 56% on longer flights. Alternative aviation fuels' mitigation potential is limited because of short-lived climate forcings and additional fuel demand to accommodate LH2 fuel. Our results highlight the importance of integrating system models into LCAs and are of value to researchers and decision-makers engaged in climate change mitigation in the aviation and transport sectors.

Abstract This paper describes an extension of Duchin's world trade model to include the explicit representation of transportation costs, permitting the endogenous determination of bilateral trade flows and region-specific prices. The original model is a linear program that, based on comparative advantage and the minimization of factor use, determines regional production and trade flows as well as world prices and scarcity rents for m regions, n good, and k factors. The new world trade model with bilateral trade achieves its objectives by introducing transportation services and geographically dependent transportation requirements for each traded good and each pair of potential trade partners. The formulation of this model and its major properties are presented, and results from a preliminary analysis with 11 regions, eight goods, four transportation sectors, and six factors of production are reported and compared with corresponding results from the world trade model. On the basis of this comparison, we con...

AbstractMost of the chemical products used today in our society originate from fossil sources through refinery operations. The continual price increase of fossil resources, their uncertain availability, and the environmental concerns of their exploitation have led to a demand for the elaboration of alternative chemical production patterns based on renewable sources. Besides fossils, the only resource available for producing chemicals is biomass, and the establishment of biorefinery complexes is increasingly perceived as a promising alternative to oil refineries. This work is a position paper that provides an insight in the emerging biorefinery concept, with special focus on the opportunities, perspectives, and potential regarding the use of lignocellulosic biomass as raw material in the preparation of platform chemicals needed to meet the existing demand. Results show that replacing fossil resources with wood requires large amounts of biomass and has several technological barriers that are still far from being overcome. This paper identifies the key reactions where major efficiency improvements and research efforts are needed (dehydration, fermentation, hydrogenation, etc.), as well as the possibilities when it comes to enhancing biomass conversion performances through the synthesis of new platform chemicals, with higher oxygen content, so as to accommodate the original biomass composition. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd

A comparative hybrid life cycle assessment (LCA) was conducted to evaluate two different methods for hydrogen production. The environmental impacts from nuclear assisted thermochemical water splitting are compared to hydrogen production from natural gas steam reforming with CO2 sequestration. The results show that the two methods have significantly different impacts. The nuclear alternative has lower impacts on global warming potential, acidification and eutrophication, and much higher impacts from radiation and human toxicity. A weighting procedure is not applied, hence no overall "winner" can be proclaimed. The relative importance of the different impacts remains a challenge for decision makers. Further, the assessment has demonstrated the importance of including services in a comparative assessment. Ordinary process LCA may produce distorted results, since a larger fraction of life cycle impacts may occur outside the system boundaries in one study compared to another due to different fractions of service inputs

Waste-to-Energy (WtE) plants constitute one of the most common waste management options to deal with municipal solid waste. WtE plants have the dual objective to reduce the amount of waste sent to landfills and simultaneously to produce useful energy (heat and/or power). Energy from WtE is gaining steadily increasing importance in the energy mix of several countries. Norway is no exception, as energy recovered from waste currently represents the main energy source of the Norwegian district heating system. Life-cycle assessments (LCA) of WtE systems in a Norwegian context are quasi-nonexistent, and this study assesses the environmental performance of a WtE plant located in central Norway by combining detailed LCA methodology with primary data from plant operations. Mass transfer coefficients and leaching coefficients are used to trace emissions over the various life-cycle stages from waste logistics to final disposal of the ashes. We consider different fractions of input waste (current waste mix, insertion of 10% car fluff, 5% clinical waste and 10% and 50% wood waste), and find a total contribution to Climate Change Impact Potential ranging from 265 to 637gCO2eq/kg of waste and 25 to 61gCO2eq/MJ of heat. The key drivers of the environmental performances of the WtE system being assessed are the carbon biogenic fraction and the lower heating value of the incoming waste, the direct emissions at the WtE plant, the leaching of the heavy metals at the landfill sites and to a lesser extent the use of consumables. We benchmark the environmental performances of our WtE systems against those of fossil energy systems, and we find better performance for the majority of environmental impact categories, including Climate Change Impact Potential, although some trade-offs exist (e.g. higher impacts on Human Toxicity Potential than natural gas, but lower than coal). Also, the insertion of challenging new waste fractions is demonstrated to be an option both to cope with the excess capacity of the Norwegian WtE sector and to reach Norway's ambitious political goals for environmentally friendly energy systems.

This paper investigates opportunities for increased profit and reduced emissions and cost by service differentiation within container shipping. Traditionally the strategy among the container lines has been profit maximization by utilizing economies of scale through the building of larger and faster vessels. In 2008, the financial crisis in combination with higher fuel prices put an end to this progress and in today’s market operators are basically trying to survive by providing standardized services at the lowest possible cost. This study investigates alternative strategies and the results indicate that container lines should provide two different services instead of one standardized service. A fast service to be more competitive versus air freight for fast-moving goods and a slow service to be more competitive versus traditional shipping types for transport of minor bulk, break bulk, liquid bulk and project cargo.

AbstractDeveloping comprehensive scenarios for the shipping sector has been a challenge for the Integrated Assessment Model (IAMs) community, influencing how attainable decarbonization is in the sector, and for Earth System Models (ESMs), impacting the climate contribution of shipping emissions. Here we present an approach to develop spatially explicit energy demand projections for shipping in alignment with the Shared Socioeconomic Pathways framework and IAMs projections of global fossil fuel demand. Our results show that shipping could require between 14 and 20 EJ by 2050, corresponding to a 3% and 44% increase from 2018 for the SSP1-1.9 and SSP3-7.0 scenarios. Furthermore, the energy projections we present in this publication can be combined with different fuel mixes to derive emission inventories for climate modeling and, thus, improve our understanding of the various challenges in mitigating emissions for shipping. Through that, we aim to present a framework to incorporate detailed spatial shipping inventories and increase transparency for the scientific community.