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With increasing air traffic, rising fuel costs and tighter environmental targets, efficient airport ground operations are one of the key aspects towards sustainable air transportation. This complex system includes elements such as ground movement, runway scheduling and ground services. Previously, these problems were treated in isolation since information, such as landing time, pushback time and aircraft ground position, are held by different stakeholders with sometimes conflicting interests and, normally, are not shared. However, as these problems are interconnected, solutions as a result of isolated optimisation may achieve the objective of one problem but fail in the objective of the other one, missing the global optimum eventually. Potentially more energy and economic costs are thus required. In order to apply a more systematic and holistic view, this paper introduces a multi-objective integrated optimisation problem incorporating the newly proposed Active Routing concept. Built with systematic perspectives, this new model combines several elements: scheduling and routing of aircraft, 4-Dimensional Trajectory (4DT) optimisation, runway scheduling and airport bus scheduling. A holistic economic optimisation framework is also included to support the decision maker to select the economically optimal solution from a Pareto front of technically optimal solutions. To solve this problem, a multi-objective genetic algorithm is adopted and tested on real data from an international hub airport. Preliminary results show that the proposed approach is able to provide a systematic framework so that airport efficiency, environmental assessment and economic analysis could all be explicitly optimised.

Abstract A promising and shortly emerging energy supply chain network based on residential-scale microgeneration through micro combined heat and power systems is proposed, modeled and optimized in this work. Interchange of electrical energy can take place among the members of this domestic microgrid, which is connected to the main electrical grid for potential power interchange with it. A mathematical programming framework is developed for the operational planning of such energy supply chain networks. The minimization of total costs (including microgeneration system’s startup and operating costs as well as electricity production revenue, sales, and purchases), under full heat demand satisfaction, constitutes the objective function in this study. Additionally, an alternative microgrid structure that allows the heat interchange within subgroups of the overall microgrid is proposed, and the initial mathematical programming formulation is extended to deal with this new aspect. An illustrative example is presented in order to highlight the particular significance of selecting a proper optimization goal that thoroughly takes into account the major operational, technical and economic driven factors of the problem in question. Also, a number of real-world size case studies are used to illustrate the efficiency, applicability and the potential benefits of the microgeneration energy supply chain networks suggested in this study. Finally, some concluding remarks are drawn and potential future research directions are identified.

Geoenergy sources will continue to be mainstays of the world’s energy mix for many years to come, but the technological and business realities behind these energy sources are changing in two fundamental ways. First, with much of the world’s “easy oil” already consumed, the companies behind geoenergy will have to use increasingly sophisticated technologies to find and deliver these energy sources to the market. Second, the expectations placed upon the geoenergy sector by many of its stakeholders have grown considerably with regards to environmental stewardship, safety, and human welfare. In the face of these kinds of challenges, the industry will require an increasing degree of technological and commercial sophistication to continue to be a part of the world’s sustainable energy mix. Blockchain has emerged as a promising innovation that could potentially play an important role in delivering the kinds of technological and commercial capabilities that the geoenergy sector will need to achieve these ends. In spite of the myriad ways that blockchain could potentially improve the efficiency and sustainability of the geoenergy industry, however, the technology is still evolving, and a few barriers stand in the way of its widespread deployment. This paper puts forward case study evidence from the Intel Corporation and the Energistics Consortium showing what the geoenergy sector can learn about blockchain from other industries, and highlights that the absence of data standards and interoperability has contributed to blockchain’s failure to deliver significant value in the geoenergy domain thus far.

Waste biomass is generated during the conservation management of semi-natural habitats, and represents an unused resource and potential bioenergy feedstock that does not compete with food production. Thermogravimetric analysis was used to characterise a representative range of biomass generated during conservation management in Wales. Of the biomass types assessed, those dominated by rush (Juncus effuses) and bracken (Pteridium aquilinum) exhibited the highest and lowest volatile compositions respectively and were selected for bench scale conversion via fast pyrolysis. Each biomass type was ensiled and a sub-sample of silage was washed and pressed. Demineralization of conservation biomass through washing and pressing was associated with higher oil yields following fast pyrolysis. The oil yields were within the published range established for the dedicated energy crops miscanthus and willow. In order to examine the potential a multiple output energy system was developed with gross power production estimates following valorisation of the press fluid, char and oil. If used in multi fuel industrial burners the char and oil alone would displace 3.9 × 105 tonnes per year of No. 2 light oil using Welsh biomass from conservation management. Bioenergy and product development using these feedstocks could simultaneously support biodiversity management and displace fossil fuels, thereby reducing GHG emissions. Gross power generation predictions show good potential.

Abstract The use of agricultural residues to produce biomass briquette fuel (BBF) can reduce waste of resources and consumption of fossil fuels. We report the first detailed environmental impact assessment of cornstalk-based BBF in China using a cradle-to-grave life cycle assessment (LCA). The LCA study was conducted based on a typical large-scale cornstalk BBF demonstration project in China with an integrated and automated production system. The key life cycle stages such as cornstalk growth, cornstalk transportation, BBF production, transportation and utilisation were investigated. Our results suggest that cornstalk BBF in China is much more environmentally friendly than coal and is favourable when compared with other types of solid fuels produced from different biomass feedstock. For example, the climate change and fossil depletion impacts of cornstalk BBF in China (11 g CO2 eq./MJ and 2 g oil eq./MJ, respectively) are an order of magnitude lower than those of coal (146 g CO2 eq./MJ and 26 g oil eq./MJ, respectively). The results of this study can assist policy makers in evaluating the potential benefits of the large scale use of BBF made from agricultural residues.

AbstractThis research explores the relationship between technology scale, energy security and decarbonisation within the UK energy system. There is considerable uncertainty about how best to deliver on these goals for energy policy, but a focus on supply chains and their resilience can provide useful insights into the problems uncertainty causes. Technology scale is central to this, and through an analysis of the supply chains of nuclear power and solar photovoltaics, it is suggested that smaller scale technologies are more likely to support and enable a secure, low carbon energy transition. This is because their supply chains are less complex, show more flexibility and adaptability, and can quickly respond to changes within an energy system, and as such they are more resilient than large scale technologies. These characteristics are likely to become increasingly important in a rapidly changing energy system, and prioritising those technologies that demonstrate resilience, flexibility and adaptability will better enable a transition that is rapid, sustainable, secure and affordable.

Abstract The present paper examines the co-conversion of waste activated sludge and birchwood sawdust to bio-oil via hydrothermal liquefaction. The purpose of using the sawdust with sludge was to increase the solids concentration using another waste material for possible resource recovery. The operating conditions including reaction temperature, reaction time and solids concentration were optimized based on the response surface methodology for the maximum bio-oil production. A maximum of 33.7 wt% bio-oil yield was obtained at optimum operating conditions of 310 °C, 10 min, and 10 wt% concentration. Comparison of this oil with the oil produced from only sawdust showed a significant improvement in the molecular weight of the bio-oil by having lower molecular weight (hence less viscosity), indicating the presence of lighter components, with a slight decrease in bio-oil yield. The optimized operating condition could be used to effectively co-liquefy waste activated sludge and sawdust with the advantage of producing higher quality bio-oil with respect to molecular weight. The water-soluble product which is the largest fraction of by-products from the co-conversion was tested as a feedstock for biogas production through anaerobic digestion and resulted in 800 ml bio-methane production per 0.816 g of TOC or 2.09 g of COD of this waste stream.

Abstract Around 43% of the cumulative CO2 emissions from the power sector between 2012 and 2050 could be mitigated through implementation of carbon capture and storage, and utilisation of renewable energy sources. Energy storage technologies can increase the efficiency of energy utilisation and thus should be widely deployed along with low-emission technologies. This study evaluates the techno-economic performance of cryogenic O2 storage implemented in an oxy-combustion coal-fired power plant as a means of energy storage. Such system was found to have high energy density and specific energy that compare favourably with other energy storage technologies. The average daily efficiency penalty of the analysed system was 12.3–12.5%HHV points, which is higher than the value for the oxy-combustion coal-fired power plant without energy storage (11.2%HHV points). Yet, investment associated with cryogenic O2 storage has marginal effect on the specific capital cost, and thus the levelised cost of electricity and cost of CO2 avoided. Therefore, the benefits of energy storage can be incorporated into oxy-combustion coal-fired power plants at marginal capital investment. Importantly, implementation of cryogenic O2 storage was found to increase the daily profit by 3.8–4.1%. Such performance would result in higher daily profit from oxy-combustion compared to an air-combustion system if the carbon tax is higher than 29.1–29.2 €/tCO2. Finally, utilisation of renewable energy sources for cryogenic O2 production can reduce the daily efficiency penalty by 4.7%HHV points and increase the daily profit by 11.6%. For this reason, a synergy between fossil fuel electricity generation and renewable energy sources via CO2 capture integrated with energy storage needs to be commercially established.