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Abstract This article analyzes the CFTC's Disaggregated Commitments of Traders (DCOT) Report to get more insights into the behavior of different traders during the 2008 oil bubble. The analysis shows that: (1) the Money Manager category perfectly played the oil bubble, got in early and started selling shortly before the bubble peak; (2) the Producer/Merchant/Processor/User category and the Nonreportable category were covering their short positions into the peak of the bubble; (3) the Swap/Dealer category benefited while the price of oil was rising, but incurred heavy losses as the price of oil collapsed; (4) we find no indications of speculation by any group of traders via the positive feedback trading or rational destabilization; and (5) we do, however, criticize the commercial hedgers for failing to arbitrage the soaring oil prices in 2008.

Abstract There is a growing use of metamodels to evaluate building energy performance. However, current metamodeling approaches lack a common foundation. The aim of this work was to develop a general metamodel for building energy performance. Based on the premise that each building element can have an impact on energy performance, our general metamodel assumes that the overall impact is a polynomial function of the individual impacts. The model includes time-dependent parameters such as the solar heat gain coefficient and energy system efficiency. A model derived from the general model was tested on an office located in Paris. Energy needs and consumption, the cost of energy consumption and the CO2 emissions for heating and cooling were analyzed. The study highlighted the significant impact of the choice of the performance criteria in evaluating the efficiency of building design solutions. The metamodel represents a fast way to perform calculations with an accuracy close to that of dynamic simulations. It can be used as a basis to perform parametric studies and for future building energy regulations.

Abstract Many current and future hydrogen production methods, such as steam methane reforming and thermochemical water splitting cycles, require large amounts of heat as the major energy input. Using nuclear heat is a promising option for reducing emissions of greenhouse gases and other pollutants, thereby helping achieve clean and sustainable future energy systems. Various heat transfer fluids are compared and evaluation criteria are proposed for the selection of a heat transfer fluid. It is determined that helium is a promising option due to it being inert and chemically stable and having good heat transfer properties. The intermediate heat exchanger for the heat extraction is analyzed and designed using the log mean temperature difference (LMTD) method with helium serving as the heat transfer fluid to extract heat from the supercritical water. It is found that if the heat extraction load is in the range of 100–330 MW th , which approximately corresponds to a hydrogen production range of 40–125 tonnes per day, then a multi-tube and single-shell counter flow heat exchanger with a shell diameter of 0.7–1.3 m and length of 6.7 m encapsulating 420–1600 tubes of 0.025 m diameter would be appropriate according to the practical working conditions on the shell and tube sides. The analysis also shows that the diameter of the heat exchanger does not depend strongly on the heat transfer load if the load is smaller than 330 MW th (125 tonnes H 2 /day). This provides flexibility in case adjustments to the heat extraction load become necessary. However, if the heat load is larger than 330 MW th , for example, 500 MW th for 200 tonnes hydrogen per day, then a multi-tube and single-shell counter flow heat exchanger is not appropriate because the length-to-diameter ratio is outside of the recommended range.

Abstract Global environmental change is driven by food production. Biogas from food waste is a better source of clean energy. Ghana’s energy strategy targets a 10% increase in renewable energy and modern biomass in the national electricity generation mix. Studies on the assessment of electricity generation potential and economic feasibility of biogas to electricity projects in Ghana’s major cities are scarcely available. This study assesses the electricity generation potential of biogas from food waste through anaerobic digestion technology. The municipal solid waste generation potential of Accra and Kumasi was estimated from 2020 to 2039. The potential theoretical methane yield from food waste was calculated using Buswell’s equation. The study analyzed anaerobic digestion projects’ economic feasibility using the total life cycle cost, net present value, investment payback period, levelized cost of energy, and internal rate of return methods. A sensitivity analysis based on two scenarios (optimistic and pessimistic) was performed to analyze the influence of changes in the composition of food waste, per capita waste generation rate, population growth rate, per capita GDP growth rate, discount rate, capacity factor, electricity generation efficiency, waste collection efficiency, and methane production potential on the economic feasibility of the projects. The main findings indicate that the amount of waste generation in Accra during the project life cycle is 899,000 t/y to 3,359,000 t/y, while that of Kumasi is 915,000 t/y to 3,159,000 t/y. The power generation potential of the project in Accra ranges from 80.43 to 300.49 GWh/y, and in Kumasi ranges from 60.63 to 209.31 GWh/y. Economically, the project is feasible in Accra and Kumasi. The net present value of the project in Accra and Kumasi is $217,800,000 and $156,100,000. The sensitivity analysis shows that the project is infeasible in all the cities with a discount rate exceeding 20%. When the discount rate exceeds 20%, the project becomes highly infeasible in Accra compared to Kumasi. This study will offer itself as scientific guidance for investment in biogas to electricity projects in Ghana’s cities.

Purpose Waste generation poses a significant environmental challenge in the United Arab Emirates due to the rapid urbanization, population growth and industrialization witnessed in recent decades. As a result, there has been a substantial surge in waste production. To fulfil its sustainability and circular economy aspirations in various economic domains, the UAE must prioritize efficient waste management. The purpose of this study is to assess the environmental and energy efficiency of the UAE’s economic sectors particularly within its vital energy sectors, which encompass crude oil, natural gas and mining, manufacturing and electricity, by gauging their adherence to sustainability and circularity objectives. Design/methodology/approach The authors used the data envelopment analysis input–output model to identify sectors that exhibit strong performance as well as those that are falling behind. Findings Based on this study, the agriculture, the crude oil, natural gas and mining sectors and financial services and banking were found to be the most efficient. The results of this study concluded that the UAE is making progress toward achieving its sustainability and circularity objectives; however, the findings suggest that more effort is needed to fully realize these goals. Originality/value By identifying high-performing and underperforming sectors, decision-makers can prioritize efforts to enhance sustainability and circularity in area of greatest need in the economy.

The study empirically examines the environmental Kuznets curve (EKC) hypotheses by investigating the relationship between ecological footprint, economic growth, energy consumption, and population growth. The study uses ecological footprint as a measurement of environmental degradation which is a more comprehensive indicator and considers all factors responsible for environmental degradation. Keeping in view the problem of cross-sectional dependence, a more efficient estimation tools like pooled mean group and augmented mean group have been used to estimate the long-run parameters for 22 European countries from 1995 through 2015. Results of the study found a quadratic relationship between income growth and ecological footprint and support validity of EKC. Energy consumption positively contributes to ecological footprint, while population growth plays no significant role in determining environmental quality. The long-run estimates of the study are validated through robustness analysis by employing dynamic ordinary least square (DOLS) and fully modified ordinary least square (FMOLS) techniques. Dumitrescu and Hurlin (2012) panel non-causality test indicated that there is a unidirectional causality running from GDP to ecological footprint while bidirectional causality running between energy consumption and ecological footprint. The study identified that population growth in European region is not a severe issue as compared to intensive energy consumption. Policies which restrict emission, deforestation, and water pollution should be adopted for sustainability of environment.

Abstract The impact of air-side particulate fouling on the performance of membrane-based, fixed-plate energy recovery ventilators (ERVs) is investigated for both fine and coarse (0.3–10 μm) as well as ultrafine (∼0.1 μm) aerosols. Two residential size cross-flow ERV exchanger cores were fouled with ISO A3 medium test dust. It was found that coarse dust loading, equivalent to that of a few years of exposure in a heavily polluted environment, has minimal impact on the performance of ERV exchanger cores. In both cases, the sensible and latent effectiveness were actually slightly enhanced due to boundary layer thinning and additional turbulence potentially caused by the dust layer. Heavy dust loadings, in the absence of appropriate filtration upstream, may result in a fan energy penalty (∼50%) due to the added pressure drop across the exchanger cores. Samples of three different membrane transport media, extracted from commercial HVAC ERV exchanger cores, were loaded with graphite and NaCl aerosol nanoparticles. Accelerated loading experiments were conducted in a laboratory apparatus to simulate several years of fouling in the field. Initial and post-loading water vapor permeance through the membrane samples were experimentally determined for each loading to quantify the effects of fouling. The impact of relative humidity on the performance of loaded membranes was also studied by exposing membranes loaded with particles in dry air to an elevated RH of 75%, leading to surface condensation. The experiments show that the deposition of particles in dry air can only affect the membrane when the fouling is severe enough to form a cake layer on the membrane surface comparable to the thickness of the membrane. In the case of membranes loaded with hygroscopic salt particles, surface condensation at high RH values can lead to vapor permeance reductions of up to 15% well before the cake layer formation phase of fouling, whilst no permeance reduction was observed for membranes loaded with non-hygroscopic graphite particles. This indicates a net porosity reduction in the microporous substrate layer of exposed salt-loaded samples. A pore-narrowing process of the substrate layer, due to the mobilization of salt particles in aqueous form, is a potential explanation for these observations.

Abstract The use of organic wastes as new renewable energy sources is becoming necessary to achieve the growing energy demand in Tunisia. In this work, the pyrolysis of abundant waste fish fats provided by a canned Tuna factory was examined in a laboratory fixed-bed reactor. The main objective was to analyze the properties and the composition of the produced bio-oil using in order to implement the suitable valorization strategy. Therefore, high heating value, viscosity, density, flash point, acidity index, moisture content and ash content measurements as well as FTIR and GCMS analyses were carried out to characterize the pyrolytic oil obtained during waste fish pyrolysis at 500 °C. The obtained results revealed that waste fish fats can be considered as important feedstock for biofuel production. In particular, the bio-oil characterization showed the presence of many organic compounds such as alkanes, alkenes, alkynes, cyclic hydrocarbons, carboxylic acids, aldehydes and alcohols. These compounds could be used as a valuable and sustainable chemicals source. Moreover, the bio-oil properties indicated a good calorific value (~ 9391 kcal/kg) compared to Tunisian Diesel and European biodiesel specifications. In contrast, higher acidity (~ 103 mg KOH/g sample) and viscosity (~ 7 cSt) compared to conventional fuels were obtained. These properties limit the direct use of bio-oils as alternative fuel in a Diesel engine. An efficient mixture with fossil fuel may be a promising solution to improve the fuel properties. Hence, pyrolysis seems to be an eco-friendly process to recover the fish fatty wastes in Tunisia. The implementation of such management strategy will help Tunisian agri-food industries to reduce their environmental impact and fossil fuel consumption and to promote the renewable energy use.

Sustainable strategies for nanomedicine manufacture from the cradle to the grave.