• Energy Research
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Abstract The general objective of the investigation described in this article is the experimental testing of solar assisted dryers reported earlier. The tests show good technical results with a conventional energy consumption decrease of 27–80% and an average solar system efficiency of approx. 40%. From the experimental results, it can also be concluded that, with controlled removal of the moist air, improved product quality, significant reduction in drying time and mass losses, etc. result. The introduction of solar dryers seems to be a promising way for drying various agricultural products.

Abstract Computable general equilibrium models are becoming popular for simulating emissions trading systems. However, these models make various assumptions about the production structure and the possibilities of substituting energy for productive factors or inputs. Therefore, this study aims to analyze how different options to incorporate energy into the nested production structure of a computable general equilibrium model affect the obtained impacts when an emissions trading system is implemented. A flexible computable general equilibrium model called ECOMODEL is developed, which is the first model that allows choosing any of the three nested production structures most used in the literature (KEL-M, KL-EM, or KLE-M). The Chilean economy is used as a case study since there is a current database with high disaggregation of the energy sector for calibrating the computable general equilibrium model. The results show that the simulated impacts with KEL-M and KL-EM structures are the best when elasticities of substitution equal to the values ​​most frequently used in previous studies are chosen. However, the KEL-M structure that considers energy as a substitute for capital provides overly optimistic environmental results when high elasticities of substitution are used, obtaining the lowest reduction in Gross Domestic Product and the lowest price of the emissions trading system. Furthermore, the KLE-M structure gives unrealistic results regardless of the elasticities of substitution used. In consequence, a KL-EM nested production structure should be prioritized to simulate an emissions trading system since it provides realistic results and is less sensitive to the values of the elasticities of substitution.

The increasing demand for energy and commodities has led to escalating greenhouse gas emissions, the chief of which is represented by carbon dioxide (CO2). Blue hydrogen (H2), a low-carbon hydrogen produced from natural gas with carbon capture technologies applied, has been suggested as a possible alternative to fossil fuels in processes with hard-to-abate emission sources, including refining, chemical, petrochemical and transport sectors. Due to the recent international directives aimed to combat climate change, even existing hydrogen plants should be retrofitted with carbon capture units. To optimize the process economics of such retrofit, it has been proposed to remove CO2 from the pressure swing adsorption (PSA) tail gas to exploit the relatively high CO2 concentration. This study aimed to design and numerically investigate a vacuum pressure swing adsorption (VPSA) process capable of capturing CO2 from the PSA tail gas of an industrial steam methane reforming (SMR)-based hydrogen plant using NaX zeolite adsorbent. The effect of operating conditions, such as purge-to-feed ratio and desorption pressure, were evaluated in relation to CO2 purity, CO2 recovery, bed productivity and specific energy consumption. We found that conventional cycle configurations, namely a 2-bed, 4-step Skarstrom cycle and a 2-bed, 6-step modified Skarstrom cycle with pressure equalization, were able to concentrate CO2 to a purity greater than 95% with a CO2 recovery of around 77% and 90%, respectively. Therefore, the latter configuration could serve as an efficient process to decarbonize existing hydrogen plants and produce blue H2.

Abstract Decision-making for sustainable design requires the evaluation of different options considering all sustainability dimensions simultaneously: economic, environmental and social. Each dimension has a specific relative importance, which depends on the process that is being assessed. The determination of the relative importance is not a simple task, principally, during early design stages when detailed information about the process is scarce, and when core decisions affecting the entire design are made. An example of this kind of decisions during early design stages is the selection of the chemical process route, which, once defined, provides the guidelines for the process design. The present study proposes a multi-criteria analysis based methodology to evaluate different chemical process route options under sustainability criteria and to guide the selection among them. The methodology uses normalized indicators to assess each sustainability dimension, and a multi-criteria analysis method (MCDA) to calculate the weights and influences between dimensions. Indicators, dimension weights and influences are integrated into the Sustainable Cumulative Index ( SCI ) that can be used to compare chemical process route options in sustainability terms and to support their selection. The proposed methodology is illustrated through the assessment and selection of a chemical process route to produce ethyl acetate.

Abstract Numerical model for heavy fuel oil and air mixtures combustion is presented to simulate the behavior of the fuel in an inert porous medium reactor for hydrogen production. Three-zone combustion of oil and petroleum cokes separated by temperature ranges starting from ambient temperature to 560 K, from 560 K to 673 K, and above 673 K, is presented. Hydrogen production is achieved using water gas shift equilibrium reaction on the combustion products at different temperatures. Results show a high enthalpy contribution due to coke combustion formed in the low temperature oxidation reaction, being the most important reaction in relation to its zone size. Simulations increasing filtration velocity (from 0.05 to 0.9 m/s) has a favorable effect on the maximum temperature and the combustion front velocity. The effect of the simplified combustion model lowers computational time, with acceptable results for temperature as well as hydrogen production in contrast to laboratory tests and other software simulation such as COMSOL Multiphysics.

As countries start to implement the Sustainable Development Goals in their national development agendas, reviews of the current policy environment are necessary to ensure that the goals are achievable by 2030. The present study assesses the effectiveness of energy policy in Indonesia in supporting progress towards universal energy access, a substantial increase in renewable energy deployment, and improvement in energy efficiency. Laws and regulations related to energy were reviewed, and their contribution to achieving the energy targets of the Sustainable Development Goals in Indonesia was evaluated in terms of policy effectiveness. Results show that providing electricity for the remaining 1.1 million households living in the outermost and least developed regions of the archipelago is very challenging. However, Indonesia is still on track to achieve 100% residential electrification by 2030 as long as enough budget is allocated annually. Indonesia may not be able to provide access to clean cooking fuels and technology for everyone by 2030. The current policy focusing mostly on gas for cooking will be less effective in reaching the remaining households that cook with solid biomass and usually live in poverty. Similarly, the current policy scenario is not sufficient to allow enough progress to achieve the renewable energy target. Finally, the assessment of energy efficiency policy suggests that sectoral energy use is shaped by variables and regulation not primarily intended to improve energy efficiency.

Climate change, clean energy transition, the energy security quest, and international relations have triggered the revival of renewable energy as a solution to these problems. Nowadays, there is an energy transition where renewable energies bring geopolitical changes in a world where fossil fuels are becoming less relevant. This article aims to assess how the transition influences Spain’s energy relations with other countries regarding electricity and its sources, in alignment with the European Green Deal. In order to do so, its current energy situation, the renewable energies development and its energy import-export relations are examined. The results show that despite progress in green regionalization through more electric interconnection, little difference is to be found in traditional relations with fossil fuel countries exporters, but more are the contractions in Spanish energy economic policy, as here is explained.

Abstract Northern Chile has excellent conditions to develop concentrated solar power projects. Although solar irradiation makes a significant contribution to production in the region, solar thermal projects need some support mechanisms. This study focuses on the best combinations of solar incentives and financial parameters to have lowest government cost and maximum levelized cost of electricity reduction. Key findings of this paper showed that debt fraction and discount rate illustrated meaningful sensitivities on both LCOE and government cost. ITC, PTC, and DM as tax credit and PBI as cash incentives had the best effectiveness, and reduced LCOE better than IBI and STR. The effectiveness of ITC, PTC, PBI, and DM was independent of financial parameters even though STR and IBI showed dependency. Although cash incentives had no limits to reduce LCOE, tax credit incentives reached maximum values, which meant that their impacts were limited. As cash incentives, PBI showed better results when it was compared to IBI. Maximum values of ITC maintained the same for different installed costs, while it changed for PTC. Finally, it was obtained that tax credit incentives were more meaningful at higher PPA price although PBI made more sense in lower PPA prices.