• Energy Research
• 7. Clean energy close
• DE close
• EU close
• Energy Conversion and Management close

Attempts to model any present or future power grid face a huge challenge because a power grid is a complex system, with feedback and multi-agent behaviors, integrated by generation, distribution, storage and consumption systems, using various control and automation computing systems to manage electricity flows. Our approach to modeling is to build upon an established model of the low voltage electricity network which is tested and proven, by extending it to a generalized energy model. But, in order to address the crucial issues of energy efficiency, additional processes like energy conversion and storage, and further energy carriers, such as gas, heat, etc., besides the traditional electrical one, must be considered. Therefore a more powerful model, provided with enhanced nodes or conversion points, able to deal with multidimensional flows, is being required. This article addresses the issue of modeling a local multi-carrier energy network. This problem can be considered as an extension of modeling a low voltage distribution network located at some urban or rural geographic area. But instead of using an external power flow analysis package to do the power flow calculations, as used in electric networks, in this work we integrate a multiagent algorithm to perform the task, in a concurrent way to the other simulation tasks, and not only for the electric fluid but also for a number of additional energy carriers. As the model is mainly focused in system operation, generation and load models are not developed. The financial support from EPSRC for Liz Varga on project entitled "Transforming Utilities’ Conversion Points" (no. EP/J005649/1) is gratefully acknowledged.

Attempts to model any present or future power grid face a huge challenge because a power grid is a complex system, with feedback and multi-agent behaviors, integrated by generation, distribution, storage and consumption systems, using various control and automation computing systems to manage electricity flows. Our approach to modeling is to build upon an established model of the low voltage electricity network which is tested and proven, by extending it to a generalized energy model. But, in order to address the crucial issues of energy efficiency, additional processes like energy conversion and storage, and further energy carriers, such as gas, heat, etc., besides the traditional electrical one, must be considered. Therefore a more powerful model, provided with enhanced nodes or conversion points, able to deal with multidimensional flows, is being required. This article addresses the issue of modeling a local multi-carrier energy network. This problem can be considered as an extension of modeling a low voltage distribution network located at some urban or rural geographic area. But instead of using an external power flow analysis package to do the power flow calculations, as used in electric networks, in this work we integrate a multiagent algorithm to perform the task, in a concurrent way to the other simulation tasks, and not only for the electric fluid but also for a number of additional energy carriers. As the model is mainly focused in system operation, generation and load models are not developed. The financial support from EPSRC for Liz Varga on project entitled "Transforming Utilities’ Conversion Points" (no. EP/J005649/1) is gratefully acknowledged.

In the present work, an experimental study on a lab-scale adsorption refrigerator, based on activated carbon/ethanol working pair is reported. An extensive testing campaign has been carried out at the CNR ITAE laboratory, with multiple aims. First, the performance has been evaluated in terms of both COP and Specific Cooling Power (SCP), under different boundary conditions, including both air conditioning and refrigeration applications. Attractive SCPs, up to 180 W/kg and 70 W/kg for air conditioning and refrigeration, respectively, were measured. Under the same conditions, COP between 0.17 and 0.08 were obtained. In addition, different management strategies, namely, heat recovery between adsorbers and re-allocation of phase durations, were evaluated to identify their influence on the system. Both strategies confirmed the possibility of increasing COP and SCP up to 40% and 25%, respectively. Moreover, a design analysis based on the experimental results has been carried out, to suggest possible improvements of the system. The obtained results demonstrated the possibility of employing a non-toxic refrigerant like ethanol reaching performance comparable with other harmful refrigerants like ammonia and methanol.

In the present work, an experimental study on a lab-scale adsorption refrigerator, based on activated carbon/ethanol working pair is reported. An extensive testing campaign has been carried out at the CNR ITAE laboratory, with multiple aims. First, the performance has been evaluated in terms of both COP and Specific Cooling Power (SCP), under different boundary conditions, including both air conditioning and refrigeration applications. Attractive SCPs, up to 180 W/kg and 70 W/kg for air conditioning and refrigeration, respectively, were measured. Under the same conditions, COP between 0.17 and 0.08 were obtained. In addition, different management strategies, namely, heat recovery between adsorbers and re-allocation of phase durations, were evaluated to identify their influence on the system. Both strategies confirmed the possibility of increasing COP and SCP up to 40% and 25%, respectively. Moreover, a design analysis based on the experimental results has been carried out, to suggest possible improvements of the system. The obtained results demonstrated the possibility of employing a non-toxic refrigerant like ethanol reaching performance comparable with other harmful refrigerants like ammonia and methanol.

The conversion of agricultural waste materials such as bark or straw into 2nd generation biofuels constitutes an auspicious way to meet part of the future fuel demand in a sustainable way. The number of possible production routes is diverse, and the techno-economic analyses of these routes have been conducted in very different ways. The route involving gasification, gas purification, and a subsequent Fischer-Tropsch synthesis enables the production of hydrocarbons that achieve current fuel standards after upgrading in the existing refinery infrastructure. To evaluate a promising biomass-to-liquid process, a methodology is presented that incorporates economic constraints into the process design, allowing identification of a regionally optimal process design. The production costs of the new concepts are estimated by setting up a detailed flowsheet simulation in AspenPlus® based on experimental data from the successful demonstration runs of the EU-Project COMSYN. In addition, an existing techno-economic evaluation methodology incorporated into the in-house software tool TEPET (Techno-Economic Process Evaluation Tool) has been extended to evaluate the processes’ performance in different European regions and to include transportation and refining costs. The approach enables the identification of regional sweet spots shown on a map for Central-Europe, indicating production costs and favorable process design for each region. Furthermore, the results of an automated mapping for the optimal process design depending on the heat and electricity market are presented. The performed analyses show that the techno-economic evaluation tends to expand the technology in regions with low feedstock costs, while the optimal process design is defined by the regional heat and electricity market. In this work, net production costs of less than 1.12 €2019/lbiofuel were determined for regions in Hungary, Poland and Slovakia.

The conversion of agricultural waste materials such as bark or straw into 2nd generation biofuels constitutes an auspicious way to meet part of the future fuel demand in a sustainable way. The number of possible production routes is diverse, and the techno-economic analyses of these routes have been conducted in very different ways. The route involving gasification, gas purification, and a subsequent Fischer-Tropsch synthesis enables the production of hydrocarbons that achieve current fuel standards after upgrading in the existing refinery infrastructure. To evaluate a promising biomass-to-liquid process, a methodology is presented that incorporates economic constraints into the process design, allowing identification of a regionally optimal process design. The production costs of the new concepts are estimated by setting up a detailed flowsheet simulation in AspenPlus® based on experimental data from the successful demonstration runs of the EU-Project COMSYN. In addition, an existing techno-economic evaluation methodology incorporated into the in-house software tool TEPET (Techno-Economic Process Evaluation Tool) has been extended to evaluate the processes’ performance in different European regions and to include transportation and refining costs. The approach enables the identification of regional sweet spots shown on a map for Central-Europe, indicating production costs and favorable process design for each region. Furthermore, the results of an automated mapping for the optimal process design depending on the heat and electricity market are presented. The performed analyses show that the techno-economic evaluation tends to expand the technology in regions with low feedstock costs, while the optimal process design is defined by the regional heat and electricity market. In this work, net production costs of less than 1.12 €2019/lbiofuel were determined for regions in Hungary, Poland and Slovakia.

Abstract Distributed generation and, in particular, cogeneration and trigeneration are generally considered viable solutions to reduce energy consumption and mitigate the environmental impact of developed economies. Nonetheless, such systems need to be carefully designed and managed to effectively meet all the economic and environmental expectations. The design of a distributed generation plant and the choice of its proper management policy are complex tasks that require effective support methodologies and tools. In this paper, we develop a methodology to determine the optimal control strategy for a trigeneration plant. The model enforces mass end energy balances and accounts for the nonlinear and the basic dynamic behavior of each energy converter, for the time varying energy prices and environmental conditions, for maintenance and cold start costs, and for the possibility to store energy. We built on a methodology previously developed and we dramatically broaden its field of application to complex smart grids with a very high temporal detail, by cutting down its computational costs. To this aim, we implement an heuristic procedure that reduces the computational complexity of the non linear optimization problem. The total cash flow, the primary energy consumption, the plant efficiency, and the CO 2 emissions, besides the instantaneous set-point of the plant, are among the most relevant results of the model. The model is first validated through 11 test-cases specifically designed to stress the possible weaknesses of the heuristic procedure. The validation evidences that the proposed procedure does not introduce further approximations to the mathematical model. The global optimum is retrieved for all the considered cases. Afterwards, we apply the proposed methodology to a realistic energy management scenario: the assessment of a fuel cell based trigeneration plant for a civil building for a whole year. The discussion highlights the effectiveness of the proposed method for different applications including the optimization of the control strategy for existing plants, the design of new distributed generation systems, the assessment of innovative energy conversion technologies, and the evaluation of national energy policies.