• Energy Research

Abstract The tubular SOFC generator CHP-100, built by Siemens Power Generation (SPG) Stationary Fuel Cells (SFC), is running at the Gas Turbine Technologies (GTT) in Torino (Italy), in the framework of the EOS Project. The nominal load of the generator ensures a produced electric power of around 105 kW e ac and around 60 kW t of thermal power at 250 °C to be used for the custom tailored HVAC system. Several experimental sessions have been scheduled on the generator; the aim is to characterize the operation through the analysis of some global performance index and the detailed control of the operation of the different bundles of the whole stack. All the scheduled tests have been performed by applying the methodology of design of experiment; the main obtained results show the effect of the change of the analysed operating factors in terms of distribution of voltage and temperature over the stack. Fuel consumption tests give information about the sensitivity of the voltage and temperature distribution along the single bundles. On the other hand, since the generator is an air cooled system, the results of the tests on the air stoichs have been used to analyze the generator thermal management (temperature distribution and profiles) and its effect on the polarization. The sensitivity analysis of the local voltage to the overall fuel consumption modifications can be used as a powerful procedure to deduce the local distribution of fuel utilization (FU) along the single bundles: in fact, through a model obtained by deriving the polarization curve respect to FU, it is possible to link the distribution of voltage sensitivities to FC to the distribution of the local FU. The FU distribution will be shown as non-uniform, and this affects the local voltage and temperatures, causing a high warming effect in some rows of the generator. Therefore, a discussion around the effectiveness of the thermal regulation made by the air stoichs, in order to reduce the non-uniform distribution of temperature and the overheating (increasing therefore the voltage behavior along the generator) has been performed. It is demonstrated that the utilization of one air plenum is not effective in the thermal regulation of the whole generator, in particular in the reduction of the temperature gradients linked to the non-uniform fuel distribution.

Abstract The practice of blending biogas into the gas network, especially at the distribution level, offers the opportunity to use biogas as a substitute of fossil gas. The ‘greening’ of the gas network through biogas blending would indeed take advantage of the robustness and extensiveness of an already existing energy infrastructure. A steady state and multi-component thermal-fluid-dynamic model of the gas network is applied to a portion of the Italian distribution network. The receiving potential capacity of the existing infrastructure is assessed with respect to biogas injection. Fluid-dynamic aspects of this practice are considered and commented. The maximum allowable percentage of injectable biogas (purified from sulphur compounds, O2 and siloxanes but not upgraded to bio-methane by removing CO2) is calculated on a nodal basis, referring to the actual gas network configuration, and in agreement with the quality constraints set by the current regulation (UNI/TR 11537:2016). A major hypothesis has been assumed in this work: gas quality requirements are enforced on the network as a whole (i.e., after blending the injected gas into grid) rather than at the injection point, which is instead the current prescription of most of the EU countries. By exploiting the quality-tracking feature of the model, the constraint on the quality assessment at the injection point is thus relaxed and its effect on the grid gas quality has been quantified. Results from the case study shows how biogas blending into the gas grid may lead to a reduction on the fossil natural gas dependence of up to 4.7%.

The present work investigates electricity production using a high efficiency electrochemical generator that employs as fuel a biogas from the dry anaerobic digestion of the organic fraction of municipal solid waste (OFMSW). The as-produced biogas contains several contaminants (sulfur, halogen, organic silicon and aromatic compounds) that can be harmful for the fuel cell: these were monitored via an innovative mass spectrometry technique that enables for in-line and real-time quantification. A cleaning trap with activated carbons for the removal of sulfur and other VOCs contained in the biogas was also tested and monitored by observing the different breakthrough times of studied contaminants. The electrochemical generator was a commercial Ni anode-supported planar Solid Oxide Fuel Cell (SOFC), tested for more than 300 h with a simulated biogas mixture (CH4 60 vol.%, CO2 40 vol.%), directly fed to the anode electrode. Air was added to promote the direct internal conversion of CH4 to H2 and CO via partial oxidation (POx). The initial breakthrough of H2S from the cleaning section was also simulated and tested by adding ∼1 ppm(v) of sulfur in the anode feed; a full recovery of the fuel cell performance after 24h of sulfur exposure (∼1 ppm(v)) was observed upon its removal, indicating the reliable time of anode exposure to sulfur in case of exhausted guard bed.

Abstract The SOFC CHP 100 kW e Field Unit built by Siemens is operating at the Gas Turbine Technologies in Torino. The generator started up on June 2005, and is delivering around 100 kW e of AC electrical energy to the grid and 55 kW t of thermal energy, providing heating and cooling for the facility's buildings. An experimental plan has been designed by applying the factorial analysis. Before performing the experiments on the plant, this approach has been applied to a computer model simulation: a 2 3 factorial analysis has been applied to the generator model (independent variables: fuel utilization factor, air utilization factor and air temperature at the generator inlet). First-order regression models are obtained for the investigated dependent variables (i.e. DC power, recovered heat, combustion zone temperature, etc.). The data are analyzed by applying the response surface methodology. Finally, constrained optimization methods are applied to investigate optimal operation points in terms of DC generated power or exhausts’ recovered heat. A comparison with the actual operation point of the SOFC generator is shown.

Most of the simulation studies on energy networks, including gas grids, derive their results from a limited number of network models. The findings of these works are therefore affected by a substantial case-specificity, which partially limits their validity and prevents their generalisation. To overcome this limitation, the present work proposes a novel statistical-based approach for studying distribution gas networks, enabled by a generator of random gas grids with accurate technical designs and structural features. Ten-thousand random and unique networks are produced in three different tests, where increasingly tight constraints are applied to the synthetisation process for a higher control over the generated grids. The experiments verify the accuracy of the tool and highlight that substantial variations can be found in the hydraulic behaviour (pressures and gas velocities) and structural properties (pipe diameters and network volumes) of real-world gas networks. The observed 10,000 gas grids evidence the information gain offered by statistical-based approaches with respect to traditional case-specific studies. The tool opens a broad range of applications which include, but are not limited to, statistical analyses on the distributed injection of alternative gases, like hydrogen, in integrated, low-carbon, energy systems.

The current body of research on the gender-energy nexus has largely concentrated on the effects of energy poverty within households, highlighting the impact on women in domestic settings. Nonetheless, women entrepreneurs engaged in productive activities are also pivotal in adopting new energy technologies. This second version of the dataset incorporates significant updates, presenting raw and processed data from 40 face-to-face interviews conducted across multiple African countries, now including Nigeria, which was previously excluded. The dataset focuses on micro and small-sized enterprises with at least one female owner, offering a more unified and comprehensive sample to assess energy access among women entrepreneurs in Africa and explore the potential for renewable energy adoption. The data collection through semi-structured, face-to-face interviews occurred between February and October 2024. The interviews followed a predetermined questionnaire designed to collect quantitative and qualitative data. A new notes section explains the main methods and references used in the dataset. Distinctions are also made between primary and secondary data for appliance power ratings, ensuring transparency in cases where secondary data supplements gaps. This version includes updated technical data, such as time-of-use information for appliances, enhancing the dataset's strength in providing technical insights. Key components of the dataset include: - Socio-economic factors: Enterprise location, ISIC division and industry sector classification, main production goods, gender-based ownership structures, enterprise formality (based on registration), year of establishment or business start, enterprise size (number of employees), profit margins, and business challenges related to the owner's gender. - Energy access characteristics: Type of energy carriers used, subapplications, energy supply shortages, energy consumption levels, type, number, power rating of appliances used, temperature requirements, time-of-use data, and energy expenditure. - Potential for renewable energy adoption: Type and amount of process waste, perceived barriers and drivers for renewable energy adoption, willingness to invest in new technologies, and preferred financing methods for such technologies. This updated dataset provides enhanced value for researchers, policymakers, and practitioners aiming to understand the energy access landscape for women entrepreneurs in Africa. It offers a robust foundation for developing targeted interventions that promote gender equity in energy access and encourage renewable energy adoption.

The paper deals with the testing of performances of SOFC planar cells having as mechanical support either the anode or the electrolyte. Polarization traces at different temperature and hydrogen flow have been drawn to assess the electrochemical behavior and the limiting polarization factors of anode-supported and electrolyte-supported cells. The experimental data from polarization tests has then been summarized and analyzed through a parameter estimation technique, which allowed us to compare the performances of each cell throughout some defined macroscopic parameters, each one being referred and distinctive of a certain polarization overvoltage occurring during a SOFC operation. SEM and optical micrographs have been also collected in order to characterize the fine microstructure of the tested cells, and to discuss the macroscopic polarization results with reference to the microstructure.

Abstract Gas Turbine Technologies (GTT) and Politecnico di Torino, both located in Torino (Italy), have been involved in the design and installation of a SOFC laboratory in order to analyse the operation, in cogenerative configuration, of the CHP 100 kW e SOFC Field Unit, built by Siemens-Westinghouse Power Corporation (SWPC), which is at present (May 2005) starting its operation and which will supply electric and thermal power to the GTT factory. In order to take the better advantage from the analysis of the on-site operation, and especially to correctly design the scheduled experimental tests on the system, we developed a mathematical model and run a simulated experimental campaign, applying a rigorous statistical approach to the analysis of the results. The aim of this work is the computer experimental analysis, through a statistical methodology (2 k factorial experiments), of the CHP 100 performance. First, the mathematical model has been calibrated with the results acquired during the first CHP100 demonstration at EDB/ELSAM in Westerwoort. After, the simulated tests have been performed in the form of computer experimental session, and the measurement uncertainties have been simulated with perturbation imposed to the model independent variables. The statistical methodology used for the computer experimental analysis is the factorial design (Yates’ Technique): using the ANOVA technique the effect of the main independent variables (air utilization factor U ox , fuel utilization factor U F , internal fuel and air preheating and anodic recycling flow rate) has been investigated in a rigorous manner. Analysis accounts for the effects of parameters on stack electric power, thermal recovered power, single cell voltage, cell operative temperature, consumed fuel flow and steam to carbon ratio. Each main effect and interaction effect of parameters is shown with particular attention on generated electric power and stack heat recovered.

In this paper the characteristics and problems of a SOFC CHP system is investigated in the hypothesis of hydrogen feeding. The possibility of SOFC systems fed by hydrogen is not deeply investigated: the main advantage of SOFC is the possibility to be fed by different fuels, while hydrogen has to be produced. Nevertheless, in case of a context with possibility of producing hydrogen at low cost by means of renewable sources (e.g. hydroelectricity), it could be of interest to investigate a SOFC system fed with hydrogen fuel due to a better system performance and environmental benefits. A model is proposed describing the operation of an air-cooled SOFC system: results are discussed pointing out the thermal management and its effect on the electrical performance of system. It is shown that the design of a high temperature cathode recirculation system allows one to overcome the thermal management while obtaining higher electrical performances.