Net Electrical Energy Research Articles

Synergic treatment of domestic wastewater and food waste in an anaerobic membrane bioreactor demo plant: Process performance, energy consumption, and greenhouse gas emissions

Ambient operation and large-scale demonstration have limited the implementation and evaluation of anaerobic membrane bioreactors (AnMBRs) for low-strength wastewater treatment. Here, we studied these issues at an AnMBR demo plant that treats domestic wastewater and food waste together at ambient temperatures (7–28 °C). At varied hydraulic retention times (HRTs, 8–42 h), the AnMBR achieved a COD removal efficiency and biogas production of 80.4% ± 3.9% and 66.5 ± 9.4 NL/m3-Influent, respectively. Moreover, a stable high membrane flux of 14.4 L/m2/h was reached. The electric energy consumption for the AnMBR operation was 0.269–0.433 kW·h/m3, and 49.4%–91.3% could be compensated by the electric energy produced from methane production. At an HRT of 10 h, the AnMBR system demonstrated an impressively low net electric energy consumption of merely 0.05 kW·h/m3, resulting in a net greenhouse gas emission of 0.015 CO2-eq/m3, cutting 85% compared to the conventional activated sludge process. Achievements in this study provide key parameters for the ambient operation of AnMBR and demonstrate that AnMBR is an energy-saving and low-carbon solution for low-strength wastewater treatment.

Optimization and Tradeoff Analysis for Multiple Configurations of Bio-Energy with Carbon Capture and Storage Systems in Brazilian Sugarcane Ethanol Sector.

Bio-energy systems with carbon capture and storage (BECCS) will be essential if countries are to meet the gas emission reduction targets established in the 2015 Paris Agreement. This study seeks to carry out a thermodynamic optimization and analysis of a BECCS technology for a typical Brazilian cogeneration plant. To maximize generated net electrical energy (MWe) and carbon dioxide CO2 capture (Mt/year), this study evaluated six cogeneration systems integrated with a chemical absorption process using MEA. A key performance indicator (gCO2/kWh) was also evaluated. The set of optimal solutions shows that the single regenerator configuration (REG1) resulted in more CO2 capture (51.9% of all CO2 emissions generated by the plant), penalized by 14.9% in the electrical plant's efficiency. On the other hand, the reheated configuration with three regenerators (Reheat3) was less power-penalized (7.41%) but had a lower CO2 capture rate (36.3%). Results showed that if the CO2 capture rates would be higher than 51.9%, the cogeneration system would reach a higher specific emission (gCO2/kWh) than the cogeneration base plant without a carbon capture system, which implies that low capture rates (<51%) in the CCS system guarantee an overall net reduction in greenhouse gas emissions in sugarcane plants for power and ethanol production.

Measuring Heat Dissipation and Entropic Potential in Battery Cathodes Made with Conjugated and Conventional Polymer Binders Using Operando Calorimetry.

This study explores the influence of electronic and ionic conductivities on the behavior of conjugated polymer binders through the measurement of entropic potential and heat generation in an operating lithium-ion battery. Specifically, the traditional poly(vinylidene fluoride) (PVDF) binder in LiNi0.8Co0.15Al0.05O2 (NCA) cathode electrodes was replaced with semiconducting polymer binders based on poly(3,4-propylenedioxythiophene). Two conjugated polymers were explored: one is a homopolymer with all aliphatic side chains, and the other is a copolymer with both aliphatic and ethylene oxide side chains. We have shown previously that both polymers have high electronic conductivity in the potential range of NCA redox, but the copolymer has a higher ionic conductivity and a slightly lower electronic conductivity. Entropic potential measurements during battery cycling revealed consistent trends during delithiation for all of the binders, indicating that the binders did not modify the expected NCA solid solution deintercalation process. The entropic signature of polymer doping to form the conductive state could be clearly observed at potentials below NCA oxidation, however. Operando isothermal calorimetric measurements showed that the conductive binders resulted in less Joule heating compared to PVDF and that the net electrical energy was entirely dissipated as heat. In a comparison of the two conjugated polymer binders, the heat dissipation was lower for the homopolymer binder at lower C-rates, suggesting that electronic conductivity rather than ionic conductivity was the most important for reducing Joule heating at lower rates, but that ionic conductivity became more important at higher rates.

Design and Analysis of a Net Zero Electrical Energy Building in Beirut - Lebanon

Design and Analysis of a Net Zero Electrical Energy Building in Beirut - Lebanon

Spontaneous electrochemical uranium extraction from wastewater with net electrical energy production

Spontaneous electrochemical uranium extraction from wastewater with net electrical energy production

Enhancement of proton exchange membrane fuel cell net electric power and methanol-reforming performance by vein channel carved into the reactor plate

A prospective small power system that uses fuel from a small reactor to turn methanol into hydrogen is a proton exchange membrane (PEM) fuel cell (FC). This article examines the fuel conversion ability of the small methanol steam reformer (MSR) creating different vein channels with varying widths and angles on the reactor plate and PEMFC net electric power at various heated temperatures. For each channel, the catalyst quantity remains the same. The maximum hydrogen yield is 92.44%, methanol conversion 0.01187 kmole ⋅ m−3, and cell net electric power 133.86 W. The augmentation of hydrogen yield and methanol conversion from the innovative SR reactor by the vein channel of width 1.25 mm and angle 120° achieves 84.32% and 29.52% compared to the parallel-channel SR reactor under Twall of 250 °C. The novel SR reactor, having a vein channel with a width of 1.5 mm and an angle of 90°, acquires 29.09% compared to the parallel-channel SR reactor in PEM fuel cell net electric power under Twall of 250 °C, allowing low CO exhaust. The findings show that the novel SR reactor with a venous channel enhances the net electrical energy conversion of MSR and PEM fuel cells.

4E analysis of the cryogenic CO2 separation process integrated with waste heat recovery

Carbon dioxide capture, utilization, and storage (CCUS) is an attractive method to reduce carbon dioxide (CO2) emissions originating from fossil fuels burned from large single-point sources. CO2 separation from a CO2-laden gas stream is the first stage of CCUS. In this investigation, a cryogenic distillation-based CO2 separation process (CCSP) is developed. CCSP is modified to utilize waste heat obtained in the process for reducing the energy consumption of CO2 separation. Two modifications are carried out in the process which include (i) heat integration (HI) with CCSP (CCSP + HI) of the reboiler with the heat from hot streams available in the process and further, (ii) energy recovery by using the organic Rankine cycle (ORC) operating between gas compressor temperature and ambient temperature (CCSP + HI + ORC). The parametric and 4 E (energy, exergy, economic, and environmental) analysis results obtained for the CCSP + HI, CCSP + ORC, and CCSP + HI + ORC processes are compared with those of CCSP. The net electrical energy required to operate the compressor for CCSP is 2.7%, 7%, and 21.8% higher than that for CCSP + HI, CCSP + ORC, and CCSP + HI + ORC, respectively.

Helium production and material damage rate assessment in EU DEMO HCPB divertor

EU DEMO should be the first demonstrative fusion power plant, and it is expected to show that net electric energy can be produced and supplied to the grid. The availability and lifetime of the plant will be comparable to that of a commercial fusion power plant. The capacity to provide considerable net electric power safely and continuously to the grid (from 100 MW to 500 MW) is one of DEMO's significant purposes. The neutrons cause defects, leading to the transmutation of elemental atoms when interacting with the divertor component materials. These reactions produce gases, notably helium, which can induce material swelling and embrittlement. In this paper, the DPA and helium production in divertor has been assessed, mainly focusing on the structural material: EUROFER. Helium production rates reach around 117 appm/fpy as the peak, while DPA values reach about 4 dpa/fpy as the maximum value. These calculations were performed using the MCNP6 code with FENDL 3.2 nuclear data and the ADVANTG tool.

Electrical and thermal performance analysis of photovoltaic module having evaporating surface for cooling

This paper presents a method of water evaporative cooling for a photovoltaic module, particularly the floating type, to reduce the module temperature, thereby enhancing its electrical energy performance. An experimental test was performed by attaching a hydrophilic pad made of polypropylene mixed with synthetic fiber at the rear surface of a 320 Wp mono-crystalline module with an aperture area of 1.94 m2. A small pump supplied feed water through the pad at various flow rates and inlet water temperatures. The module faced south with an 18° inclination and was installed at Chiang Mai, Thailand. A set of heat and mass transfer models was developed to investigate the module temperature and the electrical power generated from the module. The simulated results conformed with the experimental data, and over 90 % of the data were within ± 10% deviation. Using the cooling technique, the maximum photovoltaic module temperature on a clear sky day could be reduced from 73.2 °C in the case of a normal unit to approximately 46 °C, and a 10% increase in total generated electrical power could be obtained. Moreover, a higher feed water flow rate and lower feed water temperature resulted in a higher photovoltaic module performance. The models were also used to investigate the monthly net electrical energy generated by the photovoltaic module, both with and without evaporative cooling. Evidently, the concept of evaporative cooling yielded high benefits during the summer period. An approximately 6.5%–11.1% increase in net electrical energy could be obtained compared to the electrical energy generated from the unit without an evaporating surface when the inlet feed water temperature was between 20–30 °C.

Performance analysis of a hybrid aircraft propulsion system using solid oxide fuel cell, lithium ion battery and gas turbine

A novel integration of a solid oxide fuel cell (SOFC), lithium ion batteries and a gas turbine propulsion system is proposed for a hybrid electric aircraft. Methane as hydrogen storage medium is fed to the propulsion system so as to avoid the limitations associated with the use of pure hydrogen storage and utilization. An internal reformer is used in the SOFC to produce hydrogen through the steam reforming and water–gas-shift reactions of the methane and steam mixture. An afterburner is used to generate the heat required for generation of electrical power in the gas turbine and preheating the SOFC reactants by burning the remaining fuel from the SOFC. Also, a pathway for liquid water input to the hybrid system is designed in a way to first circulate through the lithium ion batteries to remove generated heat from them before it is used in the remainder of system. The variations of heat generation rate and temperature of the battery with time are predicted through electrochemical and thermal models. A performance assessment of the proposed propulsion system is conducted to investigate the compatibility and applicability of the system. It is found that at 1C (charge/discharge rate of battery), the average temperature of the lithium ion battery is maintained at about 28 °C through a water-based cooling process. The optimum net electrical power output and energy efficiency of the hybrid propulsion system are achieved at compressor pressurization ratio of 7.5. Furthermore, the net electrical power produced and energy efficiency of the hybrid propulsion system reach their maximum values (i.e., 6.6 × 106 W and 46.5 %, respectively) at a SOFC temperature of 775 °C.

Life Cycle Analysis of Thin-Film Photovoltaic Thermal Systems for Different Tropical Regions

Different energy solutions are required to satisfy the energy demand of the world’s ever-growing population. Photovoltaic Thermal systems (PVT) could propose resolutions to tackle real-time issues regarding power generation. Life Cycle Analysis (LCA) is performed to compare the environmental impact and measure the energy across different PVT modules consisting of a-Si, CdTe, and CIS thin-film solar cells. The authors performed LCA to calculate the energy payback time (EPBT) and life-cycle CO2 emissions of residential rooftop and open-field PVT systems. The primary energy needed to produce thin-film PVT modules of 1 m2 cell area was considered in the present life cycle analysis studies operated using water as the working fluid. The annual net electrical energy savings at various Indian weather conditions, such as New Delhi, Jodhpur, and Ladakh, have been calculated. For the thin-film PVT systems, the calculated values of annual energy yield for three locations with average solar radiation levels and peak sun hours in the range of 600–1000 W/m2 and 6–8 h were reported. Results show that the CO2 emissions for rooftop installation of CdTe and CIS are around 200 and 156 kg/annually, which is lower than the open field installation of the same, where CO2 emissions were found to be 295 and 250 kg/year.

Homogenization of Winding Pack Properties for the Structural Analysis of Fusion Magnets

As the experimental ITER fusion reactor faces its final construction phase, design activities of the next reactor DEMO that will supply net electrical energy to the grid are being conducted in Europe. DEMO will be significantly larger than ITER, and its magnet system will be key to confine the plasma and control its shape. In particular, the Toroidal Field (TF) Coils are necessary to generate the closed toroidal field lines that confine the plasma in a tokamak fusion reactor. The interaction of the current in these coils with the magnetic field produced by the poloidal magnet system induces out-of-plane forces that make a three-dimensional structural assessment of the TF magnet structure unavoidable. Moreover, Poloidal Field (PF) Coils are supported by the TF Coil casings and are to be included in the analysis of a global model of the magnet system. Nevertheless, due to the fact that Winding Packs (WP) in Fusion magnet coils are heterogeneous and rather complex structures, accounting for a detailed model of the WP with a fine mesh in a 3-D analysis of the magnet system can become extremely costly. Homogenization techniques are therefore commonly used to model the WP by means of a uniform elastic block with orthotropic thermo-mechanical properties. Several techniques exist for this purpose and a variety of approaches are in use in the fusion magnet community yielding different values for the effective properties. This work describes homogenization techniques stemming from an energetic criterion that forces equal stored elastic energy in the heterogeneous structure and in the homogenized volume and presents a comparison between them with the goal to contribute to the founded standardization of the structural analysis procedures in the fusion magnet field, with special emphasis in the challenging DEMO magnet coils. The mentioned standardizations are crucial if the design and construction of Fusion Magnets are to become widespread activities in the future.

Energy matrices evaluation of a conventional and modified partially covered photovoltaic thermal collector

Partially covered photovoltaic thermal collector (PVT-C) unit has the capability of generating high thermal energy/exergy and a meaningful electrical energy. This study is aimed to modify the traditional unit of PVT-C to improve energy, exergy, and electrical energy generation capability by replacing a flat absorber plate with a wavy absorber plate. A wavy absorber plate is integrated with the partially covered PVT-C unit (PVT-WPC unit) and compared with the partially covered PVT-C unit having a flat absorber plate (PVT-FPC unit). These two units are compared with the yearly values of overall energy and exergy generation capability at an airflow rate of 0.03 kg/s. This work aims to reveal the viability of the modified unit in terms of energy matrices. The findings reveal that the partially covered PVT-WPC units generate 1%, 10.9%, and 14.9% higher yearly net electrical energy, overall energy, and overall exergy than the partially covered PVT-FPC unit. In terms of yearly overall energy and overall exergy, the partially covered PVT-WPC units have achieved 8.7% and 12.5% lower energy payback time (EPBT) and 10.9% and 14.9% higher CO2 mitigation as compared to the partially covered PVT-FPC unit.

Effect of particle size on thermodynamics and lithium ion transport in electrodes made of Ti2Nb2O9 microparticles or nanoparticles

This study compares the charging mechanisms, thermodynamics, lithium ion transport, and operando isothermal calorimetry in lithium-ion battery electrodes made of Ti2Nb2O9 microparticles or nanoparticles synthesized by solid-state or sol-gel methods, respectively. First, electrochemical testing showed that electrodes made of Ti2Nb2O9 nanoparticles exhibited larger specific capacity, smaller polarization, and better capacity retention at large currents than those made of Ti2Nb2O9 microparticles. Furthermore, potentiometric entropy measurements revealed that electrodes made of either Ti2Nb2O9 microparticles or nanoparticles showed similar thermodynamics behavior governed by lithium intercalation in solid solution, as confirmed by in situ XRD measurements. However, electrodes made of Ti2Nb2O9 nanoparticles featured smaller overpotential and faster lithium ion transport than those made of Ti2Nb2O9 microparticles. In fact, operando isothermal calorimetry revealed smaller instantaneous and time-averaged irreversible heat generation rates at electrodes made of Ti2Nb2O9 nanoparticles, highlighting their smaller resistive losses and larger electrical conductivity. Finally, the measured total heat generation over a charging/discharging cycle matched the measured net electrical energy loss. Overall, Ti2Nb2O9 nanoparticles synthesized by the novel sol-gel method displayed excellent cycling performance and reduced heat generation as a fast-charging lithium-ion battery anode material. These features present major advantages for actual battery systems including larger energy and power densities, simpler thermal management, and enhanced safety.

Subsurface waste heat recovery from the abandoned steam assisted gravity drainage (SAGD) operations

A considerable fraction of the energy injected during the thermal recovery of oil remains in the subsurface and wasted in the surrounding geological formations after the profitable life of oil wells is over. This work studied the concept of thermal energy extraction from the abandoned SAGD operations in oil sands reservoirs for generating electric power. The cold water is injected as a working fluid to extract heat after the oil production is ceased, and the produced hot water is fed to a surface binary cycle to generate electric power. The results show that an oil sands reservoir after SAGD operations could be regarded as an artificial geothermal system suitable for thermal energy extraction. It is demonstrated that a total net electric energy output of 57 GWh could be achieved based on a single SAGD well pair during a ten-year heat-extraction time, indicating the huge heat extraction potential at full field scale. The results show that the thermal energy conversion efficiency to electricity for the abandoned SAGD wells can reach as high as 12%. The demonstrated subsurface waste heat recovery from the abandoned SAGD sites revealed that between 15 and 36% reduction in CO2 emission could be achieved.

Development and experimental testing of an integrated prototype based on Stirling, ORC and a latent thermal energy storage system for waste heat recovery in naval application

This paper focuses on an advanced energy system, able to increase the overall efficiency of ships by recovering the heat wasted by the propulsion system. A small-scale prototype has been realized, developed, and tested under realistic operating conditions of boat during a winter and summer cruise. The main novelty of the research that has been presented in this paper lies in a significant contribution by developing an integrated dynamic device for electrical production and thermal energy storage. It is based on a 1000 cm3 light duty compression ignition engine coupled with a properly adapted Stirling Engine (SE), an Organic Rankine Cycle group (ORC) and a latent Thermal Energy Storage system (TES). All the components have been managed by means of a specifically developed electronic control, simulating two standard cruise profiles. Scaled engine power data have been imposed to simulate port, manoeuvring and open sea navigation phases. The consumption of hot water has been obtained by considering the typical hourly use profile of a cruise ship.It has been demonstrated that the proposed integrated system allows recovering all the thermal energy needed to satisfy the hot water request during the cruise, avoiding the use of auxiliary boilers. The results indicate a favourable effect because the recovered thermal energy represents the 7.7 % of the total energy consumed by fuel. The net electrical energy generated by ORC and Stirling engine resulted to be about 1 % of the total fuel energy consumption, respectively 0.8 % and 0.2 %. The developed prototype can be a useful tool in viability analysis and can easily be reproduced for several uses. In conclusion, the integration of different systems with an optimal integration and sizing of the thermal energy storage considerably improve the thermodynamic, economic and environmental results for future clean ships.

Home Energy Management Strategy-Based Meta-Heuristic Optimization for Electrical Energy Cost Minimization Considering TOU Tariffs

It is well documented that both solar photovoltaic (PV) systems and electric vehicles (EVs) positively impact the global environment. However, the integration of high PV resources into distribution networks creates new challenges because of the uncertainty of PV power generation. Additionally, high power consumption during many EV charging operations at a certain time of the day can be stressful for the distribution network. Stresses on the distribution network influence higher electricity tariffs, which negatively impact consumers. Therefore, a home energy management system is one of the solutions to control electricity consumption to reduce electrical energy costs. In this paper, a meta-heuristic-based optimization of a home energy management strategy is presented with the goal of electrical energy cost minimization for the consumer under the time-of-use (TOU) tariffs. The proposed strategy manages the operations of the plug-in electric vehicle (PEV) and the energy storage system (ESS) charging and discharging in a home. The meta-heuristic optimization, namely a genetic algorithm (GA), was applied to the home energy management strategy for minimizing the daily electrical energy cost for the consumer through optimal scheduling of ESS and PEV operations. To confirm the effectiveness of the proposed methodology, the load profile of a household in Udonthani, Thailand, and the TOU tariffs of the provincial electricity authority (PEA) of Thailand were applied in the simulation. The simulation results show that the proposed strategy with GA optimization provides the minimum daily or net electrical energy cost for the consumer. The daily electrical energy cost for the consumer is equal to 0.3847 USD when the methodology without GA optimization is used, whereas the electrical energy cost is equal to 0.3577 USD when the proposed methodology with GA optimization is used. Therefore, the proposed optimal home energy management strategy with GA optimization can decrease the daily electrical energy cost for the consumer up to 7.0185% compared to the electrical energy cost obtained from the methodology without GA optimization.

Role of solar energy in achieving net zero energy neighborhoods

This paper aims at determining and highlighting the role of solar energy in achieving net zero energy status, in various neighborhood archetypes. The neighborhoods considered in this study include small neighborhood units and combinations of these units, designed according to sustainable practices in a North American context. The role of solar energy to fulfill the thermal and electrical energy of the studied neighborhoods is compared to other renewable and alternative energy resources such as wind energy, and waste-based energy. Results show that solar energy can play very significant role in fulfilling all electrical needs, even in high density and highly mixed developments, supplying between 36%-100% of the total electrical energy consumption of individual neighborhood units. Optimal combinations of neighborhood units designed to share excess on-site energy generation, assist in achieving net zero electrical energy status of all combinations, relying on roof integrated PV, on the buildings of these neighborhood combinations. Additional landscape area is required in most of the neighborhoods, especially those with higher residential density, to integrate solar thermal collectors that can fulfill the thermal loads of the neighborhood units. The required land area for thermal collectors’ integration changes significantly among neighborhoods, becoming relatively small as compared to the total land of the neighborhood (maximum of 15%), in large neighborhoods composed of optimal combinations of individual neighborhood units.

Modeling of a hybrid externally fired gas turbine applied to a landfill and green waste management facility

This work discusses the integration of an externally-fired-gas-turbine power plant in a waste disposal facility where municipal solid waste is disposed in a landfill while green waste is pre-treated and selected to be sold as fuel for biomass power plants. The advantages deriving from the in situ green waste biomass conversion using the externally-fired-gas-turbine power plant is simulated using a thermodynamic model implemented in Matlab Simulink. Two different configurations are simulated: a Standard-Externally-Fired-Gas-Turbine (S-EFGT) power plant fuelled with green-waste-derived wood chips and a Hybrid-Externally-Fired-Gas-Turbine (H-EFGT) power plant fuelled with the previous biomass together with landfill gas. Power plant subsystems are modelled through a black box approach. Inputs and outputs of each box are interconnected together to create the overall models. Preliminary simulations were performed for each configuration at the same working fluid flow rate to compare the electrical and thermal efficiency of both power plants. Full scale simulations, considering an existing case study, are then developed. First, energy fluxes and the resulting efficiencies of each configuration are evaluated. Then the techno-economical comparison between the proposed solutions is discussed. Results show a net electrical energy production of 9392 MWh/year with an electrical efficiency of 14.03% for the S-EFGT using about 18,294 ton/year of wood biomass; the H-EFGT energy yield is 25,392 MWh/year with an electrical efficiency of 17.89% using the same biomass consumption and an average flow rate of 1200 Nm3/h of landfill gas. The economic analysis is completed considering the wood biomass sale, the Net Present Value (NPV) analysis showed a payback time of 7 years for the S-EFGT investment and 5.5 years for the H-EFGT one, the NPV value is 1.310.600,00 € and 6.655.792,00 € for the S-EFGT and H-EFGT configuration, respectively.

Thermo-economic analysis and optimization of the very high temperature gas-cooled reactor-based nuclear hydrogen production system using copper-chlorine cycle

An improved very high temperature gas-cooled reactor (VHTR) and copper-chlorine (Cu–Cl) cycle-based nuclear hydrogen production system is proposed and investigated in this paper, in order to reveal the unknown thermo-economic characteristics of the system under variable operating conditions. Energy, exergy and economic analysis method and particle swarm optimization algorithm are used to model and optimize the system, respectively. Parametric analysis of the effects of several key operating parameters on the system performance is conducted, and energy loss, exergy loss, and investment cost distributions of the system are discussed under three typical production modes. Results show that increasing the reactor subsystem pressure ratio can enhance the system's thermo-economic performance, and the total efficiencies and cost of producing compressed hydrogen from nuclear energy are respectively lower and higher than that of generating electricity. When the system operates at the maximum hydrogen production rate of 403.1 mol/s, the system's net electrical power output, thermal efficiency, exergy efficiency, and specific energy cost are found to be 38.77 MW, 39.3%, 41.26%, and 0.0731 $/kW·h, respectively. And when the system's hydrogen production load equals to 0, these values are respectively calculated to be 177.25 MW, 50.64%, 53.29%, and 0.0268 $/kW·h. In addition, more than 90% of the system's total energy losses are caused by condenser and Cu–Cl cycle, and about 50–60% of the system's total exergy destructions occur in VHTR. About 60% and 30% of the system's specific energy cost are respectively caused by the equipment investment and the system operation & maintenance, and the investment costs of VHTR and Cu–Cl plant are the system's main capital investment sources.