China, People’s Republic
Resource Assessment for Green Hydrogen Production in Kazakhstan
Jan 2023
Publication
Kazakhstan has long been regarded as a major exporter of fossil fuel energy. As the global energy sector is undergoing an unprecedented transition to low-carbon solutions new emerging energy technologies such as hydrogen production require more different resource bases than present energy technologies. Kazakhstan needs to consider whether it has enough resources to stay competitive in energy markets undergoing an energy transition. Green hydrogen can be made from water electrolysis powered by low-carbon electricity sources such as wind turbines and solar panels. We provided the first resource assessment for green hydrogen production in Kazakhstan by focusing on three essential resources: water renewable electricity and critical raw materials. Our estimations showed that with the current plan of Kazakhstan to keep its water budget constant in the future producing 2–10 Mt green hydrogen would require reducing the water use of industry in Kazakhstan by 0.6–3% or 0.036–0.18 km3/year. This could be implemented by increasing the share of renewables in electricity generation and phasing out some of the water- and carbon-intensive industries. Renewable electricity potential in South and West Kazakhstan is sufficient to run electrolyzers up to 5700 and 1600 h/year for wind turbines and solar panels respectively. In our base case scenario 5 Mt green hydrogen production would require 50 GW solar and 67 GW wind capacity considering Kazakhstan's wind and solar capacity factors. This could convert into 28652 tons of nickel 15832 tons of titanium and many other critical raw materials. Although our estimations for critical raw materials were based on limited geological data Kazakhstan has access to the most critical raw materials to support original equipment manufacturers of low-carbon technologies in Kazakhstan and other countries. As new geologic exploration kicks off in Kazakhstan it is expected that more deposits of critical raw materials will be discovered to respond to their potential future needs for green hydrogen production.
A Study of Thermoelectric Generation Coupled with Methanol Steam Reforming for Hydrogen Production
Nov 2022
Publication
Waste heat recovery was considered as a promising candidate for energy conservation and emission reduction. Methanol steam reforming was considered to be an effective means for hydrogen production because of its advantages. In this work a micro reactor was constructed and thermoelectric generation coupled with hydrogen production from methanol steam reforming was innovatively used to recycle waste heat which was simulated by hot air from a hot air gun. The waste heat was converted into electricity and hydrogen at the same time. The characteristic of thermoelectric generation coupled with methanol steam reforming was investigated. It was experimentally verified that both the hydrogen production rate and methanol conversion increased with the increasing inlet temperature but thermal efficiency increased firstly and then decreased with the increasing temperature. The methanol steam reforming could effectively maintain cold side temperature distribution of thermoelectric generation. In the case of the thermoelectric module (1) the highest temperature difference of 37 ◦C was determined and the maximum open circuit voltage of 2 V was observed. The highest methanol conversion of 64.26% was achieved at a space velocity of 0.98 h−1 when the temperature was 543 K comprehensively considering the CO content and thermal efficiency.
Solid Air Hydrogen Liquefaction, the Missing Link of the Hydrogen Economy
Mar 2023
Publication
The most challenging aspect of developing a green hydrogen economy is long-distance oceanic transportation. Hydrogen liquefaction is a transportation alternative. However the cost and energy consumption for liquefaction is currently prohibitively high creating a major barrier to hydrogen supply chains. This paper proposes using solid nitrogen or oxygen as a medium for recycling cold energy across the hydrogen liquefaction supply chain. When a liquid hydrogen (LH2) carrier reaches its destination the regasification process of the hydrogen produces solid nitrogen or oxygen. The solid nitrogen or oxygen is then transported in the LH2 carrier back to the hydrogen liquefaction facility and used to reduce the energy consumption cooling gaseous hydrogen. As a result the energy required to liquefy hydrogen can be reduced by 25.4% using N2 and 27.3% using O2. Solid air hydrogen liquefaction (SAHL) can be the missing link for implementing a global hydrogen economy.
Distinct facets to enhance the process of hydrogen production via methanol steam reforming—A review
Jan 2022
Publication
Methanol steam reforming manifests great potential for generating hydrogen owing to its lower reaction temperature (200–300 °C) and higher hydrogen/carbon ratio comparing with ethanol and methane reforming. In this case methanol steam reforming is applied in various renewable energy systems to assist the energy conversion and improve the system efficiency. The performance of methanol steam reforming reaction strongly depends on the catalysts and reactor structure. In this paper the development of the copper-based the noble metal–based and the nanomaterial catalysts were summarized by analyzing the effects of different modification methods which indicates that cutting the cost and simplifying the manufacturing process are the future goal of catalyst modification. Moreover the reaction mechanism of different catalyst type was discussed. For the reactor performance conventional miniature micro and membrane reactors were discussed and compared where conventional reactor with high CO tolerance is more suitable for industrial application while membrane reactor with high H2 purity and compact structure is ideal for fuel cell technology. The integration of the methanol steam reforming system into renewable power systems was reviewed as well. Methanol steam reforming technology is of great potential in exhaust heat recovery cogeneration system and other renewable energy field where more comprehensive research should be performed.
Experimental Investigation of Stress Corrosion on Supercritical CO2 Transportation Pipelines Against Leakage for CCUS Applications
Nov 2022
Publication
Carbon Capture Utilization and Storage (CCUS) is one of the key technologies that will determine how humans address global climate change. For captured CO2 in order to avoid the complications associated with two-phase flow most carbon steel pipelines are operated in the supercritical state on a large scale. A pipeline has clear Stress Corrosion Cracking (SCC) sensitivity under the action of stress and corrosion medium which will generally cause serious consequences. In this study X70 steel was selected to simulate an environment in the process of supercritical CO2 transportation by using high-temperature high-pressure Slow Strain Rate Tensile (SSRT) tests and high-temperature high-pressure electrochemical test devices with different O2 and SO2 contents. Studies have shown that 200 ppm SO2 shows a clear SCC sensitivity tendency which is obvious when the SO2 content reaches 600 ppm. The SCC sensitivity increases with the increase of SO2 concentration but the increase amplitude decreases. With the help of advanced microscopic characterization techniques such as scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) through the analysis of fracture and side morphology the stress corrosion mechanism of a supercritical CO2 pipeline containing SO2 and O2 impurities was obtained by hydrogen embrittlement fracture characteristics. With the increase of SO2 content the content of Fe element decreases and the corrosion increases demonstrating that SO2 plays a leading role in electrochemical corrosion. This study further strengthens the theoretical basis of stress corrosion of supercritical CO2 pipelines plays an important role in preventing leakage of supercritical CO2 pipelines and will provide guidance for the industrial application of CCUS.
Progress in Energy Storage Technologies and Methods for Renewable Energy Systems Application
May 2023
Publication
This paper provides a comprehensive review of the research progress current state-ofthe-art and future research directions of energy storage systems. With the widespread adoption of renewable energy sources such as wind and solar power the discourse around energy storage is primarily focused on three main aspects: battery storage technology electricity-to-gas technology for increasing renewable energy consumption and optimal configuration technology. The paper employs a visualization tool (CiteSpace) to analyze the existing works of literature and conducts an in-depth examination of the energy storage research hotspots in areas such as electrochemical energy storage hydrogen storage and optimal system configuration. It presents a detailed overview of common energy storage models and configuration methods. Based on the reviewed articles the future development of energy storage will be more oriented toward the study of power characteristics and frequency characteristics with more focus on the stability effects brought by transient shocks. This review article compiles and assesses various energy storage technologies for reference and future research.
Integrated Demand Response Design of Integrated Energy System with Mobile Hydrogen Energy Storage in Time-Domain Two-Port Model
Dec 2022
Publication
With the development of energy integration technology demand response (DR) has gradually evolved into integrated demand response (IDR). In this study for the integrated energy system (IES) on the distribution grid side with electricity heat natural gas network and hydrogen energy equipment the analogy relationship between the thermal and mobile hydrogen energy storage networks is proposed. Moreover a unified model that reflects network commonalities across different energy forms is established. Then considering the time delay of the IES in the nontransient network a time-domain two-port model of the IES considering the time delay is established. This model shows the joint effect of time and space on system parameters. Finally this study validates the model in the application of DR. The verification results show that in DR the time-domain two-port model can accurately “cut peaks and fill valleys” for the IES and effectively reduce the operating cost of the IES system.
Multi-Objective Optimization-Based Health-Conscious Predictive Energy Management Strategy for Fuel Cell Hybrid Electric Vehicles
Feb 2022
Publication
The Energy Management Strategy (EMS) in Fuel Cell Hybrid Electric Vehicles (FCHEVs) is the key part to enhance optimal power distribution. Indeed the most recent works are focusing on optimizing hydrogen consumption without taking into consideration the degradation of embedded energy sources. In order to overcome this lack of knowledge this paper describes a new health-conscious EMS algorithm based on Model Predictive Control (MPC) which aims to minimize the battery degradation to extend its lifetime. In this proposed algorithm the health-conscious EMS is normalized in order to address its multi-objective optimization. Then weighting factors are assigned in the objective function to minimize the selected criteria. Compared to most EMSs based on optimization techniques this proposed approach does not require any information about the speed profile which allows it to be used for real-time control of FCHEV. The achieved simulation results show that the proposed approach reduces the economic cost up to 50% for some speed profile keeping the battery pack in a safe range and significantly reducing energy sources degradation. The proposed health-conscious EMS has been validated experimentally and its online operation ability clearly highlighted on a PEMFC delivery postal vehicle.
Multi-layer Coordinated Optimization of Integrated Energy System with Electric Vehicles Based on Feedback Correction
Sep 2022
Publication
The integrated energy system with electric vehicles can realize multi-energy coordination and complementarity and effectively promote the realization of low-carbon environmental protection goals. However the temporary change of vehicle travel plan will have an adverse impact on the system. Therefore a multi-layer coordinated optimization strategy of electric-thermal-hydrogen integrated energy system including vehicle to grid (V2G) load feedback correction is proposed. The strategy is based on the coordination of threelevel optimization. The electric vehicle charging and discharging management layer comprehensively considers the variance of load curve and the dissatisfaction of vehicle owners and the charging and discharging plan is obtained through multi-objective improved sparrow search algorithm which is transferred to the model predictive control rolling optimization layer. In the rolling optimization process according to the actual situation selectively enter the V2G load feedback correction layer to update V2G load so as to eliminate the impact of temporary changes in electric vehicle travel plans. Simulation results show that the total operating cost with feedback correction is 4.19% lower than that without feedback correction and tracking situation of tie-line planned value is improved which verifies the proposed strategy.
Optimization of High-Temperature Electrolysis System for Hydrogen Production Considering High-Temperature Degradation
Mar 2023
Publication
Solid oxide electrolysis cells (SOECs) have great application prospects because of their excellent performance but the long-term applications of the stacks are restricted by the structural degradation under the high-temperature conditions. Therefore an SOEC degradation model is developed and embedded in a process model of the high-temperature steam electrolysis (HTSE) system to investigate the influence of the stack degradation at the system level. The sensitivity analysis and optimization were carried out to study the influence factors of the stack degradation and system hydrogen production efficiency and search for the optimal operating conditions to improve the hydrogen production efficiency and mitigate the stack degradation. The analysis results show that the high temperature and large current density can accelerate the stack degradation but improve the hydrogen production efficiency while the high temperature gradually becomes unfavorable in the late stage. The low air-to-fuel feed ratio is beneficial to both the degradation rate and hydrogen production efficiency. The results show that the optimization method can improve the hydrogen production efficiency and inhibit the stack degradation effectively. Moreover part of the hydrogen production efficiency has to be sacrificed in order to obtain a lower stack degradation rate.
Optimal Design and Operation of Dual-Ejector PEMFC Hydrogen Supply and Circulation System
Jul 2022
Publication
A proton exchange membrane fuel cell (PEMFC) system requires an adequate hydrogen supply and circulation to achieve its expected performance and operating life. An ejector-based hydrogen circulation system can reduce the operating and maintenance costs noise and parasitic power consumption by eliminating the recirculation pump. However the ejector’s hydrogen entrainment capability restricted by its geometric parameters and flow control variability can only operate properly within a relatively narrow range of fuel cell output power. This research introduced the optimal design and operation control methods of a dual-ejector hydrogen supply/circulation system to support the full range of PEMFC system operations. The technique was demonstrated on a 70 kW PEMFC stack with an effective hydrogen entrainment ratio covering 8% to 100% of its output power. The optimal geometry design ensured each ejector covered a specific output power range with maximized entrainment capability. Furthermore the optimal control of hydrogen flow and the two ejectors’ opening and closing times minimized the anode gas pressure fluctuation and reduced the potential harm to the PEMFC’s operation life. The optimizations were based on dedicated computational fluid dynamics (CFD) and system dynamics models and simulations. Bench tests of the resulting ejector-based hydrogen supply/circulation system verified the simulation and optimization results.
Experimental Study of the Feasibility of In‐Situ Hydrogen Generation from Gas Reservoir
Nov 2022
Publication
Due to there is no better way to exploit depleted gas reservoirs and hydrogen can generate from natural gas combustion. In this paper the possibility of in‐situ hydrogen generation in air injected gas reservoirs was determined through pseudo dynamic experiments. The study indicated that highertemperature and steam/methane ratio can generate more hydrogen and the temperature should not be lower than 600 °C within gas reservoirs. The debris has positive catalysis for hydrogen generation. The maximum mole fraction of hydrogen was 26.63% at 600 °C.
An Integrated Demand Response Dispatch Strategy for Low-carbon Energy Supply Park Considering Electricity-Hydrogen-Carbon Coordination
Apr 2023
Publication
Driven by the goal of ‘carbon peak carbon neutrality’ an integrated demand response strategy for integrated electricity– hydrogen energy systems is proposed for low-carbon energy supply parks considering the multi-level and multi-energy characteristics of campus-based microgrids. Firstly considering the spatial and temporal complementary nature of wind and photovoltaic generation and energy utilization the energy flow framework of the park is built based on the electricity and hydrogen energy carriers. Clean energy is employed as the main energy supply and power heat cooling and gas loads are considered energy consumption. Secondly the operation mechanism of coupled hydrogen storage hydrogen fuel cell and carbon capture equipment is analyzed in the two-stage power-to-gas conversion process. Thirdly considering the operating costs and environmental costs of the park an integrated demand response dispatch model is constructed for the coupled electricity– hydrogen–carbon system while satisfying the system equipment constraints network constraints and energy balance constraints of the park system. Finally Case study in an energy supply park system is implemented. The dispatch results of the integrated demand response with customer participation in the conventional electricity–hydrogen and electricity–hydrogen–carbon modes are compared to verify the effectiveness of the proposed strategy in renewable accommodation environmental protection and economic benefits.
Numerical Investigation on the Flame Structure and CO/NO Formations of the Laminar Premixed Biogas–Hydrogen Impinging Flame in the Wall Vicinity
Nov 2021
Publication
The near-wall flame structure and pollutant emissions of the laminar premixed biogashydrogen impinging flame were simulated with a detailed chemical mechanism. The spatial distributions of the temperature critical species and pollutant emissions near the wall of the laminar premixed biogas–hydrogen impinging flame were obtained and investigated quantitatively. The results show that the cold wall can influence the premixed combustion process in the flame front which is close to the wall but does not touch the wall and results in the obviously declined concentrations of OH H and O radicals in the premixed combustion zone. After flame quenching a high CO concentration can be observed near the wall at equivalence ratios (ϕ) of both 0.8 and 1.2. Compared with that at ϕ = 1.0 more unburned fuel is allowed to pass through the quenching zone and generate CO after flame quenching near the wall thanks to the suppressed fuel consumption rate near the wall and the excess fuel in the unburned gases at ϕ = 0.8 and 1.2 respectively. By isolating the formation routes of NO production it is found that the fast-rising trend of NO concentration near the wall in the post flame region at ϕ = 0.8 is attributed to the NO transportation from the NNH route primarily while the prompt NO production accounts for more than 90% of NO generation in the wall vicinity at ϕ = 1.2. It is thus known that thanks to the effectively increased surface-to-volume ratio the premixed combustion process in the downsized chamber will be affected more easily by the amplified cooling effects of the cold wall which will contribute to the declined combustion efficiency increased CO emission and improved prompt NO production.
Low-Carbon Strategic Planning of Integrated Energy Systems
Mar 2022
Publication
With the rapid promotion of renewable energy technologies and the trend to a low-carbon society the positive impacts of an integrated energy system that realizes various forms of energy-utilizing improvement and carbon reduction have fully emerged. Hydrogen with a decarbonized characteristic being integrated into the integrated energy system has become a viable option to offset the intermittency of renewables and decline the fossil fuel usage. An optimal planning model of a wind–photovoltaic–hydrogen storage-integrated energy system with the objective of total economic and environmental cost minimization by considering various energy technology investments is proposed. Case studies are developed to compare the economic and environmental benefits of different energy investment scenarios especially hydrogen applications. The cost–benefit analysis was carried out to prove that hydrogen investment is not a cost-competitive option but can alleviate the burden of carbon emissions somehow. Finally sensitivity analysis of key parameters of sale capacity carbon tax and renewable penetration level was performed to indicate the rational investment for a wind–photovoltaic–hydrogen storage-integrated energy system.
Optimal Configuration of Multi-Energy Storage in an Electric–Thermal–Hydrogen Integrated Energy System Considering Extreme Disaster Scenarios
Mar 2024
Publication
Extreme disasters have become increasingly common in recent years and pose significant dangers to the integrated energy system’s secure and dependable energy supply. As a vital part of an integrated energy system the energy storage system can help with emergency rescue and recovery during major disasters. In addition it can improve energy utilization rates and regulate fluctuations in renewable energy under normal conditions. In this study the sizing scheme of multienergy storage equipment in the electric–thermal–hydrogen integrated energy system is optimized; economic optimization in the regular operating scenario and resilience enhancement in extreme disaster scenarios are also considered. A refined model of multi-energy storage is constructed and a two-layer capacity configuration optimization model is proposed. This model is further enhanced by the integration of a Markov two-state fault transmission model which simulates equipment defects and improves system resilience. The optimization process is solved using the tabu chaotic quantum particle swarm optimization (TCQPSO) algorithm to provide reliable and accurate optimization results. The results indicate that addressing severe disaster situations in a capacity configuration fully leverages the reserve energy function of energy storage and enhances system resilience while maintaining economic efficiency; furthermore adjusting the load loss penalty coefficients offers a more targeted approach to the balancing of the system economy and resilience. Thus new algorithmic choices and planning strategies for future research on enhancing the resilience of integrated energy systems under extreme disaster scenarios are provided.
The Hydrogen Fuel Cell Battery: Replacing the Combustion Engine in Heavy Vehicles
Nov 2022
Publication
This opinion piece describes how the optimal integration of hydrogen-fuel-cell with battery in a heavy highly-utilised vehicle can extend vehicle range while cutting refuelling time and reducing cost compared to a pure battery electric vehicle.
Deep Decarbonisation Pathways of the Energy System in Times of Unprecedented Uncertainty in the Energy Sector
May 2023
Publication
Unprecedented investments in clean energy technology are required for a net-zero carbon energy system before temperatures breach the Paris Agreement goals. By performing a Monte-Carlo Analysis with the detailed ETSAPTIAM Integrated Assessment Model and by generating 4000 scenarios of the world’s energy system climate and economy we find that the uncertainty surrounding technology costs resource potentials climate sensitivity and the level of decoupling between energy demands and economic growth influence the efficiency of climate policies and accentuate investment risks in clean energy technologies. Contrary to other studies relying on exploring the uncertainty space via model intercomparison we find that the CO2 emissions and CO2 prices vary convexly and nonlinearly with the discount rate and climate sensitivity over time. Accounting for this uncertainty is important for designing climate policies and carbon prices to accelerate the transition. In 70% of the scenarios a 1.5 ◦C temperature overshoot was within this decade calling for immediate policy action. Delaying this action by ten years may result in 2 ◦C mitigation costs being similar to those required to reach the 1.5 ◦C target if started today with an immediate peak in emissions a larger uncertainty in the medium-term horizon and a higher effort for net-zero emissions.
Design of a Multi-inlet Solar Thermochemical Reactor for Steam Methane Reforming with Improved Performance
Feb 2023
Publication
Reactor structure design plays an important role in the performance of solar-thermal methane reforming reactors. Based on a conventional preheating reactor this study proposed a cylindrical solar methane reforming reactor with multiple inlets to vary the temperature field distribution which improved the temperature of the reaction region in the reactor thereby improving the reactor performance. A multi-physical model that considers mass momentum species and energy conservation as well as thermochemical reaction kinetics of methane reforming was applied to numerically investigate the reactor performance and analyze the factors that affect performance improvement. It was found that compared with a conventional preheating reactor the proposed cylindrical reactor with inner and external inlets for gas feeding enhanced heat recovery from the exhausted gas and provided a more suitable temperature field for the reaction in the reactor. Under different operating conditions the methane conversion in the cylindrical reactor with multi-inlet increased by 9.5% to 19.1% and the hydrogen production was enhanced by 12.1% to 40.3% in comparison with the conventional design even though the total reaction catalyst volume was reduced.
Environmental Economical Dispatching of Electric–Gas Integrated Energy System Considering Hydrogen Compressed-Natural Gas
Dec 2022
Publication
As a high-quality secondary energy hydrogen energy has great potential in energy storage and utilization. The development of power-to-hydrogen (P2H) technology has alleviated the problem of wind curtailment and improved the coupling between the power grid and the natural gas grid. Under the premise of ensuring safety using P2H technology to mix the produced hydrogen into the natural gas network for long-distance transmission and power generation can not only promote the development of hydrogen energy but also reduce carbon emissions. This paper presents a new model for incorporating hydrogen into natural gas pipelines. To minimize the sum of wind curtailment cost operation cost and carbon emission cost an electric–gas integrated energy system (EGIES) model of hydrogen-compressed natural gas (HCNG) containing P2H for power generation is constructed. Aiming at the problem of global warming caused by a lot of abandoned wind and carbon emissions the economy and environmental protection of the system model are analyzed. The results show that the model of EGIES considering HCNG can not only absorb excess wind power but also reduce carbon emission costs and system costs which can reduce the total cost of the environmental economic dispatch of the EGIES by about 34.1%. In the context of the EGIES the proposal of this model is of great significance to the economical and environmentally friendly operation of the system.
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