Production & Supply Chain
Evaluation of Stability and Catalytic Activity of Ni Catalysts for Hydrogen Production by Biomass Gasification in Supercritical Water
Mar 2019
Publication
Supercritical water gasification is a promising technology for wet biomass utilization. In this paper Ni and other metal catalysts were synthesized by wet impregnation. The stability and catalytic activities of Ni catalysts were evaluated. Firstly catalytic activities of Ni Fe Cu catalysts supported on MgO were tested using wheat straw as raw material in a batch reactor at 723 K and water density of 0.07 cm3/g. Experimental results showed that the order of metal catalyst activity for hydrogen generation was Ni/MgO > Fe/MgO > Cu/MgO. Secondly the influence of different supports on Ni catalysts performance was investigated. The results showed that the order of the Ni catalysts’ activity with different supports was Ni/MgO > Ni/ZnO > Ni/Al2O3 > Ni/ZrO2. Finally the effects of Ni loading and the amount of Ni catalyst addition on hydrogen production and the stability of Ni/MgO catalyst were studied. It was found that serious deactivation of Ni catalyst in the process of supercritical water gasification took place. Even if carbon deposited on the catalyst surface was removed by high temperature calcination and the catalyst was reduced with hydrogen the activity of used catalyst was only partially restored.
Current Status and Development Trend of Wind Power Generation-based Hydrogen Production Technology
Jan 2019
Publication
The hydrogen production technology by wind power is an effective mean to improve the utilization of wind energy and alleviate the problem of wind power curtailment. First the basic principles and technical characteristics of the hydrogen production technology by wind power are briefly introduced. Then the history of the hydrogen production technology is reviewed and on this basis the hydrogen production system by wind power is elaborated in detail. In addition the prospect of the application of the hydrogen production technology by wind power is analyzed and discussed. In the end the key technology of the hydrogen production by wind power and the problems to be solved are comprehensively reviewed. The development of hydrogen production technology by wind power is analyzed from many aspects which provides reference for future development of hydrogen production technology by wind power
Hydrogen Production in the Swedish Power Sector: Considering Operational Volatilities and Long-term Uncertainties
Nov 2020
Publication
With more renewables on the Swedish electricity market while decommissioning nuclear power plants electricity supply increasingly fluctuates and electricity prices are more volatile. There is hence a need for securing the electricity supply before energy storage solutions become widespread. Electricity price fluctuations moreover affect operating income of nuclear power plants due to their inherent operational inflexibility. Since the anticipated new applications of hydrogen in fuel cell vehicles and steel production producing hydrogen has become a potential source of income particularly when there is a surplus supply of electricity at low prices. The feasibility of investing in hydrogen production was investigated in a nuclear power plant applying Swedish energy policy as background. The analysis applies a system dynamics approach incorporating the stochastic feature of electricity supply and prices. The study revealed that hydrogen production brings alternative opportunities for large-scale electricity production facilities in Sweden. Factors such as hydrogen price will be influential and require in-depth investigation. This study provides guidelines for power sector policymakers and managers who plan to engage in hydrogen production for industrial applications. Although this study was focused upon nuclear power sources it can be extended to hydrogen production from renewable energy sources such as wind and solar.
Ultra-clean Hydrogen Production by Ammonia Decomposition
Jan 2016
Publication
A rigorous heterogeneous mathematical model is used to simulate a cascade of multi-stage fixed bed membrane reactors (MSFBMR) with inter-stage heating and fresh sweep gas for the decomposition of ammonia to produce high purity hydrogen suitable for the PEM fuel cells. Different reactor configurations are compared. The comparison between a single fixed bed reactor (FBR) and a single fixed bed membrane reactor (FBMR) shows that the FBMR is superior to the FBR and gives 60.48% ammonia conversion higher than the FBR. However 20.91% exit ammonia conversion obtained by the FBMR is considered to be poor. The FBMR is limited by the kinetics at low temperatures. The numerical results show that the MSFBMR of four beds achieve 100.0% ammonia conversion. It was found that the membrane plays the prime role in the displacement of the thermodynamic equilibrium. The results also show that a linear relationship exists between the number of beds and the feed temperature and a correlation has been developed. A critical point for an effective hydrogen permeation zone has been identified. It is observed that the diffusion limitation is confined to a slim region at the entrance of the reactor. It is also observed that the heat load assumes a maximum inflection point and explanations offered. The results show that the multi-stage configuration has a promising potential to be applied successfully on-site for ultra-clean hydrogen production.
Hydrogen Generation by Photocatalytic Reforming of Potential Biofuels: Polyols, Cyclic Alcohols, and Saccharides
Jan 2018
Publication
We have studied hydrogen gas production using photocatalysis from C2-C5 carbon chain polyols cyclic alcohols and mono and di-saccharides using palladium nanoparticles supported on a TiO2 catalyst. For many of the polyols the hydrogen evolution rate is found to be dictated by the number of hydroxyl groups and available a-hydrogens in the structure. However the rule only applies to polyols and cyclic alcohols while the sugar activity is limited by the bulky structure of those molecules. There was also evidence of ring opening in photocatalytic reforming of cyclic alcohols that involved dehydrogenation and decarbonylation of a CC bond.
The Global Status of CCS 2019: Targeting Climate Change
Dec 2019
Publication
CCS is an emissions reduction technology critical to meeting global climate targets. The Global Status of CCS 2019 documents important milestones for CCS over the past 12 months its status across the world and the key opportunities and challenges it faces. We hope this report will be read and used by governments policy-makers academics media commentators and the millions of people who care about our climate.
Earth-Abundant Electrocatalysts for Water Splitting: Current and Future Directions
Mar 2021
Publication
Of all the available resources given to mankind the sunlight is perhaps the most abundant renewable energy resource providing more than enough energy on earth to satisfy all the needs of humanity for several hundred years. Therefore it is transient and sporadic that poses issues with how the energy can be harvested and processed when the sun does not shine. Scientists assume that electro/photoelectrochemical devices used for water splitting into hydrogen and oxygen may have one solution to solve this hindrance. Water electrolysis-generated hydrogen is an optimal energy carrier to store these forms of energy on scalable levels because the energy density is high and no air pollution or toxic gas is released into the environment after combustion. However in order to adopt these devices for readily use they have to be low-cost for manufacturing and operation. It is thus crucial to develop electrocatalysts for water splitting based on low-cost and land-rich elements. In this review I will summarize current advances in the synthesis of low-cost earth-abundant electrocatalysts for overall water splitting with a particular focus on how to be linked with photoelectrocatalytic water splitting devices. The major obstacles that persist in designing these devices. The potential future developments in the production of efficient electrocatalysts for water electrolysis are also described.
Resource Assessment for Hydrogen Production
Jul 2020
Publication
This analysis was conducted in support of the U.S. Department of Energy's H2@Scale initiative and this report examines the resources required to meet demand for an additional 10 million metric tonnes (MMT) of hydrogen in 2040. The technical potential of hydrogen production from fossil nuclear and renewable energy resources is presented. Updated maps describe the geographical distribution of hydrogen production potential from renewable energy resources. The results conclude that the technical resource availability of domestic energy resources is sufficient to meet an additional 10 MMT of hydrogen demand in 2040 without placing significant pressure on existing resources. While this level of hydrogen demand could result in a significant increase in renewable energy consumption in particular the technical potential of each resource is estimated to be sufficient to meet the demand. Future research to enable the large-scale integration of hydrogen in the U.S. energy and other sectors will include analyzing the geographic distribution of resources in relation to hydrogen demand for a variety of applications. Additional techno-economic analysis is also needed to understand the economic potential of hydrogen in other industries beyond transportation; such analysis is currently being undertaken by a multi-lab project initiated by DOE in 2016. Finally information from techno-economic analyses should be used to continually update and inform R&D targets for energy production hydrogen production and hydrogen utilization technologies.
Heat Recovery from a PtSNG Plant Coupled with Wind Energy
Nov 2021
Publication
Power to substitute natural gas (PtSNG) is a promising technology to store intermittent renewable electricity as synthetic fuel. Power surplus on the electric grid is converted to hydrogen via water electrolysis and then to SNG via CO2 methanation. The SNG produced can be directly injected into the natural gas infrastructure for long-term and large-scale energy storage. Because of the fluctuating behaviour of the input energy source the overall annual plant efficiency and SNG production are affected by the plant operation time and the standby strategy chosen. The re-use of internal (waste) heat for satisfying the energy requirements during critical moments can be crucial to achieving high annual efficiencies. In this study the heat recovery from a PtSNG plant coupled with wind energy based on proton exchange membrane electrolysis adiabatic fixed bed methanation and membrane technology for SNG upgrading is investigated. The proposed thermal recovery strategy involves the waste heat available from the methanation unit during the operation hours being accumulated by means of a two-tanks diathermic oil circuit. The stored heat is used to compensate for the heat losses of methanation reactors during the hot-standby state. Two options to maintain the reactors at operating temperature have been assessed. The first requires that the diathermic oil transfers heat to a hydrogen stream which is used to flush the reactors in order to guarantee the hot-standby conditions. The second option entails that the stored heat being recovered for electricity production through an Organic Rankine Cycle. The electricity produced is used to compensate the reactors heat losses by using electrical trace heating during the hot-standby hours as well as to supply energy to ancillary equipment. The aim of the paper is to evaluate the technical feasibility of the proposed heat recovery strategies and how they impact on the annual plant performances. The results showed that the annual efficiencies on an LHV basis were found to be 44.0% and 44.3% for the thermal storage and electrical storage configurations respectively.
Roadmap to Hybrid Offshore System with Hydrogen and Power Co-generation
Sep 2021
Publication
Constrained by the expansion of the power grid the development of offshore wind farms may be hindered and begin to experience severe curtailment or restriction. The combination of hydrogen production through electrolysis and hydrogen-to-power is considered to be a potential option to achieve the goal of low-carbon and energy security. This work investigates the competitiveness of different system configurations to export hydrogen and/or electricity from offshore plants with particular emphasis on unloading the mixture of hydrogen and electricity to end-users on land. Including the levelized energy cost and net present value a comprehensive techno-economic assessment method is proposed to analyze the offshore system for five scenarios. Assuming that the baseline distance is 10 km the results show that exporting hydrogen to land through pipelines shows the best economic performance with the levelized energy cost of 3.40 $/kg. For every 10 km increase in offshore distance the net present value of the project will be reduced by 5.69 MU$ and the project benefit will be positive only when the offshore distance is less than 53.5 km. An important finding is that the hybrid system under ship transportation mode is not greatly affected by the offshore distance. Every 10% increase in the proportion of hydrogen in the range of 70%–100% can increase the net present value by 1.43–1.70 MU$ which will increase by 7.36–7.37 MU$ under pipeline transportation mode. Finally a sensitivity analysis was carried out to analyze the wind speed electricity and hydrogen prices on the economic performance of these systems.
Computational Intelligence Approach for Modeling Hydrogen Production: A Review
Mar 2018
Publication
Hydrogen is a clean energy source with a relatively low pollution footprint. However hydrogen does not exist in nature as a separate element but only in compound forms. Hydrogen is produced through a process that dissociates it from its compounds. Several methods are used for hydrogen production which first of all differ in the energy used in this process. Investigating the viability and exact applicability of a method in a specific context requires accurate knowledge of the parameters involved in the method and the interaction between these parameters. This can be done using top-down models relying on complex mathematically driven equations. However with the raise of computational intelligence (CI) and machine learning techniques researchers in hydrology have increasingly been using these methods for this complex task and report promising results. The contribution of this study is to investigate the state of the art CI methods employed in hydrogen production and to identify the CI method(s) that perform better in the prediction assessment and optimization tasks related to different types of Hydrogen production methods. The resulting analysis provides in-depth insight into the different hydrogen production methods modeling technique and the obtained results from various scenarios integrating them within the framework of a common discussion and evaluation paper. The identified methods were benchmarked by a qualitative analysis of the accuracy of CI in modeling hydrogen production providing extensive overview of its usage to empower renewable energy utilization.
Production Costs for Synthetic Methane in 2030 and 2050 of an Optimized Power-to-Gas Plant with Intermediate Hydrogen Storage
Aug 2019
Publication
The publication gives an overview of the production costs of synthetic methane in a Power-to-Gas process. The production costs depend in particularly on the electricity price and the full load hours of the plant sub-systems electrolysis and methanation. The full-load hours of electrolysis are given by the electricity supply concept. In order to increase the full-load hours of methanation the size of the intermediate hydrogen storage tank and the size of the methanation are optimised on the basis of the availability of hydrogen. The calculation of the production costs for synthetic methane are done with economics for 2030 and 2050 and the expenditures are calculated for one year of operation. The sources of volume of purchased electricity are the short-term market long-term contracts direct-coupled renewable energy sources or seasonal use of surpluses. Gas sales are either traded on the short-term market or guaranteed by long-term contracts. The calculations show that an intermediate storage tank for hydrogen adjustment of the methanation size and operating electrolysis and methanation separately increase the workload of the sub-system methanation. The gas production costs can be significantly reduced. With the future expected development of capital expenditures operational expenditure electricity prices gas costs and efficiencies an economic production of synthetic natural gas for the years 2030 especially for 2050 is feasible. The results show that Power-to-Gas is an option for long-term large-scale seasonal storage of renewable energy. Especially the cases with high operating hours for the sub-system methanation and low electricity prices show gas production costs below the expected market prices for synthetic gas and biogas.
Life Cycle Assessments on Battery Electric Vehicles and Electrolytic Hydrogen: The Need for Calculation Rules and Better Databases on Electricity
May 2021
Publication
LCAs of electric cars and electrolytic hydrogen production are governed by the consumption of electricity. Therefore LCA benchmarking is prone to choices on electricity data. There are four issues: (1) leading Life Cycle Impact (LCI) databases suffer from inconvenient uncertainties and inaccuracies (2) electricity mix in countries is rapidly changing year after year (3) the electricity mix is strongly fluctuating on an hourly and daily basis which requires time-based allocation approaches and (4) how to deal with nuclear power in benchmarking. This analysis shows that: (a) the differences of the GHG emissions of the country production mix in leading databases are rather high (30%) (b) in LCA a distinction must be made between bundled and unbundled registered electricity certificates (RECs) and guarantees of origin (GOs); the residual mix should not be applied in LCA because of its huge inaccuracy (c) time-based allocation rules for renewables are required to cope with periods of overproduction (d) benchmarking of electricity is highly affected by the choice of midpoints and/or endpoint systems and (e) there is an urgent need for a new LCI database based on measured emission data continuously kept up-to-date transparent and open access.
A Comparison of Steam Reforming Concepts in Solid Oxide Fuel Cell Systems
Mar 2020
Publication
Various concepts have been proposed to use hydrocarbon fuels in solid oxide fuel cell (SOFC) systems. A combination of either allothermal or adiabatic pre-reforming and water recirculation (WR) or anode off-gas recirculation (AOGR) is commonly used to convert the fuel into a hydrogen rich mixture before it is electrochemically oxidised in the SOFC. However it is unclear how these reforming concepts affect the electrochemistry and temperature gradients in the SOFC stack. In this study four reforming concepts based on either allothermal or adiabatic pre-reforming and either WR or AOGR are modelled on both stack and system level. The electrochemistry and temperature gradients in the stack are simulated with a one-dimensional SOFC model and the results are used to calculate the corresponding system efficiencies. The highest system efficiencies are obtained with allothermal pre-reforming and WR. Adiabatic pre-reforming and AOGR result in a higher degree of internal reforming which reduces the cell voltage compared to allothermal pre-reforming and WR. Although this lowers the stack efficiency higher degrees of internal reforming reduce the power consumption by the cathode air blower as well leading to higher system efficiencies in some cases. This illustrates that both stack and system operation need to be considered to design an efficient SOFC system and predict potentially deteriorating temperature gradients in the stack.
Is Hydrogen the Future of Nuclear Energy?
Jan 2008
Publication
The traditionally held belief is that the future of nuclear energy is electricity production. However another possible future exists: nuclear energy used primarily for the production of hydrogen. The hydrogen in turn would be used to meet our demands for transport fuels (including liquid fuels) materials such as steel and fertilizer and peak-load electricity production. Hydrogen would become the replacement for fossil fuels in these applications that consume more than half the world’s energy. Such a future would follow from several factors: (a) concerns about climatic change that limit the use of fossil fuels (b) the fundamental technological differences between hydrogen and electricity that may preferentially couple different primary energy sources with either hydrogen or electricity and (c) the potential for other technologies to competitively produce electricity but not hydrogen. Electricity (movement of electrons) is not fundamentally a large-scale centralized technology that requires centralized methods of production distribution or use. In contrast hydrogen (movement of atoms) is intrinsically a large-scale centralized technology. The large-scale centralized characteristics of nuclear energy as a primary energy source hydrogen production systems and hydrogen storage systems naturally couple these technologies. This connection suggests that serious consideration be given to hydrogen as the ultimate product of nuclear energy and that nuclear systems be designed explicitly for hydrogen production.
Toward Design of Synergistically Active Carbon-Based Catalysts for Electrocatalytic Hydrogen Evolution
Apr 2014
Publication
Replacement of precious catalyst with cost-effective alternatives would be significantly beneficial for hydrogen production via electrocatalytic hydrogen evolution reaction (HER). All candidates thus far are exclusively metallic catalysts which suffer inherent corrosion and oxidation susceptibility during acidic proton-exchange membrane electrolysis. Herein based on theoretical predictions we designed and synthesized nitrogen (N) and phosphorus (P) dual-doped graphene as a non-metallic electrocatalyst for sustainable and efficient hydrogen production. The N and Phetero-atoms could coactivate the adjacent C atom in the graphene matrix by affecting its valence orbital energy levels to induce a synergistically enhanced reactivity toward HER. As a result the dual-doped graphene showed higher electrocatalytic HER activity than single-doped ones and comparable performance to some of the traditional metallic catalysts.
Electrified Hydrogen Production from Methane for PEM Fuel Cells Feeding: A Review
May 2022
Publication
The greatest challenge of our times is to identify low cost and environmentally friendly alternative energy sources to fossil fuels. From this point of view the decarbonization of industrial chemical processes is fundamental and the use of hydrogen as an energy vector usable by fuel cells is strategic. It is possible to tackle the decarbonization of industrial chemical processes with the electrification of systems. The purpose of this review is to provide an overview of the latest research on the electrification of endothermic industrial chemical processes aimed at the production of H2 from methane and its use for energy production through proton exchange membrane fuel cells (PEMFC). In particular two main electrification methods are examined microwave heating (MW) and resistive heating (Joule) aimed at transferring heat directly on the surface of the catalyst. For cases the catalyst formulation and reactor configuration were analyzed and compared. The key aspects of the use of H2 through PEM were also analyzed highlighting the most used catalysts and their performance. With the information contained in this review we want to give scientists and researchers the opportunity to compare both in terms of reactor and energy efficiency the different solutions proposed for the electrification of chemical processes available in the recent literature. In particular through this review it is possible to identify the solutions that allow a possible scale-up of the electrified chemical process imagining a distributed production of hydrogen and its consequent use with PEMs. As for PEMs in the review it is possible to find interesting alternative solutions to platinum with the PGM (Platinum Group Metal) free-based catalysts proposing the use of Fe or Co for PEM application.
Potential and Economic Analysis of Solar-to-Hydrogen Production in the Sultanate of Oman
Aug 2021
Publication
Hydrogen production using renewable power is becoming an essential pillar for future sustainable energy sector development worldwide. The Sultanate of Oman is presently integrating renewable power generations with a large share of solar photovoltaic (PV) systems. The possibility of using the solar potential of the Sultanate can increase energy security and contribute to the development of the sustainable energy sector not only for the country but also for the international community. This study presents the hydrogen production potential using solar resources available in the Sultanate. About 15 locations throughout the Sultanate are considered to assess the hydrogen production opportunity using a solar PV system. A rank of merit order of the locations for producing hydrogen is identified. It reveals that Thumrait and Marmul are the most suitable locations whereas Sur is the least qualified. This study also assesses the economic feasibility of hydrogen production which shows that the levelized cost of hydrogen (LCOH) in the most suitable site Thumrait is 6.31 USD/kg. The LCOH in the least convenient location Sur is 7.32 USD/kg. Finally a sensitivity analysis is performed to reveal the most significant influential factor affecting the future’s green hydrogen production cost. The findings indicate that green hydrogen production using solar power in the Sultanate is promising and the LCOH is consistent with other studies worldwide.
Improved Hydrogen-Production-Based Power Management Control of a Wind Turbine Conversion System Coupled with Multistack Proton Exchange Membrane Electrolyzers
Mar 2020
Publication
This paper deals with two main issues regarding the specific energy consumption in an electrolyzer (i.e. the Faraday efficiency and the converter topology). The first aspect is addressed using a multistack configuration of proton exchange membrane (PEM) electrolyzers supplied by a wind turbine conversion system (WTCS). This approach is based on the modeling of the wind turbine and the electrolyzers. The WTCS and the electrolyzers are interfaced through a stacked interleaved DC–DC buck converter (SIBC) due to its benefits for this application in terms of the output current ripple and reliability. This converter is controlled so that it can offer dynamic behavior that is faster than the wind turbine avoiding overvoltage during transients which could damage the PEM electrolyzers. The SIBC is designed to be connected in array configuration (i.e. parallel architecture) so that each converter operates at its maximum efficiency. To assess the performance of the power management strategy experimental tests were carried out. The reported results demonstrate the correct behavior of the system during transient operation.
Calculation and Analysis of Efficiencies and Annual Performances of Power-to-Gas Systems
Mar 2017
Publication
This paper describes a generic and systematic method to calculate the efficiency and the annual performance for Power-to-Gas (PtG) systems. This approach gives the basis to analytically compare different PtG systems using different technologies under different boundary conditions. To have a comparable basis for efficiency calculations a structured break down of the PtG system is done. Until now there has not been a universal approach for efficiency calculations. This has resulted in a wide variety of efficiency calculations used in feasibility studies and for business-case calculations. For this the PtG system is divided in two sub-systems: the electrolysis and the methanation. Each of the two sub-systems consists of several subsystem boundary levels. Staring from the main unit i.e. the electrolysis stack and/or methanation reactor further units that are required to operate complete PtG system are considered with their respective subsystem boundary conditions. The paper provides formulas how the efficiency of each level can be calculated and how efficiency deviations can be integrated which are caused by the extended energy flow calculations to and from energy users and thermal losses. By this a sensitivity analysis of the sub-systems can be gained and comprehensive goal functions for optimizations can be defined. In a second step the annual performance of the system is calculated as the ratio of useable output and energetic input over one year. The input is the integral of the annual need of electrical and thermal energy of a PtG system depending on the different operation states of the plant. The output is the higher heating value of the produced gas and – if applicable – heat flows that are used externally. The annual performance not only evaluates the steady-state operating efficiency under full load but also other states of the system such as cold standby or service intervals. It is shown that for a full system operation assessment and further system concept development the annual performance is of much higher importance than the steady-state system efficiency which is usually referred to. In a final step load profiles are defined and the annual performance is calculated for a specific system configuration. Using this example different operation strategies are compared.
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