H2 Production Cost Research Articles

Revisiting magnesium oxide to boost hydrogen production via water-gas shift reaction: Mechanistic study to economic evaluation

Herein, we report the use of a MgCeOx-supported Cu (MgCuCe) catalyst with a unique bead structure to augment the water-gas shift (WGS) reaction. The MgCuCe catalyst exhibited an exceptionally high reaction rate of 83 μmol g−1 s‒1 at 300 °C, compared with that without MgO (30 μmol g−1 s‒1). Very few studies have focused on MgO-supported catalysts owing to the reports on the inferior activity of MgO. However, this paper reports unprecedented enhancements by introducing MgO and illustrates the WGS reaction mechanism: (1) numerous defects promoted water dissociation and subsequent associative mechanism; (2) the labile oxygen in MgO participated in redox mechanisms. The hydrogen production cost realized due to the use of the MgCuCe was 0.63 USD/kg H2, which is lower than that achieved by using commercial and CeO2-supported catalysts. This study paves the way for exploiting earth-abundant MgO in developing efficient catalysts and contributes to reducing H2 production costs.

In-Operando Insights on the Hydrogen Evolution Reaction Activity and Stability of Non-Noble Metal Electrocatalysts for Water Electrolysis

Market penetration of proton exchange membrane water electrolysers (PEMWE) as energy conversion technologies in a renewable energy sector would imply, given the 2.3$/Kg H2 production cost aimed by the DoE,1 a drastic decrease in total noble metal electrocatalyst loading. For the state-of-the-art hydrogen evolution reaction (HER) catalyst, platinum, recent targets suggest this limit to be 0.05mgPt/cm2.2 In some applications, like direct photoelectrochemical water splitting, application of any amount of noble metal as a co-catalyst cannot be tolerated at all. Thus, given increasing scarcity of platinum, alternative materials based on earth-abundant non-noble metals represent a significant interest as promising HER catalysts. Among them, transition metal dichalcogenides such as molybdenum disulfide (MoS2) have provided excellent performances, particularly in their cluster-based allotropic structure [Mo3S13]2-.3 Whilst the role of sulfide atoms in the Mo-terminated edges as HER active sites in crystalline MoS2 is well-established, the HER mechanism of [Mo3S13]-based materials is still under debate. Preceded by an electrochemical activation step, operando spectroscopic studies ascribed the active sites to the electrochemically-cleaved S2 2-,4 but other reports have suggested undercoordinated Mo sites to be responsible for the HER activity.5 To date, no study has evaluated the in operando activity and stability of [Mo3S13]-based materials, shown to be intimately dependent on the electrochemical conditioning and electrolyte pH.6 This work devotes to the simultaneous detection of Mo and S species under HER operating conditions in pristine and anchored [Mo3S13]2- clusters to nitrogen-doped carbon nanotubes, by use of our dedicated on-line inductively-coupled plasma mass spectrometry (on-line ICP-MS). Our findings demonstrate, contrary to previous understanding, that the electrochemical activation step is mostly related to Mo dissolution rather than S loss, which is one order of magnitude lower. After such activation, Mo dissolution is significantly mitigated, whereas S dissolution is still observed, with magnitudes dependent on the anchoring material. The overarching picture obtained by such study enabled to shed light on the HER activation mechanism, and demonstrate that the stabilities of these materials are comparable to some Ir-based catalysts. The aforementioned results provide further guidelines to implement non-noble HER metal electrocatalysts in PEMWE.

Techno-economic analysis of H2 energy storage system based on renewable energy certificate

A techno-economic analysis (TEA) was conducted to evaluate the economic profitability and feasibility for a H2 energy storage system using an alkaline and a polymer electrolyte membrane water electrolysis for 1 MW water electrolysis operation. Many economic analysis methods such as itemized cost estimation, profitability analysis using a cumulative cash flow diagram, and uncertainty analysis employing a Monte-Carlo simulation method were utilized to perform a TEA. In particular, a renewable energy certificate (REC) was considered as an additional benefit of a renewable energy use. From itemized cost estimation, respective levelized costs of H2 of 7.21 and 9.19 $ kgH2−1 were obtained for both H2 energy storage systems in an alkaline and a polymer electrolyte membrane water electrolysis by considering current economy situation and therefore it is still difficult to be cost-competitive compared to a commercial H2 production cost. From profitability and uncertainty analysis results, an appropriate REC weight was confirmed in terms of discounted profitability criteria like a discounted payback period, a net present value, a present value ratio, and a discounted cash flow rate of return. In addition, a REC weight was affected on a net present value compared to a REC trading cost fluctuation.

Conceptual feasibility studies for cost-efficient and bi-functional methylcyclohexane dehydrogenation in a membrane reactor for H2 storage and production

As the global trend towards transition to a “hydrogen society” continues to gain momentum, a lot of studies on alternative hydrogen (H2) production methods are on the rise. Among them, methylcyclohexane (MCH) dehydrogenation in a membrane reactor (MR) is reported here as one possible candidate, affording its enhanced H2 yield and a compact design. In this study, techno-economic analysis and carbon footprint analysis (CFA) of MCH dehydrogenation in an MR are carried out to investigate economic and environmental feasibility providing techno-economic and environmental guidelines for realizing it as mature technology. The economic parameters are determined through process simulation using Aspen Plus®, and the unit H2 production costs are obtained for a packed-bed reactor (PBR) and an MR in H2 production capacities of 30, 100, 300, and 700 m3 h−1. The effects of each economic parameter on the unit H2 production cost are identified through sensitivity analysis (SA) and scenario analysis is performed under various conditions to investigate the effects of technical parameters of the membrane, such as the H2 production capacity, temperature, and H2 permeance on the unit H2 production costs. CFA is also performed to investigate the environmental feasibility of MCH dehydrogenation in an MR by considering CO2 emissions at each part.

Techno-economic analysis of thermochemical water-splitting system for Co-production of hydrogen and electricity

The two-step thermochemical metal oxide water-splitting cycle with the state-of-the-art material ceria inevitably produces unutilized high-quality heat, in addition to hydrogen (H2). This study explores whether the ceria cycle can be of greater value by using the excess heat for co-production of electricity. Specially, this technoeconomic study estimates the H2 production cost in a hybrid ceria cycle, in which excess heat produces electricity in an organic Rankine cycle, to increase revenue and decrease H2 cost. The estimated H2 cost from such a co-generation multi-tower plant is still relatively high at $4.55/kg, with an average H2 production of 1431 kg/day per 27.74 MWth tower. Sensitivity analyses show opportunities and challenges to achieving $2/kg H2 through improvements such as increased solar field efficiency, increased revenue from electricity sales, and a decreased capital recovery factor from baseline assumptions. While co-production improves overall system efficiency and economics, achieving $2/kg H2 remains challenging with ceria as the active material and likely will require a new material.

Economic and environmental analysis for PEM water electrolysis based on replacement moment and renewable electricity resources

An environmental issue such as global warming causing series of disasters has been considered as a serious matter, which asks global cooperation, leading the Paris Agreement. As a result, considerable attention has been paid to H2 due to utilization and storage of renewable electricity expected to increase as time passes. A polymer membrane electrolyte (PEM) water electrolysis using renewable electricity generating from bioenergy, geothermal, onshore wind, etc., has been introduced to store electricity in form of H2. For preparing successful H2 society, an economic analysis was conducted considering PEM water electrolyzer cell replacement and renewable electricity resources to figure out economic feasibility. In this study, profitability analysis by drawing discounted cash flow diagram and uncertainty analysis using Monte-Carlo simulation based on itemized cost estimation result were carried out. The results presented that replacement preferred to occur at 2.20 V of max voltage of the PEM water electrolysis cell if electricity price is low and degradation rate is high. Furthermore, H2 selling price has been more influential factor to a net present value (NPV) than renewable electricity price and hydro and onshore wind energies are regarded as promising renewable electricity resources to achieve goal of H2 production cost. Moreover, CO2 footprint analysis was conducted to provide guidelines on the replacement of PEM water electrolysis in terms of environmental aspect.

Renewable methanol synthesis from renewable H2 and captured CO2: How can power-to-liquid technology be economically feasible?

With the growing concern about environmental issues including high CO2 emission, which is the main contributor to global warming resulting in climate change, CO2 utilization technologies have received much attention. Among diverse technologies, renewable methanol synthesis using H2 generated from the water electrolysis and the CO2 captured from various industrial processes as well as the atmosphere has received significant attention. In this context, the technical and economic feasibility analysis of renewable methanol synthesis was conducted in this study. Using a commercial process simulation program, Aspen HYSYS®, parametric studies were conducted to investigate the effects of diverse operating parameters, such as the reaction pressure, temperature, and H2/CO2 ratio, on the technical performance of this process. Under the optimum conditions of 100 bar and 493 K derived from thermodynamic studies, an economic analysis was performed to estimate the unit methanol production costs at different methanol production capacities using itemized cost estimation, sensitivity analysis, and predictive cost analysis. Predictive cost analysis was conducted to determine how the unit methanol production cost could be rendered reasonable compared to the existing one, which indicated that decreasing the renewable H2 production cost as well as increasing in the CO2 tax credit for a methanol production capacity of 100 ton per day would make the renewable methanol synthesis an economically feasible process.

Can Industrial-Scale Solar Hydrogen Supplied from Commodity Technologies Be Cost Competitive by 2030?

Summary Expanding decarbonization efforts beyond the power sector are contingent on cost-effective production of energy carriers, like H2, with near-zero life-cycle carbon emissions. Here, we assess the levelized cost of continuous H2 supply (95% availability) at industrial-scale quantities (∼100 tonnes/day) in 2030 from integrating commodity technologies for solar photovoltaics, electrolysis, and energy storage. Our approach relies on modeling the least-cost plant design and operation that optimize component sizes while adhering to hourly solar availability, production requirements, and component inter-temporal operating constraints. We apply the model to study H2 production costs spanning the continental United States and, through extensive sensitivity analysis, explore system configurations that can achieve $2.5/kg levelized costs or less for a range of plausible 2030 technology projections at high-irradiance locations. Notably, we identify potential sites and system configurations where PV-electrolytic H2 could substitute natural gas-derived H2 at avoided CO2 costs (≤$120/ton), similar to the cost of deploying carbon capture and sequestration.

Techno-economic and environmental assessment of methanol steam reforming for H2 production at various scales

According to global trend of transition to a hydrogen society, needs for alternative hydrogen (H2) production methods have been on the rise. Among them, methanol steam reforming (MSR) in a membrane reactor (MR) has received a great attention due to its improved H2 yield and compact design. In this study, 3 types of economic analysis – itemized cost estimation, sensitivity analysis, and uncertainty analysis – and integrative carbon footprint analysis (iCFA) were carried out to investigate economic and environmental feasibility. Unit H2 production costs of MSR in a packed-bed reactor (PBR) and an MR for various H2 production capacities of 30, 100, 300, and 700 m3 h−1 and CO2 emission rates for both a PBR and an MR in H2 production capacity of 30 m3 h−1 were estimated. Through itemized cost estimation, unit H2 production costs of a PBR and an MR were obtained and scenario analysis was carried out to find a minimum H2 production cost. Sensitivity analysis was employed to identify key economic factors. In addition, comprehensive uncertainty analysis reflecting unpredictable fluctuation of key economic factors of reactant, labor, and natural gas obtained from sensitivity analysis was also performed for a PBR and an MR by varying them both simultaneously and individually. Through iCFA, lowered CO2 emission rates were obtained showing environmental benefit of MSR in an MR.

Ca-Mg-Al-oxide Sorbents Prepared from Hydrotalcite Precursors for CO2 Capture at Realistic Calcium Looping Conditions

The calcium looping (CaL) process, based on the cyclic carbonation/calcination of CaO sorbents, has been widely investigated recently as a potential technique to capture CO2 at reduced energy penalty. This process can be used in facilities such as power plants and produce a concentrated CO2 which is suitable for storage. In recent years, the hydrogen production processes become more important due to the development of sustainable energy. The CaL process can also be combined with reforming process to produce a concentrated stream of H2 >98 vol. % in a single step, which is known as sorption-enhanced reforming (SER) process, reducing the cost of H2 production effectively. The capture capacities and multicycle stabilities of sorbents are crucial in these uses. In this study, a series of CaMgAl oxide materials for CO2 capture, derived from layered-double hydroxides (LDHs), were prepared to test their performances at realistic calcium looping conditions, namely at high CO2 concentration in the calcination stage. A series of materials with different CaMgAl molar ratios were tested at different regeneration temperatures, regeneration times, and in different CO2 concentrations at the regeneration stage to find out the optimal treatment conditions. The multicycle capture capacities of these materials were examined and compared with that of limestone. Materials regenerated for 15 minutes at 930°C and 70∼100% CO2 had good performances. The Ca/Al = 7/1 materials possessed well capture capacity and multicycle stability compared with that of limestone. Addition of magnesium oxide can further improve its performance. In the 40 cycles test, although the initial capture capacity of the CaMgAl material was lower than that of the CaAl materials, because of the better stability of the former, its capture performance was better than that of the CaAl material at the end of the loop. These materials have the potential to be applied in hydrogen production and other related processes in the future.

Rh2S3/N‐Doped Carbon Hybrids as pH‐Universal Bifunctional Electrocatalysts for Energy‐Saving Hydrogen Evolution

AbstractUsing hydrazine oxidation reaction (HzOR) to replace the oxygen evolution reaction is an effective way to decrease the overpotential of the anodic reaction in overall water splitting (OWS), facilitating cost‐effective and safe hydrogen production. Herein, Rh2S3/N‐doped carbon hybrids (Rh2S3/NC) are first reported as novel and efficient bifunctional electrocatalysts for hydrazine‐assisted hydrogen generation over a wide pH range. Specifically, Rh2S3/NC exhibits low overpotentials for the hydrogen evolution reaction (HER) in alkaline (38 mV), neutral (46 mV), and acidic (21 mV) electrolytes, to reach the current density of 10 mA cm−2, and maintains the activities over 70 h. Meanwhile, Rh2S3/NC also displays competitive HzOR performance at all‐pH electrolytes. Thus, serving as a bifunctional electrocatalyst for both HER and HzOR, Rh2S3/NC shows overwhelming‐Pt/C performance in three electrolytes, and can save over 93.3%, 85.2%, and 78.3% energy consumption compared to the corresponding OWS system. Moreover, theoretical calculations confirm that Rh2S3/NC owns low free‐energy changes of the H adsorption and the dehydrogenation of adsorbed NHNH both of which are beneficial to enhance catalytic activity. This work develops a novel bifunctional electrocatalyst with free pH‐dependent condition for the hydrazine‐assisted electrolysis system to furtherly reduce the cost of massive industrial H2 production.

In-Operando Insights on the Hydrogen Evolution Reaction Activity and Stability of Non-Noble Metal Electrocatalysts for Water Electrolysis

Market penetration of proton exchange membrane water electrolysers (PEMWE) as energy conversion technologies in a renewable energy sector would imply, given the 2.3$/Kg H2 production cost aimed by the DoE,1 a drastic decrease in total noble metal electrocatalyst loading. For the state-of-the-art hydrogen evolution reaction (HER) catalyst, platinum, recent targets suggest this limit to be 0.05mgPt/cm2.2 In some applications, like direct photoelectrochemical water splitting, application of any amount of noble metal as a co-catalyst cannot be tolerated at all. Thus, given increasing scarcity of platinum, alternative materials based on earth-abundant non-noble metals represent a significant interest as promising HER catalysts. Among them, transition metal dichalcogenides such as molybdenum disulfide (MoS2) have provided excellent performances, particularly in their cluster-based allotropic structure [Mo3S13]2-.3 Whilst the role of sulfide atoms in the Mo-terminated edges as HER active sites in crystalline MoS2 is well-established, the HER mechanism of [Mo3S13]-based materials is still under debate. Preceded by an electrochemical activation step, operando spectroscopic studies ascribed the active sites to the electrochemically-cleaved S2 2-,4 but other reports have suggested undercoordinated Mo sites to be responsible for the HER activity.5 To date, no study has evaluated the in operando activity and stability of [Mo3S13]-based materials, shown to be intimately dependent on the electrochemical conditioning and electrolyte pH.6 This work devotes to the simultaneous detection of Mo and S species under HER operating conditions in pristine and anchored [Mo3S13]2- clusters to nitrogen-doped carbon nanotubes, by use of our dedicated on-line inductively-coupled plasma mass spectrometry (on-line ICP-MS). Our findings demonstrate, contrary to previous understanding, that the electrochemical activation step is mostly related to Mo dissolution rather than S loss, which is one order of magnitude lower. After such activation, Mo dissolution is significantly mitigated, whereas S dissolution is still observed, with magnitudes dependent on the anchoring material. The overarching picture obtained by such study enabled to shed light on the HER activation mechanism, and demonstrate that the stabilities of these materials are comparable to some Ir-based catalysts. The aforementioned results provide further guidelines to implement non-noble HER metal electrocatalysts in PEMWE.

Formulation of a Low-cost Medium for Improved Cost-effectiveness of Hydrogen Production by Thermococcus onnurineus NA1

Hydrogen has been receiving considerable attention as a clean energy carrier. Thermococcus onnurineus NA1, a hyperthermophilic archaeon, is capable of producing hydrogen using carbon monoxide (CO) in a growth-associated manner, providing a promising platform to upcycle industrial waste gases. In order to improve cost-effectiveness of the biological hydrogen production from carbon monoxide (CO), we developed formulation of a low-cost medium for T. onnurineus 156T by substituting fishmeal and sea salt for yeast extract (YE) and reagentgrade salts, respectively. In serum bottle cultures, hydrogen production by the 156T strain was less than 30% in fishmeal-containing media when compared to that of the YE-containing MM1 medium. However, hydrogen production was increased substantially by adaptive evolution in the fishmeal-sea salt (FMSS) medium. In bioreactor experiments, the resulting strain 156T-FA showed shorter lag phase and 70% higher maximum hydrogen production rate in FMSS medium than the parent strain 156T. Our results showed that the H2 production cost was reduced by ca. 95%, when YE and chemical salts were replaced by fishmeal and sea salt, respectively.

A techno-economic evaluation of the hydrogen production for energy generation using an ethanol fuel processor

The techno-economic analysis of a process to convert ethanol into H2 to be used as a fuel for PEM fuel cells of H2-powered cars was done. A plant for H2 production was simulated using experimental results obtained on monolith reactors for ethanol steam reforming and WGS steps. The steam reforming (Rh/CeSiO2) and WGS (Pt/ZrO2) monolith catalysts remained quite stable during long-term startup/shut down cycles, with no carbon deposition. The H2 production cost was significantly affected by the ethanol price. The monolith catalyst costs contribution was lower than that of conventional reactors. The H2 production cost obtained using the expensive Brazilian ethanol price (0.81 US$/L ethanol) was US$ 8.87/kg H2, which is lower than the current market prices (US$ 13.44/kg H2) practiced at H2 refueling stations in California. This result showed that this process is economically feasible to provide H2 as a fuel for H2-powered cars at competitive costs in refueling stations.

Assessment of the economic potential: COx-free hydrogen production from renewables via ammonia decomposition for small-sized H2 refueling stations

In this paper, techno-economic feasibility assessment on ammonia decomposition as a COx-free H2 production method for a small-scale on-site H2 refueling station with a capacity of 30 m3 h−1 in Korea was conducted to evaluate the feasibility of the proposed process in terms of technical and economic aspects. A robust process simulation model validated by experimental data from a laboratory-scale reactor was developed. Based on the process simulation model, economic feasibility studies were performed in terms of itemized cost estimation, profitability analysis, and sensitivity analysis. The itemized cost estimations showed a reduced unit H2 production cost of 6.27 $ kgH2−1 for 30 m3 h−1 compared to 9.97 $ kgH2−1 for 0.9 m3 h−1 (laboratory). The unit H2 selling price considering both production and dispensing was 9.06 $ kgH2−1, comparable to the current equivalent gasoline cost of 10.65 $ kgH2−1. Different depreciation methods produced slight differences in the net present value, discounted payback period, and present value ratio. For a new depreciation method, the net present value was $318,666, the discounted payback period was 2.24 years, and the present value ratio was 3.35, which confirmed the economic feasibility of this technology. Sensitivity analysis showed that the most important economic factor for the unit H2 production cost was the raw material (ammonia); in addition, the H2 selling price considerably affected the net present value, which critically influenced the profitability of the proposed project.

Development and techno-economic analyses of a novel hydrogen production process via chemical looping

In this work, a novel hydrogen production process (Integrated Chemical Looping Water Splitting “ICLWS”) has been developed. The modelled process has been optimised via heat integration between the main process units. The effects of the key process variables (i.e. the oxygen carrier-to-fuel ratio, steam flow rate and discharged gas temperature) on the behaviour of the reducer and oxidiser reactors were investigated. The thermal and exergy efficiencies of the process were studied and compared against a conventional steam-methane reforming (SMR) process. Finally, the economic feasibility of the process was evaluated based on the corresponding CAPEX, OPEX and first-year plant cost per kg of the hydrogen produced. The thermal efficiency of the ICLWS process was improved by 31.1% compared to the baseline (Chemical Looping Water Splitting without heat integration) process. The hydrogen efficiency and the effective efficiencies were also higher by 11.7% and 11.9%, respectively compared to the SMR process. The sensitivity analysis showed that the oxygen carrier–to-methane and -steam ratios enhanced the discharged gas and solid conversions from both the reducer and oxidiser. Unlike for the oxidiser, the temperature of the discharged gas and solids from the reducer had an impact on the gas and solid conversion. The economic evaluation of the process indicated hydrogen production costs of $1.41 and $1.62 per kilogram of hydrogen produced for Fe-based oxygen carriers supported by ZrO2 and MgAl2O4, respectively - 14% and 1.2% lower for the SMR process H2 production costs respectively.

Alternative production of methanol from industrial CO2

Carbon dioxide valorization into value added products have become subject to much study to reduce industrial CO2 emissions and fossil energy resource consumption. In this context, the purpose of this study is to evaluate and highlight the interest of CO2 conversion into methanol through a complete techno-economic and environmental assessment of the entire process chain. The integrated process, successfully implemented in Aspen Plus®, is designed to treat the CO2 coming from a conventional cement plant. A MEA-based CO2 capture process is considered, and the captured CO2 is then directly sent to the conversion unit for its catalytic conversion. Consequently, combining the two units leads to relevant integrations, especially regarding the reuse of the heat provided by the exothermal methanol reactions for the regeneration of the CO2 capture solvent. An economic assessment is proposed to estimate the operational and investment costs, as well as the net present value, which demonstrates that the economic feasibility strongly depends on electricity and H2 production costs. A Life Cycle Analysis method is finally performed to identify the main environmental hotspots. The underlying process design offers a significant reduction in greenhouse gases (besides other categories) when compared to the conventional fossil production from natural gas.

Deterministic and stochastic economic analysis based on historical natural gas and CO2 allowance prices for steam reforming of methanol

As an appropriate hydrogen supply system for high temperature polymer electrolyte membrane fuel cells, steam reforming of methanol (SRM) is proposed because reformate gas including low quality H2 with some impurities can be directly used as the fuel. In this study, we compare two SRM systems with and without the use of tail gas from pressure swing adsorption and comprehensive economic analysis is performed for the SRM process with the use of tail gas to estimate a unit H2 production cost (CUHP) based on historical data of natural gas and the CO2 allowance prices for Korea, Europe, Western Climate Initiative (WCI), and Regional Greenhouse Gas Initiative (RGGI). From deterministic economic analysis with a H2 production capacity of 700 m3 h−1, the CUHP values are 6.88 $ kgH2−1 for Korea, 6.84 $ kgH2−1 for Europe, 6.50 $ kgH2−1 for WCI, and 6.54 $ kgH2−1 for RGGI, respectively. Furthermore, additional two scenarios, pessimistic and optimistic ones (Scenario 1 and 2, respectively), are investigated to evaluate the current level of CUHP values for H2 production capacities from 30 to 700 m3 h−1. With a Monte-Carlo simulation method, stochastic economic analysis is carried out to predict the ranges of potential CUHP values for each region. The CUHP values for WCI and RGGI show the narrow distributions meaning lower change of CUHP; however, a wide range of distribution for Korea and Europe suggest that there is considerably higher variation, demonstrating the necessity of stochastic uncertainty analysis when assessing the economic feasibility.

A technoeconomic analysis of centralised and distributed processes of ammonia dissociation to hydrogen for fuel cell vehicle applications

Ammonia (NH3) has been proposed as a hydrogen (H2) carrier for energy services in the carbon-constrained future. This paper presents a technoeconomic feasibility study of using NH3 as H2 carrier for fuel cell vehicles (FCVs) applications. Two cases with different scales of anticipated operations: (1) centralised installation (1000 tonnes day−1) and (2) distributed refuelling station (500 kg day−1), were considered. Aspen HYSYS v8.6 was utilised to simulate the processes. The H2 production cost, internal rate of return, payback period and net present value were examined and compared. The results indicate the centralised H2 production is both technically and economically feasible while distributed H2 production, falling foul of economy of scale, is not economically viable. The overall H2 production cost of the centralised H2 production can reach as low as USD 5.50 kg−1 H2 accounting for capital expenditure, operating expenses, and decommissioning costs. The sensitivity analysis shown that the overall H2 production cost is highly sensitive to NH3 price and moderately affected by utility price and various corporate tax rates considered.

Techno-economic assessment of a chemical looping reforming combined cycle plant with iron and tungsten based oxygen carriers

Chemical looping reforming (CLR) is an efficient technology that transforms hydrocarbons into hydrogen (H2) and carbon dioxide (CO2) with the use of an oxygen carrier. The three-reactor CLR (TRCLR) uses natural gas as fuel similar to a conventional steam-methane reforming (SMR) process. In the current study, two of the most suitable oxygen carriers with base metals iron (Fe) and tungsten (W) are investigated. The model of the CLR unit integrated with a combined cycle power plant is developed using Aspen Plus. The results show that the W-based TRCLR plants are 4 %-points more efficient in terms of H2 production efficiency. In terms of electrical efficiency, the Fe-based TRCLR plant produces excess power at an efficiency of 1.6% whereas the W-based plant requires 3% of extra power from the grid. As a result, the Fe-based plant is 2.6 %-points more efficient than the W-based plant in terms of global efficiency. The costs of H2 production for the Fe and W-based plants are estimated to be $1.66/kg and $16.92/kg, respectively. Compared to the SMR process, the cost of H2 production from the Fe-based TRCLR plant is about 31% lower.