Techno-economic and environmental assessment of PEM water electrolysis for green H2 production

School of Energy and Chemical Engineering (Chemical Engineering)With the increased interest in environmental issues, green H2 production technology, which split H2O into H2 and O2, using electricity generated from renewable energy sources, has received much attention to de-carbonize the energy production and to achieve carbon neutrality by 2050. Green H2 is a carbon-free energy carrier, but higher unit H2 production cost from green H2 production owing to the high water electrolysis system price as well as the levelized cost of electricity generated from renewable energy sources than one from grey H2 production (i.e., methane steam reforming without carbon capture and storage), is to be solved for the realization of green H2 society. Therefore, a techno-economic assessment was conducted for green H2 production by polymer electrolyte membrane water electrolysis using electricity generated from solar photovoltaic, onshore wind, and hydropower, to identify the effect of electrochemical parameters on H2 yield, to assess the economic feasibility for current and future level based on process simulation results, and to identify how to make this technology cost-competitive by considering scale-up, technology development of polymer electrolyte membrane water electrolysis system, manufacturing cost reduction by learning-by-doing effect, and the decrease in levelized cost of electricity, increasing in the installed renewable energy capacity, in terms of capital and operating cost reduction in this work. Based on techno-economic analysis results, economic parity analysis on green H2, which is a switching point to be equal or less than unit H2 production cost from green H2 production compared to one from grey H2 production, was performed to investigate when H2 parity can occur and then it can be clearly shown that only green H2 production using solar photovoltaic-based electricity happens to H2 parity in approximately 2040 and 2025, in current and future level, respectively. In addition, life cycle assessment was carried out to identify the environmental impacts such as CO2 emission for global warming, ozone depletion, and fine particular matter formation, for overall green H2 production through SimaPro and find out hot-spot to account for the large portion of total environmental impacts for the entire process. From life cycle assessment results, green H2 production using hydropower-based electricity is higher CO2 emissions than other renewable energy sources (solar photovoltaic and onshore wind) as well as even grey H2 production. Onshore wind is the best candidate as a renewable energy source for electricity generation, in terms of environmental impact. Taken together, the analytic hierarchy process, which is one of the multi-criteria decision analyses, was conducted to determine the appropriate renewable energy source for green H2 production by polymer electrolyte membrane water electrolysis based on different weighted values of techno-economic and environmental results, under determination and uncertainty. From analytic hierarchy process results, it can be shown that onshore wind is the attractive renewable energy source for green H2 production, when considering techno-economic and environmental aspects, simultaneously, although the best alternative should be changed according to the weighted value of criterion. Furthermore, hydropower is the most suitable renewable energy source for green H2 production at the current level, when economic feasibility is the important factor, because the levelized cost of electricity from hydropower is cheaper than others at the current level, resulting in the lower unit H2 production cost. However, the higher levelized cost of electricity due to the lower installed hydropower capacity as well as environmental issues can lead to the worst alternative to the renewable energy source for green H2 production at the future level. In the same way, relatively higher CO2 emission can result in the second alternative for solar photovoltaic, when considering high weighted values of environmental criterion, although green H2 production using solar photovoltaic-based electricity has the lowest unit H2 production cost in the future. Therefore, techno-economic analysis, as well as environmental impact assessment results, should be taken into account, simultaneously, to determine the most appropriate renewable energy source for green H2 production by polymer electrolyte membrane water electrolysis.ope

Concept for Temperature-Cascade Hydrogen Release from Organic Liquid Carriers Coupled with SOFC Power Generation

For a sustainable hydrogen economy, large-scale transportation and storage of hydrogen becomes increasingly important. Typically, hydrogen is compressed or liquified, but both processes are energy intensive. Liquid organic hydrogen carriers (LOHCs) present a potential solution for mitigating these challenges while making use of the existing fossil fuel transportation infrastructure. Here, we present a process intensification strategy for improved LOHC dehydrogenation and an example of clean power generation using solid oxide fuel cells. Four LOHC candidates???ammonia, biphenyl-diphenylmethane eutectic mixture, N-phenylcarbazole, and N-ethylcarbazole???have been compared as stand-alone and integrated systems using comprehensive process simulation. ???Temperature cascade??? dehydrogenation was shown to increase the energy generated per unit mass (kWh/kg LOHC) by 1.3???2 times in an integrated system compared to stand-alone LOHC systems, thus providing a possibility for a positive impact on a LOHC-based hydrogen supply chain. ?? 2020 The Author(s)Liquid organic hydrogen carriers (LOHCs) are a potentially safer alternative to conventional hydrogen storage processes. Here, Brigljevi?? et al. select four similar LOHC compounds and exploit differences in their physical chemistry, presenting the concept of a temperature-cascading process for a more energy-efficient dehydrogenation. ?? 2020 The Author(s

When Bigger Is Not Greener: Ensuring the Sustainability of Power- to-Gas Hydrogen on a National Scale

As the prices of photovoltaics and wind turbines continue to decrease, more renewable electricity-generating capacity is installed globally. While this is considered an integral part of a sustainable energy future by many nations, it also poses a significant strain on current electricity grids due to the inherent output variability of renewable electricity. This work addresses the challenge of renewable electricity surplus (RES) utilization with target-scaling of centralized power-to-gas (PtG) hydrogen production. Using the Republic of Korea as a case study, due to its ambitious plan of 2030 green hydrogen production capacity of 0.97 million tons year-1, we combine predictions of future, season-averaged RES with a detailed conceptual process simulation for green H2 production via polymer electrolyte membrane (PEM) electrolysis combined with a desalination plant in six distinct scale cases (0.5-8.5 GW). It is demonstrated that at scales of 0.5 to 1.75 GW the RES is optimally utilized, and PtG hydrogen can therefore outperform conventional hydrogen production both environmentally (650-2210 Mton CO2 not emitted per year) and economically (16-30% levelized cost reduction). Beyond these scales, the PtG benefits sharply drop, and thus it is answered how much of the planned green hydrogen target can realistically be if on an industrial scale

Melatonin Synergizes with Sorafenib to Suppress Pancreatic Cancer via Melatonin Receptor and PDGFR-β/STAT3 Pathway

Background/Aims: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignant tumors with poor prognosis. Conventional chemotherapies including gemcitabine have failed owing to weak response and side effects. Hence novel treatment regimens are urgently needed to improve the therapeutic efficacy. In this study, we aimed to assess the anticancer activity of melatonin and sorafenib as a novel therapy against PDAC. Methods: We used various apoptosis assay and PDAC xenograft model to assess anticancer effect in vitro and in vivo. We applied phospho-receptor tyrosine kinase (RTK) array and phospho-tyrosine kinase array to explore the mechanism of the combined therapy. Western blotting, proximity ligation assay, and immunoprecipitation assay were also performed for validation. Results: Melatonin synergized with sorafenib to suppress the growth of PDAC both in vitro and in vivo. The effect was due to increased apoptosis rate of PDAC cells that was accompanied by mitochondria dysfunction. The enhanced anticancer efficacy by the co-treatment could be explained by blockade of PDGFR-β/STAT3 signaling pathway and melatonin receptor (MT)-mediated STAT3. Conclusions: Melatonin reinforces the anticancer activity of sorafenib by downregulation of PDGFR-β/STAT3 signaling pathway and melatonin receptor (MT)-mediated STAT3. The combination of the two agents might be a potential therapeutic strategy for treating PDAC

ARTREA : A Korean Art Website

With over 500 museums and galleries in South Korea, the Korean art market is established and growing rapidly. In addition to Seoul, which is arguably, the cultural heart of Korean art, Daegu, Gwangju, and Jeju Island are transforming into art-centric places. While the Korean art market size has increased significantly, some issues such as the lack of exhibition information, are still hindering the accessibility of the audience. ARTREA will become the fastest and most accurate Korean art information delivery platform. ARTREA will be an ‘all-in-one’ website integrating Korean art exhibition listings, artists, art news, and art jobs. It will expand the South Korean art market to support more domestic artists. ARTREA will then be the largest platform for collecting, discovering, and archiving Korean art, targeting not only South Korea, but also those located internationally with an appreciation for Korean art. ARTREA will host all art institutions in South Korea – around 500 art galleries, 14 auction houses, 49 art fairs, and 230 art museums. The platform will feature Korea’s leading galleries, museums, collections, foundations, artist estates, art fairs, and auctions. It will function as an essential online database for Korean artists of historical, modern and contemporary styles. As a repository, ARTREA will be a significant domestic resource. To appeal to the global market, ARTREA will also provide opportunities for international representation. For instance, a Korean artist’s exhibition situated in New York would be promoted, exposing the consumer to global viewing and purchase opportunities

Numerical modeling studies for a methane dry reforming in a membrane reactor

Numerical modeling studies have been performed for a methane dry reforming using a shell and tube type packed-bed reactor and a membrane reactor both with a heating tube as heat source in the center of a reactor. Mathematical models for a reformer bed, a heating tube, and an insulating jacket coupled with reaction kinetics were proposed to investigate axial and radial temperature and concentration profiles within both reactors with a reformer temperature of 923 K and heating tube temperatures from 1023 to 1223 K. 3-D visualizations of temperature, CH4 conversion, CH4 concentration, and H-2 concentration profiles were possible by COMSOL Multiphysics modeling software and significant variations within both reactors were observed providing a critical guideline for an efficient reactor design. Further studies for the effect of hydrogen mass flux on a hydrogen yield enhancement revealed that a threshold hydrogen mass flux in a membrane reactor to outperform a packed-bed reactor exists with a trend of a lower threshold hydrogen mass flux for a higher heating tube temperature

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For a natural gas steam reforming, comparative studies of the performance in a conventional packed-bed reactor and a membrane reactor, a new conceptual reactor consisting of a reactor with series of hydrogen separation membranes, have been performed. Based on experimental kinetics reported by Xu and Froment, a process simulation model was developed with Aspen HYSYSⓇ, a commercial process simulator, and effects of various operating conditions like temperature, H2 permeance, and Ar sweep gas flow rate on the performance in a membrane reactor were investigated in terms of reactant conversion and H2 yield enhancement showing improved H2 yield and methane conversion in a membrane reactor. In addition, a preliminary cost estimation focusing on natural gas consumption to supply heat required for the system was carried out and feasibility of possible cost savings in a membrane reactor was assessed with a cost saving of 10.94% in a membrane reactor

Parametric studies for CO2 reforming of methane in a membrane reactor as a new CO2 utilization process

A one-dimensional reactor model was employed to perform parametric studies for CO2 reforming of methane in a membrane reactor to investigate its feasibility as a new CO2 utilization process. The effect of key variables such as hydrogen permeance and Ar sweep gas flow rate to facilitate H-2 transport from a shell side (retentate) to a tube side (permeate) on the performance in a membrane reactor was studied at various temperatures with numerical simulation validated by experimental results. In addition, increase in CH4 conversion and H-2 yield enhancement observed in membrane reactor was successfully confirmed by profiles of H-2 partial pressure difference between shell and tube sides. From the numerical simulation studies, the feasibility of using a membrane reactor for CO2 reforming of methane was confirmed by increased CH4 conversion and H-2 yield enhancement compared to a packed-bed reactor at the same condition, which in turn leads to significant cost reductions due to a reduced operating temperature. Moreover, a window of H-2 permeance and a guideline for Ar sweep gas flow rate for the efficient membrane reactor design was obtained from this study

Sustainable and carbon-neutral green diesel synthesis with thermochemical and electrochemical approach: Techno-economic and environmental assessments

In this work, techno-economic and environmental assessments were conducted for green diesel production. In particular, two green diesel production pathways through thermochemical and electrochemical processes, which have different syngas production methods, were covered to evaluate the sustainability in terms of economic and environmental perspectives. The process modeling was performed for three cases, classifying cases according to the component composition, and verified by comparing the physical properties of conventional diesel and green diesel produced from syngas. From process modeling results, case 2 has the most relevant properties of conventional diesel showing the potential for alternative diesel fuel. With the process modeling results, cost estimation was carried out to calculate the current unit diesel production costs for three scenarios (according to the renewable energy sources); 0.0507, 0.0647, and 0.0547 $MJ(-1) via the thermochemical process and 0.0477, 0.0606, and 0.0514$ MJ(-1) through the electrochemical process for hydropower, solar PV, and onshore wind, respectively, showing the infeasibility due to the lower conventional ones (0.0164-0.0276$ MJ(-1)). To make the green diesel production attractive, uncertainty analysis and projected cost analysis were conducted to obtain the possible cost ranges due to the cost fluctuations of key economic parameters and the estimated unit diesel production cost in 2030, with the projected levelized cost of electricity by 2030 and learning rates by cumulative production of H2 and CO demands. Moreover, environmental assessment should be performed to identify whether the green diesel production is more eco-friendly or not than conventional one, by considering direct emission and indirect one emitted from energy consumption. From environmental assessment results, lower CO2 emissions can be investigated according to the renewable energy sources for green diesel production and the electrochemical green diesel production with onshore wind has the lowest CO2 emission among all scenarios covered in this work

Techno-economic analysis for CO2 reforming of a medium-grade landfill gas in a membrane reactor for H-2 production

In this paper, we report techno-economic analysis for CO2 reforming of a medium-grade landfill gas in a membrane reactor (MR) for a H-2 production capacity of 7 m(3) h(-1) in Korea. Parametric studies for the effect of key operating conditions like a H-2 permeance, a H2O sweep gas flow rate, and temperature on the performance in a conventional packed-bed reactor (PBR) and a MR were conducted using Aspen HYSYSe, a commercial process simulator. Based on process simulation studies, economic analysis was carried out to find a unit H-2 production cost for both a PBR and a MR. Respective unit H-2 production costs of 9.72 and 6.46 $ kgH(2)(-1) were obtained for a PBR and a MR showing about 34% reduction in the MR. Sensitivity analysis was employed to identify key economic factors to determine a unit H-2 production cost with labor the most influential factor for both reactors. Probability analysis (PA) was performed with influential factors based on a Monte-Carlo simulation method as uncertainty analysis and a cumulative probability (CP) curve was created for a PBR and a MR under various discount rates from 2 to 10% and key factor ranges from +/- 10 to +/- 40%. PA using stochastic approach provided a wide range of a unit H-2 production cost coupled with its probability and a critical CP value at which the effect of key factor range on a unit H-2 production cost was reversed