Reduction In Capital Cost Research Articles

Economics and lifecycle carbon assessment of coconut oil as an alternative to paraffin phase change materials in North America

Globally, almost 40% of carbon emissions are attributable to building operation and embodied carbon. Phase change materials (PCMs) can store solar energy during peak periods to decrease summer cooling loads and overnight winter heating loads and emissions. At present, most PCMs are non-renewable paraffins with high embodied carbon; plant-based oils such as coconut oil may maintain the conditioning load reductions, while reducing the sustainability and embodied carbon of PCMs. The objective of this study was to determine the economic and emissions of coconut oil as an alternative to paraffins via full house simulations in three North American locations within different climate zones. It was found that paraffin PCM had greater embodied carbon and annual heating and cooling reductions than the coconut oil, causing the lifecycle carbon footprint to be lower with paraffin PCM than with the coconut oil over the house lifetime. This indicates the importance of developing bio-based PCMs with latent heat capacity that more closely compare to paraffins, in order to minimize total building carbon footprint. It was also found that the economic payback period of both PCMs may exceed the lifetime of the house and thus render the PCMs infeasible without reductions in capital costs or increased carbon pricing.

Design, energy, exergy, economy, and environment (4E) analysis, and multi-objective optimization of a novel integrated energy system based on solar and geothermal resources

Increasing energy consumption rates and concerns over environmental problems like global warming have led researchers to provide new energy supply solutions, one of which is the use of combined energy systems. Combining conventional fossil energy cycles with renewable cycles is one of the most effective ways to improve their performance and also help harvest green energy. To address this solution, in this paper, a hybrid novel energy system including a gas cycle, a steam cycle, two organic Rankine cycles (ORC), and a renewable cycle based on geothermal and solar energy sources using concentrating photovoltaic thermal panels (CPVT) is proposed. A comprehensive study has been conducted on this system from the perspective of energy, efficiency, economy, and the environment. Different fluids have been investigated for use in ORC subsystems in this study. Additionally, a parametric study has been conducted to determine how the cycle's overall performance is affected. Multi-objective optimization using the Non-dominated Sorting Genetic Algorithm second version (NSGA-II) has been performed based on the objective variables of exergy efficiency and capital costs. In this paper, Engineering Equation Solver (EES) and MATLAB are used for modeling and optimization. The results show that the best fluids to use in ORC are R123 in the first cycle and Ammonia in the second cycle, which energy efficiency, exergy efficiency, exergy destruction rate, and generated power in the base state for the whole cycle are 50.59%, 25.44%, 1537.35 kW and 524.66 kW, respectively. Also, the amount of annual capital cost and the amount of carbon dioxide emission from energy and exergy are 107,034 dollars, 11,672, and 35,401 kg per month, respectively. The optimization results indicate a 0.25% improvement in exergy efficiency and a 500$ annual capital cost reduction at the optimal point.

Heat Exchanger Network (HEN) Analysis of The Power Plant Industry Using Aspen Energy Analyzer Software

Heat recovery is considered as the key to improve energy efficiency in the process design. An appropriate heat exchanger network (HEN) design is an effective tool to maximize heat recovery from the process streams and to minimize energy consumption. The objectives of this study were arranging optimum HEN based on the annual cost in the power industry. HEN in the Paiton Steam Power Plant, East Java, Indonesia, was designed using spreadsheet and Aspen Energy Analyzer with Peng-Robinson equation. Pinch analysis was conducted by comparing Tmin (10°C - 19°C) to obtain Maximum Energy Recovery (MER) and Heat Exchanger Area (HEA). The HEN design was optimized using grid diagram. Simulation in this study succeeded to reduce the annual cost the most effectively at ∆Tmin 16°C. This design optimized the process integration and contributed to the capital, operation, and total annual cost reduction of 14.3%. The maximum energy recovery was 286,706 kW and HEA 138.790 m2. This result is a solution for Steam Power Plant as an effort for enhancing energy efficiency and the company competitiveness.

Development of Chinese Dynamic Optimal Power Expansion Planning Model Integrated with Hydrogen and Fuel Cell System

This study evaluates optimal carbon‐neutral power supply strategy in China up to 2060 with a multi‐region high spatial and temporal dynamic optimal power expansion planning model. Furthermore, this study explores installable potential of hydrogen and fuel cell system and analyzes the influences of its capital cost reduction at different levels. The results show that the national installed capacity would rise to be over 9000 GW in 2060, in which wind and solar PV will take up around 61%; the intermittency of renewable power generation is mainly managed with hydrogen production, power output curtailment and charge and discharge of energy storage; hydrogen and fuel cell system would improve the capacity factor and reduce the curtailment rate of renewable power generation. © 2023 The Authors. IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Influence of the Distance between Two Catalysts for CO2 to Dimethyl Ether Tandem Reaction

AbstractTandem reactions, with their great potential for reduction of capital and operational costs, reaction time, and byproducts are becoming more prominent. Among possible tandem reaction systems for direct conversion of CO2 to green fuel, dimethyl ether synthesis via methanol route is of vital importance. However, there are several parameters which must be considered for the combination of two catalysts to achieve promising performance, of those, the distance between the two catalysts is a crucial one. This distance can affect the overall performance of the tandem system by causing external mass transfer limitations or the poisoning of the catalysts. This work presents a systematic study on the influence of the distance between the two catalysts for the CO2 to dimethyl ether tandem system.

Cooperative Solutions for Working Capital Cost Management

An advancement of the framework for reduction and redistribution of joint working capital costs in financial supply chain networks with combined topology is represented: factoring, reverse factoring, and inventory financing were chosen as the financial supply chain instruments to reduce the cost of joint working capital, a characteristic function is set and Core and Shepley values are chosen as optimality principles, the developed framework is compared with similar methods constructed by other authors, and also tested on the case study of the automotive industry.

Small-Scale Hybrid Methanol–Methane Production Based on Biogas: Stochastic Sensitivity Analysis of the Economic Sustainability

This study investigates the economic viability at the pre-feasibility level of a hybrid methanol and biomethane plant based on biogas coupled to a photovoltaic (PV) power plant and a proton exchange membrane (PEM) electrolyzer. The reference case settled in Uganda consisted of two units powered by a 200 kW PV plant and grid power: a 25 Nm3/h anaerobic digester and a 140 kW PEM electrolyzer-based methanol plant. Its production of 33.3 tons of methanol and 70.1 tons of biomethane per year can provide cooking fuel for 750 households. Response Surface Methodology was used to evaluate the impact of the three main factors on the simple payback period (PBP). The size of the PV plant had the most significant impact on PBP, followed by the cost of electricity, the interaction between these factors, and the PEM electrolyzer capital cost reduction, in this contribution order. These findings point to energy generation costs as the primary factor affecting the economic viability of these small-scale designs, even more than the PEM’s capital cost. The response surface analysis revealed that only in a reduced region of the design space are values found that meet the threshold of 10 years for plant economic viability.

Redox flow desalination for tetramethylammonium hydroxide removal and recovery from semiconductor wastewater

As part of humankind’s path towards more sustainable water technologies, redox flow desalination (RFD) has emerged as a promising technology due to its high energy efficiency and easy operation. So far, RFD research has focused on removing and recovering inorganic salts such as lithium-ions, heavy metal ions, or phosphate and nitrate ions. Thus, the potential of RFD in water desalination and resource recovery processes has not been fully demonstrated. Therefore, this study aimed to assess RFD for the valorization of tetramethylammonium hydroxide (TMAH) as value-added organic compounds from wastewater beyond inorganic elements, which is widely being used as an etching solvent, photoresist developer, and surfactant in semiconductor and display industries. By applying a low cell voltage (<1.2 V), a reversible redox reaction allowed a continuous removal of TMAH from the wastewater stream and a simultaneous recovery for reuse as a form of tetramethylammonium cation. The TMAH removal rate was approximately 4.3 mM/g/h with a 40% recovery ratio. With various operational conditions (i.e., TMAH concentration, cell voltage, and flow rate), our system exhibited a high potential for the valorization of TMAH with 60% reduction in capital cost compared to conventional desalination processes.

Effect of Actual Recuperators’ Effectiveness on the Attainable Efficiency of Supercritical CO2 Brayton Cycles for Solar Thermal Power Plants

One of the most promising concentrated solar power technologies is the central receiver tower power station with heliostat field, which has attracted renewed research interest in the current decade. The introduction of the sCO2 recompression Brayton cycles in the near future installations instead of the Rankine cycle is very probable, due to the prospects of a significant efficiency improvement, process equipment size and capital cost reduction. In this study, energy and exergy analysis of a recompression Brayton cycle configuration for a central receiver power station are performed. Special emphasis is given to the computation of actual performance for the High-Temperature Recuperator and the Low-Temperature Recuperator. The results define realistic thermal and exergetic efficiency limits for the specific cycle configurations applied on a central receiver solar power plant with variable turbine entry temperature. Thermal efficiency, predicted with the improved accuracy of heat exchanger computations, does not exceed the 50% target. Overall, a realizable total power plant efficiency of 37% at 900 K turbine entry temperature is predicted, which is a significant improvement on the current state-of-the-art with steam Rankine cycles.

Magnesium Cobaltite Embedded in Corncob-Derived Nitrogen-Doped Carbon as a Cathode Catalyst for Power Generation in Microbial Fuel Cells.

Microbial fuel cells (MFCs) have drawn attention among renewable energy devices. High capital cost, poor durability, and slow oxygen reduction reaction (ORR) kinetics are the major hindrances in the commercialization of the technology. In this work, an environmentally benign approach is followed to synthesize a composite of magnesium cobaltite (MgCo2O4) embedded in nitrogen-doped carbon to optimize the performance of MFCs. Detailed characterization confirms the formation of MgCo2O4 nanostructures in the catalyst treated at 700 °C. Electrochemical studies suggest the superior performance of the MgCo2O4/NC-700 catalyst with a peak reduction current of -0.068 mA and a charge transfer resistance (Rct) of 40.5 Ω. The performance of the air cathodes is evaluated using activated sludge as inoculum in the anode chamber in single-chamber MFCs. The power output of MFC with MgCo2O4/NC-700 as an air cathode reaching 873.81 mW m-2 is 59.56 and 216.05% higher than those of MFCs with Pt/C (547.65 mW m-2) and Co/NC-700 (276.48 mW m-2) cathodes, respectively. These findings suggest that substituting magnesium in transition metal-nitrogen-carbon composites could help realize long-term application as air cathodes for power generation and wastewater treatment in MFCs.

Removal of glycerol from biodiesel using multi-stage microfiltration membrane system: industrial scale process simulation

Abstract Biodiesel purification is one of the most important downstream processes in biodiesel industries. The removal of glycerol from crude biodiesel is commonly conducted by an extraction method using water, however this method results in a vast amount of wastewater and needs a lot of energy. In this study, microfiltration membrane was used to remove glycerol from biodiesel, and a process simulation was carried out for an industrial scale biodiesel purification plant using a microfiltration membrane system. The microfiltration experiment using a simulated feed solution of biodiesel containing glycerol and water showed that the membrane process produced purified biodiesel that met the international standards. The result of the process simulation of a multi-stage membrane system showed that the membrane area could be minimized by optimizing the concentration factor of every stage with the aid of a computer program that was written in Phyton programming language with Visual Studio Code. The overall productivity of a single stage membrane system was the same with that of the multi-stage system, however the single stage system required a larger membrane area. To produce 750 m3 day−1 of purified biodiesel, a multi-stage membrane system consisting of 10 membrane modules required a total membrane area of 1515 m2 that was 57% smaller compared to the single stage system consisting of one membrane module. This membrane area reduction was equivalent to a reduction of the total capital cost of 30%. Based on the analysis of the total capital cost, it was found that the optimum number of stages was 4 since it showed a minimum value of the total capital cost with a membrane area of 1620 m2 that was equivalent to the reduction of the total capital cost of 34%. The result of this simulation showed that the multi-stage microfiltration membrane has great potential to replace the conventional method in biodiesel industries.

Nanofluid applications in pressurized water reactors: A review

The main purpose of this paper was to review nanofluid applications as the main coolant of pressurized water reactors (PWRs) with both solid and dual-cooled annular fuel. In this regard, first, theoretical and experimental models for calculating thermo-physical properties of nanofluids including density, specific heat, thermal conductivity, viscosity, and heat transfer coefficient were reviewed and the effects of different variables such as particle volume concentration, particle size, shape, and temperature on these parameters were determined. In the following, research related to neutronic, thermal-hydraulic, and safety investigations of nanofluids as the main coolant of PWRs with solid and dual-cooled annular fuel were reviewed. Corresponding methods, codes, and results were discussed and compared. Based on studies, it was concluded that nanofluids' effects on key neutronic parameters (keff, neutron flux and radial and axial power peaking factor) depend on the used nanoparticle, volume concentration, and nanoparticle deposition on the cladding, while nanofluids can increase heat transfer, critical heat flux, and minimum departure from nuclear boiling ratio (MDNBR). Also, it was found that nanofluids with low volume concentration in reactor core with dual-cooled annular fuel can replicate the same advantages. Furthermore, using dual-cooled annular fuel instead of solid fuel increases MDNBR margin and reduces coolant flow which leads to a more compact design of the reactor core and a reduction of capital cost. Finally, incoming challenges and future works were presented.

The fractal pack: New equipment for ion exchange operations in the sugar industry

The fractal pack is a new patented ion exchange configuration that is conceptually similar to a plate and frame filter press and contains a number of ion exchange plates held within a frame. With bed depths as shallow as 3 to 24 inches, this ion exchange system design results in a substantial reduction in capital cost by delivering the following benefits: compact equipment, modularity (by easy addition or removal of resin chambers from the existing frame), inexpensive capacity expansion / reduction and reduced installation costs. Furthermore, the capital and operating costs benefit from reductions in cycle times (and hence reduced resin fouling), regenerant use (and hence reduced chemical consumption and waste production), pressure drop, water consumption and product dilution. Increased resin loadings and longer life may also be possible. The plates are manufactured from corrosion resistant materials, making it possible to use aggressive resin regeneration chemicals if necessary. Testing has been carried out on both a small pilot / bench scale as well as a large pilot scale for several potential applications across a range of industries. In the sugar industry, successful performance has been demonstrated in the decolorization and softening of juice and syrups. Experimental work at various scales has confirmed that performance is maintained on scale-up to fractal pack plates of full industrial size.

Solid-State Transformer and Hybrid Transformer With Integrated Energy Storage in Active Distribution Grids: Technical and Economic Comparison, Dispatch, and Control

Solid-state transformer (SST) and hybrid transformer (HT) are promising alternatives to the line-frequency transformer (LFT) in smart grids. The SST features medium-frequency isolation, full controllability for voltage regulation, reactive power compensation, and the capability of battery energy storage system (BESS) integration with multiport configuration. The HT has a partially rated converter for fractional controllability and can integrate a small BESS. Fast grid-edge voltage fluctuations from increased solar photovoltaic (PV) and electric vehicle (EV) penetration are difficult to manage for mechanical load tap changers. Hence, along with the trend toward more BESS in the grid, the controllability and the storage-integration capability of the SST and HT are of strong interest. However, a review of literature shows existing SST and HT research is mostly at converter level, while system-level assessments are scarce. Assessing technical and economic impacts is critical to understanding the benefits and role of the SST and HT to guide future research, which is presented for the first time in this article. Experimental results from medium-voltage (MV) SST and MV HT prototypes are shown to confirm equipment-level feasibility, where the voltage controllability waveforms of an MV HT prototype are reported for the first time. Comparative simulations are performed on a modified IEEE 34-bus system. A grid-model-less decentralized grid-edge voltage control method and a day-ahead BESS dispatch method are proposed for the SST and HT. The simulations show that the SST and HT with integrated storage can host more PV, achieve peak shaving, mitigate voltage fluctuation and reverse power flow, and support energy arbitrage for operational cost reduction, compared to the LFT. Moreover, comprehensive analyses of net present value (NPV) and internal rate of return (IRR) are performed under different installed PV capacities, HT’s partial converter ratings, and BESS capacities. Sensitivities to future cost reductions of the PV and BESS are studied. Although the NPV and IRR are currently negative, 60% capital cost reduction or 150% revenue increase will make the SST and HT economically viable in the use case studied.

Fabrication of Anti-Icing Surface Structures on Aluminum Alloy for Aerospace Applications

Icing, the phenomenon of the formation and accumulation of ice or frost on a surface due to the solidification of water droplets at low temperature can be undesirable in many applications. Surface icing can lead to increased energy consumption in aerospace and automotive applications due to increased aerodynamic drag. Ice formation can also present a mechanical and electrical safety hazard, and as such significant work has been done to produce surfaces with anti-icing properties through surface modification to decrease ice formation and adhesion to surfaces. One route toward the generation of anti-icing surfaces is through laser surface processing. Laser micro/nanostructuring of surfaces has advanced greatly in recent years due to advancements in laser source technology and reduction in capital costs for ultrafast femtosecond pulsed machining lasers. Laser material processing offers a rapid, scalable, and non-contact method for fabricating large area anti-icing surfaces. In this work, the production of anti-icing surfaces using femtosecond laser micro-and nanostructuring on aluminum alloy 7075 surfaces was examined. With an aim to optimize the anti-icing properties of the substrates, laser parameters such as pulse energy, repetition rate and beam scanning speed were varied to produce highly defined microstructures on the aluminum surface.Various functional properties such as hydrophobicity and surface roughness are examined.

Novel ultrasonic dynamic vapor sorption apparatus for adsorption drying, cooling and desalination applications

Adsorption systems for desalination, drying, and cooling applications could be powered by renewable energy sources. Thus, it is a promising technology for solving energy and water problems. Designing an efficient adsorption system and evaluating its performance depend mainly on the adsorption isotherms and kinetics of nanoporous materials. The present work designs and manufactures a precise gravimetric sorption apparatus to measure the adsorption isotherms and kinetics of water vapor onto porous materials. It is equipped with a high-precision mass balance to record the change in mass of the tested sample. The main feature of the present apparatus is using an ultrasonic device to generate water vapor allowing easy control of the water vapor flow rate and operating pressure. This novel approach leads to a significant reduction in the apparatus capital cost. To confirm the accuracy and reliability of the proposed instrument, the adsorption kinetics and isotherms of water vapor onto three different materials are measured using the proposed apparatus and compared to the corresponding data in literature. The maximum deviation is found to be less than 4%, indicating the high accuracy of the proposed instrument. During the repeatability tests, a maximum uncertainty of 1.1% is observed at a relative pressure of 0.8, which is within the accuracy of the electronic mass balance. Accordingly, it is confirmed that the developed apparatus could measure the adsorption isotherm and kinetics of water vapor onto nanoporous materials with high accuracy and reliability.

Near Neutral Aqueous Fe-Cr Complex Flow Battery

A redox-flow battery (RFB), as schematically shown is a unique type of rechargeable battery in which the electrochemical energy is stored in soluble redox couples contained in electrolyte tanks, and the electrical energy and the chemical energy are converted back and forth inside a device called “stack”. This unique structure successfully separates the power (stack) and the energy (electrolyte) of the battery system and can be economically designed for long-duration energy storage applications. While vanadium flow batteries have achieved initial commercial deployments, the cost of a four-hour system at deployment-scale is still more than $300/kWh, more than 50% of which comes from the cost of the energy storage media – Vanadium element. DOE’s multiple programs clearly indicates that future capital cost reductions will require replacing vanadium with lower cost raw materials to approach the $100/kWh targets required for wider-scale deployment of energy storage systems. Since 2018, attracted by its low electrolyte cost, our team have been working on the legendary Fe-Cr redox flow battery system, which was first invented by Dr. Lawrence Thaller of US NASA in 1975, to develop a low[1]cost flow battery product. The energy storage capacity decay caused by H2 generation, which comes from the negative electrode due to the low standard potential of Cr 2+ /Cr 3+ , makes it not practical for long-term energy[1]storage operations. After two years’ research, we have successfully developed an advanced Fe-Cr redox flow battery system. In this system, no capacity decay over continuous charge and discharge operation has been successfully achieved by an extremely low H2 generation design and a unique capacity recovery technology using a reductant and a homogeneous catalyst. Continuous operation of a test stand using a kW-scale stack and 100L electrolyte for a total 1000 cycles has been successfully achieved. Related information and results were published in the granted US patents US 10,826,102 and US 10,777,836, and the US patent applications 20200373594, 20200373595, 20200373600, 20200373601. During our previous development of the advance Fe-Cr redox flow battery, we discovered that the stability and electrochemical activity of Fe- and Cr-containing species in the aqueous solution can be remarkably improved by complexing them with some ligands. The acidity of this novel electrolyte solution is much weaker than that of the traditional Fe-Cr flow battery system, i.e., ~0.1M vs. >2M, which largely reduces the corrosivity of the electrolyte and allows for wider applications of this system with minimal environmental impact, especially for residential users and small-scale commercial and industrial users. Several different complexing ligands were identified. All showed very stable performance and low side reactions. Up to now, the test has been continuously carried out for more than three months and more than 500 cycles, using a kW-scale stack and 100 L electrolyte solution. Much-improved electrochemical reactivity of the Fe- and Cr-complex also eliminates the need for metal catalysts for the Cr 2+ +e ↔ Cr 3+ reaction, significantly improved the stability of the system for long-term operation.

Economic and environmental impacts of public investment in clean energy RD&D

Learning curve theory has been adopted for investigating the relationship between technological learning and technology cost developments. The aim of this paper is to explore the impacts of public investment in clean energy research, development, and demonstration (RD&D) on future technology cost developments by using a two-factor learning curve approach. Learning-by-deploying and learning-by-researching were chosen as the main sources of learning. The focus is on onshore wind and solar photovoltaics in the United States of America. By using publicly available data, we estimated learning-by-deploying rates of 31.4% and 27.6%; and learning-by-researching rates of 2.3% and 4.7% for onshore wind and solar PV, respectively. By adopting a logistic curve approach, an additional $1322 and $819 mil. were forecast to be spent by 2050 in RD&D for onshore wind and solar PV, respectively. We explored the plausible long-term effects of diverse RD&D investment scenarios on electricity generation and greenhouse gas (GHG) emissions using a system dynamics model. The findings reveal that public investment in RD&D for clean energy technologies may play a key role in the pace of capital cost reductions and technology diffusion. However, relatively little long-term effects of RD&D efforts alone were found on market dynamics and GHG emissions.

Removal of contaminants of emerging concern from secondary-effluent reverse osmosis retentates by continuous supercritical water oxidation- parametric study and conceptual design

The continuous removal of TOC and the degradation efficiency of carbamazepine and 17β-estradiol were investigated using actual secondary municipal-effluent RO-retentate solutions. A specific set of operating parameters were applied within the supercritical water oxidizing conditions: temperature range 420–480 °C, 25.1 MPa, hydraulic retention time (HRT) of 1–2 min, excess oxidant molar-ratio of 3–10 and presence of a homogenous catalyst (IPA) at 50–100 mg/L. > 99% organic carbon mineralization, along with complete degradation of model pollutants, was observed at 450 °C/1 min/OC= 5–10 and 100 mgIPA/L. The outlet estrone concentration, 1.03 ± 1.14 ng/L, representing estrogenic pollutants, dropped to the "no effect" range. A model for a SCWO plant treating secondary-municipal-effluent-RO-retentate for a city of 100,000 capita-equivalent was developed, based on a shell & tube SCWO flow reactor, showing > 75% energy-efficiency. The model yielded that for the extreme case of a zero caloric-value feed-solution, the total OPEX and CAPEX would be < $6.0 ± 2.5 per m3 of secondary effluents, i.e., two orders of magnitude lower than the reported environmental shadow-price associated with CECs (contaminants of emerging concern). Further work is required on the continuous and efficient separation of the salt-matrix, which can lead to higher overall heat transfer coefficients and enable further reduction in capital costs.

Minimizing the cost of hydrogen production through dynamic polymer electrolyte membrane electrolyzer operation

Growing imbalances between electricity demand and supply from variable renewable energy sources (VREs) create increasingly large swings in electricity prices. Polymer electrolyte membrane (PEM) electrolyzers can help to buffer against these imbalances and minimize the levelized cost of hydrogen (LCOH) by ramping up production of hydrogen through high-current-density operation when low-cost electricity is abundant, and ramping down current density to operate efficiently when electricity prices are high. We introduce a technoeconomic model that optimizes current density profiles for dynamically operated electrolyzers, while accounting for the potential of increased degradation rates, to minimize LCOH for any given time-of-use (TOU) electricity pricing. This model is used to predict LCOH from different methods of operating a PEM electrolyzer for historical and projected electricity prices in California and Texas, which were chosen due to their high penetration of VREs. Results reveal that dynamic operation could enable reductions in LCOH ranging from 2% to 63% for historical 2020 pricing and 1% to 53% for projected 2030 pricing. Moreover, high-current-density operation above 2.5 A cm −2 is increasingly justified at electricity prices below $0.03 kWh −1 . These findings suggest an actionable means of lowering LCOH and guide PEM electrolyzer development toward devices that can operate efficiently at a range of current densities. • Dynamic operation reduces levelized cost of hydrogen by up to 63% for 2020 prices • Dynamic operation reduces hydrogen cost by up to 53% for projected 2030 prices • Operation above 2.5 A cm −2 is justified at electricity prices below $0.03 kWh −1 • Capital cost reduction of $601 from $898 kW −1 lowers hydrogen cost by 25% Electricity contributes most to the levelized cost of hydrogen (LCOH) from water electrolysis. Abundant low-cost electricity from variable renewable energy justifies operating electrolyzers at high current densities to increase H 2 production. Ginsberg et al. introduce a model to minimize LCOH by optimizing current density for any electricity pricing scheme.