Economic analysis of hydrogen production from wastewater and wood for municipal bus system

The levelized cost of hydrogen for municipal fuel cell buses has been determined using the DOE H2A model for steam methane reforming (SMR), molten carbonate fuel cell reforming (MCFC), and wood gasification using wastewater biogas and willow wood chips as energy feedstocks. 300 kg H₂/day was chosen as the design capacity. Greenhouse gas emissions were calculated for each for the three processes and compared to diesel bus emissions in order to assess environmental impact. The levelized cost per kilogram for SMR, MCFC, and gasification is $5.12, $8.59, and $10.62, respectively. SMR provided the lowest sensitivity to feedstock price, and lowest levelized cost at various scales, with competitive cost to diesel on a cost/km basis. All three technologies provide a reduction in total greenhouse gases compared to diesel bus emissions, with MCFC providing the largest reduction. These results provide preliminary evidence that small scale distributed hydrogen production for public transportation can be relatively cost-effective and have minimal environmental impact.     

Lifecycle impacts of natural gas to hydrogen pathways on urban air quality

In this paper we examine the potential air quality impacts of hydrogen transportation fuel from a lifecycle analysis perspective, including impacts from fuel production, delivery, and vehicle use. We assume that hydrogen fuel cell vehicles are introduced in a specific region, Sacramento County, California. We consider two levels of market penetration where 9% or 20% of the light duty fleet are hydrogen fuel cell vehicles. The following three natural gas to hydrogen supply pathways are assessed in detail and compared in terms of emissions and the resulting changes in ambient air quality: (1) onsite hydrogen production; (2) centralized hydrogen production with gaseous hydrogen pipeline delivery systems; and (3) centralized hydrogen production with liquid hydrogen truck delivery systems. All the pathways examined use steam methane reforming (SMR) of natural gas to produce hydrogen. The source contributions to incremental air pollution are estimated and compared among hydrogen pathways. All of the hydrogen pathways result in extremely low contributions to ambient air concentrations of _NOx${\mathrm{NO}}_x$, CO, particulates, and _SOx${\mathrm{SO}}_x$, typically less than 0.1% of the current ambient pollution for both levels of market penetration. Among the hydrogen supply options, it is found that the central SMR with pipeline delivery systems is the lowest pollution option available provided the plant is located to avoid transport of pollutants into the city via prevailing winds. The onsite hydrogen pathway is comparable to the central hydrogen pathway with pipeline systems in terms of the resulting air pollution. The pathway with liquid hydrogen trucks has a greater impact on air quality relative to the other pathways due to emissions associated with diesel trucks and electricity consumption to liquefy hydrogen. However, all three hydrogen pathways result in negligible air pollution in the region.     

Low carbon hydrogen production in Canada via natural gas pyrolysis

Large scale, low cost, and low carbon intensity hydrogen production is needed to reduce emissions in the energy and transportation sectors. We present a techno-economic analysis and life cycle assessment of natural gas pyrolysis technologies for hydrogen production, with carbon black (CB) as a co-product. Four designs were considered based on the source of heat to the pyrolysis system, the combustion medium, and use of carbon capture (CC) technology. The oxygen-fired-CB design with CC is the most attractive from financial and environmental perspectives, superior to a conventional steam methane reformer (SMR) process with CC. The estimated pre-tax minimum hydrogen selling prices for the pyrolysis technologies range between $1.08/kg and $2.43/kg when natural gas (NG) costs $3.76/GJ. Key advantages include near-zero onsite GHG emissions of the oxygen-fired-CB design with CC and up to 41% lower GHG emissions compared to the SMR + CC process. The results indicate that natural gas pyrolysis may be a feasible pathway for hydrogen production.     

Effective utilization of by-product oxygen from electrolysis hydrogen production

To avoid fossil-fuel consumption and greenhouse-gas emissions, hydrogen should be produced by renewable energy resources. Water electrolysis using proton exchange membrane (PEM) is considered a promising hydrogen-production method, although the cost of the hydrogen from PEM would be very high compared with that from other mature technologies, such as steam methane reforming (SMR). In this study, we focus on the effective utilization of by-product oxygen from electrolysis hydrogen production and discuss the potential demand for it, as well as evaluating its contribution to improving process efficiency. Taking as an example the utilization of by-product oxygen for medical use, we compare the relative costs of hydrogen production by means of PEM electrolysis and SMR.     

Hydrogen production from methane and solar energy – Process evaluations and comparison studies

Three conventional and novel hydrogen and liquid fuel production schemes, i.e. steam methane reforming (SMR), solar SMR, and hybrid solar-redox processes are investigated in the current study. H₂ (and liquid fuel) productivity, energy conversion efficiency, and associated CO₂ emissions are evaluated based on a consistent set of process conditions and assumptions. The conventional SMR is estimated to be 68.7% efficient (HHV) with 90% CO₂ capture. Integration of solar energy with methane in solar SMR and hybrid solar-redox processes is estimated to result in up to 85% reduction in life-cycle CO₂ emission for hydrogen production as well as 99–122% methane to fuel conversion efficiency. Compared to the reforming-based schemes, the hybrid solar-redox process offers flexibility and 6.5–8% higher equivalent efficiency for liquid fuel and hydrogen co-production. While a number of operational parameters such as solar absorption efficiency, steam to methane ratio, operating pressure, and steam conversion can affect the process performances, solar energy integrated methane conversion processes have the potential to be efficient and environmentally friendly for hydrogen (and liquid fuel) production.     

Natural gas usage as a heat source for integrated SMR and thermochemical hydrogen production technologies

This paper investigates various usages of natural gas (NG) as an energy source for different hydrogen production technologies. A comparison is made between the different methods of hydrogen production, based on the total amount of natural gas needed to produce a specific quantity of hydrogen, carbon dioxide emissions per mole of hydrogen produced, water requirements per mole of hydrogen produced, and a cost sensitivity analysis that takes into account the fuel cost, carbon dioxide capture cost and a carbon tax. The methods examined are the copper–chlorine (Cu–Cl) thermochemical cycle, steam methane reforming (SMR) and a modified sulfur–iodine (S–I) thermochemical cycle. Also, an integrated Cu–Cl/SMR plant is examined to show the unique advantages of modifying existing SMR plants with new hydrogen production technology. The analysis shows that the thermochemical Cu–Cl cycle out-performs the other conventional methods with respect to fuel requirements, carbon dioxide emissions and total cost of production.     

A retrospective analysis of benefits and impacts of U.S. renewable portfolio standards

As states consider revising or developing renewable portfolio standards (RPS), they are evaluating policy costs, benefits, and other impacts. We present the first U. S. national-level assessment of state RPS program benefits and impacts, focusing on new renewable electricity resources used to meet RPS compliance obligations in 2013. In our central-case scenario, reductions in life-cycle greenhouse gas emissions from displaced fossil fuel-generated electricity resulted in $2.2 billion of global benefits. Health and environmental benefits from reductions in criteria air pollutants (sulfur dioxide, nitrogen oxides, and particulate matter 2.5) were even greater, estimated at $5.2 billion in the central case. Further benefits accrued in the form of reductions in water withdrawals and consumption for power generation. Finally, although best considered resource transfers rather than net societal benefits, new renewable electricity generation used for RPS compliance in 2013 also supported nearly 200,000 U. S.-based gross jobs and reduced wholesale electricity prices and natural gas prices, saving consumers a combined $1.3–$4.9 billion. In total, the estimated benefits and impacts well-exceed previous estimates of RPS compliance costs.     

Opportunities and challenges of low-carbon hydrogen via metallic membranes

Today, electricity & heat generation, transportation, and industrial sectors together produce more than 80% of energy-related CO₂ emissions. Hydrogen may be used as an energy carrier and an alternative fuel in the industrial, residential, and transportation sectors for either heating, energy production from fuel cells, or direct fueling of vehicles. In particular, the use of hydrogen fuel cell vehicles (HFCVs) has the potential to virtually eliminate CO₂ emissions from tailpipes and considerably reduce overall emissions from the transportation sector. Although steam methane reforming (SMR) is the dominant industrial process for hydrogen production, environmental concerns associated with CO₂ emissions along with the process intensification and energy optimization are areas that still require improvement. Metallic membrane reactors (MRs) have the potential to address both challenges. MRs operate at significantly lower pressures and temperatures compared with the conventional reactors. Hence, the capital and operating expenses could be considerably lower compared with the conventional reactors. Moreover, metallic membranes, specifically Pd and its alloys, inherently allow for only hydrogen permeation, making it possible to produce a stream of up to 99.999+% purity.For smaller and emerging hydrogen markets such as the semiconductor and fuel cell industries, Pd-based membranes may be an appropriate technology based on the scales and purity requirements. In particular, at lower hydrogen production rates in small-scale plants, MRs with CCUS could be competitive compared to centralized H₂ production. On-site hydrogen production would also provide a self-sufficient supply and further circumvent delivery delays as well as issues with storage safety. In addition, hydrogen-producing MRs are a potential avenue to alleviate carbon emissions. However, material availability, Pd cost, and scale-up potential on the order of 1.5 million m³/day may be limiting factors preventing wider application of Pd-based membranes.Regarding the economic production of hydrogen, the benchmark by the year 2020 has been determined and set in place by the U.S. DOE at less than $2.00 per kg of produced hydrogen. While the established SMR process can easily meet the set limit by DOE, other carbon-free processes such as water electrolysis, electron beam radiolysis, and gliding arc technologies do not presently meet this requirement. In particular, it is expected that the cost of hydrogen produced from natural gas without CCUS will remain the lowest among all of the technologies, while the hydrogen cost produced from an SMR plant with solvent-based carbon capture could be twice as expensive as the conventional SMR without carbon capture. Pd-based MRs have the potential to produce hydrogen at competitive prices with SMR plants equipped with carbon capture.Despite the significant improvements in the electrolysis technologies, the cost of hydrogen produced by electrolysis may remain significantly higher in most geographical locations compared with the hydrogen produced from fossil fuels. The cost of hydrogen via electrolysis may vary up to a factor of ten,d epending on the location and the electricity source. Nevertheless, due to its modular nature, the electrolysis process will likely play a significant role in the hydrogen economy when implemented in suitable geographical locations and powered by renewable electricity.This review provides a critical overview of the opportunities and challenges associated with the use of the MRs to produce high-purity hydrogen with low carbon emissions. Moreover, a technoeconomic review of the potential methods for hydrogen production is provided and the drawbacks and advantages of each method are presented and discussed.     

Economic and environmental competitiveness of high temperature electrolysis for hydrogen production

Alternative hydrogen production technologies are sought in part to reduce the greenhouse gas (GHG) emissions intensity compared with Steam Methane Reforming (SMR), currently the most commonly employed hydrogen production technology globally. This study investigates hydrogen production via High Temperature Steam Electrolysis (HTSE) in terms of GHG emissions and cost of hydrogen production using a combination of Aspen HYSYS® modelling and life cycle assessment. Results show that HTSE yields life cycle GHG emissions from 3 to 20 kg CO_2e/kg H₂ and costs from $2.5 to 5/kg H₂, depending on the system parameters (e.g., energy source). A carbon price of $360/tonne CO_2e is estimated to be required to make HTSE economically competitive with SMR. This is estimated to potentially decrease to $50/tonne CO_2e with future technology advancements (e.g., fuel cell lifetime). The study offers insights for technology developers seeking to improve HTSE, and policy makers for decisions such as considering support for development of hydrogen production technologies.     

Renewable-powered hydrogen economy from Australia's perspective

This article broadly reviews the state-of-the-art technologies for hydrogen production routes, and methods of renewable integration. It outlines the main techno-economic enabler factors for Australia to transform and lead the regional energy market. Two main categories for competitive and commercial-scale hydrogen production routes in Australia are identified: 1) electrolysis powered by renewable, and 2) fossil fuel cracking via steam methane reforming (SMR) or coal gasification which must be coupled with carbon capture and sequestration (CCS). It is reported that Australia is able to competitively lower the levelized cost of hydrogen (LCOH) to a record $(1.88–2.30)/kg_H2 for SMR technologies, and $(2.02–2.47)/kg_H2 for black-coal gasification technologies. Comparatively, the LCOH via electrolysis technologies is in the range of $(4.78–5.84)/kg_H2 for the alkaline electrolysis (AE) and $(6.08–7.43)/kg_H2 for the proton exchange membrane (PEM) counterparts. Nevertheless, hydrogen production must be linked to the right infrastructure in transport-storage-conversion to demonstrate appealing business models.     

Comparison of well-to-wheels energy use and emissions of a hydrogen fuel cell electric vehicle relative to a conventional gasoline-powered internal combustion engine vehicle

The operation of hydrogen fuel cell electric vehicles (HFCEVs) is more efficient than that of gasoline conventional internal combustion engine vehicles (ICEVs), and produces zero tailpipe pollutant emissions. However, the production, transportation, and refueling of hydrogen are more energy- and emissions-intensive compared to gasoline. A well-to-wheels (WTW) energy use and emissions analysis was conducted to compare a HFCEV (Toyota Mirai) with a gasoline conventional ICEV (Mazda 3). Two sets of specific fuel consumption data were used for each vehicle: (1) fuel consumption derived from the U.S. Environmental Protection Agency's (EPA's) window-sticker fuel economy figure, and (2) weight-averaged fuel consumption based on physical vehicle testing with a chassis dynamometer on EPA's five standard driving cycles. The WTW results show that a HFCEV, even fueled by hydrogen from a fossil-based production pathway (via steam methane reforming of natural gas), uses 5%–33% less WTW fossil energy and has 15%–45% lower WTW greenhouse gas emissions compared to a gasoline conventional ICEV. The WTW results are sensitive to the source of electricity used for hydrogen compression or liquefaction.     

Abating transport GHG emissions by hydrogen fuel cell vehicles: Chances for the developing world

Fuel cell vehicles, as the most promising clean vehicle technology for the future, represent the major chances for the developing world to avoid high-carbon lock-in in the transportation sector. In this paper, by taking China as an example, the unique advantages for China to deploy fuel cell vehicles are reviewed. Subsequently, this paper analyzes the greenhouse gas (GHG) emissions from 19 fuel cell vehicle utilization pathways by using the life cycle assessment approach. The results show that with the current grid mix in China, hydrogen from water electrolysis has the highest GHG emissions, at 3.10 kgCO₂/km, while by-product hydrogen from the chlor-alkali industry has the lowest level, at 0.08 kgCO₂/km. Regarding hydrogen storage and transportation, a combination of gas-hydrogen road transportation and single compression in the refueling station has the lowest GHG emissions. Regarding vehicle operation, GHG emissions from indirect methanol fuel cell are proved to be lower than those from direct hydrogen fuel cells. It is recommended that although fuel cell vehicles are promising for the developing world in reducing GHG emissions, the vehicle technology and hydrogen production issues should be well addressed to ensure the life-cycle low-carbon performance.     

Performance analysis of a membrane‐based reformer‐combustor reactor for hydrogen generation

Hydrogen is mostly produced in conventional steam methane reforming plants. In this work, we proposed a membrane‐based reformer‐combustor reactor (MRCR) for hydrogen generation in order to improve heat recovery and overall thermal efficiency. The proposed configuration will also reduce the complexity in existing steam methane reforming (SMR) plants. The proposed MRCR comprises combustion zone, hydrogen permeate zone, and SMR zone. A computational fluid dynamics model was developed using ANSYS‐Fluent software to simulate and analyze the performance of the proposed MRCR. Results show that high hydrogen yields were observed at high reformer pressures (RPs) and low gas hourly space velocities (GHSVs). Furthermore, by increasing the steam to methane ratio and addition of excess air in the combustion side, the hydrogen yield from the MRCR decreases. This is attributed to the reduction in the effective temperature of the hydrogen membrane. High RP, low GHSV, and low steam to methane ratio that increased the hydrogen yield also decreased carbon monoxide (CO) emissions. For an increased RP from 1 to 10 bar, the CO emission decreased by about 99%. The reduction in CO emission at high RP would be attributed to the effect of water gas shift reaction in the MRCR. Results of the extensive parametric study presented in this work can be used to determine the operating conditions based on tradeoffs between hydrogen yield (mole H₂/mole CH₄), hydrogen production rate (kg of H₂/h), allowable CO emissions, and exhaust gas temperature for other applications such as gas turbine.     

A techno-economic appraisal of hydrogen generation and the case for solid oxide electrolyser cells

There is significant interest in alternatives to fossil fuels in order to reduce carbon dioxide emissions. One option is the use of hydrogen in applications such as fuel cells. There are various routes to the production of hydrogen, one being via the electrolysis of water. Water electrolysers are already operational within industry on a small-scale, accounting for 4% of world hydrogen production. These electrolysers operate at low temperatures and require electrical power input that has been shown to be costly due to the limited efficiency of the electrolysis process. However, the use of high temperature solid oxide electrolyser cells (SOECs) has the potential to generate hydrogen with a higher electrical efficiency which may allow electrolysis to become cost competitive with steam methane reforming (SMR), depending on where the heat and electrical power to service the SOEC comes from.This paper examines the various routes to hydrogen production and, in particular electrolysis technologies. The cost of hydrogen production is examined in the context of the source of the electricity and the efficiency of the electrolysis process compared to SMR generation. It is found that to become cost competitive with SMR, the lowest cost electricity is required, sourced either from nuclear or combined cycle gas turbine plants with electrolysis efficiency as high as possible, meaning that SOEC technology is particularly attractive.     

Techno-economic and environmental assessment of LNG export for hydrogen production

A critical requirement of a widely contemplated hydrogen economy is the development of a low carbon hydrogen supply chain that is cost competitive. This comprehensive techno-economic assessment demonstrates, for the first time, the viability of a complete hydrogen supply chain based on the transport of liquefied natural gas (LNG). This is demonstrated via the established LNG trade route from Australia to Japan against three key performance indicators (KPIs): delivered hydrogen cost, CO₂ emissions intensity (EI) across the entire supply chain, and technology readiness level (TRL). The hydrogen supply chain entails LNG export to Japan where it is used for blue hydrogen production; the by-product CO₂ is then liquefied and repatriated to Australia for sequestration or utilisation. Within this supply chain, various hydrogen production technologies are assessed, including steam methane reforming (SMR), autothermal reforming (ATR) and natural gas pyrolysis (NGP). SMR with carbon capture and storage (CCS) resulted in the lowest total hydrogen supply cost of 19 USD/GJ (2.3 USD/kgH2) which comfortably meets the 2030 Japanese hydrogen cost target of 25 USD/GJ (3 USD/kgH2) and is very close to the 17 USD/GJ 2050 Japanese hydrogen cost target. This technology also obtained the lowest CO₂ emission intensity (EI) of 38 kgCO2/GJ (4.5 kgCO2/kgH2); this was surprisingly lower than ATR with CCS primarily due to the emissions associated with ATR electricity provision for air separation. Future technologies and strategies are detailed so as to further reduce cost and supply chain emissions; these were shown to be able to reduce total CO2 EI to 14 kgCO2/GJ (1.6 kgCO2/kgH2). Hence this analysis indicates that this supply chain can act to significantly reduce CO2 emissions whilst uniquely meeting targeted hydrogen supply costs up to 2050. As such it is proposed here as an eminently viable hydrogen export option deploying both existing technology and capacity, at least until other hydrogen supply chain vectors (such as liquid hydrogen and ammonia) derived from green hydrogen production become competitive across all the KPIs.     

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.     

Spatial and temporal optimization of hydrogen fuel supply chain for light duty passenger vehicles in British Columbia

British Columbia is well positioned to capitalize on its natural resources and its carbon policies towards the development of a hydrogen fueling network. A multi-period optimization model was developed to design a hydrogen fuel supply chain based on a mixed integer linear programming formulation. The model was applied to the light duty passenger vehicle sector in British Columbia under three hydrogen demand scenarios. As part of the objective function, the model incorporated the current provincial emissions mitigation policies, i.e., a carbon tax and a low-carbon fuel standard (LCFS). Based on cost, our model indicates that steam methane reforming (SMR) is the least costly hydrogen production technology even with carbon policies in place. However, SMR would result in higher emissions (compared to other pathways). Coupling the carbon tax with the LCFS can be a suitable policy option when hydrogen price and GHG emissions are weighted equally.     

Environmental life cycle feasibility assessment of hydrogen as an automotive fuel in Western Australia

A life cycle assessment has been undertaken in order to determine the environmental feasibility of hydrogen as an automotive fuel in Western Australia. The criterion for environmental feasibility has been defined as having life cycle impacts equal to or lower than those of petrol. Two hydrogen production methods have been analysed. The first is steam methane reforming (SMR), which uses natural gas (methane) as a feedstock. The second method analysed is alkaline electrolysis (AE), a mature technology that uses water as a feedstock. The life cycle emissions and impacts were assessed per kilometre of vehicle travel.     

Life-cycle analysis of greenhouse gas emissions from hydrogen delivery: A cost-guided analysis

The cost of hydrogen delivery for transportation accounts for most of the current H₂ selling price; delivery also requires substantial amounts of energy. We developed harmonized techno-economic and life-cycle emissions models of current and future H₂ production and delivery pathways. Our techno-economic analysis of dispensed H₂ costs guided our selection of pathways for the life-cycle analysis. In this paper, we present the results of market expansion scenarios using existing capabilities (for example, those that use H₂ from steam methane reforming, chlor-alkali, and natural gas liquid cracker plants), as well as results for future electrolysis plants that use nuclear, solar, and hydroelectric power. Reductions in greenhouse gas emissions for fuel cell electric vehicles compared to conventional gasoline pathways vary from 40% reduction for fossil-derived H₂ to 20-fold for clean H₂. Supplemental tables with greenhouse gas emissions data for each step in the H₂ pathways enable readers to evaluate additional scenarios.     

Relative economic incentives for hydrogen from nuclear,renewable, and fossil energy sources

The specific hydrogen market determines the value of hydrogen from different sources. Each hydrogen production technology has its own distinct characteristics. For example, steam reforming of natural gas produces only hydrogen. In contrast, nuclear and solar hydrogen production facilities produce hydrogen together with oxygen as a by-product or co-product. For a user who needs both oxygen and hydrogen, the value of hydrogen from nuclear and solar plants is higher than that from a fossil plant because “free” oxygen is produced as a by-product. Six factors that impact the relative economics of fossil, nuclear, and solar hydrogen production to the customer are identified: oxygen by-product, avoidance of carbon dioxide emissions, hydrogen transport costs, storage costs, availability of low-cost heat, and institutional factors. These factors imply that different hydrogen production technologies will be competitive in different markets and that the first markets for nuclear and solar hydrogen will be those markets in which they have a unique competitive advantage. These secondary economic factors are described and quantified in terms of dollars per kilogram of hydrogen.