Life cycle assessment of hydrogen production from biomass gasification. Evaluation of different Spanish feedstocks

Gasification of biomass can be used for obtaining hydrogen reducing the total greenhouse gases emissions due the fixation of CO₂ during photosynthetic processes. The kind of raw materials is an important variable since has a great influence on the energy balance and environmental impacts. Wastes from forestry are considered as the most appropriate raw materials since they do not compete for land. The aim of this work is to determine the environmental feasibility of four Spanish lignocellulosic wastes (vine and almond pruning and forest waste coming from pine and eucalyptus plantation) for the production of hydrogen through gasification. LCA methodology was applied using global warming potential, acidification, eutrophication and the gross energy necessary for the production of 1 Nm³ of hydrogen as impact categories. As expected, the use of biomass instead of natural gas leads to the reduction of CO₂ emissions. Regarding to the different feedstocks, biomass coming from forestry is more environmental-friendly since does not need cropping procedures. Finally, the distribution of environmental charges between pruning wastes and fruits (grape and almond) and the use of obtained by-products have a great influence, reducing the environmental impacts.     

Harmonising methodological choices in life cycle assessment of hydrogen: A focus on acidification and renewable hydrogen

The environmental sustainability of hydrogen energy systems is often evaluated through Life Cycle Assessment (LCA). In particular, environmental suitability is usually determined by comparing the life-cycle indicators calculated for a specific hydrogen energy system with those of a reference system (e.g., conventional hydrogen from steam methane reforming, SMR-H₂). In this respect, harmonisation protocols for comparative LCA of hydrogen energy systems have recently been developed in order to avoid misleading conclusions in terms of carbon footprints and cumulative energy demand. This article expands the scope of these harmonisation initiatives by addressing a new life-cycle indicator: acidification. A robust protocol for harmonising the acidification potential of hydrogen energy systems is developed and applied to both SMR-H₂ and a sample of case studies of renewable hydrogen. According to the results, unlike other energy systems, there is no correlation between acidification and carbon footprint in the case of hydrogen energy systems, which prevents the estimation of harmonised acidification results from available harmonised carbon footprints. Nevertheless, an initial library of harmonised life-cycle indicators of renewable hydrogen is now made available.     

Life cycle assessment of hydrogen production by methane decomposition using carbonaceous catalysts

Methane decomposition to yield hydrogen and carbon (CH₄ ? 2H₂ + C) is one of the cleanest alternatives, free of CO₂ emissions, for producing hydrogen from fossil fuels. This reaction can be catalyzed by metals, although they suffer a fast deactivation process, or by carbonaceous materials, which present the advantage of producing the catalyst from the carbon obtained in the reaction. In this work, the environmental performance of methane decomposition catalyzed by carbonaceous catalysts has been evaluated through Life Cycle Assessment tools, comparing it to other decomposition processes and steam methane reforming coupled to carbon capture systems. The results obtained showed that the decomposition using the autogenerated carbonaceous as catalyst is the best option when reaction conversions higher than 65% are attained. These were confirmed by 2015 and 2030 forecastings. Moreover, its environmental performance is highly increased when the produced carbon is used in other commercial applications. Thus, for a methane conversion of 70%, the application of 50% of the produced carbon would lead to a virtually zero-emissions process.     

Life cycle energy consumption and GHG emissions of hydrogen production from underground coal gasification in comparison with surface coal gasification

Developing underground coal gasification (UCG)-based hydrogen production (UCG-H₂) is expected to alleviate hydrogen supply and demand contradiction, but its energy consumption and environmental impact need to be clarified. In this paper, comparative study of energy consumption and greenhouse gas (GHG) emissions between UCG-H₂ and typical surface coal gasification (SCG)-based hydrogen production (SCG-H₂) is carried out using life cycle assessment method. Result shows energy consumption of UCG-H₂ is only 61.2% of that of SCG-H₂, which is 1,327,261 and 2,170,263 MJ respectively, reflecting its obvious energy saving advantage. 80% capture rate can achieve an appropriate balance between energy consumption and emissions. Under this capture rate, emissions of UCG-H₂ and SCG-H₂ are roughly equivalent, which are 207,582 and 197,419 kg CO₂-eq respectively. Scenario analysis indicates energy consumption in hydrogen industry can reduce by 38.8% when hydrogen production is substituted by UCG with CCS to fully meet demand of 21 Mt in 2030.     

Exergy analysis of hydrogen production from steam gasification of biomass: A review

Exergy analysis of hydrogen production from steam gasification of biomass was reviewed in this study. The effects of the main parameters (biomass characteristics, particle size, gasification temperature, steam/biomass ratio, steam flow rate, reaction catalyst, and residence time) on the exergy efficiency were presented and discussed. The results show that the exergy efficiency of hydrogen production from steam gasification of biomass is mainly determined by the H₂ yield and the chemical exergy of biomass. Increases in gasification temperatures improve the exergy efficiency whereas increases in particle sizes generally decrease the exergy efficiency. Generally, both steam/biomass ratio and steam flow rate initially increases and finally decreases the exergy efficiency. A reaction catalyst may have positive, negative or negligible effect on the exergy efficiency, whereas residence time generally has slight effect on the exergy efficiency.     

A framework for assessing economics of blue hydrogen production from steam methane reforming using carbon capture storage & utilisation

Hydrogen (H₂) generation using Steam Methane Reforming (SMR) is at present the most economical and preferred pathway for commercial H₂ generation. This process, however, emits a considerable amount of CO₂, ultimately negating the benefit of using H₂ as a clean industrial feedstock and energy carrier. That has prompted growing interest in enabling CO₂ capture from SMR for either storage or utilisation and producing zero-emission “blue H₂”. In this paper, we propose a spatial techno-economic framework for assessing blue hydrogen production SMR hubs with carbon capture, utilisation and storage (CCUS), using Australia as a case study. Australia offers a unique opportunity for developing such ‘blue H₂’ hubs given its extensive natural gas resources, availability of known carbon storage reservoirs and an ambitious government target to produce clean/zero-emission H₂ at the cost of <A$2 kg^?1 by 2030. Our results highlight that the H₂ production costs are unsurprisingly dominated by natural gas, with the additional capital requirement of carbon capture and storage (CCS) also playing a critical role. These outcomes are especially pertinent for eastern Australian states, as they are experiencing high natural gas costs and would generally require extensive CO₂ transport and storage infrastructure to tap potential storage reservoirs, ultimately resulting in a higher cost of producing H₂ (>A$2.7 kg_H2^?1). On the other hand, Western Australia offers lower gas pricing and relatively lesser storage costs, which would lead to more economically favourable hydrogen production (<A$2.2 kg_H2^?1). We further explore the possibility of utilising the emissions captured at blue SMR hubs by converting them into formic acid through CO₂ electroreduction, yielding revenue that will decrease the cost of blue H₂ and reduce the reliance on CO₂ storage. Our analysis reveals that formic acid production utilising a 10 MW CO₂ electrolyser can potentially reduce H₂ production costs by between 4 and 9%. Further cost reduction is possible by scaling the CO₂ electrolyser capacity to convert a larger portion of the emissions captured, albeit at the cost of higher capital investment, electricity consumption and saturating the market for formic acid. Thus, carbon utilisation for a range of products with high market demand represents a more promising approach to replacing the need for costly carbon storage. Overall, our modelling framework can be adapted for global application, particularly for regions interested in generating blue H₂ and extended to include other CO₂ utilisation opportunities and evaluate other hydrogen production technologies.     

Techno-economic analysis and life cycle assessment of hydrogen production from different biomass gasification processes

The paper presents techno-economic analyses and life cycle assessments (LCA) of the two major gasification processes for producing hydrogen from biomass: fluidized bed (FB) gasification, and entrained flow (EF) gasification. Results indicate that the thermal efficiency of the EF-based option (56%, LHV) is 11% higher than that of the FB-based option (45%), and the minimum hydrogen selling price of the FB-based option is $0.3 per kg H₂ lower than that of the EF-based option. When a carbon capture and liquefaction system is incorporated, the efficiencies of the EF- and FB-based processes decrease to 50% and 41%, respectively. The techno-economic analysis shows that at a biomass price of $100 per tonne, either a minimum price of $115/tonne CO_2e or a minimum natural gas price of $5/GJ is required to make the minimum hydrogen selling price of biomass-based plants equivalent to that of commercial natural gas-based steam methane reforming plants. Furthermore, the LCA shows that, biomass as a carbon-neutral feedstock, negative life cycle GHG emissions are achievable in all biomass-based options.     

Chemical looping gasification for hydrogen production: A comparison of two unique processes simulated using ASPEN Plus

The research compares the simulations of two chemical looping gasification (CLG) types using the ASPEN Plus simulation software for the production of H₂. The simulated biomass type was poultry litter (PL). The first CLG type used in situ CO₂ capture utilizing a CaO sorbent, coupled with steam utilization for tar reforming, allowing for the production of a CO₂-rich stream for sequestration. Near-total sorbent recovery and recycle was achieved via the CO₂ desorption process. The second type utilized iron-based oxygen carriers in reduction–oxidation cycles to achieve 99.8% Fe₃O₄ carrier recovery and higher syngas yields. Temperature and pressure sensitivity analyses were conducted on the main reactors to determine optimal operating conditions. The optimal temperatures ranged from 500 to 1250 °C depending on the simulation and reactor type. Atmospheric pressure proved optimal in all cases except for the reducer and oxidizer in the iron-based CLG type, which operated at high pressure. This CLG simulation generated the most syngas in absolute terms (2.54 versus 0.79 kmol/kmol PL), while the CO₂ capture simulation generated much more H₂-rich syngas (92.45 mol-% compared to 62.94 mol-% H₂).     

Production of hydrogen-rich syngas from absorption-enhanced steam gasification of biomass with conch shell-based absorbents

In this study, steam gasification of pine sawdust is conducted in a fixed-bed reactor in the temperature range 650–700 °C with calcined conch shell (CS) serving as a starting absorbent. The CS is further subjected to hydration (HCS) and calcination (CHCS) to prepare a modified absorbent. It is found that the hydration-calcination treatment of CS causes smaller CaO crystal grains with a larger BET surface area and more porous surface. As a consequence, CHCS exhibits higher catalytic activity for tar reforming, faster reaction rate for CO₂ absorption and better performance for H₂ selectivity than CS. Elevating the temperature contributes to tar reduction but results in lower H₂ content and higher CO₂ content, while an increase in Ca/C leads to higher H₂ content. And the H₂ content can reach approximately 76% with the use of CHCS when temperature and Ca/C ratio are 650 °C and 2, respectively.     

Hydrogen-rich gas from catalytic steam gasification of biomass in a fixed bed reactor: Influence of temperature and steam on gasification performance

The catalytic steam gasification of biomass was carried out in a lab-scale fixed bed reactor in order to evaluate the effects of temperatures and the ratio of steam to biomass (S/B) on the gasification performance. The bed temperature was varied from 600 to 900 and the S/B from 0 to 2.80. The results show that higher temperature contributes to more hydrogen production.     

Catalytic steam reforming of tar for enhancing hydrogen production from biomass gasification: a review

Presently, the global search for alternative renewable energy sources is rising due to the depletion of fossil fuel and rising greenhouse gas (GHG) emissions. Among alternatives, hydrogen (H₂) produced from biomass gasification is considered a green energy sector, due to its environmentally friendly, sustainable, and renewable characteristics. However, tar formation along with syngas is a severe impediment to biomass conversion efficiency, which results in process-related problems. Typically, tar consists of various hydrocarbons (HCs), which are also sources for syngas. Hence, catalytic steam reforming is an effective technique to address tar formation and improve H₂ production from biomass gasification. Of the various classes in existence, supported metal catalysts are considered the most promising. This paper focuses on the current researching status, prospects, and challenges of steam reforming of gasified biomass tar. Besides, it includes recent developments in tar compositional analysis, supported metal catalysts, along with the reactions and process conditions for catalytic steam reforming. Moreover, it discusses alternatives such as dry and autothermal reforming of tar.     

Life cycle assessment of hydrogen production from biomass gasification systems

In this study, a Life Cycle Assessment (LCA) of biomass-based hydrogen production is performed for a period from biomass production to the use of the produced hydrogen in Proton Exchange Membrane (PEM) fuel cell vehicles. The system considered is divided into three subsections as pre-treatment of biomass, hydrogen production plant and usage of hydrogen produced. Two different gasification systems, a Downdraft Gasifier (DG) and a Circulating Fluidized Bed Gasifier (CFBG), are considered and analyzed for hydrogen production using actual data taken from the literature. Fossil energy consumption rate and Green House Gas Emissions (GHG) are defined and indicated first. Next, the LCA results of DG and CFBG systems are compared for 1 MJ/s hydrogen production to compare with each other as well as with other hydrogen production systems. While the fossil energy consumption rate and emissions are calculated as 0.088 MJ/s and 6.27 CO₂ eqv. g/s in the DG system, they are 0.175 MJ/s and 17.13 CO₂ eqv. g/s in the CFBG system, respectively. The Coefficient of Hydrogen Production Performance (CHPP) (newly defined as a ratio of energy content of hydrogen produced from the system to the total energy content of fossil fuels used) of the CFBG and DG systems are then determined to be 5.71 and 11.36, respectively. Thus, the effects of some parameters, such as energy efficiency, ratio of cost of hydrogen, on natural gas and capital investments efficiency are investigated. Finally, the costs of GHG emissions reduction are calculated to be 0.0172 and 0.24 $/g for the DG and CFBG systems, respectively.     

A novel process simulation model for hydrogen production via reforming of biomass gasification tar

Process modeling and simulation are very important for new designs and estimation of operating variables. This study describes a new process for the production of hydrogen from lignocellulosic biomass gasification tars. The main focus of this research is to increase hydrogen production and improve the overall energy efficiency of the process. In this study, Aspen HYSYS software was used for simulation. The integration structure presented in this research includes sections like tar reforming and ash separation (Ash), combined heat and power cycle (CHP), hydrogen sulfide removal unit (HRU), water-gas shift (WGS) reactor, and gas compression as well as hydrogen separation from a mixture of gases in pressure swing adsorption (PSA). It was found that the addition of CHP cycle and the use of the plug flow reactor (PFR) model, firstly, increased the overall energy efficiency of the process by 63% compared to 29.2% of the base process. Secondly it increased the amount of hydrogen production by 0.518 kmol (H2)/kmol Tar as compared with 0.475 of the base process. Process analysis also demonstrated that the integrated process of hydrogen production from biomass gasification tars is carbon neutral.     

Life cycle assessment of various hydrogen production methods

A comprehensive life cycle assessment (LCA) is reported for five methods of hydrogen production, namely steam reforming of natural gas, coal gasification, water electrolysis via wind and solar electrolysis, and thermochemical water splitting with a Cu–Cl cycle. Carbon dioxide equivalent emissions and energy equivalents of each method are quantified and compared. A case study is presented for a hydrogen fueling station in Toronto, Canada, and nearby hydrogen resources close to the fueling station. In terms of carbon dioxide equivalent emissions, thermochemical water splitting with the Cu–Cl cycle is found to be advantageous over the other methods, followed by wind and solar electrolysis. In terms of hydrogen production capacities, natural gas steam reforming, coal gasification and thermochemical water splitting with the Cu–Cl cycle methods are found to be advantageous over the renewable energy methods.     

Life cycle assessment of solar PV based electricity generation systems: A review

Sustainable development requires methods and tools to measure and compare the environmental impacts of human activities for various products viz. goods, services, etc. This paper presents a review of life cycle assessment (LCA) of solar PV based electricity generation systems. Mass and energy flow over the complete production process starting from silica extraction to the final panel assembling has been considered. Life cycle assessment of amorphous, mono-crystalline, poly-crystalline and most advanced and consolidate technologies for the solar panel production has been studied.     

Syngas production from biomass gasification in China: A clean strategy for sustainable development

Biomass gasification, which can be categorized as a set of relatively clean processes, is a good option for hydrogen production. The main purpose of the present work was to focus on the use of natural olivine as a bed material to minimize the tar content and enhance the hydrogen yield. The catalytic gasification tests were carried out in a fluidized bed gasifier using steam as the fluidizing medium. Hydrogen yield slightly increased from 51.9 to 53.1 g/kg biomass, as biomass particle size (BP) decreased from 5.0 to 2.0 mm. The yield of tar also decreased from 0.15 to 0.07 g/Nm³ with BP decreasing from 5.0 to 2.0 mm. With an increase in the catalyst-to-biomass ratio (C/B) from 0.2 to 0.8, HY increased from 47.8 to 51.9 g/kg biomass and tar content (TC) decreased from 0.8 to 0.15 g/Nm³. Temperature and steam/biomass ratio (S/B) were also affected the syngas composition and HY, significantly.     

Economic analysis of hydrogen production from steam reforming process: A literature review

The interest in steam reforming process as an efficient method for hydrogen production has been greatly increasing, due to its efficiency during hydrogen production and low environmental problems compared to other techniques. The main objective of this review was to present a comprehensive study of environmental, economic aspects of hydrogen production from steam reforming of raw materials such as biomass, bio-gas, ethanol, and natural gas. From literature review, it was found that among methods for hydrogen production, steam reforming of natural gas has lower installed capital due to the precence of high amounts of unconverted hydrocarbons in the produced gas (so-called tar) during other methods such as steam reforming of bio-gas.     

Hydrogen-rich gas from catalytic steam gasification of biomass in a fixed bed reactor: Influence of particle size on gasification performance

The catalytic steam gasification of biomass was carried out in a lab-scale fixed bed reactor in order to evaluate the effects of particle size at different bed temperatures on the gasification performance. The bed temperature was varied from 600 to 900 °C and the biomass was separated into five different size fractions (below 0.075 mm, 0.075–0.15 mm, 0.15–0.3 mm, 0.3–0.6 mm and 0.6–1.2 mm). The results show that with decreasing particle size, the dry gas yield, carbon conversion efficiency and H₂ yield increased, and the content of char and tar decreased. And the differences due to particle sizes in gasification performance practically disappear as the higher temperature bound is approached. Hydrogen and carbon monoxide contents in the produced gas increase with decreasing particle size at 900 °C, reaching to 51.2% and 22.4%, respectively.     

Characteristics of hydrogen production from steam gasification of plant-originated lignocellulosic biomass and its prospects in Vietnam

Demands for the decline of CO₂ emissions resulted in a significant transformation of the energy systems working on carbon sources towards more sustainable, clean, and renewable characteristics. Hydrogen is emerging as a secondary energy vector with ever-increasing importance in the decarbonisation progress. Indeed, hydrogen, a green and renewable energy source, could be produced from steam gasification of plant-originated lignocellulosic biomass. In this current review, key factors affect the hydrogen production yield from steam gasification of plant-originated lignocellulosic biomass, including the design of the gasifier, temperature, pressure, and steam-to-biomass ratio, steam flow rate, moisture and particle size of fed biomass, and catalysts were thoroughly analysed. Moreover, the effects of the abovementioned factors on the reduction of tar formation, which is also a key parameter towards ensuring the trouble-free operation of the reactor, were critically evaluated. More importantly, the separation of produced hydrogen from steam gasification of biomass and challenges over technological, environmental, and economic aspects of biomass gasification were also presented in detail. In addition, this paper is also profiling the prospect of Vietnam in fulfilling its hydrogen economy potential because Vietnam has vast biomass due to its tropical weather and availability of arable land, providing abundant lignocellulosic biomass with 45% of agricultural waste, 30% of firewood, and 25% of other sources. Besides, some primary factors hindering the broad application of biomass for hydrogen production were indicated. Finally, some solutions for implementing the hydrogenization strategy in Vietnam have also been discussed.     

Low-carbon energy transition with the sun and forest: Solar-driven hydrogen production from biomass

There is a need to derive hydrogen from renewable sources, and the innovative stewardship of two natural resources, namely the Sun and forest, could provide a new pathway. This paper provides the first comparative analysis of solar-driven hydrogen production from environmental angles. A novel hydrogen production process proposed in this paper, named Solar-Driven Advanced Biomass Indirect-Gasification (SABI-Hydrogen), shows promise toward achieving continuous operation and scalability, the two key challenges to meet future energy needs. The calculated Global Warming Potential for 1 kg of solar-driven hydrogen production is 1.04 kg CO₂-eq/kg H₂, less than half of the current biomass gasification process which emits 2.67 kg CO₂-eq/kg H₂. Further, SABI-Hydrogen demonstrates the least-carbon intensive pathway among all current hydrogen production methods. Thus, solar-driven hydrogen production from biomass could lead to a sustainable supply, essential for a low-carbon energy transition.