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Open accessJournal ArticleDOI: 10.3390/PR9030462

Techno-Economic Assessment of Solar-Driven Steam Gasification of Biomass for Large-Scale Hydrogen Production

04 Mar 2021-Vol. 9, Iss: 3, pp 462
Abstract: Solar biomass gasification is an attractive pathway to promote biomass valorization while chemically storing intermittent solar energy into solar fuels. The economic feasibility of a solar gasification process at a large scale for centralized H2 production was assessed, based on the discounted cash-flow rate of return method to calculate the minimum H2 production cost. H2 production costs from solar-only, hybrid and conventional autothermal biomass gasification were evaluated under various economic scenarios. Considering a biomass reference cost of 0.1 €/kg, and a land cost of 12.9 €/m2, H2 minimum price was estimated at 2.99 €/kgH2 and 2.48 €/kgH2 for the allothermal and hybrid processes, respectively, against 2.25 €/kgH2 in the conventional process. A sensitivity study showed that a 50% reduction in the heliostats and solar tower costs, combined with a lower land cost of below 0.5 €/m2, allowed reaching an area of competitiveness where the three processes meet. Furthermore, an increase in the biomass feedstock cost by a factor of 2 to 3 significantly undermined the profitability of the autothermal process, in favor of solar hybrid and solar-only gasification. A comparative study involving other solar and non-solar processes led to conclude on the profitability of fossil-based processes. However, reduced CO2 emissions from the solar process and the application of carbon credits are definitely in favor of solar gasification economics, which could become more competitive. The massive deployment of concentrated solar energy across the world in the coming years can significantly reduce the cost of the solar materials and components (heliostats), and thus further alleviate the financial cost of solar gasification.

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Topics: Solar energy (63%), Biomass (50%)
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Open accessJournal ArticleDOI: 10.3390/PR9040687
14 Apr 2021-
Abstract: The solar gasification of biomass represents a promising avenue in which both renewable solar and biomass energy can be utilized in a single process to produce synthesis gas. The type of oxidant plays a key role in solar-driven biomass gasification performance. In this study, solar gasification of beech wood biomass with different oxidants was thermodynamically and experimentally investigated in a 1.5 kWth continuously-fed consuming bed solar reactor at 1200 °C under atmospheric pressure. Gaseous (H2O and CO2) as well as solid (ZnO) oxidants in pellet and particle shapes were utilized for gasifying beech wood, and the results were compared with pyrolysis (no oxidant). As a result, thermodynamic predictions provided insights into chemical gasification reactions against oxidants, which can support experimental results. Compared to pyrolysis, using oxidants significantly promoted syngas yield and energy upgrade factor. The highest total syngas yield (63.8 mmol/gbiomass) was obtained from biomass gasification with H2O, followed by CO2, ZnO/biomass mixture (pellets and particles), and pyrolysis. An energy upgrade factor (U) exceeding one was achieved whatever the oxidants, with the maximum U value of 1.09 from biomass gasification with ZnO, thus highlighting successful solar energy storage into chemical products. ZnO/biomass pellets exhibited greater gas yield, particularly CO, thanks to enhanced solid–solid reaction. Solid product characterization revealed that ZnO can be reduced to high-purity Zn through solar gasification, indicating that solar-driven biomass gasification with ZnO is a promising innovative process for CO2-free sustainable co-production of metallic Zn and high-quality syngas.

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Topics: Syngas (59%), Biomass (56%), Pyrolysis (51%) ... read more

1 Citations


Open accessJournal ArticleDOI: 10.1016/J.IJHYDENE.2021.09.008
Abstract: Solar thermochemical gasification is an opportunity for the production of sustainable fuels from carbonaceous resources including biomass. Substituting conventional gasification processes by solar-driven technologies may enable cleaner production of H2-rich syngas while saving feedstock resources and alleviating CO2 emissions. This work addresses hybrid solar-autothermal gasification of mm-sized beech wood particles in a lab-scale 1.5 kWth spouted-bed reactor. Hybridization under reduced solar power input was performed by injecting oxygen and additional biomass inside the gasifier for complementary heat supply. Increasing O2:C molar ratios (in the range 0.14–0.58) allowed to heat the reactor cavity and walls progressively, while gradually impairing the reactor performance with an increase of the syngas CO2 content and a decrease of the reactor cold gas efficiency (CGE). Gasification with mixed H2O and O2 was then assessed at thermodynamic equilibrium and global trends were validated experimentally, showing that control of H2:CO ratio was compatible with in-situ combustion. The impact of reaction temperature (1200–1300 °C) and heating mode (direct or indirect) was experimentally studied during both allothermal and hybrid gasification. Higher H2 and CO yields were achieved at high temperatures (1300 °C) under direct reactor heating. Hybridization was able to counterbalance a 40% drop of the nominal solar power input, and the measured CGE reached 0.82, versus values higher than 1 during allothermal gasification.

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Topics: Syngas (56%), Wood gas generator (56%), Combustion (52%)

1 Citations


Open accessJournal ArticleDOI: 10.1016/J.FUPROC.2021.107118
Abstract: Oil palm empty fruit bunch (OPEFB) is an abundant waste that is commonly incinerated, causing environmental pollution. In this study, an alternative waste management approach was investigated to produce value-added syngas from OPEFB using solar steam gasification. The three operating variables were temperature (1100–1300 °C), H2O/OPEFB molar ratio (1.7–2.9), and OPEFB flowrate (0.8–1.8 g/min). Central composite design (CCD) was conducted to investigate and optimise the effects of these operating variables on H2/CO molar ratio and solar to fuel energy conversion efficiency (ηsolar to fuel). The findings revealed that all investigated operating variables were significant. Experimentally, the highest H2/CO molar ratio (1.6) was obtained at 1300 °C, H2O/OPEFB molar ratio of 2.9, and OPEFB flowrate of 1.8 g/min, with a high carbon conversion reaching 95.1%. Results from CCD analysis showed that a higher H2/CO molar ratio (above 1.8) could be reached at 1200 °C, H2O/OPEFB molar ratio of ≥3.0, and OPEFB flowrate of ≥2.0 g/min. The maximum ηsolar to fuel of 19.6% was achieved at 1200 °C, H2O/OPEFB molar ratio of 1.3, and OPEFB flowrate of 1.3 g/min, whereby a favourable energy upgrade factor (1.2) was achieved. The statistical model showed adequacy to predict H2/CO molar ratio.

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Topics: Environmental pollution (52%)

Open accessJournal ArticleDOI: 10.1016/J.IJHYDENE.2021.10.124
Abstract: Hydrogen is a renewable energy carrier that is one of the most competent fuel options for the future. The majority of hydrogen is currently produced from fossil fuels and their derivatives. These technologies have a negative impact on the environment. Furthermore, these resources are rapidly diminishing. Recent research has focused on environmentally friendly and pollution-free alternatives to fossil fuels. The advancement of bio-hydrogen technology as a development of new sustainable and environmentally friendly energy technologies was examined in this paper. Key chemical derivatives of biomass such as alcohols, glycerol, methane-based reforming for hydrogen generation was briefly addressed. Biological techniques for producing hydrogen are an appealing and viable alternative. For bio-hydrogen production, these key biological processes, including fermentative, enzymatic, and biocatalyst, were also explored. This paper also looks at current developments in the generation of hydrogen from biomass. Pretreatment, reactor configuration, and elements of genetic engineering were also briefly covered. Bio-H2 production has two major challenges: a poor yield of hydrogen and a high manufacturing cost. The cost, benefits, and drawbacks of different hydrogen generation techniques were depicted. Finally, this article discussed the promise of biohydrogen as a clean alternative, as well as the areas in which additional study is needed to make the hydrogen economy a reality.

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Topics: Hydrogen economy (65%), Hydrogen production (56%), Environmentally friendly (51%) ... read more

References
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36 results found


Journal ArticleDOI: 10.1109/JPROC.2011.2156750
01 Feb 2012-
Abstract: This paper reviews water electrolysis technologies for hydrogen production and also surveys the state of the art of water electrolysis integration with renewable energies. First, attention is paid to the thermodynamic and electrochemical processes to better understand how electrolysis cells work and how they can be combined to build big electrolysis modules. The electrolysis process and the characteristics, advantages, drawbacks, and challenges of the three main existing electrolysis technologies, namely alkaline, polymer electrolyte membrane, and solid oxide electrolyte, are then discussed. Current manufacturers and the main features of commercially available electrolyzers are extensively reviewed. Finally, the possible configurations allowing the integration of water electrolysis units with renewable energy sources in both autonomous and grid-connected systems are presented and some relevant demonstration projects are commented.

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Topics: High-temperature electrolysis (66%), Electrolysis (57%), Electrolytic process (57%) ... read more

745 Citations


Open accessJournal ArticleDOI: 10.1016/J.IJHYDENE.2017.10.045
Oliver Schmidt1, Ajay Gambhir1, Iain Staffell1, Adam Hawkes1  +2 moreInstitutions (1)
Abstract: The need for energy storage to balance intermittent and inflexible electricity supply with demand is driving interest in conversion of renewable electricity via electrolysis into a storable gas. But, high capital cost and uncertainty regarding future cost and performance improvements are barriers to investment in water electrolysis. Expert elicitations can support decision-making when data are sparse and their future development uncertain. Therefore, this study presents expert views on future capital cost, lifetime and efficiency for three electrolysis technologies: alkaline (AEC), proton exchange membrane (PEMEC) and solid oxide electrolysis cell (SOEC). Experts estimate that increased R&D funding can reduce capital costs by 0–24%, while production scale-up alone has an impact of 17–30%. System lifetimes may converge at around 60,000–90,000 h and efficiency improvements will be negligible. In addition to innovations on the cell-level, experts highlight improved production methods to automate manufacturing and produce higher quality components. Research into SOECs with lower electrode polarisation resistance or zero-gap AECs could undermine the projected dominance of PEMEC systems. This study thereby reduces barriers to investment in water electrolysis and shows how expert elicitations can help guide near-term investment, policy and research efforts to support the development of electrolysis for low-carbon energy systems.

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Topics: Capital cost (54%), Expert elicitation (51%)

654 Citations


Journal ArticleDOI: 10.1016/S0360-3199(01)00177-X
Aldo Steinfeld1, Aldo Steinfeld2Institutions (2)
Abstract: The production of hydrogen from water using solar energy via a two-step thermochemical cycle is considered. The first, endothermic step is the thermal dissociation of ZnO(s) into Zn(g) and O 2 at 2300 K using concentrated solar energy as the source of process heat. The second, non-solar, exothermic step is the hydrolysis of Zn(l) at 700 K to form H 2 and ZnO(s); the latter separates naturally and is recycled to the first step. Hydrogen and oxygen are derived in different steps, thereby eliminating the need for high-temperature gas separation. A 2nd-law analysis performed on the closed cyclic process indicates a maximum exergy conversion efficiency of 29% (ratio of Δ G 298 K °| H 2 +0.5 O 2 → H 2 O for the H 2 produced to the solar power input), when using a solar cavity-receiver operated at 2300 K and subjected to a solar flux concentration ratio of 5000. The major sources of irreversibility are associated with the re-radiation losses from the solar reactor and the quenching of Zn(g) and O 2 to avoid their recombination. An economic assessment for a large-scale chemical plant, having a solar thermal power input into the solar reactor of 90 MW and a hydrogen production output from the hydrolyser of 61 million-kWh/yr, indicates that the cost of solar hydrogen ranges between 0.13 and 0.15$/kWh (based on its low heating value and a heliostat field cost at 100–150$/m 2 ) and, thus, might be competitive vis-a-vis other renewables-based routes such as electrolysis of water using solar-generated electricity. The economic feasibility of the proposed solar process is strongly dependent on the development of an effective Zn/O 2 separation technique (either by quench or by in situ electrolytic separation) that eliminates the need for an inert gas. The chemical aspects of the reactions involved and the present status of the pertinent chemical reactor technology are summarized.

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Topics: Solar energy (65%), Thermochemical cycle (64%), Zinc–zinc oxide cycle (63%) ... read more

618 Citations


Journal ArticleDOI: 10.1016/J.ENERGY.2005.11.002
01 Nov 2006-Energy
Abstract: Hydrogen, a promising and clean energy carrier, could potentially replace the use of fossil fuels in the transportation sector. Currently, no environmentally attractive, large-scale, low-cost and high-efficiency hydrogen production process is available for commercialization. Solar-driven water-splitting thermochemical cycles may constitute one of the ultimate options for CO2-free production of hydrogen. The method is environmentally friendly since it uses only water and solar energy. First, the potentially attractive thermochemical cycles must be identified based on a set of criteria. To reach this goal, a database that contains 280 referenced cycles was established. Then, the selection and evaluation of the promising cycles was performed in the temperature range of 900–2000 °C, suitable to the use of concentrated solar energy. About 30 cycles selected for further investigations are presented in this paper. The principles and basis for a thermodynamic evaluation of the cycles are also given.

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Topics: Thermochemical cycle (60%), Solar energy (54%), Hydrogen production (51%) ... read more

346 Citations


Journal ArticleDOI: 10.1016/J.RSER.2015.10.026
Deepak Yadav1, Rangan Banerjee1Institutions (1)
Abstract: This paper reviews development in the field of solar thermochemical processing by considering experimental demonstrations, reactor technology development, thermodynamic, economic and life cycle analyses. The review then builds on these aspects and compares various solar thermochemical processes. Solar upgrading of carbon feed has been demonstrated on pilot scale. It is observed that for the thermochemical cycles, only iron and ceria based redox pair have been demonstrated on pilot scale. For industrial applications, solar thermochemical production of zinc, upgrading of landfill gas and organic waste have been demonstrated on pilot scale. However, long term performance data of these pilot plants is not reported in literature. Thermodynamic comparison reveals that the processes involving upgrading of carbon feed have energy and exergy efficiency at 50–90% and 46–48% respectively. Multistep thermochemical cycles operating at 900–1200 K have energy efficiency of 34–38%. Metal oxide redox pair based thermochemical cycles operating at 1900–2300 K have energy and exergy efficiencies of 12–32% and 20–36% respectively. Methane reforming and lime production processes have chemical efficiencies of 55% and 35% respectively and have demonstrated better performance than other solar thermochemical processes. A few processes like solar gasification of solid carbon feed have demonstrated lower chemical efficiency of around 10% even at pilot scale. The hydrogen production cost for solar upgrading of fossil fuels is estimated at 3.21–6.10$/kg and is lower than thermochemical cycles at 7.17–19.26$/kg and CSP driven electrolysis at 3.15–10.23$/kg. It is observed that there is limited actual data and significant uncertainty in cost. Under these circumstances, it is recommended that initial screening of processes be done by net energy, material and life cycle analysis.

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Topics: Thermochemical cycle (62%), Solar energy (57%), Exergy efficiency (53%) ... read more

214 Citations