Production & Supply Chain

The increasing integration of renewable energy sources (RES) in Spain is leading to substantial amounts of surplus electricity presenting a strategic opportunity for green hydrogen production as a key enabler of energy storage and decarbonisation. This study quantifies this untapped potential for 2024. Based on the difference between installed renewable capacity and actual generation an economically viable surplus of 18419 GWh was identified within an optimal 10-h operating window. The hydrogen production potential was modelled for three electrolysis technologies—Alkaline (AEL) Proton Exchange Membrane (PEM) and Anion Exchange Membrane (AEM)—using total energy consumption values of 57.40 65.55 and 59.95 MWh/t H2 respectively including auxiliary systems. The estimated annual hydrogen production ranges from 280999 t (PEM) to 320897 t (AEL) with AEM yielding an intermediate value of 307247 t. The analysis reveals a strong regional concentration with more than 63% of the potential located in Castile and León Andalusia Castile-La Mancha and Extremadura. While this range represents an upper technical limit it highlights the significant opportunity to valorise surplus renewable energy contingent on targeted investment and a supportive regulatory framework.

This study evaluates the performance of three anion-exchange membranes (FAS-50 AMX Fujifilm-AEM) and a diaphragm separator (Zirfon® UTP 500) in alkaline water sono-electrolysis using a 25 % KOH electrolyte at ambient temperature. Energy efficiency hydrogen production kinetics and membrane stability were assessed experimentally and through modeling. Among the tested separators Zirfon achieved the highest energy efficiency outperforming AEM AMX and FAS-50. Hydrogen production rates under silent conditions ranged from 2.55 µg/s (AEM) to 2.92 µg/s (FAS-50) while sonication (40 kHz 60 W) increased rates by 0.03–0.12 µg/s with the strongest relative effect observed for FAS-50 (≈4.0 % increase). By contrast Zirfon and AEM showed slight efficiency reductions (0.5–2 %) under ultrasound due to their higher structural resistance. Ion-exchange capacity tests confirmed significant degradation of polymeric membranes (IEC losses of 60–90 %) while Zirfon maintained stability in 25 % KOH. Modeling results showed that the diaphragm resistance was dominated by the ohmic losses (55–86 %) with ultrasound reducing bubble coverage and associated resistance only marginally (<0.02 V). Overall Zirfon demonstrated superior stability and efficiency for long-term operation while ultrasound primarily enhanced hydrogen evolution kinetics in mechanically weaker polymeric membranes.

Blue hydrogen technology generated from natural gas through carbon capture and storage (CCS) technology is a promising solution to mitigate greenhouse gas emissions and meet the growing demand for clean energy. To improve the sustainability of blue hydrogen it is crucial to explore alternative feedstocks production methods and improve the efficiency and economics of carbon capture storage and utilization strategies. Two established technologies for hydrogen synthesis are Steam Methane Reforming (SMR) and Autothermal Reforming (ATR). The choice between SMR and ATR depends on project specifics including the infrastructure energy availability environmental goals and economic considerations. ATR-based facilities typically generate hydrogen at a lower cost than SMR-based facilities except in cases where electricity prices are elevated or the facility has reduced capacity. Both SMR and ATR are methods used for hydrogen production from methane but ATR offers an advantage in minimizing CO2 emissions per unit of hydrogen generated due to its enhanced energy efficiency and unique process characteristics. ATR provides enhanced utility and flexibility regarding energy sources due to its autothermal characteristics potentially facilitating integration with renewable energy sources. However SMR is easier to run but may lack flexibility compared to ATR necessitating meticulous management. Capital expenditures for SMR and ATR hydrogen reactors are similar at the lower end of the capacity spectrum but when plant capacity exceeds this threshold the capital costs of SMR-based hydrogen production surpass those of ATR-based facilities. The less profitably scaled-up SMR relative to the ATR reactor contributes to the cost disparity. Additionally individual train capacity constraints for SMR CO2 removal units and PSA units increase the expenses of the SMR-based hydrogen facility significantly.

Aqueous phase reforming has been posed as a promising technology for renewable hydrogen production in the framework of the transition to a sustainable energy economy. Since the use of chemical compounds as process feedstock has proven to be one of the major constraints to its potential scalability several cost-free residual biomasses have been investigated as alternative substrates. This also allows for the recovery of residues offsetting the significant costs of waste management through conventional treatment. In recent years different wastes from the food processing industry such as brewery fish canning dairy industries fruit juice extraction and corn production wastewaters have taken the attention of scientific community due to their composition favorable to this process and its high-water content. However few and heterogeneous results can be found within the literature suggesting that the research into this application is now at a stage of development which will require further investigation. Therefore this work is focused on compiling and discussing the reported studies aiming to present a critical reflection on the potential of aqueous phase reforming as a means for the valorization of this kind of residue.

Volatile fatty acid (VFA) accumulation is a common issue that compromises the performance of biological hydrogen methanation systems (BHMs). This accumulation is often triggered by fluctuations in hydrogen supply which can disrupt microbial activity and lead to system instability. To address this challenge this study investigated the impact of employing a microbial electrolysis cell (MEC) in BHMs to mitigate system instability and acid buildup. As such a conventional anaerobic digester (AD) and a microbial electrolysis cell both supplemented with exogenous hydrogen were evaluated for their performance in hydrogen methanation. The effect of exogenous hydrogen at high addition rates (>4:1 CO2:H2 molar ratio) under instantaneous and gradual injection modes was investigated. The results showed that the instantaneous addition of hydrogen resulted in the total failure of the anaerobic digestion system. Propionate accumulated in the system (>2 g/L) and resulted in low pH (pH=5.3). Methane production stopped and the reactor never recovered from hydrogen shock. However the microbial electrolysis system was able to withstand the instantaneous hydrogen addition and maintain normal operation under toxic hydrogen addition levels (>4:1 CO2:H2 molar ratio). Under the gradual injection mode both MEC and AD reactors remained reasonably unaffected; even though the hydrogen injection exceeded the stoichiometric molar ratio. This study provides a new perspective on the application of MECs for reliable operation and storage of surplus renewable energy via biological hydrogen methanation.

The United Nations has set a global vision towards emissions reduction and green growth through the Sustainable Development Goals (SDGs). Towards the realisation of SDGS 7 9 and 13 we focus on green hydrogen production as a potential pathway to achievement. Green hydrogen produced via water electrolysis powered by renewable energy sources represents a pivotal solution towards climate change mitigation. Energy access in West Africa remains a challenge and dependency on fossil fuels persists. So green hydrogen offers an opportunity to harness abundant solar resources reduce carbon emissions and foster economic development. This study evaluates the techno-economic feasibility of green hydrogen production in five West African countries: Ghana Nigeria Mali Niger and Senegal. The analyses cover the solar energy potential hydrogen production capacities and economic viability using the Levelised Cost of Hydrogen (LCOH) and Net Present Value (NPV). Results indicate substantial annual hydrogen production potential with LCOH values competitive with global benchmarks amidst the EU’s Carbon Border Adjustment Mechanism (CBAM). Despite this potential several barriers exist including high initial capital costs policy and regulatory gaps limited technical capacity and water resource constraints. We recommend targeted strategies for strengthening policy frameworks fostering international partnerships enhancing regional infrastructure integration and investing in capacity-building initiatives. By addressing these barriers West Africa can be a key player in the global green hydrogen market.

The growing demand for green hydrogen is driving the expansion of water electrolysis. The resulting oxygen byproduct offers potential added value when used in sectors with high oxygen demand such as wastewater treatment. This study investigates the techno-economic viability of using electrolysis oxygen to supplement conventional air blowers in the aeration process of municipal wastewater treatment plants (WWTPs) to reduce aeration costs and thereby improve the overall economics of hydrogen production. A comprehensive system model is developed incorporating renewable electricity supply water electrolysis hydrogen compression storage and transport as well as WWTP aeration via conventional air blowers and electrolysis oxygen. Results show that electrolysis oxygen can reduce WWTP aeration costs by up to 68%. If these cost reductions are attributed as a benefit to the hydrogen system they correspond to hydrogen supply cost savings of up to 0.39 EUR/kgH2. However the analysis indicates that economic viability is substantially influenced by factors such as the distance of hydrogen transport from the WWTP to the European Hydrogen Backbone feed-in point which should not exceed 25 km and the alignment between the scale of hydrogen production and the size of the WWTP with cost-effective integration being particularly feasible for larger WWTPs (≥500000 PE).

Climate-change mitigation in North America demands rapid deep cuts in carbon-dioxide emissions from hard-toabate industrial power-generation and transport sectors. Carbon capture and storage (CCS) is one of the few technological routes that can decouple continued use of fossil-derived energy and materials from their climate externalities. Yet deployment across the US and Canada still trails the scale implied by regional net-zero pledges. This review addresses that gap by synthesizing technical economic policy and social dimensions of CCS and complements global syntheses with a granular assessment of North America’s unique emission profile infrastructure advantages and regulatory frameworks. Methodologically the review disaggregates the CCS chain into six pillars: (i) current emission baselines; (ii) capture systems icluding post- pre- and oxy-combustion chemical-looping combustion (CLC) and direct air capture (DAC); (iii) capture technologies (e.g. absorption adsorption membrane cryogenic and hybrid processes); (iv) storage pathways (geological oceanic and emerging biological or mineral options); (v) cross-cutting economic policy and social factors; and (vi) deployment status plus future outlook. Post-combustion capture remains the most retrofit-ready option for the region’s ageing coal and gas fleet yet solvent regeneration still imposes energy penalties of 8–10 percentagepoints. Pre-combustion and oxy-fuel routes offer thermodynamic advantages for new-build plants but require high-capex gasifiers or cryogenic air separation units slowing adoption. Emerging CLC and DAC concepts could unlock low-carbon fuels and negative emissions respectively but remain costly and pre-commercial. No single technology meets all performance criteria making hybrid configurations—such as membrane–cryogenic or membrane–amine schemes—particularly promising. North America’s subsurface offers multi-teratonne theoretical storage capacity in saline formations depleted hydrocarbon reservoirs and CO2-EOR sites suggesting physical room is not the bottleneck. Instead economics dominate: levelized capture costs today range from around $15/tCO2 in natural-gas processing to over $120/t in power and cement and long-distance pipeline networks are sparse outside existing enhanced oil recovery (EOR) corridors. Recent federal incentives can shift project economics decisively yet policy volatility and permitting hurdles still threaten investment certainty. Societal acceptance emerges as another critical lever. Surveys reveal generally favorable attitudes toward CCS in principle but heightened opposition to local storage projects. Transparent monitoring–verification frameworks benefit-sharing mechanisms and durable bipartisan policies are therefore essential to secure a “social licence” for large-scale CO2 injection. This review concludes that widescale CCS in North America is technically feasible and increasingly cost-competitive when paired with robust incentives abundant storage capacity and existing pipeline know-how. Realizing its full mitigation potential will hinge on coordinated build-out of transport networks harmonized federal–provincial regulations continued R&D into low-energy capture materials and integrated assessments that weigh CCS alongside renewables efficiency and negative-emission strategies. The roadmap presented herein provides stakeholders with actionable insights to accelerate that transition positioning North America as both a proving ground and a global exemplar for scalable responsibly governed CCS.

The management of sewage sludge presents a pressing environmental and economic challenge due to its increasing global production and complex hazardous composition. Gasification offers a viable method for converting this waste into valuable energy resources. This study investigates whether integrating experimental and computational techniques can enhance the understanding and optimization of sludge gasification. Two types of sewage sludge SSG from Rethymno and SSD from Dubai were evaluated using an entrained flow gasifier under controlled thermal and flow conditions. The methodology combines equilibrium modeling computational fluid dynamics (CFD) drop tube reactor (DTR) experiments and artificial neural network (ANN) modeling. The ANN was combined with Kissinger analysis to obtain kinetics from the ANN outputs and derive thermodynamic parameters used to enhance CFD fidelity. Gas composition analysis and scanning electron microscopy (SEM) revealed that SSD decomposes more easily with a lower activation energy (42.29–138.31 kJ/mol) and a lower Gibbs free energy. In contrast SSG demonstrated greater thermal stability and reactivity. SSG achieved consistently higher cold gas efficiency (CGE) reaching 53.66 % in equilibrium modeling 45.50 % in CFD and 38.90 % in experiments compared to SSD’s 48.86 % 37.81 % and 31.19 % respectively. SEM imaging confirmed an increase in porosity and surface area for SSG after gasification. These results indicate that the type of sludge has a significant impact on energy recovery and that ANN-calibrated thermokinetics and CFD enhance process predictability. This integrated method scales hydrogen generation and promotes sustainable waste-toenergy technology.

The accelerating global demand for hydrogen is pushing for renewable and waste derived hydrogen production processes where date palm waste (DPW) has been identified as an available and unexploited agricultural residue that has the potential to be a sustainable source of hydrogen. The current work focuses on developing and evaluating four different process configurations in terms of energy environment and economics for producing hydrogen from DPW using Aspen Plus® simulation tool. Case 1 represents the standalone DPW gasification with CO₂ capture via methanol absorption Case 2 represents the DPW gasification with CaO-based chemical looping for CO₂ capture Case 3 represents the DPW gasification integrated with steam methane reforming (SMR) and methanol-based CO₂ capture and Case 4 represents the DPW gasification integrated with SMR and CaO-based CO₂ capture. Each case was evaluated in terms of syngas composition hydrogen production lower heating value CO₂ captured utility demand process efficiency and H2 production cost. Hydrogen production ranged from 974.55 t/year (Case 1) and 988.83 t/year (Case 2) to 2032.32 t/year (Case 3) and 2048.61 t/year (Case 4). CO₂ capture was also more effective in Case 4 (16929.49 t/year) compared to Case 1 (7676.30 t/year). Process efficiency improved from 33 % in Case 1 to 47 % in Case 2 and from 32 % in Case 3 to further to 55 % in Case 4. Economically Case 1 offered the highest hydrogen production cost ($5.03/kg) followed by Case 2 ($4.77/kg) while Case 3 and Case 4 achieved significantly lower production costs of $2.89/kg and $2.69/kg respectively.