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Item type:Publication, Access status: without files , Cobalt modified platinum-cellulose-carbon aerogel prepared by supercritical deposition as electrocatalyst for hydrogen evolution reaction(Elsevier, 2026-02-19); ; ; ; Green hydrogen production via water electrolysis is a key technology for reaching net-zero CO₂ emission targets due to its ability to generate high-purity hydrogen with minimal environmental impact. This study investigates the effect of Co on Pt-based electrocatalysts supported on cellulose-based carbon aerogels (cellulose-CA) using supercritical deposition (SCD) on hydrogen evolution reaction (HER) activity and stability. Pt and Co precursors were deposited onto cellulose-CA via SCD and converted via two routes (ex-situ thermal and chemical) under N₂ and H₂ flow at 1 bar and 200 °C. Characterizations (ICP-MS, STEM, XPS, SEM, Raman, and XRD) confirmed successful Pt and Co incorporation and preservation of the cellulose-CA microstructure (overall accessible surface area ∼2100 – 2700 m² g⁻¹). The Co-modified electrocatalysts exhibited similar overpotentials at 20 mA/cm² despite half the Pt loading, with thermally converted Pt–Co-cellulose-CA showing the lowest overpotential (64 mV) and potential shift (4 mV). Our results demonstrate that Co-modification via SCD enhances the activity and stability of biobased CA electrocatalysts with low Pt content around 2.8 wt%.Publicationtype: Journal Article48 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Tuning membraneless microbial electrolysis cells operation alters efficiency and anodic microbiome toward scalable hydrogen production from sludge-hydrolysate(Elsevier, 2026-01-21); ; ; ; The practical implementation of microbial electrolysis cells (MECs) is hindered by challenges in optimizing system performance with complex substrates. This study addresses that gap by evaluating MECs fed with hydrolysate, an appealing substrate rich in organic-acids. Through systematic variation of substrate concentration (20–60 %), pH (5–8), and applied anodic potential ( 0.2 to +0.4 V vs standard hydrogen electrode [SHE]), the optimal operational conditions were defined as 40 %-hydrolysate, pH 8, and +0.4 V vs SHE, yielding a mean current density of 3.4 A/m2 and coulombic efficiencies (CE) of 38 % and 96 % based on total organic carbon (TOC) and total volatile fatty acids (VFAs), respectively. Scalability was demonstrated using a 10 L rotating disk bioelectrochemical reactor (RDBER) at 0 and 0.4 V vs SHE, achieving a maximum hydrogen production rate of 30.57 L/m2/d and minimal methane formation at 0.4 V. These findings offer a framework for optimizing MECs under real-feedstock conditions.Publicationtype: Journal Article33 16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Comparing the safety of bunkering LH2 and LNG using quantitative risk assessment with a focus on ignition hazards—Sensitivity analysisHydrogen, in its various storage forms, represents a potential fuel for climate-neutral shipping. In order to evaluate the safety of bunkering liquid hydrogen and to establish a basis for a comparison with the bunkering of LNG, a quantitative risk assessment has been conducted. This paper continues this work, by first realizing a quantitative risk assessment (QRA) with adopted systems allowing for the same bunkering duration for both fuels. The investigation shows that the diameter of the pipe has a significant impact on the frequency of hazardous events. To gain a deeper understanding of the effect, a sensitivity analysis is conducted. In addition to the frequencies, a notable impact of the pipe diameter can also be observed with regards to the safety distance in the full rupture case. Furthermore, the safety distances are found to be significantly impacted by wind speed and release time. The ambient temperature and humidity are identified to have only a minor impact.Publicationtype: Journal Article15 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Renewable energy supply via carbon-based molecules – A techno-economic assessment of various import pathwaysThe EU's transition to net-zero greenhouse gas emissions (GHG) likely necessitates renewable energy imports. This paper assesses various import pathways for energy-rich “green” molecules into the EU, focusing on carbon-based molecules like “green” methanol and synthetic natural gas (SNG). These energy carriers, produced using hydrogen derived from renewable electricity and non-fossil CO2, are compared with alternative import pathways, including liquid hydrogen, ammonia, and liquid organic hydrogen carriers (LOHCs). Different forms of final energy supply are analyzed, including pure hydrogen and hydrogen derivatives. Results show, that among the examined pathways relying on carbon-based molecules, energy imports via methanol with largely closed carbon cycles are particularly promising. A closed carbon cycle reduces the cost of energy supply with methanol by around 15 % compared to CO2 provision via Direct Air Capture (DAC). For methanol, SNG and ammonia, direct use is more economical than reconversion into hydrogen. For pure hydrogen supply, importing gaseous hydrogen by pipeline or liquid hydrogen by ship results in the lowest hydrogen supply cost (∼0.15 €/kWhH2,LHV). If hydrogen is imported via carriers, methanol or ammonia should be preferred, while SNG and LOHCs are less competitive.Publicationtype: Journal Article23 29 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A novel, cost-effective approach for the production of hydrogenase enzymes and molecular hydrogen from recycled whey-based by-products(Elsevier, 2025-06); ; ; ; Cupriavidus necator produces O2-tolerant [NiFe]-hydrogenases (Hyds), and is a valuable biocatalyst for biological fuel cells, while Escherichia coli produces H2 during mixed-acid fermentation. A mixture of curd and cheese whey (CW) was used to explore two-phase growth with C. necator H16 and E. coli. Enhanced biomass, as well as Hyd activity and electrical potential (∼0.65 V) were shown for growth of C. necator in the CW medium with added glycerol. The residual growth medium made available after the cultivation of C. necator and removal of cells was then used for cultivation of E. coli. Maximum fermentative growth of E. coli was attained after 72 h and with a H2 yield of ∼6 mmol/L/g dry whey after 48 h. This study demonstrates the economically viable production of biomass, hydrogenase enzymes and H₂ using cheap, industrially produced whey within the 3R concept.Publicationtype: Journal Article16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Conditioned hydrogen for a green hydrogen supply for heavy duty-vehicles in 2030 and 2050 – A techno-economic well-to-tank assessment of various supply chains(2024-01-02); ; ; Hydrogen, seen as a promising secondary renewable energy carrier, can becompressed or liquefied as well as chemically bound to enable a more economic storage and transportation. All conditioned hydrogen options obtain specific advantages and disadvantages. Thus, this paper assess the energy efficiency and the cost of a green hydrogen supply from well to tank exemplified for fuel cell heavy-duty vehicles in Germany related to the years 2030 and 2050. Therefore, compressed gaseous hydrogen, liquid hydrogen, liquid organic hydrogen carriers, methanol and ammonia are considered and different hydrogen production regions in North and Central Germany, as well as an import from Tunisia and Argentina (Patagonia) are assumed. The assessment shows that a hydrogen supply chain in its state of aggregation as finally demanded is the lowest cost option leading to 700 bar compressed gaseous hydrogen filling costs of 5 €2020/kgH2 in 2030 and 4 €2020/kgH2 in 2050 and liquid hydrogen filling costs around 7 €2020/kgH2 in 2030 and 6 €2020/kgH2 in 2050.Publicationtype: Journal Article120 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Model-based assessment of the environmental impacts of fuel cell systems designed for eVTOLsHydrogen fuel cells have increasingly gained relevance for electric vertical take-off and landing aircraft due to their potential to overcome the main challenges related to batteries. Previous studies have investigated their feasibility for urban air mobility; however, a robust assessment of their environmental implications is still lacking. To fill this gap, this study follows a model-based life cycle engineering approach to quantify the environmental impacts of a fuel cell system designed for three ranges. The production burdens distributed along the lifetime are demonstrated, showing that, for the best case scenario, 70g CO2-eq. per passenger-kilometer is achieved. Under the premise of green hydrogen production, the stack is the main contributor to the environmental impacts. This changes for non-renewable hydrogen production pathways, where hydrogen has the highest impact contributions. Better environmental performance results from short design ranges; however, systems designed for longer ranges will likely increase attractiveness in the future.Publicationtype: Journal Article96 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Liquid Organic Hydrogen Carrier (LOHC) – Assessment based on chemical and economic properties(2019-03-08); ; ; LLC Hydrogen can be transported via long distances based on Liquid Organic Hydrogen Carriers (LOHC). Such a transport is realized based on a two-step cycle: (1) loading/storage of hydrogen (hydrogenation) into the LOHC molecule and (2) unloading/release of hydrogen (de-hydrogenation). During the storage period, hydrogen is covalently bound to the respective LOHC. Since the (optimal) LOHC is liquid at ambient conditions and shows similar properties as crude oil based liquids (e.g. diesel, gasoline), it can easily be handled, transported and stored; thus a stepwise implementation using the existing crude oil based infrastructure would be possible. Against this background this paper reviews the current knowledge in hydrogenation and de-hydrogenation of various LOHC. Therefore, a variety of LOHC is evaluated based on their properties and compared to each other. By applying different evaluation criteria representing the requirements of the three different application areas (energy-storage, energy-transport, mobility application), the LOHCs can be assigned to a field they suit best. The analysis shows that the most promising LOHC candidates to date are dibenzyltoluene for energy-transport and energy-storage as well as N-ethylcarbazole for mobility applications. In addition, a use of toluene in the transport sector is also conceivable. Methanol can potentially be applied in all three application fields due to its properties if a compromise between de-hydrogenation temperature and gas flow can be achieved based on further R&D-activities. For future implementation phenazine and formic acid show great potential, but also additional R&D especially regarding catalysis and solvents is necessary.Publicationtype: Journal Article1328 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Dynamic simulation of different transport options of renewable hydrogen to a refinery in a coupled energy system approachThree alternative transport options for hydrogen generated from excess renewable power to a refinery of different scales are compared to the reference case by means of hydrogen production cost, overall efficiency, and CO2 emissions. The hydrogen is transported by a) the natural gas grid and reclaimed by the existing steam reformer, b) an own pipeline and c) hydrogen trailers. The analysis is applied to the city of Hamburg, Germany, for two scenarios of installed renewable energy capacities. The annual course of excess renewable power is modeled in a coupled system approach and the replaceable hydrogen mass flow rate is determined using measurement data from an existing refinery. Dynamic simulations are performed using an open-source Modelica® library. It is found that in all three alternative hydrogen supply chains CO2 emissions can be reduced and costs are increased compared to the reference case. Transporting hydrogen via the natural gas grid is the least efficient but achieves the highest emission reduction and is the most economical alternative for small to medium amounts of hydrogen. Using a hydrogen pipeline is the most efficient option and slightly cheaper for large amounts than employing the natural gas grid. Transporting hydrogen by trailers is not economical for single consumers and realizes the lowest CO2 reductions.Publicationtype: Journal ArticleScopus© Citations 9 444 503 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Solar-driven pyrolysis and gasification of low-grade carbonaceous materialsHydrogen Energy Publications LLC Three low-grade carbonaceous materials from biomass (Scenedesmus algae and wheat straw) and waste treatment (sewage sludge) have been selected as feedstock for solar-driven thermochemical processes. Solar-driven pyrolysis and gasification measurements were conducted directly irradiating the samples in a 7 kW e high flux solar simulator and the released gases H 2 , CO, CO 2 and CH 4 and the sample temperature were continuously monitored. Solar-driven experiments showed that H 2 and CO evolved as important product gases demonstrating the high quality of syngas production for the three feedstocks. Straw is the more suitable feedstock for solar-driven processes due to the high gas production yields. Comparing the solar-driven experiments, gasification generates higher percentage of syngas (mix of CO and H 2 ) respect to total gas produced (sum of H 2 , CO, CO 2 and CH 4 ) than pyrolysis. Thus, solar-driven gasification generates better quality of syngas production than pyrolysis.Publicationtype: Journal Article59