Evaluation of a test set-up for combined bio-hydrogen- and methane-production at mesophilic conditions

Hydrogen is regarded as a source of energy of the future. It may be produced by various processes, including electrolysis of water, thermocatalytic reformation of hydrogen-rich organic compounds and biological processes. Currently, hydrogen is produced, predominantly, by electrolysis of water by using electricity or by stream reforming of natural gas. So both methods based on fossil fuels like coal, oil or natural gas except for the electricity generation by wind turbines or photovoltaic. At present, the production of hydrogen by biological processes finds more and more attention world far. Biological technologies for provides a wide range of approaches to generate hydrogen, including direct and indirect bio-photolysis as well as photo-fermentation and dark-fermentation. Currently these biological technologies are not suitable for solving every day energy problems (Levin, Pitt, Love, 2003). But dark-fermentation is a promising approach to produce hydrogen in a sustainable way and is already examined in some projects (e.g. Krupp, 2007). Short hydrolytic retention times and high metabolic rates are advantage of the process. The incomplete transformation of the organic components into various organic acids is a disadvantage. So a second process step is required.

A result of the batch tests is, heat treated digested sludge as well as compost are applicable to use as inocula for producing bio-hydrogen by dark fermentation at mesophilic conditions, because no methane were detected in the gasphase of all samples. The biogas production reaches values up to 450 Nml/g glucose and hydrogen concentrations between 50 % and 70 %. Furthermore a continuous stirred reactor (CSTR) with continuous operation with waste sugar solution (10 g/l) as carbon source was studied. The hydrogen step shows as results hydrogen- and carbon dioxide-concentration in the biogas between 40 % and 60 %. By using sewages containing COD and organic waste in the dark fermentation, however, they must assume that the appearing trace gases like hydrogen sulphide correspond to these approximately in the biogas of a wastewater treatment plant. So the gas quality should be examined in detail with regard to use the gas in fuel cells and an upgrading of the hydrogen rich biogas of the first process step is necessary. At least the reactor design for a combined hydrogen and methane production has worked out. The process of a two-step reactor operated continuously for the combined hydrogen and methane production out of COD loaded sewages and carbohydrate rich bio-waste is necessary for the examination of the technical and economical implementation. The experimental set-up consists of a 3 litre reactor for the bio-hydrogen step and a 30 litre reactor for the bio-methane step. At both reactors the pH-value and the temperature have to be controlled. Furthermore the barometric pressure, gas yield and gas composition of both reactors will be detected daily. Furthermore the operating efficiency of the combined production of hydrogen and methane by dark fermentation shall
be checked as a complete system, as well as the degradation and stabilization of the organic.

 

 

Hochlauf der Wasserstoffwirtschaft
© Lexxion Verlagsgesellschaft mbH (8/2024)
Überblick über und Diskussion der Maßnahmen zum beschleunigten Ausbau der Wasserstoffinfrastruktur in Deutschland

Die innerstaatliche Umsetzung des Pariser Klimaschutzübereinkommens - ein Rechtsvergleich
© Lexxion Verlagsgesellschaft mbH (8/2024)
Like all public international law treaties, the Paris Climate Accords rely on national law for their implementation. The success of the agreement therefore depends, to a large extent, on the stepstaken or not taken by national governments and legislators as well as on the instruments and mechanisms chosen for this task. Against this background, the present article compares different approaches to the implementation of the Paris Agreement, using court decisions as a means to assess their (legal) effectiveness.

Klimaschutzrecht und Erzeugung erneuerbarer Energien in der Schweiz
© Lexxion Verlagsgesellschaft mbH (8/2024)
Verschachtelte Gesetzgebung unter politischer Ungewissheit

 

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