Production & Supply Chain

Power-to-gas technology plays a key role in the success of the energy transformation. This paper addresses issues related to the legal and technical regulations specifying the rules for adding hydrogen to the natural gas network. The main issue reviewed is the effects of the addition of hydrogen to natural gas on the durability of diaphragm gas meters. The possibility of adding hydrogen to the gas network requires confirmation of whether within the expected hydrogen concentrations long-term operation of gas meters will be ensured without compromising their metrological properties and operational safety. Methods for testing the durability of gas meters applied at test benches and sample results of durability tests of gas meters are presented. Based on these results a metrological and statistical analysis was carried out to establish whether the addition of hydrogen affects the durability of gas meters over time. The most important conclusion resulting from the conducted study indicates that for the tested gas meter specimens there was no significant metrological difference between the obtained changes of errors of indications after testing the durability of gas meters with varying hydrogen content (from 0% to 15%).

Determination of the optimal design of experiments that enables efficient parametrisation of fuel cell (FC) model with a minimum parametrisation data-set is one of the key prerequisites for minimizing costs and effort of the parametrisation procedure. To efficiently tackle this challenge the paper present an innovative methodology based on the electrochemical FC model parameter sensitivity analysis and application of D-optimal design plan. Relying on this consistent methodological basis the paper answers fundamental questions: a) on a minimum required data-set to optimally parametrise the FC model and b) on the impact of reduced space of operational points on identifiability of individual calibration parameters. Results reveal that application of D-optimal DoE enables enhancement of calibration parameters information resulting in up to order of magnitude lower relative standard errors on smaller data-sets. In addition it was shown that increased information and thus identifiability inherently leads to improved robustness of the FC electrochemical model.

The bioanode is important for a microbial electrolysis cell (MEC) and its robustness to maintain its catalytic activity affects the performance of the whole system. Bioanodes enriched at a potential of +0.2 V (vs. standard hydrogen electrode) were able to sustain their oxidation activity when the anode potential was varied from -0.3 up to +1.0 V. Chronoamperometric test revealed that the bioanode produced peak current density of 0.36 A/m2 and 0.37 A/m2 at applied potential 0 and +0.6 V respectively. Meanwhile hydrogen production at the biocathode was proportional to the applied potential in the range from -0.5 to  -1.0 V. The highest production rate was 7.4 L H2/(m2 cathode area)/day at -1.0 V cathode potential. A limited current output at the bioanode could halt the biocathode capability to generate hydrogen. Therefore maximum applied potential that can be applied to the biocathode was calculated as -0.84 V without overloading the bioanode.

Hydrogen will presumably become an important substitute for carbon as a reductant in the metallurgical industry for processes such as steel production. However the challenge to supply enough CO2 -free hydrogen for metallurgical processes has not been resolved yet. This paper reviews different production technologies for hydrogen and their advantages and drawbacks. Additionally it will highlight the development of plasma technology to produce hydrogen and carbon black which has been taking place at SINTEF during the last 30 years.

Photosynthesis is considered to be one of the promising areas of cheap and environmentally friendly energy. Photosynthesis involves the process of water oxidation with the formation of molecular oxygen and hydrogen as byproducts. The aim of the present article is to review the energy (light) phase of photosynthesis based on the published X-ray studies of photosystems I and II (PS-I and PS-II). Using modern ideas about semiconductors and biological semiconductor structures the mechanisms of H+ O2↑ e− generation from water are described. At the initial stage PS II produces hydrogen peroxide from water as a result of the photoenzymatic reaction which is oxidized in the active center of PS-II on the Mn4CaO5 cluster to form O2↑ H+ e−. Mn4+ is reduced to Mn2+ and then oxidized to Mn4+ with the transfer of reducing the equivalents of PS-I. The electrons formed are transported to PS-I (P 700) where the electrochemical reaction of water decomposition takes place in a two-electrode electrolysis system with the formation of gaseous oxygen and hydrogen. The proposed functioning mechanisms of PS-I and PS-II can be used in the development of environmentally friendly technologies for the production of molecular hydrogen.

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.

This work focuses on the use of solar photovoltaic energy to capture carbon dioxide by means of a combined electrolyzer–absorption system and compares operating results obtained in two cases studies (operation during one clear and one cloudy day in March) in which real integration of solar photovoltaics electrolyzer and absorption technologies is made at the bench-scale. The system is a part of a larger process (so-called EDEN⃝R Electrochemically-based Decarbonizing ENergy) which aims to regulate solar photovoltaic energy using a reversible chloralkaline electrochemical cell. Results demonstrate the feasibility of the sequestering technology which can produce chlorine and hydrogen but also the sequestration of CO2 and its transformation into a mixture of sodium chloride bicarbonate and carbonate useful as raw matter. Efficiencies over 70% for chlorine 60% for hydrogen and 90% for sodium hydroxide were obtained. The sequestration of carbon dioxide reached 24.4 mmol CO2/Ah with an average use of 1.6 mmol NaOH/mmol CO2. Important differences are found between the performance of the system in a clear and a cloudy day which point out the necessity of regulating the dosing of the electrochemically produced sodium hydroxide to optimize the sequestration of CO2.

In the frame of a sustainable development investigations dealing with massive Hydrogen production by means of nuclear heating are carried out at CEA. For nuclear safety thermodynamic efficiency and waste minimization purposes the technological solution privileged is the coupling of a gas cooled Very High Temperature Reactor (VHTR) with a plant producing Hydrogen from an Iodine/Sulfur (I/S) thermochemical cycle. Each of the aforementioned facilities presents different risks resulting from the operation of a nuclear reactor (VHTR) and from a chemical plant including Hydrogen other flammable and/or explosible substances as well as toxic ones. Due to these various risks the safety approach is an important concern. Therefore this paper deals with the preliminary CEA investigations on the safety issues devoted to the whole plant focusing on the safety questions related to the coupling between the nuclear reactor and the Hydrogen production facility. Actually the H2 production process and the energy distribution network between the plants are currently at a preliminary design stage. A general safety approach is proposed based on a Defence In Depth (DID) principle permitting to analyze all the system configurations successively in normal incidental and accidental expected operating conditions. More precisely the dynamic answer of an installation to a perturbation affecting the other one during the previous conditions as well as the potential aggressions of the chemical plant towards the nuclear reactor have to be considered. The methodology presented in this paper is intended to help the designer to take into account the coupling safety constraints and to provide some recommendations on the global architecture of both plants especially on their coupling system. As a result the design of a VHTR combined to a H2 production process will require an iterative process between design and safety requirements.

This paper deals with site selection problems for hydrogen production plants and aims to propose a structural procedure for determining the most feasible sites. The study area is Adrar province Algeria which has a promising wind potential. The methodology is mainly composed of two stages: the first stage is to evaluate and select the best locations for wind-powered hydrogen production using GIS and MCDM technique. the AHP is applied to weigh the criteria and compute a LSI to evaluate potential sites and the second stage is applying different filtration constraints to select the suitable petrol stations for such hydrogen refuelling station modification. The result map showed that the entire Adrar province is almost suitable for wind-powered hydrogen production with varying suitability index. The LSI model groups sites into three categories: High suitable areas Medium suitable areas and Low suitable. As a result 2.95 % (12808.97 km2) of the study area has high suitability 54.59 % (236320.16 km2) has medium suitability 1.12 %(4842.94 km2) has low suitability and 41.34 % (178950.35 km2) of the study area is not suitable for wind hydrogen production. By applying the constraints about 4 stations are suitable for wind-powered hydrogen refuelling system retrofitting in Adrar province.

In this work the flexible operation of an Integrated Solar Combined Cycle (ISCC) power plant has been optimized considering two different energy storage approaches. The objective of this proposal is to meet variable users’ grid demand for an extended period at the lowest cost of electricity. Medium temperature thermal energy storage (TES) and hydrogen generation configurations have been analyzed from a techno-economic point of view. Results found from annual solar plant performance indicate that molten salts storage solution is preferable based on the lower levelized cost of electricity (0.122 USD/kWh compared to 0.158 USD/kWh from the hydrogen generation case) due to the lower conversion efficiencies of hydrogen plant components. However the hydrogen plant configuration exceeded in terms of plant availability and grid demand coverage as fewer design constraints resulted in a total demand coverage of 2155 h per year. It was also found that grid demand curves from industrial countries limit the deployment of medium-temperature TES systems coupled to ISCC power plants since their typical demand curves are characterized by lower power demand around solar noon when solar radiation is higher. In such scenarios the Brayton turbine design is constrained by noon grid demand which limits the solar field and receiver thermal power design. View Full-Text