Production & Supply Chain

Reversible solid oxide cells (r-SOCs) can be operated in either solid oxide fuel cell or solid oxide electrolysis cell mode. They are expected to become important in the support of renewable energy due to their high efficiency for both power generation and hydrogen generation. The exchange current density is one of the most important parameters in the quantification of electrode performance in solid oxide cells. In this study four different fuel electrodes and two different air electrodes are fabricated using different materials and the microstructures are compared. The temperature fuel humidification and oxygen concentration at the air electrode are varied to obtain the apparent exchange current density for the different electrode materials. In contrast to ruthenium-and-gadolinia-doped ceria (Rh-GDC) as well as nickel-and-gadolinia-doped ceria (Ni-GDC) electrodes significant differences in the apparent exchange current density were observed between electrolysis and fuel cell modes for the nickel-scandia-stabilized zirconia (Ni-ScSZ) cermet. Variation of gas concentration revealed that surface adsorption sites were almost completely vacant for all these electrodes. The apparent exchange current densities obtained in this study are useful as a parameter for simulation of the internal properties of r-SOCs.

Electrocatalysts are capable of transforming water into hydrogen oxygen and therefore into energy in an environmentally friendly and sustainable manner. However the limitations in the research of high performance catalysts act as an obstructer in the development of using water as green energy. Here we report on a delicate method to prepare novel bimetallic metal organic framework derived electrocatalysts (C–NiCu–BDC–GO–CC) using graphene oxide (GO) modified carbon cloth as a 3D flexible and conductive substrate. The resultant electrocatalyst C–NiCu–BDC– GO–CC exhibited very low electron transfer resistance which benefited from its extremely thin 3D sponge-like morphology. Furthermore it showed excellent oxygen evolution reaction (OER) activity achieving 10 mA/cm2 at a low overpotential of 390 mV in 1 M KOH electrolyte with a remarkable durability of 10 h.

As governments focus on dealing with the Covid-19 health emergency they are increasingly turning their attention to the impact of shutting down their economies and how to revive them quickly through stimulus measures. Economic recovery packages offer a unique opportunity to create jobs while supporting clean energy transitions around the world.

Energy efficiency and renewable energy like wind and solar PV – the cornerstones of any clean energy transition – are good places to start. Those industries employ millions of people across their value chains and offer environmentally sustainable ways to create jobs and help revitalise the global economy.

But more than just renewables and efficiency will be required to put the world on track to meet climate goals and other sustainability objectives. IEA analysis has repeatedly shown that a broad portfolio of clean energy technologies will be needed to decarbonise all parts of the economy. Batteries and hydrogen-producing electrolysers stand out as two important technologies thanks to their ability to convert electricity into chemical energy and vice versa. This is why they also deserve a place in any economic stimulus packages being discussed today.

Link to Document on IEA Website

Ni-based catalysts are attractive alternatives to noble metal electrocatalysts for the hydrogen evolution reaction (HER). Herein we present a dispersion-corrected density functional theory (DFT-D3) insight into HER activity on the (111) (110) (001) and (100) surfaces of metallic nickel nitride (Ni₃N). A combination of water and hydrogen adsorption was used to model the electrode interactions within the water splitting cell. Surface energies were used to characterise the stabilities of the Ni3N surfaces along with adsorption energies to determine preferable sites for adsorbate interactions. The surface stability order was found to be (111) < (100) < (001) < (110) with calculated surface energies of 2.10 2.27 2.37 and 2.38 Jm⁻² respectively. Water adsorption was found to be exothermic at all surfaces and most favourable on the (111) surface with E_ads = −0.79 eV followed closely by the (100) (110) and (001) surfaces at −0.66 −0.65 and −0.56 eV respectively. The water splitting reaction was investigated at each surface to determine the rate determining Volmer step and the activation energies (Ea) for alkaline HER which has thus far not been studied in detail for Ni₃N. The E_a values for water splitting on the Ni₃N surfaces were predicted in the order (001) < (111) < (110) < (100) which were 0.17 0.73 1.11 and 1.60 eV respectively overall showing the (001) surface to be most active for the Volmer step of water dissociation. Active hydrogen adsorption sites are also presented for acidic HER evaluated through the ΔG_H descriptor. The (110) surface was shown to have an extremely active Ni–N bridging site with ΔG_H = −0.05 eV.

The study is focused on the technology and manipulation of production strategies for the cultivation of biomass from four strains of microalgae. Species of microalgae studied are: Chlorella vulgaris Dunaliella Scenedesmus quadricauda and Synechococcus spp. The effects of the rate and amount of CO₂ removal from the atmosphere and sequestration with dissolved oxygen on lipid production from accumulated biomass were studied. Also the rate of sequestration of both total and dissolved carbon was  investigated. Daily measurements of total organic and inorganic carbon sequestrated optical densities proximate analysis and kinetic parameters of the growing and cultivated microalga were monitored and carried out during the two phases of cultivation: dark and light phases. The values of maximum rate of carbon (IV) oxide removed rmax varied from 11.73 mg L ^-1 min ^-1 to 18.84 mg L ^-1 min ^-1 from Chlorella vulgaris to Synechoccocus spp. Important parameters such as biomass productivity maximum pH values obtained at cultivation lipid content of the produced biomass and the hydraulic detection time for all four strains of microalgae were considered and presented in comparison and with their individual and collective effects. The ratios of the rate of CO₂ absorption constant and the constant for the CO₂ desorption rate (k1/k2) occurred highest in Dunaliella suggesting that with a high uptake of CO₂ the algal strain is more effective in CO₂ CO2 sequestration. The best biomass producer in this study was the C. vulgaris (Xmax = 5400 mg L^-1 and Px = 35.1 mg L h ^-1) where biomass productivity is Px and the maximum cellular concentration is Xmax. C. vulgaris has the highest lipids productivity of 27% while Synechoccocus has the least (11.72%). In general biomass productivity may be inversely related; this fact may be explained by greater metabolic involvement of lipid biosynthesis. This pioneer study may be advanced further to developing models for strategic manipulation and optimisation approach in micro algal biomass cultivation.

Anion exchange membrane (AEM) water electrolysis is considered a promising solution to future cost reduction of electrochemically produced hydrogen. We present an AEM water electrolyzer with CuCoOx as the anode catalyst and Aemion as membrane and electrode binder. Full cell experiments in pure water and 0.1 M KOH revealed that the optimum binder content depended on the type of electrolyte employed. Online dissolution measurements suggested that Aemion alone was not sufficient to establish an alkaline environment for thermodynamically stabilizing the synthesized CuCoOx in a neutral electrolyte feed. A feed of base is thus indispensable to ensure the thermodynamic stability of such non-noble catalyst materials. Particle loss and delamination of the catalyst layer during MEA operation could be reduced by employing a heat treatment step after electrode fabrication. This work summarizes possible degradation pathways for low-cost anodes in AEMWE and mitigation strategies for enhanced system durability and performance.

The search for alternatives to fossil energy traditional sources led to the development of a set of energy conversion processes which include biomass thermochemical conversion technologies such as torrefaction pyrolysis hydrothermal liquefaction or gasification. These conversion technologies have shown significant evolutions and there are already several examples available of application on an industrial scale. Biomass gasification processes have also presented significant developments mainly when associated with the production of syngas with potential for energy recovery or to produce synthetic fuels but mainly due to its potential to be used as a sustainable hydrogen production technology. In the present work a bibliographic review of the current state-of-the-art of the biomass gasification is carried out focusing in the gasification technologies syngas cleaning processes simulation methodologies on process parameters. Finally future developments and possibilities are also analyzed and discussed with the introduction of a new approach to hydrogen production based on the use of an adapted combustion process with air deficit.

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.

In the context of hydrogen production from biomass or organic waste with dark fermentation this study analysed 55 studies (339 experiments) in the literature looking for the effect of operating parameters on the process performance of dark fermentation. The effect of substrate concentration pH temperature and residence time on hydrogen yield productivity and content in the biogas was analysed. In addition a linear regression model was developed to also account for the effect of nature and pretreatment of the substrate inhibition of methanogenesis and continuous or batch operating mode. The analysis showed that the hydrogen yield was mainly affected by pH and residence time with the highest yields obtained for low pH and short residence time. High hydrogen productivity was favoured by high feed concentration short residence time and low pH. More modest was the effect on the hydrogen content. The mean values of hydrogen yield productivity and content were respectively 6.49% COD COD−1 135 mg L−1 d −1 51% v/v while 10% of the considered experiments obtained yield productivity and content of or higher than 15.55% COD COD−1 305.16 mg L−1 d −1 64% v/v. Overall this study provides insight into how to select the optimum operating conditions to obtain the desired hydrogen production.

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.