Production Of Synthetic Fuels Research Articles

Synthetic fuels in aviation – Current barriers and potential political measures

Alternative fuels can contribute to sustainable air transport since these fuels reduce aviation’s climate-relevant emissions. Most promising options from today’s point of view are: biofuels and synthetic fuels (power-to-liquid, short: PtL or e-fuels). Results from a supply perspective show that biofuels are advantageous in the short term while synthetic fuels could be favorable in the long run. As it would certainly be too costly to finance a transitional biofuel system, it might be better to prioritize the use of synthetic fuels from the start. Due to the international character of aviation, the future production and use of synthetic fuels in aviation is a global issue. This paper investigates the following questions: Which are the current barriers to the use of e-fuels in air transport? Which political measures could facilitate the use of e-fuels?

Термодинамический анализ плазменной газификации отходов сельского хозяйства

Most of the agricultural waste (AW) comes from poultry farms and livestock farms mainly in the form of bird droppings and cattle dung. Irrational use of large volumes of such waste negatively affects the environment. Modern technologies allow utilizing agricultural waste to produce energy gas. Plasma recycling of waste from the agro-industrial complex allows intensifying the process of obtaining energy gas consisting mainly of synthesis gas (СО+Н2) and a 150–200-fold increase in the gas productivity of the plasma gasifier compared with biogas generators. This article is devoted to the thermodynamic modelling of AW plasma-processing. The thermodynamic analysis of the waste plasma processing was performed using the universal program of thermodynamic calculations TERRA. In the work under the AW means the excrement of farm animals (manure). For research, dried mixed manure (dung with 30% moisture content) from cattle is used. Thermodynamic calculations showed that during plasma gasification and pyrolysis of AW, high-calorie combustible gas is produced with a synthesis gas yield of 65.2 and 68.5%, respectively. No harmful components were detected. Plasma gasifier will allow to effectively process various types of AW into high calorific energy gas, consisting mainly of synthesis gas, and into neutral slag. The technological scheme of AW plasma processing has been developed. Using proposed plasma plant that implements this scheme, depending on the composition of the AW, up to 1.7 m3 of dry energy gas can be obtained from 1 kg of AW. At the same time, its caloric content will vary from 8500 to 300 MJ/Nm3. The composition of the energy gas will be following, vol.%: H2 - 35-39, CO - 29-31, CO2 - 4-6, N2 - 10-14, H2O - 13-18. Such gas can be used as a working medium of highly efficient electric generators of a new generation, including solid oxide fuel cells or as a raw material for the production of synthetic motor fuels (methanol, dimethylether)

Highly Efficient Power Technological Complex for the Use of Natural Gas for Electricity, Heat, and Synthetic Fuels Production with Partial Sequestration of Carbon Dioxide Emissions into the Atmosphere

Highly Efficient Power Technological Complex for the Use of Natural Gas for Electricity, Heat, and Synthetic Fuels Production with Partial Sequestration of Carbon Dioxide Emissions into the Atmosphere

Structure transition from oxygen-enhanced to oxy-fuel methane non-premixed flames near extinction

As an alternative to usual combustion processes with air as oxidant, oxy-fuel or oxygen-enhanced processes are attractive in high temperature thermal or thermochemical processes, novel power plant concepts or in gasification processes. Especially for production of basic chemicals or synthetic fuels, high-purity synthetic gas without nitrogen dilution is required for further industrial processing. In case of oxy-fuel combustion, the absence of nitrogen leads to higher flame temperatures and larger concentration of major species as well as intermediate species. Because of the increased reactivity, most combustors are designed in non-premixed configuration.In the present work, the extinction limits of non-premixed CH4/N2/O2 flames were numerically calculated using the CHEMKIN Pro opposed flow code together with the GRI 3.0 mechanism. The inlet compositions were varied from high nitrogen dilution to pure oxy-fuel conditions. Additionally, the stoichiometric mixture fraction was varied by shifting the (inert) N2-fraction stepwise from the oxidizer to the fuel side. Therewith, the equilibrium temperature of the mixture is constant for a fixed N2-dilution.The results show, that as expected, the extinction occurs at higher strain rates with increasing the flame temperatures by reducing the N2-diluation. Additionally, the extinction limits strongly increase for a fixed N2-dilution with increasing the stoichiometric mixture fraction. The shift of the N2 from the oxidizer to the fuel side leads to a movement of the stagnation plane towards the fuel side and hence, a significant change of the temperature field and the flame structure. Thus, the radical chain branching occurs at higher temperature level, which strengthen the flame resistance against strain. The increase of the stoichiometric mixture leads to a shift of the flame towards the fuel side and crosses at high values the stagnation plane.

Application of Pd-Based Membrane Reactors: An Industrial Perspective.

The development of a chemical industry characterized by resource efficiency, in particular with reference to energy use, is becoming a major issue and driver for the achievement of a sustainable chemical production. From an industrial point of view, several application areas, where energy saving and CO2 emissions still represent a major concern, can take benefit from the application of membrane reactors. On this basis, different markets for membrane reactors are analyzed in this paper, and their technical feasibility is verified by proper experimentation at pilot level relevant to the following processes: (i) pure hydrogen production; (ii) synthetic fuels production; (iii) chemicals production. The main outcomes of operations in the selected research lines are reported and discussed, together with the key obstacles to overcome.

(Solar) Mixed Reforming of Methane: Potential and Limits in Utilizing CO2 as Feedstock for Syngas Production—A Thermodynamic Analysis

The reforming of natural gas with steam and CO2 is commonly referred to as mixed reforming and considered a promising route to utilize CO2 in the production of synthetic fuels and base chemicals such as methanol. In the present study, the mixed reforming reaction is assessed regarding its potential to effectively utilize CO2 in such processes based on simple thermodynamic models. Requirements for the mixed reforming reactions based on process considerations are defined. These are the avoidance of carbon formation in the reactor, high conversion of the valuable inlet streams CH4 and CO2 as well as a suitable syngas composition for subsequent synthesis. The syngas composition is evaluated based on the module M = ( z H 2 − z CO 2 ) / ( z CO 2 + z CO ) , which should assume a value close to 2. A large number of different configurations regarding CO2/H2O/CH4 at the reactor inlet, operating pressure and outlet temperature are simulated and evaluated according to the defined requirements. The results show that the actual potential of the mixed reforming reaction to utilize CO2 as feedstock for fuels and methanol is limited to approximately 0.35 CO2/CH4, which is significantly lower than suggested in literature. At 900 °C and 7 bar at the reactor outlet, which is seen suitable for solar reforming, a ratio of H2O/CH4 of 1.4 can be set and the resulting value of M is 1.92 (CO2/CO/H2 = 0.07/0.4/1).

The Project Carbon2Chem®

AbstractKeeping carbon in the loop is a short sentence that describes the Carbon2Chem® project. Climate protection requires a reduction of CO2 emissions as well as less use of fossil fuels. In the project, a consortium from industry and science works on implementing a flexible carbon capture and utilization (CCU) concept for the carbon‐based industry. An example is the cross‐industrial network of steel industry, chemical industry, and energy industry. Instead of being harmful waste, top gases from the steel mill now serve as raw material for the production of synthetic fuels, plastics, and basic chemicals. This is possible through the systemic use of renewable energy.

(Invited) Conductive Biopolymers for Selective Metal-Devoid Electrocatalysis

Electrocatalysis can be useful in energy conversion, in particular for the production of synthetic fuels from renewable energy. However, this requires catalytic conductors, which sustain the reaction conditions that foremost occur in aqueous solution. Conducting polymers represent a chemically robust but conductive materials class that could be harnessed for aqueous electrocatalytic processes in order to facilitate the important reactions steps to electrosynthesize fuels. In terms of CO2 reduction this has been demonstrated by using a conducting form of polydopamine.(1–3) This system no than other incorporates a richly functionalized backbone able to attach CO2 and electro-reduce to formate efficiently. We shed light on the relevant electro-activation of the incorporated functional themes in the biopolymer and compare this mechanisms to similarly efficient inorganic catalysts. We find that it is the actual nature of the incorporated theme that significantly influences its final selectivity. Such tunability enables the tailoring of selective and highly active catalytic surfaces from organic-functional matter. The functionalzed organic catalysts rely on different reaction mechanisms than state-of-the-art metal-based systems and possibly can be optimized as future sustainable contenders for metal-based electrocatalysts. H. Coskun et al., Chemical vapor deposition - based synthesis of conductive polydopamine thin-films. Thin Solid Films. 645, 320–325 (2018).X. Zheng et al., Sulfur-Modulated Tin Sites Enable Highly Selective Electrochemical Reduction of CO2 to Formate. Joule (2017), doi:10.1016/j.joule.2017.09.014.H. Coskun et al., Biofunctionalized conductive polymers enable efficient CO2 electroreduction. Sci. Adv. 3, e1700686 (2017).

Synthetic Diesel Production as a Form of Renewable Energy Storage

Production of synthetic hydrocarbon fuels as a means for renewable energy storage has gained attention recently. Integration of solid oxide co-electrolysis of steam and carbon dioxide with the Fischer-Tropsch process to transform renewable electricity into Fischer-Tropsch diesel is one of the promising suggested pathways. However, considering the intermittency of produced renewable electricity such integration will have a low capacity factor. Besides, locating a reliable source of carbon dioxide near the installed integrated system may prove to be difficult. A novel integration for production of Fischer-Tropsch diesel from various renewable sources is suggested in this study. The proposed integrated system includes solid oxide electrolysis, entrained gasification, Fischer-Tropsch process and an upgrading system. Gasification is assumed to have a continuous operation which increases capacity factor of the integrated system. Carbon dioxide supplied via gasification of biomass provides a reliable source for on-site co-electrolysis. Technical capabilities of the proposed integrated system examined by investigating performance in relation with electricity, and diesel demand of four different European cities. Results show that the proposed system is capable of supplying Fischer-Tropsch diesel of between 0.9–32% of the annual diesel demand for road transportation respective to the location of installation, with a high emission savings (around 100%). Cost of produced diesel is not competitive with conventional diesel for all cases, even when all the other by-products were assumed to be sold to the market.

Application of Plasma Technology in Fischer-Tropsch Catalysis for the Production of Synthetic Fuels

Application of Plasma Technology in Fischer-Tropsch Catalysis for the Production of Synthetic Fuels

CONVERSION OF CO2 TO HYDROCARBON SYNFUEL BY UTILIZING NUCLEAR HYDROGEN COGENERATION

A study of the utilization of hydrogen cogeneration with nuclear energy as a technology for the conversion of CO2 into synthetic liquid hydrocarbon fuels has been carried out. The aim of the study is to understand the conversion of CO2 and H2 into synthetic fuels, as well as the role of nuclear hydrogen cogeneration for the production of hydrogen and as a source of process heat energy. The method used is literature study based on the results of existing research. Conventionally, synthetic fuel production from coal is produced through coal gasification process, followed by reacting synthesis gas (mixture of CO and H2) in FT reactor to synthesis fuel. In this study, we studied the production of synthetic fuels with CO2 and H2 raw materials. CO2 comes from emissions of coal-fired plants, whereas H2 is produced by nuclear hydrogen cogeneration systems. The results show that compared to conventional processes, CO2 and H2-based processes supported by coal cogeneration systems provide significant advantages in terms of CO2 emissions. The process based on coal gasification and nuclear cogeneration, capable of reducing emissions by up to 75% and saving up to 40% of coal consumption. While the process based only on CO2 and nuclear hydrogen cogeneration (without coal gasification), teoretically can operate witout any CO2 emission at all. Even this process can captured and utilize CO2 emissions from coal fired plant, and use it as a raw material for the process.

Making synthetic fuels for the road transportation sector via solid oxide electrolysis and catalytic upgrade using recovered carbon dioxide and residual biomass

The search for beneficial biofuels with positive energy gains and reduced carbon dioxide emissions is a key target of the road transportation sector. This work focuses on alternative fuels for fossil fuel substitution in the transportation sector and we have examined the production of three different types of synthetic fuels: Dimethyl Ether, Synthetic Natural Gas and the diesel fraction of the Fischer-Tropsch synthesis products. We analyze different pathways to make green synthetic fuels starting from waste carbon dioxide recovered from various sources and residual biomass. Processes for biofuel production that combine high temperature co-electrolysis in a solid oxide electrolysis cell (supplied with renewable electricity) to a downstream catalytic reactor that upgrades further the electrolysis-derived syngas are investigated. The integrated co-electrolysis catalytic upgrade is a way to “recycle” CO2 to either a gas or liquid fuel depending on the selected catalytic route. We have considered two different sources for waste carbon dioxide recovery: the CO2-rich off-gas of biogas-to-biomethane plants and CO2 that could be available from fossil fuel power plants with carbon capture. Residual biomass is the other CO2 source analyzed in this work. Fuel demand and, the CO2 and renewable electricity resources available on a regional scale have been assessed to develop a case study of synthetic fuels production in Italy. Results show how synfuel production from biogas off-gas and residual biomass allow to cover a limited percentage of the overall fuel demand (ranging from 1.5% to 37% depending on the synfuel), while using carbon dioxide recovered from fossil power plants could potentially provide enough synfuel to cover completely the fuel demand using Dimethyl Ether or Synthetic Natural Gas. However, an increase of renewable electricity would be needed (ranging from 50% to a three-fold increase depending on the synfuel). Finally, the impact of fuel substitution on the overall carbon dioxide emissions has been investigated showing that a complete substitution of fossil fuels using synfuels produced from waste recovered CO2 could lead to an emission reduction of almost 40% with respect to the current fossil fuel dominated scenario.

Bacterial Biofilm As Active Matrix for Catalytic Centers: Electroreduction of Carbon Dioxide

There is constantly growing interest in the electrochemical reduction of CO2 and applying the process of binding the carbon to synthetic fuels production, as well as alcohols, hydrocarbons, aldehydes or carboxylic acids. Because of the stability of the CO2 molecule, its electrocatalytic reduction is characterized by high over-potentials: consequently selective and efficient electrocatalysts are needed. A typical approach to efficient electroreduction of carbon dioxide is the use of metallic catalysts (e.g. Cu, Pd, Pt, Ru), either in heterogeneous and homogeneous reactions. Recently, the alternative for efficient CO2 electroreduction is also utilization of biological systems, including microbial electrocatalysts and whole cell biocatalysts. These systems often utilize microorganisms in a form of bacterial biofilms at the electrode surfaces, to enhance rates of chemical reactions. Biofilms are very stable layers composed of microbes well-adhering to various surfaces. Differentiation in microbial metabolic pathways, associated with the occurrence of different types of enzymes in microbial cells, creates opportunity to catalyze redox processes at ambient conditions, also carbon dioxide electroreduction. Methods for improvements of electrical connection between microbial cells and electrode surfaces are needed, and one of the ideas is to utilize highly porous conductive polymers, which provide good electrical coupling and facilitate immobilization of the cells. Practical bioelectrochemical systems often use also carbon nanotubes together with biological layers due to their capabilities of penetrating microbial structures and improving the overall conductivity. These properties are particularly important in developing biosensors and microbial fuel cells. There has been proposed a hybrid multilayered matrix, composed of polyaniline-supported Yersinia enterocolitica biofilm, multi-walled carbon nanotubes (MWCNTs) and dispersed Pt nanoparticles (nPt) on the top. The underlayer of polymer, biofilm and MWCNTs has been demonstrated to work as highly active assistance for nPt during carbon dioxide electroreduction in neutral electrolyte (phosphate buffer at pH=6.1). Application of the hybrid system allows clear distinction of the CO2-reduction currents from those originating from the hydrogen evolution, unlike the bare nPt dispersed at glassy carbon surface. The result complies with the enhancement effect toward process of carbon dioxide reduction rather than hydrogen evolution. Bacterial biofilm itself is not catalytically active toward reduction of CO2, however its hydrated structure allows water molecules to easily move through it, and permits aqueous electrolyte to flow undisrupted at the electrocatalytic interface. Application of polyaniline can be commentated in terms of improvement and stabilization of the biofilm adherence and utilization of MWCNTs improve charge distribution within the hybrid film. Assessing based on the results of the diagnostic stripping-type voltammetric experiments, carbon monoxide seems to be the main product of CO2-reduction process at the proposed hybrid layer-supported nPt catalyst. However formation of some quantities of formic acid and methanol cannot be excluded.

Intermediate Product Regulation in Tandem Solid Catalysts with Multimodal Porosity for High‐Yield Synthetic Fuel Production

AbstractTandem catalysis is an attractive strategy to intensify chemical technologies. However, simultaneous control over the individual and concerted catalyst performances poses a challenge. We demonstrate that enhanced pore transport within a Co/Al2O3 Fischer–Tropsch (FT) catalyst with hierarchical porosity enables its tandem integration with a Pt/ZSM‐5 zeolitic hydrotreating catalyst in a spatially distant fashion that allows for catalyst‐specific temperature adjustment. Nevertheless, this system resembles the case of close active‐site proximity by mitigating secondary reactions of primary FT α‐olefin products. This approach enables the combination of in situ dewaxing with a minimum production of gaseous hydrocarbons (18 wt %) and an up to twofold higher (50 wt %) selectivity to middle distillates compared to tandem pairs based on benchmark mesoporous FT catalysts. An overall 80 % selectivity to liquid hydrocarbons from syngas is attained in one step, attesting to the potential of this strategy for increasing the carbon efficiency in intensified gas‐to‐liquid technologies.

Intermediate Product Regulation in Tandem Solid Catalysts with Multimodal Porosity for High-Yield Synthetic Fuel Production.

Tandem catalysis is an attractive strategy to intensify chemical technologies. However, simultaneous control over the individual and concerted catalyst performances poses a challenge. We demonstrate that enhanced pore transport within a Co/Al2 O3 Fischer-Tropsch (FT) catalyst with hierarchical porosity enables its tandem integration with a Pt/ZSM-5 zeolitic hydrotreating catalyst in a spatially distant fashion that allows for catalyst-specific temperature adjustment. Nevertheless, this system resembles the case of close active-site proximity by mitigating secondary reactions of primary FT α-olefin products. This approach enables the combination of in situ dewaxing with a minimum production of gaseous hydrocarbons (18 wt %) and an up to twofold higher (50 wt %) selectivity to middle distillates compared to tandem pairs based on benchmark mesoporous FT catalysts. An overall 80 % selectivity to liquid hydrocarbons from syngas is attained in one step, attesting to the potential of this strategy for increasing the carbon efficiency in intensified gas-to-liquid technologies.

A method for assessing infrastructure for [formula omitted] utilization: A case study of Finland

Synthetic hydrocarbons can be produced sustainably with power-to-gas processes, resulting in a net reduction of greenhouse gas emissions due to the substitution of conventional natural gas and other fossil fuels with carbon-neutral alternatives. Acquisition of the CO2 for the synthetic fuel production can be implemented in multiple ways. This work introduces a node-based model to assess different implementation strategies of CO2 utilization systems, taking into account temporal effects, regional variation, and economies of scale for CO2 capture. Intermediate storage volumes, capture costs, transport quantities, and other relevant infrastructural aspects of the CCU system can be estimated with the model. Finland is used as a case study, focusing specifically on the national and regional scale. CO2 capture costs are significant, being nearly four times larger than the cost of storage in the baseline scenario (354M€, 85M€). CO2 sources with smaller annual emissions increases capture costs by 14% compared to baseline. This increase in cost is comparable to the cost of transporting over a quarter of all captured CO2 to off-site processing (varying distance, 100–400km). Seasonal storage of CO2 is found to be beneficial for the cost-efficient production of synthetic fuels, owing to the temporal disparity between CO2 emissions and utilization, as well as the overall cost structure of the components. Five key decision categories are proposed for a carbon utilization system: scale, type, units, location, and technological decisions. These may be applied to describe any carbon utilization system, helping to form a more comprehensive picture of a future energy system, where carbon is widely used as a raw material.

Thermoneutral Operation of Solid Oxide Electrolysis Cells in Potentiostatic Mode

High temperature electrolysis based on solid oxide electrolysis cells (SOECs) is a very promising technology for energy storage and production of synthetic fuels. Compared with conventional low temperature electrolysis cells, SOEC has several advantages. The high operating temperature results in faster reaction kinetics and lower internal resistance. Besides, the heat demand required for electrolysis can be obtained from the Joule heat originating from the cell internal resistance or from renewable or waste heat sources, thus reducing the total electrical energy demand. A close to 100 % electricity-to-fuel efficiency can be reached if the SOEC is operated at the thermoneutral voltage (defined as the minimum thermodynamic voltage at which a perfectly insulated electrolysis unit would operate, if there is no net inflow or outflow of heat) [1]. In recent years extensive efforts have been devoted to improving performance and durability of SOEC cells and stacks. A number of long-term single cell or stack tests have been reported by various groups, with the longest testing period reaching 20,000 hours [2-4]. Due to historical reasons and the easiness of doing constant current tests, (almost) all the reported SOEC tests have been galvanostatic. The cell voltages were either below or above the thermoneutral voltage (~1.29 V for electrolysis of steam), resulting in an exothermic or endothermic electrolysis process, respectively, and lower efficiency. From a SOEC system point of view, it is highly desirable to operate the SOEC at constant thermoneutral voltage (or slightly above in order to account for potential heat losses), to ensure high efficiency and to ease the heat management of SOEC stacks and systems. Besides, from a testing point of view, the natural test method should be potentiostatic (constant voltage), because the electrochemical driving force of an electrode process is the overpotential, which is directly related to the cell voltage, and most probably some future applications will ask for constant voltage output.In this work, we report test results on two types of SOEC cells operated for electrolysis of steam in potentiostatic mode at thermoneutral voltage. Both cells are Ni/YSZ fuel electrode supported type, one with LSCF/CGO (LSCF: (La,Sr)(Co,Fe)O3; CGO: (Ce,Gd)O2- d) and the other with LSC/CGO (LSC: (La,Sr)CoO3) oxygen electrode. In our previous studies, the LSC/CGO cell showed lower degradation rate than the LSCF/CGO cell when tested at -1 A/cm2 in galvanostatic mode [5]. When tested at 750 oC and 1.29 V in potentiostatic mode, with a mixture of 50 % H2O + 50 % H2 supplied to Ni/YSZ, the LSC/CGO cell again showed superior initial performance, demonstrating an initial current density of -1.1 A/cm2 at 1.29 V. The LSCF/CGO cell showed a bit inferior performance, with an initial current density of -0.8 A/cm2 at 1.29 V. The two cells differ also in the long-term degradation over the 2000 h testing period. The LSC/CGO cell showed large and irreversible degradation, while the LSCF/CGO cell degraded in the first 400 h, but afterwards activated and stabilized after 1500 h. Both cells reached a current density of about -0.6 A/cm2 at the end of test period. Detailed impedance analysis indicates that degradation happened mainly at the Ni/YSZ electrode for both cells. Based on the experimental results and 2-D electrochemical modeling, the different degradation behavior of the two cells was further correlated to distribution of the over-potential across the cell and along the steam/hydrogen flow direction. Large over-potential on the Ni/YSZ fuel electrode was identified as the main cause of the degradation. Operation strategies were further proposed for fuel-electrode supported cells when operated at thermoneutral voltage. [1] S. D. Ebbesen, S. H. Jensen, A. Hauch, and M. B. Mogensen, Chemical Reviews, 114 [21] 10697-10734 (2014).[2] G. Corre and A. Brisse, ECS Transactions, 68 [1] 3481-3490 (2015).[3] X. Sun, M. Chen, P. V. Hendriksen, and M. B. Mogensen, pp. B1305 in 11th European SOFC & SOE Forum, Lucerne, Switzerland, 2014.[4] A. Brisse, J. Schefold, J. Dailly, pp. A0801 in 12th European SOFC & SOE Forum, Lucerne, Switzerland, 2016.[5] P. Hjalmarsson, X. Sun, Y.-L. Liu, and M. Chen, Journal of Power Sources, 262 [0] 316-322 (2014).

Optimization of ESC Performance for Co-Electrolysis Operation

Production of synthetic hydrocarbon fuels from co-electrolysis of steam/CO2 mixtures using renewable energy has been already presented as a promising solution to diminish problems from energy and environmental point of view. The possibility to recycle CO2 into chemicals and value-added fuels helps to reduce the accumulation of atmospheric CO2 and realize the carbon neutral cycling of fuels. The solid oxide cells have great potential within this field and can been used for converting of steam/CO2 mixtures to the syngas for following Fischer-Tropsch conversion by excessive electricity at high temperatures above 750°C. It presents an opportunity for recycling of CO2 into a useful liquid fuel. While the co-electrolysis is more complicated than steam electrolysis, the electrochemical performance electrolyte supported cell with G3 electrodes were investigated over a wide range of operating conditions (SOEC as well as SOFC), varying the ratio of H2O/H2 and CO2/CO, the operating temperature (750–850°C) and current. Comparable activity for operation in the SOEC and SOFC modes was observed and electrodes exhibited similar polarization losses during operation in steam electrolysis and steam/CO2 co-electrolysis. During electrolysis and co-electrolysis operation anomalous increase of polarization resistance during first 50 h on both sides has been observed. The raise of polarization resistance was reversible and diminished after switching to SOFC operation mode. Operating temperature variation during co-electrolysis helped to get insight into relationship between observed performance and electrodes microstructure. Additional experiments and electrochemical testing combined with detailed microstructural analysis have been carried out to better understand the observed phenomena. Obtained performance for single cell has been reproduced also on stack level. To improve electrochemical performance the additional modification of both electrodes, especially of their microstructure, is done. Durability of solid oxide electrolyte supported electrolysis cells (standard G3 and modified) tested at different current densities (from -300 mA/cm2 up to -500 mA/cm2) for high temperature steam or steam/CO2 electrolysis is investigated under stack relevant operating conditions (up to 5,000 h) and showed power degradation rate of ca. 1%/1,000 h for steam electrolysis. The changes in polarization resistance of single cells under different operating conditions as well as during durability tests are performed and discussed on basis of analysis of impedance spectra. Microstructure observations at the interfaces in both electrodes were carried out after long-term tests to understand the reasons for degradation. The cell with optimized fuel and air electrodes was successfully tested for ~2400 hours at 803°C under co-electrolysis conditions (H2/CO2/H2O/CO mixture as fuel, j = -400 mA/cm2). The calculated linear power degradation rate over all durability test (~2400 h) is about 0.4%/1,000 h. Further development of ESC for co-electrolysis and its verification in stack is topic of ongoing activities. Fig. 1 Power density vs. time for long-term test with modified G3 cell based on 165µm 10Sc1CeSZ electrolyte at 803°C in air : (H2/CO2/H2O/CO) mixture (j = - 400 mA/cm2). As reference point the power density in SOFC mode (air : H2/H2O) mixture (j = 300 mA/cm2) is also represented. Figure 1

Optimization of ESC Performance for Co-Electrolysis Operation

Production of synthetic hydrocarbon fuels from co-electrolysis of steam/CO2 mixtures using renewable energy has been already presented as a promising solution to diminish environmental problems. The possibility to recycle CO2 into chemicals and value-added fuels helps to reduce the accumulation of atmospheric CO2 and realize the carbon neutral cycling of fuels. While the co-electrolysis is more complicated than steam electrolysis, the electrochemical performance of electrolyte supported cell with LSMM’/ScSZ and Ni/GDC electrodes were investigated over a wide range of operating conditions (SOEC as well as SOFC), varying the ratio of H2O:H2 and CO2:CO, the operating temperature (750–850°C) and current. The modified G3´´ cell with optimized fuel and air electrodes was successfully tested for ~2400 hours at 803°C under co-electrolysis conditions (H2/H2O/CO2/CO mixture as fuel, j = -400 mA/cm2). The calculated linear power degradation rate over all durability test (~2400 h) is about 0.4%/1,000 h.

Process simulation and techno economic analysis of renewable diesel production via catalytic decarboxylation of rubber seed oil – A case study in Malaysia

This work describes the economic feasibility of hydroprocessed diesel fuel production via catalytic decarboxylation of rubber seed oil in Malaysia. A comprehensive techno-economic assessment is developed using Aspen HYSYS V8.0 software for process modelling and economic cost estimates. The profitability profile and minimum fuels selling price of this synthetic fuels production using rubber seed oil as biomass feedstock are assessed under a set of assumptions for what can be plausibly be achieved in 10-years framework. In this study, renewable diesel processing facility is modelled to be capable of processing 65,000 L of inedible oil per day and producing a total of 20 million litre of renewable diesel product per annual with assumed annual operational days of 347. With the forecasted renewable diesel retail price of 3.64 RM per kg, the pioneering renewable diesel project investment offers an assuring return of investment of 12.1% and net return as high as 1.35 million RM. Sensitivity analysis conducted showed that renewable diesel production cost is most sensitive to rubber seed oil price and hydrogen gas price, reflecting on the relative importance of feedstock prices in the overall profitability profile.