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This paper presents a techno-economic model of two interconnected hybrid microgrids (MGs) whose electricity and thermal dispatch strategy are managed with Sequential Least Squares Programming (SLSQP) optimization technique. MGs combine multiple thermal and electric power generation, transmission, and distribution systems as a whole, to gain a tight integration of weather-dependent distributed renewable generators with multiple stochastic load profiles. Moreover MGs allow to achieve an improvement in the return of investment and better cost of energy. The first part of the work deals with a method to obtain an accurate prediction of climate variables. This method makes use of Fast Fourier Transform (FFT) and polynomial regression to manipulate climate datasets issued by the European Centre for Medium-Range Weather Forecasts (ECMWF). The second part of the work is focused on the optimization of interconnected MGs operations through the SLSQP algorithm. The objective is to obtain the best financial performance (IRR) when clean distributed energy resources (DERs) are exchanging both thermal and electric energy. SLSQP optimizes the energy flows by balancing their contribution with their nominal Levelized Cost of Energy (LCOE). The proposed algorithm is used to simulate innovative business scenarios where revenue streams are generated via sales of energy to end users, sell backs and deliveries of demand response services to the other grids. A business case dealing with two MGs providing clean thermal and electric energies to household communities nearby the city of Bremen (Germany) is examined in the last part of the work. This business case with a payback in two years, an internal rate of return (IRR) at 65% and a LCOE at 0.14 €/kWh, demonstrates how the interconnection of multiple hybrid MGs with SLSQP optimization techniques, makes renewable and DERs outcompeting and could strand investments in fossil fuel generation, shaping the future of clean energy markets.

The flexible operation of alkaline water electrolyzers enables power-to-x plants to react efficiently to different energy scenarios. In this work, a novel scheduling model for alkaline water electrolysis is formulated as a mixed-integer linear program. The model is constructed by implementing operational states (production, standby, idle) and transitions (cold/full startup, shutdown) as integer variables, while the power loading and hydrogen flowrate are set as continuous variables. The operational characteristics (load range, startup time, ramp rates) are included as model constraints. The proposed model allows finding optimal number of electrolyzers and production schedules when dealing with large data sets of intermittent energy and electricity price. The optimal solution of the case study shows a balance between hydrogen production, energy absorption, and operation and investment costs. The optimal number of electrolyzers to be installed corresponds to 54% of the ones required to absorb the highest energy peak, being capable of loading 89.7% of the available energy during the year of operation, with an overall plant utilization of 93.7% and 764 startup/shutdown cycles evenly distributed among the units.

This contribution presents an integer-linear model of a post-combustion carbon capture plant featuring discrete sizing, part load operation and dynamic behavior. In particular, the model covers a design space from 200 tCO2/h (size of Petra Nova) down to 7.5 tCO2/h, a part load operation range from 50% to 100%, and a CO2 concentration range from 7.5% to 12%. Starting with detailed, partly rate-based, models in Aspen Plus and deriving linear performance planes thereof allows to bring process model information into a linear system modeling domain for a reasonable range of design specifications. By applying this model to a low-emission energy system design optimization, its practicability and added value could be demonstrated. The simulations show that especially for systems with high non-dispatchable energy generation, the information about the carbon capture plant's dynamic behavior is essential. To fit the scope of this paper, the mathematical formulation of the model is reported in a condensed manner. However, all information required to formulate the model is provided.

Achieving the United Nations sustainable development goals requires industry and society to develop tools and processes that work at all scales, enabling goods delivery, services, and technology to large conglomerates and remote regions. Process Intensification (PI) is a technological advance that promises to deliver means to reach these goals, but higher education has yet to totally embrace the program. Here, we present practical examples on how to better teach the principles of PI in the context of the Bloom's taxonomy and summarise the current industrial use and the future demands for PI, as a continuation of the topics discussed in Part 1. In the appendices, we provide details on the existing PI courses around the world, as well as teaching activities that are showcased during these courses to aid students' lifelong learning. The increasing number of successful commercial cases of PI highlight the importance of PI education for both students in academia and industrial staff. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of Institution of Chemical Engineers. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

In this paper, a novel mathematical model that combines a membrane filtration model, component balances and reaction kinetics models for an intensified separation-reaction process in membrane reactor producing biofuels was developed. A unique feature is that the proposed model can capture the dynamics of membrane fouling as function of both reversible and irreversible fouling; which leads to cyclic behavior. Fouling leads to the decline of the reactor productivity. With an appropriate fouling-model, the operational strategy can be optimized. In the case study of biodiesel production, the developed model was validated with experimental data. The model was in good agreement with the data, where R-squared are 0.96 for the permeate flux and 0.95 for the biodiesel yield. From a further analysis, the efficiency of membrane reaction system in term of productivity can be significantly improved by changing the backwashing frequency under specific operating conditions. As the backwashing frequency increased eight times, the biodiesel yield increased to more than two to three times before the permeate flux dropped under a predetermined limit due to the increase of irreversible membrane fouling.

In this work an all-electric regenerator is developed for the desorption of CO2 from air-capture sorbents using microwaves. An electromagnetic model was made for a continuous flow radial desorber and its dimensions were optimised for maximal microwave utilisation. Based on the optimal dimensions an actual prototype, capable of desorbing CO2 from a commercial supported amine sorbent in fixed- or moving-bed configuration was built to demonstrate the concept and to study performance characteristics. TSA experiments using nitrogen as purge gas to produce enriched air (1 to 2 vol.% CO2) were done. Productivities of up to 1.5 kg CO 2 / kg sorb . / d were demonstrated, with a total energy duty of 25 MJ / kg CO 2 . Compared to traditional TVSA desorption, the energy duty is similar while the productivity is significantly higher. The process can be further improved by creating an even more homogeneous electric field (preventing hot spots in the regenerator) and by enabling desorption under vacuum conditions to produce pure CO2. Overall, microwave desorption is demonstrated as an effective way to circumvent heat transfer limitations present during more traditional thermal desorption processes using polymeric sorbents.

The chemical industry is currently facing the challenge of developing biobased production processes suitable for a more sustainable chemical industry. Acrylic acid produced from monopropylene glycol is a good candidate to become a cost-competitive and sustainable platform chemical. The propylene glycol price is expected to drop due to the expected abundance of propylene glycol as a sugar hydrogenolysis byproduct, which is required to make the conversion to acrylic acid cost-competitive. Two different processes for the conversion of propylene glycol to acrylic acid are evaluated in this work, either by (1) low temperature oxidation of propylene glycol to lactic acid and high temperature dehydration to acrylic acid or by (2) high temperature dehydration of propylene glycol to allyl alcohol and further high temperature oxidation to acrylic acid. Liquid-liquid extraction was found to be a key operation in both production processes. At similar overall yields, the allyl alcohol route appears inherently favored, as a result of the opportunity to integrate the reaction heat available at high temperature. To conclude, the price of propylene glycol has to drop by 45-55% to make the biobased production of acrylic acid from propylene glycol economically feasible.

BACKGROUND: Ethyl levulinate (EL) is an important chemical that can be used as a bio-based replacement of fuel additives such as methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME). EL production from lactic acid and ethanol is a viable option, as both precursors can be obtained from biomass. However, the problem of EL production by esterification is that this reaction is hindered by the chemical equilibrium limitations and the boiling points ranking, which is not the most favorable. RESULTS: This study provides novel optimally designed reactive distillation (RD) processes for the production of EL, taking into account costs, environmental impact and safety. The thermally coupled RD process is the most appealing, with the lowest energy use (1.667 MJ kg−1 EL), minimal investment cost, major energy savings (up to 54.3% lower than other RD processes), reduced environmental impact (up to 51% lower ECO99 index value) and similar safety as other RD processes considered (less than 2% differences in the individual risk (IR) indicator). CONCLUSION: The multi-objective optimization approach used here showed its robustness, practicality and flexibility to provide multiple optimal designs of intensified processes that are economically attractive, environmentally friendly and inherently safe.

This article is meant to frame the challenges and opportunities of the methane conversion to methanol via a chemical looping (or redox) process by comparison with the industrial performance criteria. Accordingly, the low methanol productivity and the expected long cycle time result in an overall production rate that falls a factor of ∼50 below the industrial threshold and leads to the prohibitive material cost. With this analysis, we aim to stimulate the diversification of the research directions toward making the process more economically interesting. We also extend this analysis to a variety of the chemical looping processes and conclude that they all fall short of the simple productivity criteria. We therefore recommend researchers pay more attention to improving productivity in these processes.

This work presents a fully open-source superstructure optimization model for bi-criteria process design optimization. This model is implemented in the Open sUperstrucTure moDeling and OptimizatiOn fRamework (OUTDOOR). It combines mass, energy and cost balances with a more sophisticated heat integration concept with low computational effort and acceptable accuracy. The model is applied to a Power-to-Methanol (PtM) process design case study. A cost optimal methanol plant is identified at net production costs (NPC) of 892 €/tMeOH and net production emissions (NPE) of -1.937 tCO2-eq./tMeOH. It utilizes CO2 captured from refinery flue gas and hydrogen supply via. ambient pressure alkaline electrolysis. A plant configuration, designed for minimum CO2 emissions yields costs of 979 €/tMeOH with emissions of -2.191 tCO2-eq./tMeOH, using CO2 from ambient air and refinery and cement factory flue gases. A sensitivity analysis on electricity prices forecasts cost competitive methanol at large production capacities and low electricity prices of 2 ct/kWh.

Ammonia may be one of the energy carriers in the hydrogen economy. Although research has mostly focused on electrochemical ammonia synthesis, this however remains a scientific challenge. In the current article, we discuss the feasibility of single-pass thermochemical ammonia synthesis as an alternative to the high-temperature, high-pressure Haber-Bosch synthesis loop. We provide an overview of recently developed low temperature ammonia synthesis catalysts, as well as an overview of solid ammonia sorbents. We show that the low temperature, low pressure single-pass ammonia synthesis process can produce ammonia at a lower cost than the Haber-Bosch synthesis loop for small-scale ammonia synthesis (

Reverse electrodialysis harvests energy from salinity gradients establishing a renewable energy source. High energy efficiencies are fundamental to up-scale the process and to minimize feedwater pre-treatment and pumping costs. The present work investigates electrode segmentation to strategically optimize the output power density and energy efficiency. Electrode segmentation allows the current density to be tuned per electrode segment. Segmentation experiments were performed with a dedicated electrode configuration in a cross-flow stack using a wide range of residence times. Moreover, an experimentally validated model was extended and used to further compare single and segmented electrode configurations. While operating the electrode segments, the highest efficiencies were obtained when considering the overall power, i.e. not maximized by segment. Results show that at a given net power density (0.92 W·m−2), electrode segmentation increases the net energy efficiency from 17% to 25%, which is a relative increase of 43%. Plus, at 40% net energy efficiency the net power output for a segmented electrode configuration (0.67 W·m−2) is 39% higher than in a single electrode configuration. Higher power density reduces capital investment and higher energy efficiency reduces operating costs. Electrode segmentation increases these parameters compared to a single electrode and can be potentially applied for up-scaling.

Pressure swing adsorption (PSA) processes are frequently used in the (petro)chemical industry, but they suffer from ineffective use of the sorbent and slow heat transfer. A pressurized multi-stage fluidized bed (MSFB) for continuous PSA is proposed in this work to overcome these drawbacks. A one stage fluidized bed adsorber was used to determine minimum fluidization velocities of the used amine sorbent at various pressures up to 10 bara. The design of a pilot scale experimental setup is described, together with supporting experiments to show the proof of concept. Removal from 37,000 mol ppm CO2 to

N-ethylbutyl amine (EBA) has been reported as switchable solvent for the extraction of lipids from microalgae. To properly assess the technical feasibility as well as the sustainability of the lipid extraction process with EBA, solvent recovery is an essential process consideration. In this paper, opportunities for solvent recovery from both the aqueous raffinate stream and the solid algal residue were investigated, and two approaches for solvent recovery from the extracted lipids were investigated. In the first approach, CO2 switching is applied, which switches EBA from a neutral molecule into an ionic liquid that phase splits from the lipids. In the second approach, the strong effect on water solubility of EBA due to its lower critical solution temperature (LCST) behavior is used in a temperature swing back-extraction. For both approaches, a conceptual process was designed, and for all unit operations where important information was missing, the missing information was obtained by experiment and/or using process simulation software (Aspen Plus V8.8). From the conceptual process evaluation, it was concluded that the process making use of CO2 switching suffers from large solvent losses due to the switching mechanism. With the temperature swing back-extraction, it was much better possible to recover the EBA, and design a feasible process that costs 12.4 MJ/kg lipids, which considering the energy content of 1 kg lipids, is net energy gain of 22.4 MJ/kg lipids.

The overall mass balance of an electrochemical reactor is a key factor in determining the economic potential of a process. We provide a method to estimate the overall mass balance and electrolyte composition of electrochemical conversion systems and apply it to several CO2 conversion systems. Next to the reactions at the electrodes, the influence of transport across the membrane and homogeneous reactions are considered. It is thereby shown that potassium bicarbonate – an often proposed electrolyte for aqueous CO2 reduction - does not provide the conditions required for CO2 conversion to formic acid. The requirements for an electrolyte that does result in that conversion are described. The simplicity and versatility of the simplified method and the necessity of establishing a complete mass balance make the method a valuable addition to the electrochemist’s toolbox.

Biogas is one of the most popular alternative energy resources to replace fossil fuels. The product of anaerobic fermentation in a digester contains several impurities such as H2S and especially CO2 that needs to be removed in order to upgrade the gas quality. Supported amine sorbents (SAS) might provide an attractive option to remove these impurities. However, little is known about the regeneration of the sorbent. This study evaluates experimentally and by modeling the options for regeneration of the SAS. Theoretically, pressure swing adsorption without purge flow is the most energy efficient method (1.7 MJ/kg CO2). It was found that when using a purge flow the desorption rate is strongly influenced by the equilibrium between the gas and adsorbed phase. With elevated temperature (>80 °C) both the working capacity and the productivity increase significantly. Finally, an energy evaluation for a typical biogas case study is carried out, showing the trade-offs between power consumption, heat demand, and sorbent inventory. Interestingly, at the expense of a somewhat higher power consumption, the use of inexpensive air as purge gas at 60 °C could be an attractive option, but case-specific costs are needed to identify the economic optimum.

Currently there are significant amounts of natural gas that cannot be produced and treated to meet pipeline specifications, because that would not be economically viable. This work investigates a bench scale multistage fluidized bed (MSFB) with shallow beds for sour gas removal from natural gas using a commercially available supported amine sorbent. A MSFB is regarded as a promising adsorber type for deep sour gas removal to parts per million concentrations. A series of experiments was conducted using carbon dioxide as sour gas and nitrogen to mimic natural gas. Removal below 3 mol ppm was successfully demonstrated. This indicates that gas bypassing is minor (that is, good gas–solid contacting) and that apparent adsorption kinetics are fast for the amine sorbent applied. Tray efficiencies for a chemisorption/adsorption system were reported for one of the first times. Current experiments performed at atmospheric pressure strongly indicate that deep removal is possible at higher pressures in a multistage fluidized bed.

Combustion of pyrolysis oil has attracted many attention in recent years as a renewable and environmental friendly fuel. However, pyrolysis oil as an multi-component fuel has some differences compared to conventional fossil fuels. One of the main differences is the formation of solid char in the droplet during evaporation. The goal of this work is to study the effect of the solid char on the combustion characteristics of multi-component fuel. An Euler-Lagrange model of three phase gas/liquid/solid combustion is developed to study the detailed information about every phenomena in the process such as: heat, mass and momentum transfer between droplet and gas phase, droplet evaporation, homogeneous and heterogeneous reactions. The results indicate that the presence of the solid char and consequently its combustion elongates significantly the combustion region in a typical spray injection chamber/burner. Moreover, the gas phase reaches higher temperatures as a result of char combustion that creates more heat by heterogeneous oxidation as a kind of afterburner.

Wet granulation lines in pharmaceutical manufacturing facilities typically comprise a dryer that removes the excess moisture content after wet granulation. In this study, a semi-continuous dryer installed in the ConsiGma 25 wet granulation line was investigated. The goal was to highlight specific characteristics of this type of dryer, utilizing the available process data and the corresponding data obtained via material characterization. This paper addresses typical effects and issues associated with the dryer’s setup and operation (e.g., unexpected cell temperature profiles, the effects of air flow and temperature on the granule properties, variations in the granule moisture between the dryer cells). Since in many situations the liquid-to-solid ratio is based on the properties of granules after the granulation step, the selection of inlet air flow rate and the inlet air temperature of the dryer as well as the overall line throughput (affecting the cell fill level in the dryer) are of particular interest from a practical point of view. This paper discusses these issues and provides suggestions on how to address them when setting up the process. A novel approach for characterizing the fluidization inside the dryer by means of quantifying the “smoothness” of the temperature profile is proposed. The paper should be viewed as a hands-on guideline, which highlights possible pitfalls during the process setup and offers solutions.

The extraction of CO2 directly from the atmosphere (Direct Air Capture) is commonly employed using supported-amine sorbents. This adsorption technology is under rapid development with novel sorbent materials emerging and with processes being demonstrated on increasingly larger scale. Optimization of such processes requires accurate knowledge on sorbent characteristics and knowledge on how operational variables affect process performance. This study primarily focuses on the latter, where we aim to quantify the influence of operational parameters on the energy duty and CO2 productivity. In addition, we examine the influence of weather conditions on the adsorption rate. For this, we develop a dynamic model of the complete temperature-vacuum swing adsorption cycle (TVSA). This model was validated by experimental results on a kg-scale direct air capture system. The impact of selected operational variables was assessed by two-dimensional sensitivity analyses. We show that desorption temperature is preferably high, limited by the chemical stability of the sorbent material in this particular case. In addition, the sorbent working capacity should be high when opting for an optimization towards energy duty, whereas it reaches a clear optimum in terms of CO2 productivity. Finally, we conclude that weather conditions and diurnal variations can significantly affect the performance of a direct air capture process and should certainly be considered during design and operation. With these insights and the developed model, this study provides a sound basis for further process development and optimization of direct air capture using fixed bed technology combined with solid amine sorbents.

The objective is to design a plant from raw material to product for the production of aniline by direct amination of benzene. The process design is started on a conceptual level and ended on a basic engineering level as well as a techno-economical evaluation. The amination of benzene by hydroxylamine was used as basis. For the production of hydroxylamine four routes are proposed. The most promising route is the chemical reduction of nitric oxide with hydrogen. The process evaluation shows that 27 % of the atomic nitrogen is lost. The atomic carbon efficiency is close to unity. Furthermore, a significant amount of steam can be produced. From an economical perspective, there is still room for improvement because the return of investment is quite low and the payback period is quite high.

Recently, a novel heat-pump-assisted extractive distillation process taking place in a dividing-wall column was proposed for bioethanol dehydration. This integrated design combines three distillation columns into a single unit that allows over 40% energy savings and low specific energy requirements of 1.24 kWh/kg ethanol. However, these economic benefits are possible only if this highly integrated system is also controllable to ensure operational availability. This paper is the first to address the challenges related to process dynamics and control of this highly integrated system. After showing the control difficulties associated with the original design owing to thermal unbalance, an efficient control structure is proposed which introduces a by-pass and an additional external duty stream to the side reboiler. The range of the external duty is rather small, about 5% of the combined duty of the reboilers, but sufficient to stabilize the system by controlling the temperature on the pre-concentration side of the column. Two quality control loops ensure product purity when the system is affected by feed flowrate and composition disturbances.

Depleting fossil energy resources and the changes in climatic conditions have propelled humanity to find alternative sustainable resources to satisfy the increasing energy demand. Lignocellulosic biomass is one of the carbon-based renewable resources which can be used to produce fuels and chemicals. Fast pyrolysis is a promising technologies in which lignocellulosic biomass is decomposed at ~500 °C and in the absence of oxygen, to produce oil (~75%), char (~12%) and gas (~13%). Pyrolysis oil can be upgraded to fuel or platform chemicals via downstream processing. The research described in this thesis aims at advancing the current understanding of the three simultaneously occurring processes, viz. chemical reactions (decomposition, cracking, polymerisation), heat transfer and mass transfer (evaporation, sublimation, random ejection), and their interplay during the fast pyrolysis of cellulose, lignin and lignocellulosic biomass. For that, a dedicated screen-heater reactor was used, which was designed to minimise non-isothermality, to control the reaction time inside the reacting particle by the escape rate of compounds from the reaction zone by variation of the pressure, and to minimise reactions outside the reacting particle by minimising hot vapour residence time followed by fast quenching of products. Experiments were also carried out in a bench-scale 1 kg h-1 fluidised bed unit equipped with a fractional condensation system to investigate the effect of hot vapour residence time. From this work it can be concluded that besides the heating rate of sample, hot vapour residence time of products and the temperature during the pyrolysis, the system pressure is the key parameter, which alters the residence time of products in/on the hot reacting particle, thereby, providing a means to steer the yields and composition of the products of pyrolysis.

This thesis deals with the design and development of a process for the conversion of wet biomasses, primarily to H2. Wet biomasses contain over 80% moisture, such as bio-wastes and wastewaters produced in the food and agro-industries. In order to overcome the energy-intensive drying step for traditional biomass conversion technologies, a newer route for conversion involves the use of water as a reaction medium. Such processes are hydrothermal in nature. The process under consideration in this thesis is a two-step catalytic process for hydrothermal gasification with simultaneous reduction of the organic content of the residual water phase. The first part of the thesis (Chapters 2 and 3) includes studies focussed on obtaining a more fundamental understanding of the two main catalytic processes under consideration: stabilisation and gasification. Stabilisation, described in Chapter 2, was successfully applied to convert highly reactive aqueous carbohydrates to more stable molecules that would subsequently minimise, if not eliminate, coke production upon further processing. In Chapter 3, the hydrothermal gasification of sorbitol was studied using a 5 wt % Pt on γ-Al2O3 catalyst, with an without N2 as a sweep gas. The complex reaction mechanisms were described through a path-lumped kinetic scheme. The reactor model was used to demonstrate the feasibility of the process on an industrial scale. The second part of this thesis (Chapters 4 and 5) includes work focussed on process development with an aim to identify whether the process is ready for implementation on a larger, industrial scale. In Chapter 4, a sequential combination of the studied gasification catalysts (Pt and Ru) was found to provide a two-fold advantage to the hydrothermal gasification process, through the optimal production of H2, at complete carbon to gas conversions. In Chapter 5, a process development and economic analysis was conducted. An energy balance demonstrated that the process an overall energy efficiency of 65 %. The rest of the energy produced (~ 35 %) was used to meet the process demands of electricity, steam and fired heat. The price of H2 obtained was comparable to H2 prices obtained from other renewable technologies.

Since the start of the industrial era, the CO2 concentration in the air has risen from 250ppm to more than 400ppm nowadays. A large part of the increase can be contributed to use of fossil fuels for energy production. To reduce CO2 emissions, more and more capacity of renewable energy sources such as, wind power, solar PV and hydro-power are installed. However, most of these sources result in intermittent supply of electricity leading to a mismatch in supply and demand. To level supply and demand, storage of electricity is required. In this thesis, the storage of renewable electricity into methanol is studied. The goal of thesis is to develop technology for direct air capture of and improve efficiency of -- small scale -- CO2 to methanol technology. Technologies for conversion of H2O into H2 -- required for the synthesis of methanol -- are outside the scope of this project. In Chapter 1 it is shown that for long term and large scale storage (i.e. seasonal storage), storage in chemicals is required. Methanol is liquid at ambient conditions and therefore an excellent storage medium, as it is easy to store and transport. Moreover, it can be produced from the abundant available chemicals CO2 and H2O. Furthermore, methanol is a very flexible product as it can be converted back to electricity, used as a gasoline substituent, converted to a diesel replacement and used as feedstock in the chemical industry. To produce the CO2 required for the production of methanol, the transport phenomena for CO2 adsorption in solid amine sorbents are studied in Chapter 2. The adsorption kinetics are determine to be able to optimize CO2 air capture systems. For this, a new experimental method is developed to exclude heat and mass transfer limitations during kinetic adsorption experiments. Hereto, a novel contactor was designed and good process control, working with pure CO2 and small particle diameters enabled the measurement of intrinsic kinetics. A mathematical model describing convection, diffusion and reaction rate inside a particle confirmed the absence of mass and heat transfer limitations in the experiments. During normal adsorption conditions however, the uptake rate of CO2 will be strongly inhibited by diffusional resistances inside the particle.Linear driving force and Toth-isotherm reaction rate equations are evaluated for the CO2 adsorption process studied. The results show that the experimental particle loading with time could not be described by the linear driving force models. On the other hand, the Toth reaction rate equation, consistent with the Toth isotherm to describe the adsorption equilibrium, showed a very good fit to the experimental data. This shows that a rate based isotherm equation is necessary for consistent prediction of both, adsorption rate and equilibrium loading. In Chapter 3 and 4 the desorption of CO2 from the adsorbent is studied. While Chapter 3 focuses on the regeneration of sorbents, Chapter 4 focuses on the production of high purity CO2 from air. In Chapter 3 the regeneration conditions of a solid amine sorbent are evaluated by experiments and equilibrium modelling. It was found that when using an inert purge flow the desorption rate is strongly influenced by equilibrium between the gas and adsorbed phase. Because of the strong dependency of the isotherm on temperature, heat transfer is found to be an important design parameter. With elevated temperature (>80°C) both the working capacity and the productivity increase significantly. Therefore, most important design considerations are heat transfer and the trade-off between sorbent working capacity and energy consumption for sorbent heating. The effects of water co-adsorption and steam purge on the CO2 working capacity and energy requirement for CO2 desorption are reported in Chapter 4. Working capacities are studied by fixed bed operation for changing temperature, pressure and amount of steam purge. Results show that for pressure-temperature swing adsorption a temperature above 100°C and a pressure below 200 mbar as desorption conditions are required to maximize CO2 working capacity and reduce energy requirement for desorption. Co-adsorption of water reduces energy requirement due to an increased CO2 working capacity. Application of a steam purge increases the CO2 working capacity and hence reduces sorbent inventory required. However, the net energy requirement per kilogram CO2 does not decrease due to the latent heat of water. Concluding, steam purge regeneration for air capture does not reduce OpEx but might reduce CapEx. A novel reactor concept for the conversion of CO2 and H2 to methanol is developed in Chapter 5. Conversion limitations because of thermodynamic equilibrium are bypassed via in situ condensation of a water/methanol mixture. Two temperatures zones inside the reactor ensure optimal catalyst temperature, automatic gas circulation by natural convection and full conversion by condensation at a lower temperature in a separate zone. Experimental work confirmed full carbon conversion (>99.5%) and high methanol selectivity (>99.5% on carbon basis). Because of full gas conversion there is no need for an external recycle of unconverted reactants. Moreover, proof of concept for operation under natural convection conditions was shown. A more detailed analysis of the condensing reactor for conversion of CO2 to methanol is given in Chapter 6. The reactor is characterized under forced convective conditions, both experimentally and by modelling. The goal of the study is to optimize the operation conditions and identify limitations of the reactor concept. Experimental results show that the productivity is limited by reaction equilibrium and mass transport at high temperature (> 250°C), while reaction kinetics limit productivity at low temperature (> 220°C). Further analysis of the LOGIC concept is performed by an adiabatic 1D-reactor model in combination with an equilibrium flash condenser model. To enable autothermal operation without excessive heat exchange area, it was found that a condenser temperature below 70°C is required. Most important design parameter is found to be the conversion per pass over the catalyst bed. Increasing dimensions of the catalyst section will increase the conversion per pass, unless equilibrium is reached. On the other hand, heat exchanger and condenser area are reduced because of a lower recycle ratio. With the model developed, overall reactor performance can be optimized by finding the most optimal combination of reaction and condenser conditions. In Chapter 7 a 100MW wind power to methanol process has been evaluated to determine the capital requirement and power to methanol efficiency. Power available for electrolysis determines the amount of hydrogen produced. The stoichiometric amount, for the methanol synthesis, of CO2 is produced using direct air capture. Capital cost for all process steps is estimated using short-cut equipment sizing and economics. Power to methanol efficiency was determined to be around 50%. The cost of methanol is around 800€ ton-1 including wind turbine capital cost. Excluding 300M€investment cost for 100MW of wind turbines, total plant capital cost is around 200M€. About 45% of the capital cost is reserved for electrolysers, 50% for the CO2 air capture installation, and 5% for the methanol synthesis system. The conceptual design and evaluation shows that renewable Methanol from CO2 from air, water and renewable electricity is becoming a realistic option at reasonable costs of 750-800 € ton-1. The production of renewable methanol using direct air capture and electrolysis is currently not economical viable. As discussed in Chapter 7 the cost of wind energy, electrolysis, and air capture are expected to go down in the future, improving process economics. As discussed in Chapter 8, government legislation might be an important driver for the process. For example, the European Renewable Energy Directive II) requires 14% of renewable energy to be used in transportation by 2030. Moreover, the European Commission proposes a climate-neutral Europe in 2050, thereby renewable methanol could fulfil the role of sustainable carbon source for the chemical industry.

Reactive distillation (RD) is an efficient process intensification technique that integrates chemical reaction and distillation in a single apparatus. The process is also known as catalytic distillation when a solid catalyst is used. RD technology has many key advantages such as reduced capital investment and significant energy savings, as it can surpass equilibrium limitations, simplify complex processes, increase product selectivity, and improve separation efficiency. However, RD is also constrained by thermodynamic requirements (related to volatility differences and heat of reaction), the need to align the reaction and distillation operating conditions, and the availability of catalysts that are active, selective, and with sufficient longevity. This paper is the first to provide an overview and insights into novel integrated reactive distillation technologies that combine RD principles with other intensified distillation technologies - e.g., dividing-wall column (DWC), cyclic distillation, HiGee distillation, heat-integrated distillation column (HIDiC), and membrane-, microwave-, or ultrasound-assisted distillation - potentially leading to the development of new processes and applications.

In the quest for a sustainable bio-based economy, biorefineries play a central role as they involve the sustainable processing of biomass into marketable products and energy. This paper aims to provide a perspective on applications of separations that can make a great difference in biorefineries, by significantly reducing the costs and thus making the processes competitive without subsidies. A parallel is drawn between bio-refinery and petro-refinery, to highlight the specific separation challenges encountered in biorefineries and point out the impact of separations on the total costs. Existing and foreseen separations in biorefineries are reviewed, and the upcoming challenges in the bio-domain (additional to current fossil) are identified. Relevant industrial examples are provided to illustrate the tremendous eco-efficiency benefits of well-designed separation processes based on process intensification principles (e.g. reactive separations, dividing-wall column, affinity and trigger-enhanced separations). These examples also illustrate the low sustainability of several bio-separations currently practiced, in terms of high relative energy requirements, large amounts of gypsum co-production and/or excess use of caustic.

When investigating a new catalytic reaction, scientists may wonder if the crude reaction product can be easily separated and purified. We present here a new concept-distillation resistance-to assess the potential of distillation as a purification technique and to guide catalyst formulation or operation at the very early stage of the research. Distillation resistance, which has been developed from the analysis of 15 industrial distillation trains, can be quickly calculated with knowledge of only the product composition and atmospheric boiling points of the components. It can be directly converted into a preliminary distillation cost that considers investment and energy cost. Its application and its potential guidance in catalysis research are illustrated through a few cases studies derived from biorefinery processes.

Reactive distillation (RD) is a useful process intensification technique used in the chemical process industries as it offers important advantages such as energy and cost savings, relative to conventional technologies. However, industrial application of RD is still limited by the complexity of designing and understanding such a complex process. While simple, robust shortcut design methods that require only basic information (such as the relative volatility ofcomponents) exist for conventional distillation, such methods for evaluating the applicability of RD are not yet established. This work fills this gap by presenting a new systematic framework for assessing the RD applicability based on a mapping method. The method enables RD designs to be screenedusing only relative volatilities and chemical equilibrium constant as input data. The evaluation focuses on reactions involving four components (A + B ⇌ C + D) with various boiling point orders, which are of most industrial importnace. The proposed systematic framework is validated through its application to five case studies, (trans-)esterifications presenting various separation challenges due to the formation of azeotropes. This novel approach offers a valuable aid for engineers in taking an educated go/no-go decision in the very initial stages ofconceptual design, before performing any rigorous simulations of RD flowsheets.

This study characterizes mass transfer processes in a multi-stage fluidized bed (MSFB) using shallow fluidized beds. Multi-stage fluidized beds are of interest for sour gas removal using adsorption, examples are H 2 S/CO2 removal from natural gas and CO2 capture by amine sorbents. A phenomenological model based on the classical two-phase fluidization model is used to study the mass transfer process. Independent measurements and literature data are used to describe mixing, hold-ups, intraparticle mass transfer and adsorption kinetics. The bubble hold-up was experimentally measured. Mixing was investigated with a temperature response measurement. The mixing in the emulsion gas phase varies between plug flow and ideal mixing with increasing superficial gas velocity, while the solid phase is always ideally mixed. The presented fluidized bed model is able to describe the effects of superficial gas velocity, solid flux, bed height and inlet concentration. Mass transfer was further studied using a sensitivity analysis, which showed that the used shallow fluidized bed is already fairly optimized with respect to mass transfer. Shallow fluidized beds benefit from fast gas interchange because bubbles do not have the chance to grow. Optimal mass transfer and gas interchange conditions can be achieved in shallow fluidized beds for application in MSFBs.

A 100 MW stand-alone wind power to methanol process has been evaluated to determine the capital requirement and power to methanol efficiency. Power available for electrolysis determines the amount of hydrogen produced. The stoichiometric amount of CO2 – required for the methanol synthesis – is produced using direct air capture. Integration of utilities for CO2 air capture, hydrogen production from co-harvested water and methanol synthesis is incorporated and capital costs for all process steps are estimated. Power to methanol efficiency is determined to be around 50%. The cost of methanol is around 300€ ton−1 excluding and 800€ ton−1 including wind turbine capital cost. Excluding 300 M€ investment cost for 100 MW of wind turbines, total plant capital cost is around 200 M€. About 45% of the capital cost is reserved for the electrolysers, 50% for the CO2 air capture installation, and 5% for the methanol synthesis system. The conceptual design and evaluation shows that renewable methanol produced from air captured CO2, water and renewable electricity is becoming a realistic option at reasonable costs of 750–800 € ton−1.

CO2 emissions related to human activities utilizing fossil fuels are generally believed to cause climate changes. Conventional CO2 capture technologies focus on capturing CO2 at large pointed sources, such as power plants. But distributed sources account for around one-third to one-half of the total emissions, which cannot be captured by conventional CO2 capture technologies. Those emissions can be mitigated by one technology – CO2 capture direct from ambient air (DAC), which attracts increasing attention nowadays. For DAC, a process based on the use of regenerative solid sorbents may be an attractive, energy efficient alternative to the use of aqueous solvents due to a lower specific heat. Among solid sorbents, amine-functionalized sorbents have been identified as promising sorbents for DAC, due to their relatively high CO2 capacities under the air capture conditions and a moderate desorption temperature (100 – 120 °C). In this thesis, a novel process is developed and experimentally demonstrated, for CO2 capture from ambient air to produce CO2 enriched air to enhance microalgae cultivation. First, an amine functionalized sorbent is selected, initially based on its water and CO2 equilibrium adsorption capacity. Subsequently, the selected sorbent is characterized on its stability under different conditions for a wide range. After selecting the sorbent, a selection of operating conditions for the adsorption step is made, targeting fast sorbent saturation and a low pressure drop. After establishing proper adsorption conditions as well as a suitable adsorber configuration, sorbent desorption is investigated in view of the production of CO2 enriched air for microalgae cultivation. The established process uses a radial flow reactor for CO2 adsorption and a fluidized bed for desorption using air as the sweep gas, with sorbent circulation between adsorber and desorber. This process is evaluated and, based on the operating costs, found to be an economically competitive way to capture CO2 from ambient air for use in microalgae cultivation.

In this chapter the concepts of social life cycle assessment and combined social and environmental LCA were explored through the application of existing LCA methods to the global value chain of jeans. The social and environmental life cycle assessment (SELCA) method resulted from this explorative research that aims to contribute to the battery of impact assessment tools of products whose value chain scope is multinational (global). From a broader perspective, SELCA has a double-folded purpose to (i) identify opportunities for environmental and social improvement at any of the value chain phases of products, for remediation goals, and (ii) predict the environmental and social performance of different ways (scenarios) to produce the same product, using it as a product design tool. To simplify SELCA development, it was decided to use a single product (jeans) as a showcase from the global textile sector. In this showcase, four scenarios for jeans assembly were compared; three of them were defined under the circular economy principles by including recycled materials (cotton, PET and nylon 6) during the yarn production. During the application of the SELCA method, some new challenges were encountered related to inventory analysis, in particular during data acquisition for social inventories. This is later mainly due to the extensive list of key stakeholders for the showcase and the qualitative nature of social metrics. This list starts with cotton cultivators from different countries where regulations and codes of conduct seem to have contextualised interpretations and consequently different levels of implementation. In this regard, governmental intervention to instrument the transition towards suitable social/environmental performance along the global jeans value chain was also discussed in this chapter.

Reactive distillation (RD) is a great process intensification concept applicable to equilibrium limited reaction systems, but how can anyone decide quickly if RD is indeed worth applying? To answer this question, this study proposes a mapping method for checking the applicability of reactive distillation (RD). The initial development is for one of the most relevant subset of quaternary reversible reactions (A + B ⇄ C + D, with boiling points Tb,C

Process intensification in distillation systems receives much attention with the aim of increasing both energy and separation efficiency. Several technologies have been investigated and developed, as for example: dividing-wall column, HiGee distillation, or internal heat-integrated distillation. Cyclic distillation is a different method based on separate phase movement—achievable with specific internals and a periodic operation mode—that leads to key advantages: increased column throughput, reduced energy requirements, and better separation performance. This article is the first to report the performance of a pilot-scale distillation column for ethanol-water separation, operated in a cyclic mode. A comparative study is made between a pilot-scale cyclic distillation column and an existing industrial beer column used to concentrate ethanol. Using specially designed trays that truly allow separate phase movement, the practical operation confirmed that 2.6 times fewer trays and energy savings of about 30% are possible as compared with classic distillation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2581–2591, 2015

BACKGROUND: Di-n-pentyl ether (DNPE) is a good candidate for diesel fuel formulations due to its blending cetane number, good cold flow properties and effectiveness in reducing diesel exhaust emissions, particulates and smokes. However, novel processes are required in order to drive the production costs down and to increase the efficiency at industrial scale. RESULTS: The dehydration of 1-pentanol to yield DNPE is catalyzed by thermally stable resins, such as Amberlyst 70 which has high activity and selectivity at temperatures up to 190 °C. Two process options are proposed for a plant capacity of 26.5 ktpy: a reaction-separation-recycle (R-S-R) system based on an adiabatic tubular reactor and a catalytic distillation process. Both processes were optimized in terms of total annual costs (481 and 523 k$ year-1), leading to specific energy requirements of 225 and 256 kWh ton-1 DNPE, respectively. The controllability was assessed by dynamic simulation performed in Aspen Dynamics. CONCLUSION: Compared with the membrane reactor reported earlier, the new DNPE process alternatives (i.e. conventional reaction-separation-recycle system and catalytic distillation) are better process candidates, requiring simpler units leading to much smaller investment costs, while also having good controllability.

The purification of bioethanol fuel involves an energy-intensive separation process to concentrate the diluted streams obtained in the fermentation stage and to overcome the azeotropic behavior of the ethanol-water mixture. The conventional separation sequence employs three distillation columns that carry out several tasks, penalized by high-energy requirements: preconcentration of ethanol, extractive distillation, and solvent recovery. To solve this problem, we propose here a novel heat-pump-assisted extractive distillation process taking place in a dividing-wall column (DWC). In this configuration, the ethanol top vapor stream of the extractive DWC is recompressed from atmospheric pressure to over 3.1 bar (thus to a higher temperature) and used to drive the side reboiler of the DWC, which is responsible for the water vaporization. For a fair comparison with the previously reported studies, we consider here a mixture of 10 wt % ethanol (100 ktpy plant capacity) that is concentrated and dehydrated using ethylene glycol as mass-separating agent. Rigorous process simulations of the proposed vapor recompression (VRC) heat-pump-assisted extractive DWC were carried out in AspenTech Aspen Plus. The results show that the specific energy requirements drop from 2.07 kWh/kg (classic sequence) to only 1.24 kWh/kg ethanol (VRC-assisted extractive DWC); thus, energy savings of over 40% are possible. Considering the requirements for a compressor and use of electricity in the case of the heat-pump-assisted alternative, it is possible to reduce the total annual cost by approximately 24%, despite the 29% increase of the capital expenditures, for the novel process as compared to the optimized conventional separation process.

Reactive distillation (RD) is a great process intensification concept taking advantage of the synergy created when combining (catalyzed) reaction and separation into a single unit, which allows the concurrent production and removal of products. This feat improves the productivity and selectivity, reduces the energy usage, eliminates the need for solvents, and leads to highly-efficient systems with improved sustainability metrics (e.g. less waste and emissions). This paper provides an overview of the key features of RD processes, with emphasis on novel catalytic/reactive distillation processes that can make a difference at large scale and pave the way for a more sustainable chemical process industry that is more profitable, safer and less polluting. These examples include the production of: acrylic and methacrylic monomers, unsaturated polyesters resins, di-alkyl ethers, fatty esters, as well as other short alkyl esters (e.g. by enzymatic reactive distillation). The main drivers for such new RD applications are: economical (large reduction of costs and energy use), environmental (lower CO2 emissions, no or reduced waste) and social (improved safety and health due to lower reactive content, reduced footprint and run away sensitivity). Hence RD technology strongly contributes to all three pillars of sustainability in the chemical process industry. Nonetheless, the potential of RD technology has not been fully tapped yet, and there is still undergoing research to improve it further by various means: e.g. ultrasound or microwave assisted RD, use of high-gravity fields (HiGee), internally heat integration, cyclic operation, or coupling RD with other operations such as membrane separations.

Much research has been carried out in the last decade to convert bio-based feedstock into fuels and chemicals. Most of the research focuses on developing active and selective catalysts, with much less attention devoted to their long-term stability. This Review considers the main challenges in long-term catalyst stability, discusses some fundamentals, and presents options for their mitigation. Three main challenges are discussed: catalyst fouling, catalyst poisoning, and catalyst destruction. Fouling is generally related to the deposition of insoluble components present in the feed or formed by degradation of the feed or intermediates. Poisoning is related to the deposition of electropositive contaminants (e.g. alkali and alkaline earth metals) on acid sites or of electronegative contaminants (e.g. N and S) at hydrogenation sites. Catalyst destruction results from the thermodynamic instability of most oxidic supports, solid acids/bases, and hydrogenation functions under hydrothermal conditions.

A preliminary study based on a conceptual process design methodology that includes a technical evaluation and an economic study has been carried out for the use of the metal-organic framework NH2-MIL-53(Al) as adsorbent for the separation of carbon dioxide from methane. Among the alternatives considered, a vacuum pressure swing adsorption was chosen in the detailed design phase. The combination of a design with columns in parallel and the possibility of recirculating some of the streams ensures a high degree of separation and a final product with high quality without compromising the operation costs. A comparison with the state-of-the-art technology, amine scrubbing, and with a process based on membranes demonstrates that the proposed process is competitive as a result of its low operation costs and the energy demand

We report a process concept for lignocellulose liquefaction in a refinery stream that will be coprocessed with the resulting biocrude and that, therefore, does not require the recovery and recycling of the liquefaction solvent. Light cycle oil and vacuum gas oil were found to be the two most promising solvents. Both refinery streams could provide a liquid yield of 58 C % (64 % energy yield). A techno-economic assessment indicates that the biocrude could be produced at an energy-equivalent crude oil price of 51-64 $ per barrel at a wood cost of 85 $ per dry ton.

A systematic approach was applied to study the process of hydrotreating vegetable oils. During the three phases of conceptual, detailed, and final design, unit operations were designed and sized. Modeling of the process was performed with UniSim Design®. Producing green diesel and jet fuel from vegetable oils was found to be technically possible via a flexible process of hydrotreatment. The resulting mass and energy balances indicated high carbon atom and energy yield. An economic evaluation proved that the operational expenses mainly depend on the cost of raw materials. Currently, the margin between crude palm oil and the retail diesel price is too low to operate an economically viable process. However, production and utilization of biofuels is required by international regulations.

Since the late 1990’s there has been a tremendous growth in literature on ionic liquids (ILs) for a broad range of applications, i.e. catalysis, electrolytes for batteries, in solvolysis of biomass, and also in separation technology. ILs can be applied as solvents for absorption (e.g. of CO2), extractive distillation and extraction processes. That ILs are not magic solvents but have their limitations has also become evident during the past years. Especially the high costs associated with ILs and the lack of experience with these materials in the industrial practice are factors limiting industrial adoption of ILs. The often praised versatility of properties that can be achieved through combination of different cations and anions generates a huge amount of options and makes it difficult to decide where to start when selecting/designing a solvent. This paper focuses on solvent selection/design for applications in extractive distillations and liquid-liquid extractions; also, solvent performance in several specific case studies taken from the open literature is discussed. Important recommendations include: a) make a conceptual process design including the recovery step, regeneration of the IL may be a critical parameter; b) if extractions from aqueous streams are studied, the uptake of water by the IL is an important factor because such co-extracted water is evaporated during the regeneration; c) compare the process with conventional processes to check whether it performs better than the state-of-the-art in industry.

Enzymatic Reactive Distillation (ERD) is a bioreactive process, in which enzymes are immobilized on column internal surface, and helps to overcome chemical reaction and phase equilibrium limitations. The activation of enzymes by ultrasound (US) leads to ultrasound-assisted ERD (US-ERD) which might display more eco-efficiency than standard processing of valuable chemicals. Reaction rate improvements of more than 50% could be achieved by the assistance of US. An US-ERD process for the synthesis of butyl butyrate (10 kilotons per year, 99 wt% purity) was designed. A techno-economic evaluation via process optimization was carried out to minimize the annual costs, by using an evolutionary algorithm. The techno-economic evaluation shows that the US-ERD process and the ERD share nearly equal costs. Installation costs of the US equipment are high but they are compensated by a 12% lower reactive section height and a 7% lower total height of the US-ERD column in comparison to ERD.

Current research focuses on new energy alternatives which could compete with the traditional energy sources based on fossil fuels, and eventually diminish the consequences on climate. Recently, butanol produced by ABE fermentation attracted more attention since its energy power is comparable to that of gasoline. But some hurdles are involved in the establishment of this fuel as an immediate substitute of fossil fuels, e.g. lower butanol concentration in the fermentation effluents and the expensive separation steps to purify the effluent. This work is the first to report the use of hybrid separation based on liquid-liquid extraction (LLX) combined with dividing-wall column (DWC) technology for the purification of the ABE (acetone-butanol-ethanol) mixture. The configurations proposed are the result of multi-objective optimization that aims to find designs that fulfill the tradeoff between those objectives: cost minimization, reduce environmental impact, and increase controllability. The downstream processing alternatives are designed and optimized by minimizing three objective functions simultaneously: the total annual cost (TAC) as an economical index, the eco-indicator 99 as an environmental function, and the condition number (CN) as control index. Among the four designs, the scheme where only a reboiler is included showed the best economic performances and relatively good values of condition number and eco indicator 99.

Biogas from fermentation of manure and organic residues produces a gas stream that can be fed into the natural gas grid, provided impurities (CO2, H2S and H2O) are removed according to specifications prior to grid injection. Compared to conventional technologies, supported amine sorbents (SAS) seem attractive for their high working capacity and fast uptake rate. In this study a technical evaluation for the conceptual design of a system for CO2 capture from biogas with SAS is carried out and the performance is compared with liquid amine scrubbing. As the basis of this study, 1000 Nm3/h of raw biogas with 45%-v of CO2 is to be upgraded to gas product containing max. 10%-v of CO2, according to low calorific gas specifications. For the selected SAS (Lewatit VP OC 1065 and PEI/SiO2) capacity measurements were carried out and results were correlated by Toth sorption isotherms. The heat of adsorption was calculated from the isotherms using the Clausius-Clapeyron equation and validated by measurements at different temperatures using calorimetry. Using the isotherms, a process analysis study with Aspen Plus software was carried out to obtain the best operating conditions for temperature swing between adsorption and desorption conditions, and subsequently the contactor size was determined. System integration studies show that the heat released during the adsorption can be integrated with the heat required in the digester (∼60 °C), resulting in a primary energy use of 20–22% for SAS, while for conventional amine scrubbing this is 38%. This study shows that SAS is an attractive technology option for CO2 removal from biogas.

In this paper, we publish information that has not been published before, but is needed to evaluate processes for wet lipid extraction from microalgae and recover the solvent N-ethylbutylamine (EBA), for example as presented in [1], the article entitled “Process evaluation of swing strategies to recover N-ethylbutylamine after wet lipid extraction from microalgae” in which we evaluate and interpret temperature swing and CO2-swing approaches. This includes selection of microalgae slurry concentration used in the extraction process, information on switching of EBA with CO2, data on the amount of EBA in solid residue after extraction, recoverability from the solid residue, and on recoverability of the solvent from the aqueous raffinate by liquid-liquid extraction and distillation of the solvent and EBA after the liquid-liquid extraction. Also information on phase behavior of binary mixtures of EBA and water is presented. Finally, detailed information on all flows in the process flow diagrams that are given in the article [1] is presented. Keywords: Switchable solvents, Microalgae, Lipid extraction, Lower critical solution temperature, CO2-switchable

In this work a conceptual design of a Power-to-Gas (PtG) process for storing electrical energy in form of synthetic natural gas (SNG) of gas grid quality H is presented. The combination with a conventional lignite fired power plant (LPP) was investigated for possible improvement of its economic performance in times of fluctuating renewable energy supply. In this study for a PtG facility using 80 MWel (10% of LPP nominal capacity) a capital expenditure (CAPEX) of M$ 126 and operational (OPEX) of 31-33 M$/a were estimated. PtG provides a good alternative for storing surplus electrical energy and guaranteeing a viable LPP operation if the remuneration for the flexible operation is above 45 k$/operating hour respectively 56 $/operating hour/MWel which is at least 50% additional operational&maintenance (O&M) costs for a LPP. With decreasing alkaline electrolysis costs and an increasing share of renewable energy supply this concept would represent an energy strategic as well as economic advantage for energy suppliers in future.

The present article deals with the techno-economic assessment of the hybrid steam reforming (HSR) process of glycerol (obtained via transesterification) together with natural gas to produce biomethanol via the synthesis gas route. In this techno-economic assessment, a model is developed in the UniSim Design Suite process simulator using different glycerol amounts up to 54% (on a carbon basis) together with natural gas to produce synthesis gas at reforming conditions of 900 °C, S/C3. The techno-economic analysis shows that at the current market scenario (Oct–Dec 2012) with a natural gas price of 0.2 €/Nm3 and with an assumed glycerol price of 200 €/tonne, the average cost of biomethanol is estimated as 433 €/tonne for a feed of 54 wt % of glycerol (on a carbon basis) with natural gas, which is 75 €/tonne higher than for the methanol obtained via only natural gas steam reforming. It is concluded that biomethanol from a HSR process becomes more attractive when the natural gas price exceeds 0.45 €/Nm3 or when glycerol is available at lesser than 90 €/tonne. Splitting the production capacity in methanol and biomethanol according to the feed composition would result in a price of 358 €/tonne and 470–500 €/tonne of methanol and biomethanol, respectively, depending on the amount of glycerol in the feed. This means that currently, biomethanol is not competitive with methanol unless special arrangements are made (regulations, subsidies) to promote the use of biomethanol. For example, the EC Renewable Energy Directive1 states that the energy content of biofuels from wastes and residues (for instance crude glycerol) counts double. From the sensitivity analysis, it is concluded that feedstock prices and total capital investment have major influence on the final product value of biomethanol. Furthermore, it is concluded that at the current price scenario, utilizing glycerol either in the furnace or in the reformer has no effect on the cost price. However, burning is not an option since the biomethanol will not contain the required C14 isotope

Among the various types of biomass, microalgae have the potential of becoming a significant energy source for biofuel production in the coming years. Currently, research is mainly focusing on optimization of the cultivation methods and the conversion of just a single microalgae fraction (lipids for biodiesel production). Hydrothermal liquefaction is a method for thermochemical conversion of wet microalgae, producing a liquid energy carrier called 'bio-oil' or 'biocrude', next to gaseous, aqueous and solid by-products. A review of the available literature is presented here, analyzing the influence of parameters such as temperature, holding time and catalyst dosage on the yield and properties of the different product fractions. Also, the strain selection and the status of the technology for hydrothermal processes are analyzed. Finally, based on the findings obtained from the literature review, directions for future research are suggested.