Christian Sattler

German Aerospace Center (DLR) | DLR · Department of Solar Chemical Engineering

A novel approach towards thermal energy storage of surplus renewable energy (RE) is introduced via a hybrid thermochemical/sensible heat storage concept implemented with the aid of porous structures made of redox metal oxides, capable of reversible reduction/oxidation upon heating/cooling in direct contact with air, accompanied, respectively, by en...

Catalytic sulphur trioxide splitting is the highest-temperature (650-950oC), endothermic step of several sulphur-based thermochemical cycles targeted to production of hydrogen or solid sulphur. Concentrated solar power tower plants are an attractive renewable energy source to provide the necessary heat. Furthermore, the development of solar receive...

The production of green hydrogen-based chemicals using renewable energy is essential for the decarbonization of several sectors that are difficult to address through electrification. Various electrolysis technologies are often considered for sustainable green hydrogen production. They are therefore in a phase of dynamic development. Currently, hydr...

Solar fertiliser production including the internal utilisation of the side-product oxygen is analysed as one promising example of an innovative process utilising renewable energy resources and addressing the aspect of integrated production – here in the case of nitrogen containing fertilisers. Alternative methods to supply solar energy into the ene...

This work reports on the development of a transient heat transfer model for a prototype reactor of type R2Mx for thermochemical water splitting by temperature and pressure swing of ceria. Key aspects of the R2Mx concept, which are also incorporated in the prototype design, include a movable monolithic redox structure combined with a linear transpor...

Within this work, reticulated monolithic foams and granules made from CaMnO3 − δ and strontium substituted variations are demonstrated to significantly improve the performance of a water splitting redox oxide when employed as a thermochemical oxygen pumping material. Two different process procedures are tested and foams made from Ca0.9Sr0.1MnO3 − δ...

Direct air capture (DAC) of CO2 has gained attention as a sustainable carbon source. One of the most promising technologies currently available is liquid solvent DAC (L-DAC), but the significant fraction of fossil CO2 in the output stream hinders its utilization in carbon-neutral fuels and chemicals. Fossil CO2 is generated and captured during the...

A solar receiver for the continuous reduction of redox particles under vacuum conditions has been developed previously as part of a system to produce hydrogen from solar energy. Here, we report about a joint effort of Sandia and DLR to improve the receivers design and to demonstrate a system of two receivers with different vacuum pressures at DLR’s...

This work reports on the development of a transient heat transfer model for a prototype reactor of type R2Mx for thermochemical water splitting by temperature and pressure swing of ceria. Key aspects of the R2Mx concept, which are also incorporated in the prototype design, include a movable monolithic redox structure combined with a linear transpor...

Hydrogen (H2) produced from renewables will have a growing impact on the global energy dynamics towards sustainable and carbon‐neutral standards. The share of green H2 is still too low to meet the net‐zero target, while the demand for high‐quality hydrogen continues to rise. These factors amplify the need for economically viable H2 generation techn...

The Martian atmosphere contains 0.16% oxygen, which is an example of an in-situ resource that can be used as precursor or oxidant for propellants, for life support systems and potentially for scientific experiments. Thus, the present work is related to the invention of a process to concentrate oxygen in the oxygen-deficient extraterrestrial atmosph...

CaMnO3-δ-based perovskites find application in a variety of thermochemical cycles, e.g. oxygen partial pressure adjustment, chemical looping processes, and thermochemical energy storage. The applicability of these materials is governed by their thermodynamic and kinetic properties. Therefore, tunability of these properties is desirable to adapt the...

Concentrating solar thermal technologies are drawing more attention since it can substantially contribute to a carbon-neutral society. The solar receivers are essential in this technology to convert solar energy efficiently into thermal energy. Moreover, high-temperature steam generation is the promising application for concentrated solar power pla...

Hydrogen fuel is a valuable tool to achieve the energy transition process, and according to the 2050 net zero emissions scenario its demand is expected to increase by more than 530 Mt H2. This article discusses several routes available to produce hydrogen fuel, with a special focus on solar thermochemical cycles for Water Splitting (WS). Solar ther...

For the production of sustainable ammonia, fossil-free feedstocks such as nitrogen are necessary. Therefore, a solar thermochemical process is a suitable candidate for the production of green nitrogen. To make...

Catalytic sulphur trioxide splitting is the highest-temperature (850-900 oC), endothermic step of several sulphur-based thermochemical cycles targeted to production of hydrogen or solid sulphur. The demonstrated capability of centrifugal particle solar receivers of heating particle streams at such temperatures, can allow for “allothermal” implement...

A solar receiver for the continuous reduction of redox particles under vacuum conditions has been developed previously as part of a system to produce hydrogen from solar energy. Here, we report about a joint effort of Sandia and DLR to improve the receivers design and to demonstrate a system of two receivers with different vacuum pressures at DLR’s...

Concentrated solar power is capable of providing high-temperature process streams to different applications. One promising application is the high-temperature electrolysis process demanding steam and air above 800 °C. To overcome the intermittence of solar energy, energy storage is required. Currently, thermal energy at such temperatures can be sto...

Non-abatable emissions are one of the decarbonization challenges that could be addressed with carbon-neutral fuels. One promising production pathway is the direct air capture (DAC) of carbon dioxide, followed by a solar thermochemical cycle and liquid fuel synthesis. In this study, we explore different combinations of these technologies to produce...

A proof of concept sulphuric acid splitting/decomposition prototype driven by hot bauxite particles is designed and developed. The lab-scale test reactor is a novel counter-current flow shell-and-tube heat exchanger with particles on the shell side and sulphuric acid on the tube side with mass flow rates of 10 kg/h and 2 kg/h, respectively. A one-d...

Technologies to capture carbon dioxide (CO2) from industrial processes are needed to reach the climate change goals. In case of the cement industry, calcium looping cycle (CaL cycle) for CO2 capturing has gained more attention not only because it can be integrated in an existent cement plant, but also because the calcination step of the CaL cycle c...

The influence of ionic radii and valence of dopants in Ce0.9LaxYbyZr0.1−x−yO2−δ (x = 0, 0.05, 0.1, y = 0, 0.05, 0.1) on the oxidation kinetics were investigated by thermogravimetric analysis in synthetic air and were compared to undoped ceria. Samples co-doped with Zr–La and Zr–Yb exhibited moderate oxidation kinetics that were slower than undoped...

The present work is part of an approach targeted on demonstrating a concentrated solar energy-driven thermochemical cycle employing solid elemental sulphur as a chemical energy vector and a seasonal solar energy storage medium. In exploring the concept of coupling this cycle to a centrifugal particle solar receiver, bauxite-based particles, commerc...

Synthetic Natural Gas (SNG) is the most researched option for a Power-to-Fuel pathway in Germany after hydrogen, having the advantage of being compatible with the existing infrastructure. However, it is not clear under which conditions SNG is economically and environmentally advantageous compared to natural gas usage, since this is determined by a...

The inherent capability of concentrated solar power (CSP) plants for sensible thermal energy storage ensures their continuous operation and is considered their most crucial competitive edge versus other renewable energy sources. The storage density of air‐operated CSP plants can be significantly increased by hybridizing sensible with thermochemical...

Concentrated solar thermal technologies have enormous potential to achieve a carbonneutral society. The solar receivers are essential in this technology to convert solar energy efficiently into thermal energy. High-temperature steam generation is one of the promising applications for concentrated solar power plants or industirial processes. Therefo...

This paper reports on the numerical analysis of a volumetric solar receiver-reactor for hydrogen production, using the 2-step reduction–oxidation cycle. A detailed parametric sweep covering hundreds of various parameter combinations is performed for a large solar reactor, using a transient physical model. We generate performance maps which are curr...

Copper is the third-most widely-used metal worldwide. However, copper processing is an energy-intensive process consuming large quantities of fossil fuels, both as the reducing agent and for energy which contributes significantly to anthropogenic carbon dioxide emissions. The hybrid sulphur cycle combines concentrating solar thermal energy with ele...

This study analyses experimentally the heat transfer from the wall to the particle bed in a rotating drum with and without addition of built-ins for improving the mixing of the powder. Two types of materials were employed, sand as a granular material (dp,mean=200μm) and cement raw meal as a powdery material (dp,mean=15μm). A rotating cylinder heate...

Solar thermochemical water-splitting cycle models for hydrogen production with single and multiple receivers working between 1773 K and 1173 K are developed. The receiver pressures and aperture sizes are optimized for maximum cycle efficiency. The efficiency of the cycle increases with the number of receivers because of the decrease in vacuum pump...

Methanol is an example of a valuable chemical that can be produced from water and carbon dioxide through a chemical process that is fully powered by concentrated solar thermal energy and involves three steps: direct air capture (DAC), thermochemical splitting and methanol synthesis. In the present work, we consider the whole value chain from the ha...

In solar thermochemical redox cycles for H2O/CO2-splitting, a large portion of the overall energy demand of the system is associated with heating the redox material from the oxidation temperature to the reduction temperature. Hence, an important measure to improve the efficiency is recuperation of sensible heat stored in the redox material. A solid...

Global trade of green hydrogen will probably become a vital factor in reaching climate neutrality. The sunbelt of the Earth has a great potential for large-scale hydrogen production. One promising pathway to solar hydrogen is to use economically priced electricity from photovoltaics (PV) for electrochemical water splitting. However, storing electri...

Electrolysis and thermochemical water splitting are approaches to produce green hydrogen that use either an electrical potential (electrolysis) or a chemical potential (thermochemical water splitting) to split water. Electrolysis is technologically mature when applied at low temperatures, but it requires large quantities of electrical energy. In co...

Large progress has been made in the last decades to reduce the carbon footprint of ammonia, which is an essential commodity of the food, chemical and energy industry. Apart from alternative routes for green feedstock production, such as hydrogen via electrolysis and nitrogen via solar thermochemical methods, alternatives are explored to replace the...

The high-temperature heat produced through concentrated solar irradiation facilities can be exploited to cover partially or totally the enthalpy needs of endothermal reactions of significant industrial importance and scale like methane reforming. This so-called solar thermal methane reforming can serve as a “bridge technology” based initially on fo...

Solar thermochemical redox cycles could be a path to efficient, large-scale renewable hydrogen production. A new receiver-reactor concept is presented that combines characteristics of the most successful receiver-reactor systems to date, with features of concepts showing the highest efficiency potential. The key features of the system are movable r...

Rotary kilns are very robust and versatile reactors and can be used on solar towers to perform high-temperature endothermic thermal decomposition reactions of solid materials with the aid of concentrated solar irradiation. Their easy functioning system allows flexibility with respect to a wide range of operating conditions, such as particle size, r...

Ammonia is one of the most-produced chemicals in the world. It is applied in the fertilizer industry, and nitrogen fertilizers are a necessity to feed the world's growing population. Due to the high energy demand of the Haber- Bosch ammonia synthesis process, and due to the energy-intensive production of its precursors hydrogen and nitrogen, this p...

The recently demonstrated potential of centrifugal particle receivers to provide hot particle streams of temperatures above 950°C as heat transfer fluid and solar energy storage material in the form of sensible heat opens new possibilities in performing endothermic chemical reactions that take place below this temperature in solar tower plants. Of...

Ammonia is one of the most-produced chemicals in the world. It is applied in the fertilizer industry, and nitrogen fertilizers are a necessity to feed the world's growing population. Due to the high energy demand of the Haber- Bosch ammonia synthesis process, and due to the energy-intensive production of its precursors hydrogen and nitrogen, this p...

The recently demonstrated potential of centrifugal particle receivers to provide hot particle streams of temperatures above 950°C as heat transfer fluid and solar energy storage material in the form of sensible heat opens new possibilities in performing endothermic chemical reactions that take place below this temperature in solar tower plants. Of...

Research on the combination of a PSA with a thermochemical cycle for pure nitrogen production.

The contractual objective to limit the global temperature rise well below 2°C represents a milestone in international climate policy and requires the timely development of strategies that provide solutions to how effective energy-saving pathways can be realized. The defossilisation of the energy system plays a key role here. But the transport secto...

In many concepts for the solar thermochemical production of fuels in a large scale, it is planned to place an array of receiver-reactors on a single solar tower. We investigate how each of these reactors needs to be operated and how the available power of the heliostat field should be distributed to the respective receiver-reactors to obtain maximu...

The transition towards a renewable energy-based society is challenged by spatial and temporal imbalances of energy demand and supply. Storage properties and versatility may favor hydrogen to serve as the linking element between renewable energy generation and a variety of sector coupling options. This paper examines four alternative solar-based hyd...