HTCoEl – Compact synthesis gas generation by
high-temperature co-electrolysis

Objective of “HTCoel”

How can aircrafts fly sustainably? How will chemicals be produced without fossil raw materials in the future?
The answers to these questions are Power-to-X processes that use electrolysis to produce syngas from renewable electricity. Syngas is a gas mixture of hydrogen and carbon monoxide, which can be converted in various downstream syntheses into so-called synthetic fuels, such as e-diesel, e-kerosene, or synthetic chemicals, such as e-methanol. Due to high-temperature co-electrolysis, renewable electricity, steam, and carbon dioxide can be directly converted into syngas. Additionally, the economically Power-to-Xtechnology can reduce greenhouse gas emissions from sectors that are hard-to-electrify, such as the chemical industry, as well as air, sea, and heavy goods transport. The core technology of high-temperature co-electrolysis is oxygen-ion-conducting solid oxide cells. In recent years, the cells and stacks have been continuously developed further in order to provide high-temperature co-electrolyzers for the megawatt-scale in the future. In the present project, the aim is to develop and optimize the interconnection of Balance-of-Plant (BoP) components such as heat exchangers, heaters, chemical reactors, and sensor elements in order to achieve the main product goals in terms of cost, durability and operational safety. The high operating temperatures of up to 900 degrees celsius and the corrosive gas atmospheres represent a particular challenge. This way, the project aims to develop and upscale main BoP components and their testing in an optimized hightemperature
co-electrolyzer module.

Efficiency in three steps

The project contains three work packages. In the package “Component development”, a heater, an RWGS reactor, and a heat exchanger are developed, which are necessary for adjusting the temperature and composition of the input and output gases of the process. The main focus is on the resistance of the materials under high temperatures and aggressive media environment as well as on efficient manufacturability. In the package “StackUnit detail development”, electrical feed-throughs, galvanic insulation, and a sensor system for recording the operating status of the stack unit are developed. The challenge here is to find temperature-resistant up to 900 degrees celsius, gas-tight, and cost-effective solutions. In the package “System integration and analysis”, the developed components are tested in a high-temperature coelectrolyzer module, for which an accompanying system simulation is carried out to optimize the operational management.

Academic and economic results

The consortium consists of two companies and three research institutes. Sunfire, as an electrolyzer manufacturer, is the project coordinator and responsible for the definition of requirements as well as for accompanying the development tasks and system integration and testing. Sandvik, as a key supplier of heater technologies, and the DECHEMA Forschungsinstitut are developing the components in the first work package, while the Technical University of Dresden, chair of Hydrogen and Nuclear Energy, is optimizing the gas tightness of electrical feed-throughs and the galvanic separation of stacks in the second work package. The German Aerospace Centre (DLR) e. V., Institute of Engineering Thermodynamics, investigates a high temperature co-electrolyzer module experimentally and carries out the accompanying simulation in the third package. The project’s overall result will be a highly integrated high-temperature co-electrolyzer module, whose industrial, low-cost BoP components are closely integrated with the stack module. This results in a compact system with high efficiency, that can be converted into an industrially competitive product. Also, results on life cycle estimation and tolerance requirements for components used in e-heaters
for superheating gases will be available. Furthermore, the project plans to close the scientific knowledge gap on SOC multi-reactor modules to advance the development of glass and glass-ceramic seals that are stable at high temperatures and to expand the knowledge horizon in the field of high-temperature corrosion.

HTCoEl project sheet download