Test Field for Electrolyzers and Hybrid Power Plants

Why we think of wind energy and hydrogen together

Fraunhofer IWES contributes to making wind energy production more cost-effective, for example by increasing system availability, improving efficiency and reducing costs. At present, when there is a temporary excess supply of renewable energies in the network, wind turbines are powered down in many cases so as not to overload the grid. This “surplus electricity” is then subsequently no longer available for power production, which puts pressure on cost-efficiency and is also not conducive to improving public acceptance.

Green hydrogen offers a solution to avoiding energy losses by serving as a molecular energy store. It is transportable, has a wide range of uses and can be ultimately converted back into energy through combustion. The spectrum of possible applications is extremely broad and extends beyond industry and sector boundaries. In each area of application, there are also competing products with different market prices, so the extent to which the use of hydrogen makes good economic sense must be considered individually for each specific application.

According to the Federal Ministry for Economic Affairs and Energy´s (BMWi) draft for a national hydrogen strategy, a production potential of 3 GW – ideally 5 GW – of electrolysis capacity should be established in Germany by the year 2030. The use of offshore wind energy is explicitly intended as a possible and attractive technology for the production of green hydrogen in the near future. In light of poor acceptance of the technology on the mainland, the expansion of the offshore wind energy sector offers one option for achieving the politically defined climate targets. In contrast to when imported hydrogen is used, the value creation would occur here and facilitate production under controlled conditions. At present, 90% of the hydrogen produced in Germany is still “gray”, meaning it is produced from natural gas and thus causes emissions.

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Electrolyzer test field

 

With the aim of systematically comparing the methods of hydrogen production, Fraunhofer IWES is constructing a PEM and an alkaline electrolysis unit in the scope of the “Green Hydrogen for Bremerhaven” project. Once complete, the electrolysis unit, initially planned at 2 MW, will work in full-load operation to produce around 1 ton of hydrogen/day in addition to oxygen and waste heat and will be operated by the research partners’ operating company. Additional areas for the connection of electrolyzers are available for interested industrial companies.
The construction of a test field is being financed with funds from the European Union (EFRE) and the State of Bremen.

 

Safe storage, efficient transport


Hydrogen is a highly reactive gas. LOHC (liquid organic hydrogen carrier) technology has already been explored for many years for the long-term storage as well as the safe and space-saving transport of hydrogen over large distances. The hydrogen is bound by a liquid organic carrier (e.g., dibenzyltoluene) and is therefore hardly inflammable and not explosive. Great potential for the technology is seen in the maritime segment especially: maritime navigation, inland navigation and ferries could all benefit from it. It is planned to set up a hydrogenation and dehydrogenation unit on the electrolyser test field to gain experience with it.

 

Electrical properties of electrolyzers


The connection of the electrolyzer test field to the Fraunhofer Dynamic Nacelle Testing Laboratory (DyNaLab), the leading facility for the grid-integration testing of wind turbines, produces wide-reaching synergies: a 44 MVA virtual electricity network is used to determine what effects the connection of multiple decentralized generation units (electrolyzers) has and how they could have a stabilizing effect on the grid.

The local energy systems must display suitable dynamic properties in order to ensure stable operation of the public mains supply. This depends upon both the hardware components (electrolyzers) and coordinated control and automation technology.

Today’s public power supply grid is designed for simple parallel operation of generation units in strong networks. Here, there is considerable potential for optimization, as the increasing quantity of electricity from renewable sources and the increase in decentralized generation units pose new questions for grid operators. The development of innovative testing methods by Fraunhofer IWES contributes to keeping expansion costs low and ensuring security of energy supply.

There is great interest worldwide in standardized testing procedures for the electrical properties of power generation units (PGU). Fraunhofer IWES’ active involvement in national and international standardization committees will impart transparency and reliability into the development of compliant testing methods from an early stage. Participation in the design of future grid-connection guidelines allows us to consider and further develop scenarios as well as to offer manufacturers sound advice and support when developing new models.

 

Hybrid power plant

The term hybrid power plant refers among other things to a power plant combining at least two different types of power generation to attain a higher level of efficiency. In the simple version, this is the combination of a wind turbine and electrolyzer; the advanced version additionally includes a fuel cell, which can also reconvert the hydrogen if required. This contributes to the increased flexibility of the entire system.

In the “Green Hydrogen for Bremerhaven” research project, the Fraunhofer IWES is investigating how the operation of all the components of the hybrid power plant can be optimized and developing control systems for monitoring of the measurement data of wind turbines and ensuring the highest possible availability.

 

Cooperation with HAW/CC4E

Together with the Competence Center for Renewable Energies and Energy Efficiency (CC4E) at Hamburg University of Applied Sciences (HAW), Fraunhofer IWES is investigating systematic aspects of the production of green hydrogen via electrolysis. The focus is on system-related observations, in particular on technical reliability and the improvement of efficiency factors, system time constants, and cost models. The database for these analyses is prepared using measurements from MW electrolyzers and test fields in Hamburg-Bergedorf and Bremerhaven as well as data from ongoing projects and industry partners. The aim is to compile a data pool on hydrogen-producing technologies.

 

Virtual test benches for large generation units

 

For wind turbine manufacturers, determination of the electrical properties of the individual turbine is still decisive for their type certification; for wind farm developers and operators, in contrast, it is the electrical properties of the wind farm as a whole which are most relevant. However, direct validation in the classic way (field test, wind turbine system test bench) is no longer possible.

The increased demand for the validation of the electrical properties of ever-larger generation/consumption units requires a change of thinking: the electrical properties and functions are described per component with the help of EMT models. This results in component models which can be assembled to form a complete model in the next step. Test scenarios are then simulated at local energy system level (virtual test), the results of which describe the electrical properties. The validity and accuracy of individual EMT models is verified in a special test bench test.

 

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