Three Design Concepts Put Green Hydrogen Production Offshore
Many hurdles for marinization of green hydrogen production already have been overcome in the offshore oil and wind sectors. A fresh set of challenges, however, will rise around developing and deploying hydrogen production facilities offshore.
Offshore hydrogen production has the potential to gather momentum in the next half decade.
Albeit a relatively new concept, we are today in a position to draw useful parallels from the oil and gas and offshore wind sectors—experiences that serve to fast-track offshore hydrogen production from idea to widespread reality.
Indeed, many of the critical hurdles with marinization have been overcome in the offshore oil and wind sectors, and the offshore industry as a whole has valuable lessons in marinization of equipment through the adaptation of hydrocarbon and wind applications.
A fresh set of challenges, however, will rise around developing and deploying hydrogen production facilities offshore.
The large physical scale of hydrogen production facilities, for example, presents an issue to overcome. Here, maximizing limited space will be vital if offshore hydrogen production is to be successful.
Environmental factors also will come into play so that any such facility is capable of standing up to regional-dependent conditions such as extreme winds and waves. Influences such as these can play a major role in determining a structure’s size, shape, and mooring arrangements.
For green hydrogen to work, access to renewable energy must be provided. Yet the proximity to this energy again needs to be evaluated. While a facility close to a windfarm may reduce power transmission losses, it could require longer pipelines for exporting any hydrogen produced to the shore.
Despite a variety of factors and considerations involved, several concepts for offshore green hydrogen production facilities have already been proposed.
For ease, these can be broadly grouped into three design categories by the relative locations of the electrolyzer to the renewable energy source and ocean—the critical component in achieving electrolysis that enables hydrogen production.
Electrolyzer Directly Incorporated Into the Structure of the Renewable Energy Source
The first proposal that could be applicable is with offshore wind farms, where the electrolyzer is directly integrated into the turbine structure.
This would see electricity produced by the turbine being directed to the electrolyzer where hydrogen would then be produced before being delivered to a collection manifold. Here, the gas would be compressed to the desired pressure and exported to the shore via pipelines.
Modifications may be needed to ensure that the wind turbine could accommodate the additional machinery, and pipelines would need to be laid.
Electrolyzer Located Above Water on a Platform
The second option entails the use of a platform with one centralized electrolyzer system.
This design works well with existing wind farms and other renewable energy sources because it requires very few, if any, modifications to the existing wind turbine infrastructure. Further, after incorporating the production platform into the system and on the commencement of delivering power to shore, the platform is largely independent. As hydrogen is produced, it is again compressed, then either immediately exported or compressed again and refrigerated for storage.
Retrofitting existing offshore assets such as platforms and pipelines may be possible to reduce the capital expenditure of a project.
Electrolyzer Located on the Seabed
The third option places the entire centralized electrolyzer system on the seabed—a possible alternative in areas where surface-based operations are not feasible.
This design reduces the power lost to pumping electrolyzer feed water in surface designs and negates any weather-related effects that surface designs may face, but it does add complexity and additional construction and maintenance costs to the project.