The rise of offshore hydrogen production at scale

The stage is set for producing green hydrogen from offshore wind and desalinated seawater. Building on existing and proven technology, offshore wind farms have the potential to become future production hubs for green hydrogen production at scale to meet increasing demand.

The potential for Power-to-X (P2X) and offshore hydrogen production is significant - but realising this potential is not without its challenges. How can we scale this new technology and still make it safe and profitable?

One corner stone is building on years of knowledge and expertise. Let’s explore some key technical and economic considerations.

According to the International Energy Agency (IEA), total offshore wind capacity is forecast to more than triple by 2026, reaching close to 120 GW.

Not unlike the early years of offshore wind, we’re now standing on the cusp of a new era of offshore hydrogen production of industrial volumes.

While it took decades for wind and solar to achieve grid parity with fossil fuels, green hydrogen needs to be cost-competitive with ‘grey’ hydrogen within a decade.

Revolutionising offshore wind-to-hydrogen systems

The ambition is set – and offshore hydrogen is expected to support mainstream production at scale in three main areas:

Enable more and better wind sites, possibly by operating in island-mode in which turbines are independent of grid connection
Maximise amount of wind power converted to hydrogen through reducing transmission losses
And reduce costs by modularisation and upscaling.

As we are still in the early stages of commercial offshore hydrogen production, success post-2025 will depend on several factors.

One of the largest hurdles remains cost. BloombergNEF estimates that a mid-range price for offshore wind-to-hydrogen will be around $7/kg in 2025, dropping to $1/kg by 2050.

Key components of offshore hydrogen production

When designing concepts for offshore hydrogen, the ‘green’ in green hydrogen production is a result of using an electrolyser powered by renewable wind energy to split the hydrogen from desalinated seawater. Simplified, this requires:

Offshore renewable energy
Water electrolysis
Offshore platform
Transport
Onshore facilities

An abundance of project design choices

When considering and investigating your offshore hydrogen concepts, an abundance of design choices and configurations exist. Naturally, they should always be defined and adapted to reach the optimal solution for each unique offshore project. Here, we focus on three common approaches:

A. Offshore wind + onshore electrolyser

Electricity is transmitted by a subsea cable to an onshore electrolyser, where hydrogen is produced on land.

B. Offshore wind + offshore electrolyser on a central platform

Hydrogen is produced offshore and transported to shore through a dedicated pipeline.

C. Offshore wind + offshore electrolyser integrated in each wind turbine

An electrolyser installed and fully integrated into a platform at the base of an offshore wind turbine produces hydrogen, which is then transported to shore through a dedicated pipeline.

Electrolysers for full-scale systems in offshore conditions

As described above, the location and capacity of the electrolysers are two important factors when deciding your project design.

Electrolysis is a well-known and thoroughly tested technology. However, to achieve scale and drive costs down, it will be important to have more powerful and efficient electrolysers - not only for offshore hydrogen but for the entire hydrogen spectrum.

For now, projects using onshore rather than offshore electrolysers tend to be less expensive - but as production scales, this is expected to shift past 2030 (source: BloombergNEF).

Many of today’s largest commercial electrolyser units have power limits of 5 MW. In the coming years, it is expected to grow to 10 MW. This is not insignificant given that less than a decade ago “big” was measured in kilowatt.

But for hydrogen from offshore wind, even 10 MW electrolysers won’t be enough. For this reason, modular approaches have been introduced where you group electrolysers together – such as using 100 pcs. of 5 MW units. For offshore constructions, this calls for more compact solutions with a reduced footprint, lower weight, and solutions optimised for operating efficiently under harsh offshore conditions.

Although often overlooked, it is also critical to consider operations and maintenance. Your offshore hydrogen facility should operate for the next 20-25 years, and an electrolyser unit will typically last 7-10 years. So, in addition to traditional maintenance, during the lifetime of the facility, electrolyser units will need to be replaced once or twice - without impacting operation of the other units in the modular setup.

Power supply – a delicate balance

Another and arguably just as important aspect is access to power supply and maintaining a stable electrical grid. Wind turbines have traditionally been designed to be connected to the grid directly, but as a new development some offshore wind farms for hydrogen production are not intended to be connected to the grid.

In the last 5-8 years, we have developed electrical concepts for both island mode of offshore wind farms as well as off-grid operation of electrolysers far from shore. Test runs on large offshore wind farms in operation have provided valuable knowledge and energy companies are preparing turbines for off-grid operation enabling price-competitive production of offshore hydrogen.

Can we leverage existing offshore platforms and infrastructure?

Building offshore platforms has been tried and tested for decades in both offshore wind and oil and gas. With the right expertise, several well-known elements can be adapted and retrofitted to offshore hydrogen production.

To transport and distribute the energy to end-users, there is currently no dedicated hydrogen grid network similar to that of natural gas and electricity. However, it is possible to retrofit and upgrade existing gas pipelines to transport hydrogen, which can contribute to solving a key constraint in its development.

This requires attention to differences between natural gas and hydrogen. Hydrogen molecules are considerably smaller than the main component of natural gas, methane. Therefore, it will be important to perform an integrity assessment and requalification of existing pipelines to identify potential risks of leakage, loss of integrity, and safety challenges.

Building offshore hydrogen on existing knowledge

At Ramboll, we have a long history within offshore wind – dating back to 1989 - and over four decades of experience in offshore platforms, structures, substations designs, and pipelines. Working on hundreds of projects have taught us that having the right team of experts ask the right questions is key – this is especially true when venturing into unchartered waters.

We believe that innovation drives success. Over the years, we have built successful partnerships to pioneer innovations, and we continue to do so in advancing Power-to-X and green hydrogen.

We use our experience and combine key disciplines to best consult you and your organisation in successful and profitable offshore hydrogen projects.

Did you know

...that more than 50% of all offshore wind substructures globally are designed by Ramboll?