Less energy loss on the high seas

04.10.2024

Producing hydrogen offshore is far more efficient than producing it on land. This is the conclusion reached by Fraunhofer scientists in a new study.

The researchers see the proximity to offshore wind turbines as a key advantage of producing hydrogen directly at sea.
This would reduce both energy losses and investments in long electricity transportation routes. The background to the study is the German government's plans to expand offshore wind energy to 70,000 MW by 2035. Innovative solutions for energy generation and storage, such as hydrogen production at sea, are increasingly coming into focus.

The scientists at the Fraunhofer Institute for Energy Economics and Energy System Technology IEE are convinced when presenting the results of their study: offshore hydrogen production not only has technical advantages, but also economic ones. Compared to onshore production, where the green electricity first has to be transported to the mainland, offshore production eliminates many of the costs and energy losses that are unavoidable with long transportation routes.

The study primarily examines two offshore energy islands, each connected to 10,000 MW of offshore wind energy: In one scenario, the electricity generated is converted directly into hydrogen on site; in another scenario, all of the electricity is transmitted to land via high-voltage direct current (HVDC) transmission and used there for electrolysis. The comparison of the two scenarios shows that the offshore production of hydrogen offers clear economic advantages.

The researchers forecast annual savings of up to 4.3 billion euros through the development of offshore hydrogen production. They attribute these savings primarily to lower costs for grid expansion, as the electricity does not have to be transported in large quantities over long distances from the coast to inland.

Instead, the electricity generated at sea can be converted directly into hydrogen on site and then transported, which reduces the cost of new power lines. In addition, more efficient utilization of existing HVDC lines opens up further potential for savings.

Only excess capacity for hydrogen production

Another result of the study is that offshore hydrogen production increases the flexibility of the entire energy system. The two offshore energy islands only have a limited connection to the electricity grid and are around 150 kilometers from the coast. This limited connection is made via offshore converter platforms, which also connect other wind farms to the power grid. This means that the electricity generated by the wind turbines on the islands can only be fed into the grid when there is free capacity. Otherwise, the electricity is converted into hydrogen on site.

According to the researchers, this approach allows operators to use the electricity flexibly depending on the market situation, which in turn leads to better integration of renewable energies into the overall system.

The study also emphasizes that in times of low electricity prices and a high supply of renewable energy, the electricity is converted directly into hydrogen on site. In times of low supply of renewables and higher electricity prices, however, the electricity generated on the offshore wind farms can be used to cover the electricity demand on the mainland. According to Fraunhofer, this flexible approach has positive system effects. It not only reduces costs, but also increases the security of supply in the German power grid.

The study wascarried outon behalf of the Danish offshore renewables project developer "Copenhagen Energy Islands ApS". The 32-page study "German offshore energy islands in the European energy system" can be downloaded from the Fraunhofer IEE website.

Author: Davina Spohn
Source: Energy & Management Powernews