Wind at Norway’s fixed-bottom wind site found superior to area for floating variety

According to weather data compiled by Norwegian energy officials, floating installations at Utsira Nord will have to settle for 10.7% less wind than the cheaper fixed-bottom installations at Sørlige Nordsjø II.
Photo: Norwea
Photo: Norwea

As part of the efforts to draw up better models for analyzing the power grid, the Norwegian Water Resources and Energy Directorate (NVE) has compiled an updated set of data (link in Norwegian) which includes weather data in Norway, the Nordic region and parts of Europe. This data set also encompasses weather conditions on an hourly basis for offshore wind sites Sørlige Nordsjø II and Utsira Nord dating back from 1951 until 2020.

EnergyWatch has analyzed NVE’s data and looked into how much wind power can be produced at offshore farms of 1.5GW using undersea cables with a capacity of 1.4GW. It turns out that Sørlige Nordsjø II is favored by better wind conditions through and through, resulting in a 10.7% higher projected power output than at Utsira Nord.

Least windy where offshore wind is most expensive

This is striking because Utsira Nord is too deep for fixed-bottom offshore wind, thus requiring floating installations significantly more costly than the fixed-bottom sort to be set up at Sørlige Nordsjø II.

In the energy report released by the Norwegian government, NVE estimates that fixed-bottom installations at Sørlige Nordsjø II would have levelized costs of electricity of NOK 0.78 per kWh (approx. EUR 78 per MWh), while costs related to Utsira Nord are estimated at NOK 1.35 per kWh (approx. EUR 135 per MWh).

”There are many conditions aside from wind speeds that affect production costs and opportunities for an offshore wind expansion,” says head of the Norwegian Wind Energy Association (NORWEA) Øistein Schmidt Galaaen.

He points out that the distance from land, sea floor conditions and sea depth are vital aspects, adding that authorities have also taken environmental and public interests into account when designating Utsira Nord as well suited for a floating wind venture at sea.

The distance from shore is a particularly important element in this context. Utsira Nord is located so close to land that it can be set up using alternating current cables, which makes it redundant to construct an expensive platform equipped with a direct current converter. However, this is needed for Nordsjø II with a distance of around 200 km from the site to the shore. This requires an high-voltage DC connector and a quite expensive additional platform to convert power from AC to DC before transmitting power ashore.

”Sørlige Nordsjø II is located, as is often pointed out, far from shore, and full utilization of the site must be seen in the context of a meshed network,” says Schmidt Galaaen.

Strategic bet on floating installations

Fixed-bottom wind installations are a far more mature technology than the floating variety, which is also why NORWEA finds that the allocated area must be viewed in light of the authorities’ wish to develop floating offshore wind as a priority area for Norway.

”Floating offshore wind at Utsira Nord could play an important strategic role in the industrialization of the technology and contribute to further developing Norway’s competitive edge,” says Schmidt Galaaen.

This is also evident in the government’s plans for Utsira Nord. It aims to divide the site into several sections, with some of them smaller and better suited for various types of pilot projects. However, the hearing on how to parcel out the areas showed that players disagree on how to do so.

For instance, Equinor contends that now is the time for large floating offshore wind farms, and they have previously told EnergyWatch that each site must come with a capacity of 500MW. Preferably, the company hopes to move directly from the 88MW Hywind Tampen wind farm to GW-sized projects.

NORWEA agrees that large sites are important now, arguing that Utsira Nord is an important step in that direction. Galaaen points out that the short distance to shore awards an important contribution as far as keeping down costs related to the first site for floating installations, but he expects that there will be additional areas with much longer distance to the shore.

”For industrializing offshore wind, scale and volume are the most vital objectives, and Utsira Nord can play a key role in that regard. In terms of the build-out and cost, it’s obviously an advantage that the distance to the shore is relatively short, but one of the advantages for floating offshore wind is that it can be set up in many places,” says Schmidt Galaaen.

Norway needs both floating and fixed-bottom installations

So far, Norway has opened up two areas for offshore wind, but has previously identified 15 potential sites. NVE is currently assessing these and other areas for future projects. Asked whether NVE should prioritize areas best suited for floating installations rather than bottom-fixed installations, NORWEA makes it clear that Norway needs both.

”Norway has a particular interest in developing floating offshore wind, not least because we have many deep sea areas. Opening up areas occurs from a long-term perspective, and NVE must look broadly at areas, which rank high in terms of coexistence and environment, market-related conditions such as wind speeds and proximity to high-consumption area nationally and offshore wind network initiatives internationally. Based on such assessment, both floating and fixed-bottom will most likely be relevant, says Schmidt Galaaen.

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