Equinor announced this week the opening of the Hywind Tampen wind farm that was built to help power some of its offshore oil and gas platforms.
With a capacity of 88 MW, the 11-turbine project stands out as Norway’s first offshore wind installation and also the world’s largest to employ the floating concept. Equinor is also hoping that the new floating asset becomes a template for future wind projects in the deepwater where there are just a small handful.
Located almost 140 km offshore Norway, each of the 8-MW turbines are installed in depths ranging from 260 to 300 m. The turbines have been operational since November but Equinor said they achieved full capacity for this first time this month.
The newly minted wind farm is expected to replace about a third of the gas-generated power used at five of Equinor’s platforms in the Snorre and Gullfaks oil and gas fields. The Norwegian oil and gas company added that the partial electrification of these fields will offset the equivalent of 200,000 metrics tons of CO2 each year.
The government-backed project was expected to cost about $491 million (5 billion Krones) in 2020, however, the final investment tallied up to $697.5 billion (7.4 billion Krones). Equinor blamed the budget overrun on COVID-19 pandemic-related cost increases and delays.
Despite the financial setbacks, Equinor is expressing optimism that the lessons learned will generate value as the company moves forward with floating wind power generation.
“We will use the experience and learning from this project to become even better. We will build bigger, reduce costs, and build a new industry on the shoulders of the oil and gas industry."
Concrete Innovation
Hywind Tampen is a follow-up to Equinor’s Hywind Scotland which became the first floating wind farm in the world when it started up in 2017. Like its Scottish predecessor, the turbines at Hywind Tampen are installed atop spars which were introduced in the 1990s by the deepwater oil and gas industry.
However, there are some notable differences between the two projects.
Among the most important is the cost of power at Hywind Tampen which Equinor said is about 35% lower on an inflation-adjusted basis than that of Hywind Scotland. A key driver behind the cost improvement was a switch from steel to concrete to build the massive spars.
At this year’s Offshore Technology Conference (OTC) in Houston the oil and gas company shared a number of details about the construction process and how it might improve going forward.
In OTC 32572, authors from the offshore operator and service provider Aker Solutions suggest future construction efforts will be better aided by a purpose-built yard equipped with more cranes; however, the scope of its most recent project—involving only 11 spars—did not justify such an investment. A note in the paper indicates that 30–50 spars (or more) would define large-scale production.
Without such a dedicated site, Equinor had to take a piecemeal approach. This included sourcing the cranes it needed by mooring three conventional offshore work barges next to the site.
Such ad hoc adjustments were dictated by one of the project’s most obvious hurdles, which boiled down to the large size of the spars. Each one measures 18 m in diameter at the base which narrows to 8 m at the top and has a total height of just over 107 m.
The dimensions meant that the construction had to be split between three locations when a single site would have been ideal.
While part of each spar could be built using the slipform construction method in a dry dock, their final completion had to be done at a separate deepwater facility in one of Norway’s fjords where water depths are at least 100 m. The wind turbines themselves were stored and assembled at yet another location.
If larger wind turbines are used in the future, Equinor and Aker noted that the minimum depth requirements may increase to 150 m. However, the authors added that “finding these depths close to shore is a challenge, and onshore crane capacity with reach and load can be a challenge.”
The experience reported by Equinor underlines the wider supply chain issues facing the offshore wind industry.
A new report from Wood Mackenzie estimated that $27 billion in new capital must be spent over the next 3 years to create a supply chain robust enough to support the annual addition of 30 GW of offshore wind power. The international energy consultancy added that only 24 GW of offshore wind projects are slated to come on line between 2025 and 2027, though not all of them have achieved a final investment decision.
For Further Reading
OTC 32572 Serial Production of Floating Wind Concrete Foundations by Erik Stormyr and Nils Smeland, Aker Solutions; Ørjan Rist and Andrea Reali, Equinor.
