Super-Sized Turbines and Offshore Wind Farms Bring ‘Game-Changing’ Cost Cuts – NREL

Larger wind turbines and larger offshore wind projects alone can reduce a wind farm’s Levelised Cost of Energy (LCoE) by more than 23 per cent relative to the average fixed-bottom offshore wind farm installed in 2019, according to the research carried out by the US Department of Energy’s National Renewable Energy Laboratory (NREL).

Researchers from NREL conducted one of the most comprehensive analyses currently available of the average cost per megawatt-hour to develop and maintain offshore wind farms and how those costs could change if current trends toward larger wind farms and turbines continue.

To do that, the team combined three models to compare the cost of a representative 2019 fixed-bottom offshore wind farm, which used one hundred 6 MW wind turbines for a total capacity of 600 MW, with various wind turbine and wind farm sizes – up to a maximum of 20 MW wind turbines with a plant capacity of 2,500 MW.

The models showed that scaling up both wind turbine and wind farm size can reduce balance-of-system and maintenance costs through economies of scale (e.g., spreading export cable costs over larger projects) while reducing losses from wakes. Wakes, turbine-made turbulence that can decrease power production of downstream turbines, decline as turbines are spaced further apart in larger and larger wind plants. Combined, these savings can add up to more than 23 per cent, according to NREL.

”We expected to see the costs decrease,” said Matt Shields, an NREL researcher who leads the lab’s work on techno-economic analysis of offshore wind energy and headed the study.

”But I was a little surprised about the magnitude. That’s really a game changer.”

The team’s data provide a valuable touchstone, the US DOE said. Now, the growing US offshore wind industry can more confidently invest in the supply chain needed to build bigger turbines and larger projects—a chain that is not yet sufficient to achieve the Biden administration’s goal of deploying 30 GW of offshore wind energy by 2030, the US DOE said.

The study was funded by WETO and coauthored by NREL researchers Philipp Beiter, Jake Nunemaker, Aubryn Cooperman, and Patrick Duffy.

Still, more research is needed to achieve these savings, determine whether and how this reduction applies to floating offshore wind farms, and learn whether the “bigger is better” tenet has a limit. Cost savings could plateau at a maximum wind turbine or power plant size, according to NREL.

Right now, the wind industry can’t achieve that 23 per cent. No manufacturer can build a 20-MW wind turbine – yet.

And even when they can, the rest of the supply chain will need to catch up, too. For example, today’s vessels and ports are designed to install wind turbines of 12 MW or less, NREL said.

However several companies have already ordered, or are about to order, vessels capable of transporting and installing 20 MW wind turbines such as Van Oord, Eneti, and Havfram.

Shields and his team plan to take a closer look at how innovations in technology and the supply chain might help further reduce costs in the future. In the meantime, they are working on creating a supply chain road map to find missing links.

”We need to jump-start the domestic supply chain as quickly as possible to minimize project risks, make projects even cheaper, create local jobs, and grow a more sustainable industry,” said Shields.

”We want to build offshore wind power plants to reduce our carbon footprint, and we can do it in such a way that we are positively impacting local economies.”

The supply chain must grow quickly to meet the United States’ 30-GW-by-2030 goal. And this study can help each link plan for a bigger future, NREL said.

”That’s going to be a huge challenge for us over the next decade,” said Shields. ”But it’s one that’s worth investing in.”