Governors' Wind Energy Coalition

Consumers stand to win in the race to build larger offshore wind turbines, new research shows.

The Block Island wind farm, from Montauk Point, on Long Island, New York on April 16, 2021. Credit: Mark Harrington/Newsday RM via Getty Images

Five years ago, when workers off of Rhode Island installed the first offshore wind farm in the United States, the 6-megawatt turbines were almost disorienting in their size, nearly double the height of the Statue of Liberty and its base.

But big keeps getting bigger.

Last month, GE Renewable Energy said it has begun operating a prototype of a 14-megawatt offshore wind turbine, nearly three times the height of the Statue of Liberty and its base, in the waters off Rotterdam in the Netherlands.

Siemens Gamesa and Vestas, two other leading turbine manufacturers, are developing 15-megawatt models. The growth will continue, with companies and analysts saying that a 20-megawatt turbine is within reach.

This race to build bigger turbines has a practical purpose. As turbines get taller and increase their generating capacity, they become more efficient and their electricity becomes cheaper for consumers.

A recent paper, published in the journal Applied Energy, shows the scale of the savings with a level of detail that was not previously available. The research, by the National Renewable Energy Laboratory, shows a 24 percent savings per unit of electricity for a hypothetical wind farm using 20-megawatt offshore wind turbines, compared to a wind farm using 6-megawatt turbines.

The decrease in costs is a big deal, to the point that it makes offshore wind competitive with the costs of electricity from natural gas power plants. (Onshore wind and solar are still cheaper than all other alternatives).

“A 20 percent change is significant, it’s very significant,” said Matt Shields, an engineer at the energy lab and lead author of the report.

For context, he noted that savings of 1 or 2 percent can sometimes be the difference that makes a project financially viable for developers.

Shields told me he was surprised by the extent of the savings. The findings are especially significant, he said, because they don’t take into account non-financial benefits of offshore wind, such as the climate benefits of clean energy and the fact that offshore wind farms can be built close to major population centers.

In states, like New Jersey and Virginia, that have laws requiring the construction of offshore wind, this research shows the policies can be achieved affordably. The same is true for national goals, like the Biden administration’s target of building 30 gigawatts of offshore wind by 2030.

The paper’s authors created a model of the costs and electricity output of two wind farms:

• One wind farm uses 6-megawatt turbines and has 500 megawatts of capacity. It would cost more than $1 billion to build.
• The other wind farm uses 20-megawatt turbines and has 2,500 megawatts of capacity. It would cost more than $5 billion to build.

The bigger one has a larger up-front cost, and it costs more to maintain on an annual basis, but it generates much more electricity and does so more efficiently than its smaller counterpart. The result is that the larger wind farm has a big advantage when measured in terms of its cost per unit of electricity.

The “levelized cost” of the large wind farm—which takes into account construction and operation expenses—is $53.30 per megawatt-hour, while the smaller wind farm has a levelized cost of $69.80 per megawatt-hour.

Shields said it is important to note the cost advantages come from economies of scale in both individual turbines and in having a larger capacity for the wind farm as a whole. So bigger is better in multiple ways.

While this 24 percent decrease in costs is a lot, the paper says there are many opportunities to decrease costs even more, by streamlining the process of installing turbines and finding more efficient ways of getting electricity from the turbines to the shore, among other changes.

Shields said the potential for additional cost reduction is one of the most encouraging aspects of his research.

“It gives us an indication of where we need to go next and what other innovation is needed,” he said.

But it’s important to note that 20-megawatt wind turbines don’t yet exist, partly because the industry hasn’t yet figured out how to build, deliver and assemble such large parts.

Also, the U.S. offshore wind industry doesn’t yet exist yet in any substantial form. It has mostly consisted of major announcements about projects that still need regulatory approvals and wouldn’t begin construction for years. The 30-megawatt Block Island Wind Farm remains the largest in the country.

The next big thing is Vineyard Wind 1, the 800-megawatt wind farm off of Massachusetts that is set to begin onshore assembly work this year with offshore assembly work to follow in 2022. The project will be using 13-megawatt turbines from GE Renewable Energy.

So if you’re looking for a tangible sign that the potential described by Shields might be realized, be on the lookout for some very large machines being erected south of Martha’s Vineyard.