Dr. Rebecca Barthelmie: Offshore wind energy
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The first commercial-scale offshore wind farm in the United States will begin delivering power in 2023, off the coast of Massachusetts. And in December, the United States auctioned off the first-ever commercial leases to develop “floating” wind farm sites, in deep water off the California coast. More sites and auctions are expected to follow in Oregon, the Gulf of Maine, and elsewhere.
On Wednesday, February 1, 2023, SciLine interviewed: Dr. Rebecca Barthelmie, a professor of mechanical and aerospace engineering at Cornell University and chief editor of the scientific journals Wind Energy, Wind Energy Science, and Energies. She discussed topics including: where offshore wind sites and development projects are in the United States; the pros and cons of “floating” offshore wind platforms in deeper waters; the role of offshore wind in meeting U.S. electricity demand; how offshore wind could help the U.S. meet its goals to reduce greenhouse gas emissions; and the environmental impacts of offshore wind development.
REBECCA BARTHELMIE: My name is Rebecca Barthelmie. I’m a professor in the Sibley School of Mechanical and Aerospace Engineering at Cornell University. And I study offshore wind energy. But the particular aspect of that is I look at the layout of individual turbines within wind farms and how wind farms should be arranged relative to each other to maximize the energy production.
Interview with SciLine
What is the landscape of offshore wind sites and development projects in the United States?
REBECCA BARTHELMIE: It’s a very rapidly evolving landscape, as you know. Right now, what we have in terms of wind turbines in the water is just seven, which is very few. What we’re aiming for by 2030 is to have about 2,000. So, you can see it’s really an incredible moment of growth for offshore wind energy in the United States. So, we’re aiming to get up to the point in 2030, where we have 30 gigawatts of wind energy installed offshore in the U.S. That’s less than we have currently on land, but it’s still a big transition. And if we manage that, we’ll be able to power about 15 million homes by 2030. You know, we get to the point we expect to be out by 2050, we’ll have 86 gigawatts of installed offshore wind energy, enough for about 43 million homes. So, it’s a very ambitious plan. So, this really touches everywhere in the U.S. that’s offshore.
So, there are about 30 projects running along the East Coast all the way from Maine, all the way down to the Carolinas. And obviously, those projects are in various states of development. We actually have two projects that are under construction already, that we have—the rest that are in various permitting processes—and a very long process to develop an offshore wind farm. And that’s managed by our Department of Interior Bureau of Ocean Energy Management that manages the leasing and deciding which areas are appropriate for wind energy, and then helping those developments through all of the permitting. So, it’s very busy, I think you could say.
Not that the rest of the states should feel left out. We have—just in the last month or two, we’d have to wind energy development areas that have been declared by BOEM for the Gulf of Mexico. And all along the West Coast, the same idea where we have projects that are going to be developed, most likely—they’re not quite so far forward as the East Coast, for the simple fact that we’re dealing with very, very deep water. So, we need a different technology for those West Coast states. But California has a very ambitious plan, the most ambitious plan of any state, offshore wind energy, we have Hawaii in there as well. So, every state has some kind of activity, whether it’s monitoring and research—there’s activity everywhere.
What are “floating” offshore wind platforms in deeper waters—and how are they different from those in shallower waters?
REBECCA BARTHELMIE: The technology is fundamentally different. So for most of the East Coast sites that are currently proposed, they are in water depths that are broadly speaking 60 meters of water—or a little bit less. And that means that we can use fixed-bottom foundations, which we know very well how they work from a lot of development in Europe in particular, but also in Asia. So, most of those, the majority of them are monopile. So, they’re just like big steel tubes. And we use pile drivers to ram them into the seabed. And those are cost effective and kind of technology effective. If we have—I wouldn’t say that’s shallow water, but from this perspective it is. So, those we know really well.
But for most of the U.S. resource about two thirds of it is in deeper water where we’re going to need floating wind turbines. And that requires a different technology. And there’s several technologies under development for floating, so that maybe you could even say they’re broadly two types, one where we have the turbines anchored to the seabed, but with mooring lines that are not tight. And then kind of the opposite of that is to have those lines be actually tight. So, we kind of—we keep tension in them. And there are actually several different designs then for the platforms that float. And so, what we’re doing at the moment, I think, is trying to understand for different environments, which is the best technology. And that’s going to just take a little bit of time for us to figure it out. So, there won’t be one solution for this. I don’t think—it’s going to kind of depend a bit where we are. And it’s very, very deep water off the West Coast, as you know, and we’re looking at some places with water depths of 1,000 meters. And that’s much deeper than we have developed so far. We have floating wind farms in Scotland, we have one in Norway, we have some in Asia, but they don’t tend to be in such deep water. So, it’s going to be some, some more research to be done there.
What is the role of offshore wind in meeting U.S. electricity demand?
REBECCA BARTHELMIE: Well, actually, it’s limitless, honestly. I mean, if you went on developing, there’s more than enough offshore wind resource to cover the whole electricity demands several times over. But, practically speaking, you know, we’re talking about ramping up offshore wind. So, the onshore wind energy that we have already in the United States meets around 9% of our electricity demand. And our plan, of course, is to move towards net zero by 2050. So, we’ve got quite a long way to go because fossil fuels still dominate our electricity production. But on the other hand, we can ramp these productions up fairly quickly. So, by 2030, if we meet the goals that the administration has set—of having 30 gigawatts there —we’ll only have a few percent of electricity coming from offshore wind. But if we get to 86 gigawatts, then we’ll be at 7% of our electricity coming from offshore wind. And that is a very significant contribution when you count it with the other sources of sustainable electricity that will be developed. So, as I say, we’ll continue to develop onshore wind, we’ll have hydro as we do already, we’re already meeting 20, more than 20% of our electricity needs from all of the renewables together. And I think that’s what it’s telling you is that each of these has a part to play—just like offshore wind energy will have its part but it’s unlikely to be the whole of our electricity demand.
How could offshore wind help the U.S. meet its goal to reduce greenhouse gas emissions?
REBECCA BARTHELMIE: Offshore wind energy is broadly cost effective. It’s not quite as inexpensive as onshore wind energy, but it’s getting there. So, probably in the next tranche, it will become competitive even with the cheapest fossil fuels, and probably won’t get down to quite the level of onshore wind and solar. But it’s still going to be relatively cost effective. So, that’s kind of the first move because obviously, everyone wants the price of electricity to stay about the same as we move into more sustainable electricity generation sources. But onshore wind and offshore wind together are going to have a huge impact. So, you know, the more we develop, obviously, the closer we can get to our climate goals. But if we’re really going to get to net zero by 2050, we do have to ramp up the deployment of all the renewable and electricity generating sources.
What are the environmental impacts of offshore wind development?
REBECCA BARTHELMIE: The good news is that we don’t anticipate any major impact, if we’re fairly careful with the siting. And you know, this is quite common sense. We want to avoid really big bird migration routes. We want to you avoid duck nesting areas, and you know, areas that we know are heavily used. But for the most part, we can see, if we use radar that birds actually avoid offshore wind farms, depending on the species. So, if you look at the radar images, they’re really interesting, because you can see the bird flocks approaching a wind farm and then either going round them, because remember these have big spaces in between. The spacing in between turbines that’s been proposed for the U.S. is 1.8 kilometers, you know—it’s a nautical mile. So, it’s a really big space. So, birds could go in between, but for the most part, they seem to go round or up and over the wind farms. So, if we have good visibility, birds can easily avoid offshore wind farms. And I think there’s a lot of careful research going on, but there’s nothing so far to be really concerned about. And there are a few exceptions still that we still have to think about. So, we have to think about—especially for the U.S.—we have to think about the whale populations and how they interact.
And in terms of floating there’s still some work to think about there. What do floating wind farms mean for marine mammals in particular. So, what we generally see is, as when wind farms are being built, there’s quite a lot of noise. It’s a noisy construction, and you can’t really avoid that, especially if you use monopiles, where as I said, you’re using a pile driver. But after construction is finished, we see mammals and other activity coming back to the site, and we see, generally offshore wind forms acting like artificial reefs, so they’re quite good areas for different kinds of fish and other marine activity.
Is the regulatory landscape around offshore wind in the U.S. changing? If so, how?
REBECCA BARTHELMIE: The major part falls to BOEM, this Bureau of Ocean Energy Management. They recently—actually the Department of the Interior has split off part of the activity to, I can’t remember what it stands for. It’s like the bureau of safety and something, BSEE. So, they will now be dealing with some of the work that BOEM was doing. So, I think there’s a move to try and make this much more straightforward, because we’ve seen, you know, some of the wind farms that have been constructed—now we’ve been eight years in development, you know. So, we need to try and think about how do we make this process a little bit more straightforward. And that’s happening from the administration. I think there’s a recognition there. I mean, on the other hand, you know, there’s many, many agencies involved, so BOEM has the oversight.
But states have a role also in terms of deciding where they would like to encourage port development and other economic activity relating to offshore wind farm development. You know, they have a role in thinking about how much renewable electricity would they like to buy. How will they meet their renewable energy standards. So, it’s a lot of activity also from the states. And once we get into construction, there’s many, many more agencies involved. They took about up to 35 agencies, different agencies, depending on the state, because not only is offshore wind, it’s different state by state. The regulations are different state by state, and it does make it very, very complicated for developers to navigate this.
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[Posted February 1, 2023 | Download video]