Eighties Californian Wind Rush to floating Wind Turbines

Walt Musial from US Department of Energy's National Renewable Energy Laboratories tells the story of Wind Energy in the USA, from the 'Wind Rush' of the 1980s, challenges of scaling up, to proposals for huge offshore, floating, wind turbines.

Originally broadcast 091211

Beyond Zero talks to Walt Musial of the National Renewable Energy Laboratories

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Transcript

Scott Bilby:    Hello. Welcome to Beyond Zero. This is Australia’s best global warming solutions show. We cover everything from the latest global warming news and science and community actions from right across the world. We’re broadcast weekly on community radio across Australia. This show is produced by the climate change campaign centre Beyond Zero Emissions. We believe that human caused global warming has already exceeded safe limits and that we must act immediately to reduce our levels of greenhouse gas emissions to zero and below. My name is Scott Bilby, and with me in the studio is Matthew Wright. How are you going Matthew?

Matthew Wright:    Good thank you Scott.

Scott Bilby:    And we have Rosa paneling for us this morning. Now, this morning on Beyond Zero we’re speaking with Dr Walter Musial. He’s the senior engineer for the National Wind Technology Centre at the National Renewable Energy Laboratory in the US. We call them NREL. We’ve interviewed those guys a few times before.

Now, he leads their development testing team and is responsible for all laboratory testing involving wind turbine blades and wind turbine drive trains. He’s also involved with the Ocean Energy Institute, a think tank and venture capital fund raising – fund, I should say – that addresses the challenges of US offshore renewable energy. Thanks for joining us from Colorado in the US. It’s great to have you with us.

OK, and now we usually start off just by asking our guests how they got involved in the renewable energy sector.

Walter Musial:    Oh great. I’ve been involved in the renewable energy sector since I’ve become an engineer. I actually got started in this field many years ago – I’m over 50 right now. But I started studying wind energy back in the 1970s. As you might remember, we had a president here in the US – Jimmy Carter – and it was during the Arab oil embargoes that we were having – worldwide I think – back then, that stimulated a lot of interest in the United States in renewable energy and in the field of wind energy in particular, which I got involved with when I studied at the University of Massachusetts. They happened to offer an energy option, which was in direct response to the energy crisis that was happening in the country at the time. And I – it just sounded like such a good fit for me because I was interested in doing something that hadn’t been done before. And at the time, there were no wind turbines really to speak of in the world, and we were involved in developing the first ones.

Matthew Wright:    They’re the ones in the sort of first wind rush that hit California, are they the ones that you developed?

Walter Musial:    That’s right. Back in – it was – I don’t think that anybody really planned it this way but the wind rush that you speak of started as a direct result of the incentives that started in the United States right at the end of the Carter administration, and before Ronald Reagan came into office. There were very lucrative tax incentives for investment capital and those were combined with state investment capital incentives for the state of California(?) and some – they called them standard offer four contracts(?) – that the utilities in California were offering. And so these three things combined created a very lucrative market situation for wind energy.

And it encouraged a lot of entrepreneurial spirit and innovation where everybody converged in California for a few short years. And so by the end of 1985 – really between 1981 and 1985 – we had 90 per cent of all the wind turbines in the world were located in three sites in California. There were over 10,000 wind turbines installed during that one short period. And that was really the birth of the wind industry, in the whole world.

Matthew Wright:    Now compared to today, they’re really quite small turbines. Could you envisage back then what we’d be using today?

Walter Musial:    Yeah you know, they were small and people felt comfortable making the incremental changes and experimenting with crazy ideas on the size(?) turbines we’re talking about. And they were, you know, small. Just to tell you what small was – 100 kilowatt machines. These small machines had blade lengths that were maybe 20 feet – 25 feet long and – 7 metres long.

That’s what we called small then, and that was a size that would generate electricity – maybe enough for 50 houses or something like that, or even less, but not the size we’re seeing today. But we could envision the larger machines because the government in the US did spend some money before they knew how big was sensible(?). They built very large machines during MOD program – MOD. They had a collaboration with Boeing and NASA and they built some two megawatt sized machines under the MOD 2(?) program. And so we saw these machines and said that’s way too big for us to really think about doing right now because we didn’t know enough about how to make wind turbines work - how to make them stay online and how to keep them in good repair.

And so everybody started small, but with that as an example, it was actually easy for the industry to gradually increase the size of machines until we got, really, back to that size where they are today.

Scott Bilby:    And you’re responsible for lab testing of wind turbine blades and drive trains, and you’ve been in that role for quite a while, so you’ve really seen and been at the forefront of that growth in the size of the wind turbines and the blades et cetera, et cetera.
Walter Musial:    That’s right. I’ve moved on recently into offshore(?) wind and marine energy systems and we’ve been developing those, but I continue to stay abreast of the laboratory testing. I developed all the laboratory testing facilities here at the National Renewable Energy lab in the US. And when we were developing these facilities - these are test facilities to do structural testing on wind turbine blades – and the blade is the part that sticks out from the hub(?), so if you see a three-bladed machine, there’s three blades per turbine. We would test one of those blades in our facility to make sure that it was strong enough to withstand the loads that a wind turbine sees.

And we had – our facilities were constantly being changed and we had to keep building larger and larger facilities in order to keep up with the size growth of the wind energy industry.

Scott Bilby:    So it’s been an exciting technology, and you’re now moving into the offshore wind turbines and talking up the floating turbines as well. So I guess massive load factors there. So I guess all that knowledge you had is going to really serve you well with all those even bigger winds and even bigger currents, and all that sort of stuff, is going to be hitting those blades?

Walter Musial:    Absolutely. Yeah, the offshore machines and offshore deployment is probably the next frontier for wind energy. We’re seeing lots of interest in Europe, lots of deployment starting. The machines for offshore are bigger and the challenges are new. There’s a lot of the same issues that came up, and so it’s very good that we developed land based machines first. But now going offshore there’ll be new challenges and as you mentioned floating systems would be kind of the end game – or the Holy Grail - for wind energy. We’re not there yet - we don’t have that technology ready. But it eventually will get developed and it will become I think an important part of the energy mix, not just with respect to other wind turbines, but respect to energy in general.

Matthew Wright:    Now I notice that what’s commercial now is either a driver pile(?) – a bit like how they make bridges over rivers – they drive a pile(?) in and then put the turbine up, or they have this massive gravity base – a huge lump of concrete or something. Can you tell us a bit about where the costs go up but where there’s savings when you compare offshore wind to onshore wind?

Walter Musial:    Yeah, I mean the foundation is clearly, as you mentioned, one of the big differences between an onshore turbine and an offshore turbine. And it’s not just the foundation itself is more expensive, but I think what drives the cost is the equipment that’s required to actually install those foundations. Because it’s not just the material cost, but it’s the cost of deploying these large vessels that are required to get out there and stay out there during the weather – whatever it may be - and long enough to make the installation. So big challenges developing systems that can minimise the use of the big vessels, and to develop larger machines so that you don’t have to install as many foundations, and so you can save a lot of money in deployment costs that way.

Matthew Wright:    What I was thinking of comparing it to is obviously onshore you’ve got the challenges of actually, with the bigger turbines, you know, there’s now blades that are 50 metres – or 55 metres – long, is actually getting them down roads so that you can deliver them to the site. But my understanding was that with offshore where you could make some savings was in the transportation.

Walter Musial:    Well that’s correct. I’m not sure you’re saving money but you’re actually, on land you just get to the point where you physically can’t ship(?) them, they just can’t be moved across the highway systems that we have because the bridges are too low. And the cranes that are required to install these big heavy components are too small or they take too long to deploy to the sites. I guess you could consider that a cost question on some cases.

But offshore the infrastructure and the equipment that’s traditionally been used for other industries, oil and gas for instance, is much bigger and it is capable of installing much larger things. But it’s expensive and so we want to be able to use it but there’s no limitation to the size, at least in the boundaries that we’ve drawn so far. We can go to machines that are twice as big as the size that’s being deployed on land.

Scott Bilby: Just for the audience, could you basically describe maybe a floating offshore wind turbine platform system, so people can get an idea in their head what they are. I know there’s very many different versions – perhaps the one that you guys are concentrating on, or….

Walter Musial:    ….yeah sure.

Scott Bilby:    …. just so people can visualise it.

Walter Musial: Yeah, so a big challenge for offshore is the water depth, and this is where floating turbines come in. As we get – everything that’s been installed so far has been in Europe first of all. There’s a new project going in in China so – but everything offshore – for offshore wind turbines – everything that’s been installed so far is in shallow water. And by shallow I mean less than 30 metres deep. So when we get into water depths that go beyond that we need new technology. And we’re going to look at all the different types of oil and gas technology that have been deployed before where the foundation it sticks to the bottom.

But you can imagine as that water depth gets deeper, we’re going to get into some very expensive structures. And soon that will become impractical, and we’ll have to go to a system that is floating. That means that we’ll have a blank(?) tank of some kind that is supporting a structure of a wind turbine above the water line. That tank will be moored or anchored to the seabed in some way, much like a boat would be anchored, but it would be a permanently moored system, most likely.
And there are a variety of different types of systems that you could use.

But the key thing in the design – keep in mind there’s only been one installation of a floating wind turbine so far ever deployed in the world – so we’re still learning how to do this, very much so. These turbines have to be very stable. The bases have to be – we want to minimise to as much extent possible the movement that’s caused by the waves hitting these bases, and subsequently the motions that are caused by the turbines themselves, because turbines were not meant to be jarred around by moving bases, and that’s what we’re up against right now with floating systems.

Scott Bilby: Now we’re speaking with Dr Walter Musial, he’s the senior engineer for National Wind Technology at the National Wind Technology Centre at the National Renewable Energy Laboratory in the US. Walter, so you said that there’s bigger savings in having bigger, fewer installations of these, well there would be when we start building them, there’ll be bigger savings in having bigger installations that are fewer way out in the depths and building all these bases, whether they’re floating or not I guess. But doesn’t that contradict - like if you’re out in the ocean, you’ve got all those currents and the waves hitting these things and hitting the platforms. Surely smaller turbines would be better capable of dealing with all that extra stress and stuff like that?

Walter Musial:    Well not really. I think the smaller turbines - relative to the size of the waves that are out there - they would be more likely to be overcome by large waves. And so the larger the structure, the more impervious they are to the extreme waves that might be out there. Much like a large boat would be able to survive better than a small boat in high seas.

Scott Bilby:     And now, you talk about onsite installation – so I was reading somewhere you said that towing these things out – if you can tow – build as much of it onshore as possible and just tow the bits out and plonk them in place. That’s going to be cheaper than trying to do too much kind of installation on site.

Walter Musial:    Yeah….

Scott Bilby:    ….can you just kind of describe that and how you actually tow them out there and all that sort of stuff?

Walter Musial: Yeah so – and I’m not an expert sea construction engineer – but the idea is to do as little work at sea as possible, because everything out at sea gets more expensive, because everything is more difficult, and it takes longer. So the idea would be to do as much of the fully assembled turbine on land as possible and do a load out, and then connecting it to the anchor system once it’s completely assembled. That would be the ideal situation. And then one of the advantages that I point out in, say, a mature floating system industry - if I can create this vision – we have wind farms on land where we have hundreds of machines. Hundreds of wind turbines offshore would mean mass produced facilities – mass produced substructures and turbines that would be a lot easier to plan large operations. Unlike what we’ve seen in the oil and gas industry, where almost every single oil rig that’s ever been built is a custom design for one site. And so this would change. We would have - for floating wind turbines – we would have a mass produced facility where we could load out a hundred machines in one season and deploy them in the same way and save by these economies of scale.

Matthew Wright:    Yeah, fantastic. Now, the original turbines you built versus the ones today have come a long way. For instance, you did talk about the difficulties of shipping around onshore turbines, and we notice that a company from Germany called Enercon have looked at in their big – really big – turbine, looked at dividing their wind blade into two sections.

Walter Musial:    Yes.

Matthew Wright:    Also, there’s a number of different innovations in gearbox technology. Can you tell us a bit about where that sort of technology’s going?

Walter Musial:    Yeah. So, there’s - I don’t think the industry has completely developed the perfect wind turbine yet. I think the optimum designs are still evolving. And so we, you know, much like the earlier machines, we’re still trying new ideas. The conventional machines that are used today have a three-bladed rotor made out of composite material that faces into the wind, and it has a system that yaws it - or turns it into the wind – and keeps it there by sensing where the wind’s coming from. And as the rotor spins it drives this very high torque through a gearbox and that speeds it up and that converts it – and then that high speed is then converted into electricity by a conventional generator.

So we’re looking at different ways to do this. One of the problems is that gearboxes are known to have high rates of failures – they always have. They’re getting better, but they still don’t last as long as they should, as the 20-year design life. So there’s a lot of repairs that need to still go on with wind turbine gearboxes. And these problems are being addressed right now.

But one of the ideas is to change the design so that the gearbox is completely eliminated and Enercon has done that. That’s the company you mentioned. They’ve created a direct drive generator. So instead of speeding up the wind turbine through a gearbox, they just eliminate the gearbox completely and they operate at low speeds and convert directly into electricity in a wound(?) low speed direct drive generator.

And this works very well, but the current designs are heavy and are thought to be more expensive. And I wouldn’t tell you that Enercon is not cost effective – they’ve sold many turbines – but I know that they’re heavier than a lot of other turbines that can be designed with geared systems, so there’s work to be done in reducing the weight of direct drive systems and demonstrating that they are in fact more reliable.

With respect to the blades that you mentioned, that’s the segmented blades, this would solve – on very, very long blades, say 70-metre blades – where transportation might be a limiting factor – Enercon has elected to build their blade in two pieces, and so there’s a joint maybe two-thirds of the way down the blade or somewhere in that neighbourhood and then they bolt the blade together, so that in the end they have one solid piece, but with a joint in the middle. And that solves some of those transportation problems, and maybe some of those erection problems that we talked about. But it does produce – this joint has an inherent inefficiency in it’s going to add extra weight and it’s going to add a place where the blade needs to be serviced and maintained and where it can actually fail.

So there’s a trade off there, and so we’re not saying that segmented blades are bad because, you know, I think that’s one of the solutions for land based systems – to be able to ship(?) blades more readily over land surfaces. And there are other innovations that people are looking at as well. So the work is not done yet.

Matthew Wright: Another gearbox system that we’ve come across out of somewhere near here in New Zealand involves, similar to an automatic transmission, using a hydraulic pump. Are you aware of those systems?

Walter Musial:    Yeah. I think that’s another way of doing the same kind of thing, which is basically varying the speed. Is that the one I’m thinking of?

Matthew Wright:    Yep.

Walter Musial:     So, it’s a way of – normally the most conventional way of varying the speed of a wind turbine is to change the speed using the power electronics that the generator’s connected to. Another way is to do it mechanically. Kind of like the way they do it in an automobile. But it’s basically taking one stage and allowing the gearbox speed to change speeds and that lets the rotor speed change with the wind. And there’s always one point at a given wind speed where the wind turbine is most efficient. And this allows the wind turbine rotor to follow the wind and produce the most power it possibly can. Variable speed is one of the most – the best innovations of the last decade in wind turbines and it has enabled wind turbines to become a lot more efficient.

Matthew Wright:    Now, we also spoke to an Australian innovator, and they were actually possibly challenging the notion of having the turbine blades facing the incoming wind – so upwind of the turbine. Because the argument was that there’s more cost in making the blades super rigid so that they never run into the tower itself. Can you tell us a bit about the pros and cons of having the blades - obviously the convention in the industry is to have the blades in front of the turbine rather than trailing the turbine.

Walter Musial:    Uh huh. Yeah, that’s a very interesting story actually because they’re absolutely right. It costs more to make the blades rigid enough to face upwind and, as you can imagine, the wind’s blowing hard against the blades as it’s rotating and the blades are deflecting due to the large thrust loads on that rotor. And they’re deflecting back toward tower. So as the blades get longer and longer and larger and larger, this effect gets worse and worse and the blades become – the design of the blade becomes dominated by its need to stay away from that tower and to not hit the tower, so stiffness becomes the driver and the blades become more expensive because they’re not being designed for strength anymore, they’re being designed for stiffness in order to keep them away from the tower.

So naturally, why don’t we just go downwind? If you flip the rotor around 180 degrees, let the air pass through the tower first and then let it hit the rotor, the blades will now deflect away from the tower and the blades can be made a lot lighter, less stiff and we don’t have to worry about that as much. And all of our units are good.

And there’s one – there was only one compelling reason to not do that.
And this was really due to a legacy of experience that we had, in really the late 70s, early 80s, with downwind machines that they produced impresonic(?) noise because the blades would – the wind passing through the tower would create a vortex that the blades would pass through as they rotated, and it would create this thumping noise. And this thumping noise which is hard to describe because it is not audible, it’s below – it’s impresonic(?) - it’s below the threshold of human hearing. But it can propagate a long ways. And it can actually resonate structures. And it had the effect in some cases of actually shaking people’s houses to the point where they had to move. And so it was a very - in a few cases - it was so severe that it just destroyed the reputation of the companies that were doing this, and so it became categorically excluded. Well, the downwind rotors were categorically excluded from the industry because of that – basically that noise impact.

And there was very little research and development done to try to solve that problem so, you know, I’m sitting here today saying this is quite possible to do a downwind rotor. It’s quite possible if you’re offshore that it doesn’t even matter, especially if you’re far enough where there are no people to – no structures to rattle – no problems that would replicate the same kind of problems we had in the early 80s. So I say that would be – that’s a possibility for very large machines and it’s a possibility for getting the cost down too.

Matthew Wright:    And that’s the same problem whether you have the modern solid towers versus the original lattice towers?

Walter Musial:    Um, yes, you would have the same problem. But, as I said, there was not enough research done to really document what caused it or what solutions there might be to mitigate it. So I think it’s an open issue right now and I think it’s an area that’s ripe for future research. It certainly has some potential.

Scott Bilby: Now Walt, getting back to offshore wind installations. China and the USA have the best offshore wind resource. So I guess, just to end off, I guess the audience would like to know where these things are most likely to be rolled out, and if you can kind of give us an idea of where these proposed projects are currently?

Walter Musial:    Yeah, I know – I can’t really speak for China – I know that they’re starting to look in the offshore resource areas, and generally on the continental shelves where the water is still shallow, and also where the electric cables can be run very easily to the load centres where they need to supply the electricity without undue cost.

In the US – same story – these areas in the US are really the north-east, the North Atlantic. Generally the winds are better in the north than they are in the south. That would be a global generalisation. We have a continental shelf that’s not as good as the North Sea in Europe but it does have a substantial amount of shallow water where several – I’d say dozens of projects – have already been proposed in those waters, and I think that’s where we’re going to see our first project.

I think in the US, we’re going to see that project get installed in the next few years. I’m not clear on whose going to be first. It’s kind of a horse race here where there’s a lot of contenders, and we’re not sure who’s going to make it, but there’s a lot of companies making progress right now and we’ll see.

Scott Bilby:    Excellent. We look on with great interest. Thank you very much Dr Walter Musial.

Walter Musial:    You’re welcome. My pleasure.

Scott Bilby:    Thank you very much. And we’ve just been speaking to Dr Walter Musial. He’s senior engineer for the National Wind Technology Centre at the National Renewable Energy Laboratory in Colorado in the United States, and if you would like to learn more about them you can go to nrel.gov/wind.

Transcript by Jenny