Australia's renewable energy future
Wave energy: The industry now and in the future
Wednesday, 5 November 2008
Dr Tom Denniss
Executive Director and Chief Technology Officer
Oceanlinx
Tom Denniss founded Oceanlinx in 1997, having earlier invented the core technology that has been commercialised by the company. He spent nine years as the company’s first CEO, and is now Chief Technology Officer and an Executive Director of the company. Tom has a PhD in mathematics and oceanography, and has had a varied professional career, including as a university lecturer and investment banker, prior to moving full-time to technology development in the field of wave energy.
Wave energy and ocean energy in general is somewhat the sleeper of all the renewable energies. I imagine it is the one that most of you know the least about, so hopefully you will come away from this with a lot better understanding of what it is about.
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A lot of people often ask me, 'What's the potential for wave energy? Is it really meaningful or is it just something on the periphery?' Let me give you a few details, just some background to begin with.
The global sale of electricity – this is roughly on a weighted average in different jurisdictions around the world – amounts to about $2 trillion per year. Quite a lot of money. That, in pure electricity terms, is 15 trillion kilowatt-hours or there-abouts. To give you a bit of an idea, the average house over the period of a day, which includes the night-time when it is not using so much, uses one to two kilowatts on average. So 15 trillion is obviously a lot, whether that goes into households, or industry or other uses. World GDP is about $65 trillion per annum. Therefore, the amount of electricity sold per year is of the order of 3% of world GDP.
How does that equate to energy in the ocean? Can the energy in the ocean provide any meaningful amount of that $2 trillion annually? Well, the amount of energy in the ocean, all sorts of energy – not just wave energy which I will concentrate on in general during this talk – but all sorts of energy in the ocean; if it was sold at the same price as electricity is sold in general throughout the world today it would amount to $10,000 trillion worth of sold electricity.
That's not a mistake there. That's $10,000 thousand billion or 10,000 million million dollars. However you want to think about it, it's a mind boggling amount.
Let's put it in terms of the percentage. It means that the energy in the ocean amounts to more than 5,000 times what the world currently uses in terms of electrical energy.
Now, I will qualify that a little bit because I am here to talk about wave energy specifically. There are many, many different forms of energy throughout the ocean. There's the tides, general circulation currents, temperature and salinity gradients, and all sorts of waves, waves with funny names. Waves that move sideways like a snake rather than up and down, and so on.
The ones that you are most familiar with – which wave energy technology has attempted to capture – are surface gravity waves. I will talk more about those in a moment.
Anyway, to recap on this particular slide, even if we were only able to capture a miniscule, an absolutely tiny amount of what's available in the oceans, and really that's all we'd want – if you caught it all then we would drastically be changing the nature of the oceans – even a tiny, tiny amount would go a long, long way to providing what the world needs. I should also add that's what's in the oceans. There is even more than that in the wind throughout the world and more again from the Sun.
If you add up just those three, the energy in the ocean, the wind and the Sun there is far, far more energy than the world will probably ever need, because if we were using all of that I think we would be seeing a very, very different sort of world to what we've got now.
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What is wave energy? As I just mentioned, surface gravity waves is the technical name for what you see washing onto the beaches. Unfortunately what we see washing onto the beaches is not representative of what these waves actually look like in the deep ocean. I won't go into the technical reasons for that. But when they get close to the shore the depth comes into play and the waves all move at a pretty much constant speed, and they bunch up as the depth gets shallower. We all understand that type of wave. But they look a little bit different further out to sea. That's the type of wave that wave energy technology so far has tried to capture. As I have said, there are many, many other types of waves further out to sea and no-one so far is trying to capture those, but maybe one day.
Second slide there says, 'wave energy is derived from the Sun'. Some people are surprised about that. But almost all our energy on Earth actually does come from the Sun. There is some that doesn't, for instance radioactive decay within the Earth and some tidal energy from the moon – gravitational pull of the moon and so on. Most of it, even our fossil fuels, come from the Sun originally. The energy that went into those plants that died and got buried and turned into oil and coal and so on, that energy came from the Sun.
Wind energy comes from the Sun. The Sun heats the Earth unevenly. If the Earth wasn't turning then we'd have a situation like some of the planets where we would have a very hot side and a very cold side and there would be no reason for winds to blow because everything would be in equilibrium. What happens with the Earth, because it is spinning, it can never reach equilibrium. It is always trying to attain equilibrium. It does that by setting up winds that blow to equalise the pressure.
So the energy in the wind comes from the Sun and that is what drives the waves, these surface gravity waves – not all waves, but certainly the sort we are talking about now – are set up from the blowing of the wind across the sea.
So waves, wind, solar, fossil fuels and several other sorts of energies come from the Sun.
The sort that we try to capture is in the unbroken swell. There's more energy actually in unbroken swell in deeper water than there is in the waves that you see crashing onto the beaches. As soon as they start to break and they get into shallower water they lose energy to the friction with the seabed. Then once they start to break there is turbulence and so on. So there is quite a loss of energy in that regard.
That has an important implication, because the sorts of waves that we actually try to extract energy from are not the same sort of waves that, for instance, surfers look for. So it is not like we have any reason to compete in that regard. These things can be important when you're trying to get permission for projects.
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What does a wave contain? For those of you who know a little bit about energy, if you raise a cubic metre of water – one metre by one metre by one metre – so you might think lifting it, well, you won't be able to do that because by definition it weighs a tonne. Well, actually sea water weighs a little bit more than a tonne – a cubic metre. Once a cubic metre of sea water gets raised by one metre it takes more than 10,000 joules to do that. And if it was fresh water, pure fresh water at 20 degrees Celsius it would be exactly 10,000 joules by definition. That is one of the definitions of what a joule means. Because sea water is a bit denser than fresh water it will take a bit more than 10,000 joules. You can just imagine as a wave comes by the number of cubic metres of water that has been raised; and being pushed down below sea level by a metre takes the same amount of energy. So it is up and it is down; up and down. That is just one cubic metre. All the way along the crest and the wavelength as well there is so much energy in every part of the wave as it moves up and down. By raising it you've got potential energy, but the actual movement getting up there is kinetic energy, which it oscillates back and forth between.
Wave energy is measured in kilowatts per metre of wave front. If you are familiar with wind, it's normally watts or kilowatts per square metre of swept area. It is quite different with wave energy. Imagine standing on a beach and you have a crest of wave coming towards you. If you just take a slice one metre wide, and as that one metre comes towards you we measure the amount of kilowatts as power, the rate of energy, the amount of power that that wave is providing; in other words, the amount of energy that it is delivering to you, or the rate at which that energy is being delivered in a good wave climate amounts up to about 40 kilowatts per metre average throughout the year.
Now remember I said an average household uses maybe one to two kilowatts on average throughout the day. There are peaks where it uses more than that, other times when it uses less. An average reasonable wave climate means that you've got somewhere in the vicinity of 10 to 20, maybe even more, 30 or 40 houses that the amount of energy they use is equal to what one metre-wide of wave front is delivering. So every extra metre there's another 10, 20, 40 households.
This amount, this 20 to 40 kilowatts is very much an average because it varies drastically. We all know that sometimes the oceans can be flat and at other times with storms you can have very, very large waves. When it's flat, dead flat, completely calm there is nothing, there is no power in the waves at all. However, that is not that common, so there is usually something in the waves. In major storms you can have more than 1,000 kilowatts, a megawatt per metre of wave front – which is really quite a phenomenal amount of power.
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The map here shows some of the locations around the world. Hopefully you can see the numbers involved. You can see the red bands. Waves hit coastlines no matter where you are around the world, but they tend to be bigger in the temperate zones, the red areas, generally between about 30 and 60 or 70 degrees of latitude both north and south of the equator. The reason for that is that's where the winds tend to be greater. Winds, in general, come from the west. So these waves more often than not are propagating from west to east.
The Southern Ocean is a great place because at certain latitudes around 60 or 70 degrees there's nothing in the way. So it just keeps propagating around the Earth. So there are very good wave climates there.
You can see Australia down in the southern part, 60 and 70 kilowatts per metre average throughout the year. It's 100 down in the Southern Ocean below New Zealand. That's pretty much true of the whole Southern Ocean. So we've got some pretty nice locations in Australia. They tend to be towards the southern part. Certainly up in the Gulf of Carpentaria and so on it's not really a valid place for the wave energy I'm talking about. But the southern part of Australia definitely is.
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Let's just look at the wave energy industry at the moment and the state of commercialisation? There are about 50 different wave energy companies around the world. It's very hard to keep track. When I started in this area there were about five in the industry. That goes back to about 1990. I think I have a slide that touches on that in a moment. There's almost as many different technologies as there are companies. In other words, every company pretty much has their own technology. This is very, very different to wind energy. The wind energy industry converged very quickly. There just wasn't the same number of ways of capturing wind energy as there is with wave energy. There are so many ways to capture it.
One of the things that is perplexing to venture capital investors who can see that this is an industry to get into – but they have to make a decision on what technology and what company they are going to invest in – they can't see where it is converging. What will the technology actually look like further down the track? Will there be 50 different technologies all with their own little niche, or will it converge to one or maybe just a few different types of wave energy technology?
That question still hasn't been answered yet. I could give you a bit of a biased opinion as to where it is going, but if I wanted to be completely objective and take my Oceanlinx hat off then I'd have to say to the outside observer it's not entirely clear just as yet.
Some of these technologies are very early stage R&D. In fact, most of them are, because most of them have cropped up in the last few years. There is a handful nearing commercialisation, including our own company, based in Sydney. All of the ones nearing commercialisation have been around for 10 years or thereabouts – more in our case.
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I'm just going to give you a few examples of some other technologies around the world before I concentrate on, obviously, what I know best, which is our own technology. The Pelamis is a Scottish-based technology. It has been around for about the same length of time as our own. I know the founder of this technology very well. Some would say they, along with ourselves and one or two others, are at the forefront of the wave energy industry. Pelamis is like a big long snake. You can see the sections. It is articulated. It is a big cylinder joined with a hinge and another hinge further on. As the wave goes by these cylinders go up and down and those hinges are what extract the energy. Hydraulic systems in there resist the motion, and that's what takes out the power.
The advantage of this system is that it is pretty well protected and it handles the extreme conditions well. It is like a torpedo that propels itself into the big waves and through them. The downside is that same benefit causes the efficiency to be fairly low.
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There are so many, but I am only going to show three others, beside our own. The other two are Australian-based companies. There are three Australian-based companies. The other two have been around for a lesser time than ourselves. This one has been around the second longest time in Australia. CETO, the company, is Carnegie, which is now owned by Renewable Energy Holdings in the UK. This is their first device being deployed off Fremantle. It is essentially a Western Australian company.
A more recent version of their technology is very similar to the next one I'll show. It is attached to the seabed. There is a buoyant balloon-like part to the system, and as the wave goes by the balloon tries to go up above the wave and then down as the wave recedes; it goes up and down, up and down. That causes sea water to be compressed at the base. I'm not quite sure about how the system down at the bottom works. As you can imagine, each company is a little bit secretive about their technologies. Then they pump high pressure sea water to the land. There are many ways you can extract energy once you have got high pressure sea water. They can just pump it into a reservoir, let that reservoir drain and use standard low head hydro.
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Bio power systems is a much newer technology. It is actually the brainchild of a guy who used to be at the head of technology development for Oceanlinx. That's the nature of these industries. People have ideas and they leave and pursue them, and that's fine. We still get together for a beer from time to time. This system, Bio Power, the 'bio' part of it refers to bio mimicry, which is the attempt to mimic biological systems to achieve things that biology has perfected over the years through evolution.
Once again, I don't know an awful lot about it, but there's two parts to it. You can see the fin – the shark's fin is a tidal technology, but the one on the left is supposed to mimic the way waves make kelp move. Same sort of thing. The power take-off is on the sea floor. As these objects move back and forth they create some sort of force down below, and that drives the power.
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I am just going to give you a bit of a technology comparison before I move on to our own technology. In some ways I apologise that I'll be concentrating on that one, but clearly I know so much more about it. It would be a pretty boring lecture if I was just concentrating on all the other ones because I wouldn't be able to tell you anywhere near as much.
This slide, it is a little hard to understand when you first view it, but this was produced by the European Union's independent adviser on wave energy. He doesn't hold that position now, but he did for about 20 years, from the mid eighties to the middle part of this decade.
You will see down below in blue it says 'Energetech'. Energetech is what our company used to be known as until April of last year. So Energetech and Oceanlinx are the same thing. There are different ways to view this. You have two axes and one represents investment per unit or per project. These are all leveled – climate, everything else being equal. The important one is the vertical axis. In that respect we're at the lowest point, which is very pleasing.
The guy who did this comparison is based in Oxford, in the UK. It was his opinion when he did this analysis that the generating cost in cents per kilowatt-hour for our technology will be the lowest. Don't worry too much about what the absolute number is because that will vary depending on wave climate and so on and local construction costs; what is important is its relation to the other technologies. In his opinion we are likely to be the lowest cost wave-energy technology. The nearest one, you can see there OPD; that stands for Ocean Power Delivery. That is the old name for Pelamis. We both changed our names in recent times.
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I will just tell you now about Oceanlinx the company. The technology was invented in 1990. It was pretty low key back in those days, not a lot happened. It was more of an academic exercise. There was no money around. I certainly wasn't aware of any way of deriving any funding from anywhere. There were no programs in place.
By 1997 there was enough excitement to get the company set up and registered with ASIC. As I said, it was renamed in 2007 to Oceanlinx from Energetech Australia. Our head office is in Sydney, but we do have regional offices elsewhere, in the UK and in the US. And we have patents granted in most of the main jurisdictions. It is very hard to get patents granted in every part of the world. In fact, not all countries have coastline. So it is not viable that we do. But certainly in most of the main ones that you can see there the system is patented.
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So far we have derived the third highest amount of funding in the world after the Pelamis. We are a little bit behind them. But there is another company called Ocean Power Technologies that listed as a public company in 2003, and they've raised well over $100 million – which the rest of us would love to have. It's not clear that they have actually done all that much with the money.
Anyway, in our company, we have 30 staff worldwide. A lot are engineers making sure that the technology works and getting it working properly; research staff who look at the technology and how to improve it; and of course finance and administration staff.
We recently formed a separate subsidiary, Oceanlinx Hawaii. That is because in Hawaii they are very, very keen on wave energy. They have decided that our technology is the one to be implemented there. When I say 'they', I am talking about the Hawaiian Electric Company, which is the biggest user of diesel fuel for electricity generation in the world. Basically the majority of Hawaii gets their electricity from burning diesel, which is a very poor way to create electricity. They acknowledge that. It is an historical thing. With the oil price the way it has been in recent years they have come under a lot of pressure to divest themselves of their reliance on diesel for electricity.
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The technology is based on what is called the 'Oscillating Water Column' or OWC. Everyone in the industry knows it as OWC. It is the most established of the science in wave energy; the concept has been around for a few decades. It is really an artificial blowhole. For those who know a blowhole, waves go into a big cave and compress the air and force air and often a lot of water out through some spout or blowhole.
We actually focus energy into this artificial chamber via resonance. I will touch on resonance in a moment.
When the air comes out of the spout we use a proprietary turbine which captures the energy in both directions of the flow. As the wave rises it drives air one way and as the wave recedes it sucks air back from the other direction. Our turbine needs to spin in the same direction and capture both the up and down stroke.
The only moving part is the air turbine itself. That is well above the waterline, so there are no moving parts at all in the water. That is important for the environmental aspects.
The next couple of slides are video about an exciting new innovation we've made in this latest generation of the technology using resonance. Now, resonance is a physical phenomenon that you might be familiar with. In fact, I am sure most of you are familiar with it in one way or another. For example, when you get on a swing and you start at rest, and get moving simply by pulling and pushing on the swing at the right time. The timing is vital, because if you pull and push on that swing very quickly nothing will happen, you will just wiggle back and forth; and if you do it too slowly nothing will happen. You have to time it right. As a kid we all learn how to get on a swing and pull and push it at just the right frequency to start driving the swing back and forth for resonance.
Another similar example, if you get in a bath tub. If you are lying in a bath tub and you wriggle back and forth really quickly you will just jiggle the water. If you do it really, really slowly nothing will happen. But if you do it just right you can almost empty that bath tub by sloshing it back and forth and the water will come out. That's resonance.
Audience member: Your mother kills you.
Tom Denniss: Yes, your mother kills you, or your wife, or whoever. I imagine Archimedes or someone probably emptied the bath tub at one time as well.
The most practical example, because those two examples I gave aren't overly practical, that you are all familiar with, although you might not realise it, is electromagnetic resonance of the aerial or antenna on a radio or a television. There is so much electromagnetic radiation in the air; it is all very, very weak and all different frequencies. As you tune a radio you are changing the natural resonant frequency of that aerial.
Only those electromagnetic waves of that frequency start to interact with the aerial and get amplified. The aerial actually draws in and focuses the energy that was very sparse in the ambient background. Well, that's what we do with our wave energy chamber, our oscillating water column.
I just want you to see here what happens.
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This is with two-metre waves in a wave tank. The waves are just starting to come through. You can see inside the chamber the very pronounced amplification of the wave inside. Now, that's a two-metre wave. It represents a two-metre wave at full scale. The oscillation inside – I will just play it once more (video played) – is eight metres. You've got an amplification factor of four. Because the energy in the waves is proportional to the square of the amplitude the energy in that oscillation inside the chamber is 16-times greater than what it would be if we weren't attaining resonance. It's a huge plus. That is why we have actually done away with that parabolic focusing wall, because it is not necessary. We never got anywhere near the same sort of effect as we get here.
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The next video is the same thing. In this case it is a smaller wave; you can see it is almost a flat sea, with half-metre waves. But with amplification it gets up to four metres inside. That's an eight-fold amplification. You are getting an eight-fold greater up and down motion than what you get outside. In other words, with smaller waves we get a better efficiency, but it's still pretty good in the larger waves.
The whole point of this video is not to show what is below the water line. We have applied for a patent for this particular innovation. We want to keep how we actually achieve this secret for the moment. I apologise for that. If I reveal it any patent is immediately void. Not that I would expect people to run away and start to do anything about this, but the very fact of revealing it in public voids any patent. So it's a clever design under water that achieves this.
I want to make the point too that this wasn't just an accident. We actually did the theoretical work and the analysis.
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I don't really expect anyone to understand what is on the screen. Basically, there is an equation of motion, which when solved, gave the solution below. It is one of the nice things about science. Sometimes you do the theory and it doesn't quite measure up in reality; you get a little downhearted and you go away. When you actually do the theory and it comes up just the way you thought it would, it is very satisfying. We are quite happy about that.
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This is a graphical representation of the solution in the previous slide. You can see the pink part up the top; it is all about designing the physical characteristics of the chamber so it has the right resonant period and minimal dissipation through turbulence and so on to sit at that point.
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Let me explain how the turbine works. The different aspect to it is this blade which can pitch back and forth. When the air travels in this direction it is like an aircraft wing. It creates lift and the turbine spins. At the moment the air changes direction, the blades pivot. Now when the air travels past it still creates lift on the same side. The turbine keeps spinning in the same direction. Really, it's just a matter of the turbine blade angles changing in response to the direction and magnitude of the air flow.
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Back at the end of 2006 I received a call from the International Academy of Science. I'm not sure if there is an affiliation at all with the Australian Academy of Science. These people are based in the US. Each year they award their 10 most outstanding technologies of the year, on any form of technology. I was very surprised, actually, because I had no inkling of this and hadn't been consulted at all, but they announced that we were one of the 10 technologies in the world that they had chosen. Not the winner for that year, but still for an out-of-the-blue cold call it was reasonably satisfying.
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Just quickly on the Port Kembla project. The Port Kembla project is our main project to date, commissioned in June of 2005. It was deployed permanently between December 2006 and March 2008. It is now being upgraded and will be permanently operating from, we expect, December this year. We will be grid connected with Integral Energy purchasing the power.
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There's a picture of it in one of the early deployments. People say it's not particularly attractive. I'll acknowledge that. But you've got all sorts of stuff on it that you need in the early days.
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There's a picture of it – it says 'night operation', but the Sun was coming up. A nice pink sunrise there.
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Here's a video. You can see the sea is pretty flat. This is using the old parabolic wall focusing, not the chamber of resonance, which will be even more pronounced.
You can hear that whooshing sound, which we've amplified for the purposes of the video. As the wave goes past the device, and it's only a very small crested wave, you get this whooshing sound. That's the air coming directly out of the back of that turbine. As flat as these seas were, it was still producing up to almost 100 kilowatts in these very, very flat conditions. It was quite a positive to be able to do that, because many technologies don't or cannot produce power in seas as low as this.
It's actually quite a boring video because there is nothing happening. That's why we put the sound up, so at least there was something mildly interesting about it. Really, there is nothing that you can see for this technology. The turbine is inside but you can't see it. There is no other moving part; it just sits there and produces power.
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This was in a storm at Port Kembla in the middle of last year. You can see the waves breaking over the top. This thing is 10 metres high out of the water – it might not look it, but they are very, very big waves. It stood up very well; structurally there were no problems at all. We did have some sensor cables on the outside – which we won't ever do again, because that's not a good place in a storm like this – and they were washed away. That was a lesson learnt.
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This was the same storm where the Pasha Bulka – at almost a hundred thousand tonnes – was washed up onto the shore. So it was a good test of the technology's robustness.
(Inaudible comment from the audience)
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As I said before, there are no moving parts below the waterline, so no harm to marine life. Turbine noise levels have been verified at 74 decibels, which is about the same as a household vacuum cleaner. Most of it lies below the waterline. Minimal aesthetic issues, but that's up to the individual to decide.
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We have other projects around the world. I won't dwell on those too much. These are other projects that are currently under way in some form or another.
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Now, to get to what it means in the future. Estimates for wave energy by 2020 vary from 100 megawatts to 10,000 megawatts. That's a huge range. Basically it means that no-one really knows. I read something the other day from a stock broking firm who were analysing the sector. Their view was 1,000 megawatts within six years. I wouldn't be that hopeful. But, anyway, it's nice to hear that others are expecting that. Longer term by 2050 around 100,000 megawatts, and a lot more after that.
The rate of uptake will depend on how low we can get cents per kilowatt-hour. The lower it is the quicker it will be taken up and the more you will see by any point in the future. It will initially be smaller arrays near shore, gravitating to larger wave farms beyond the horizon.
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Here is an artist's impression of what these things might look like. You might get these big arrays way beyond the horizon. No-one will see them from shore. They will have to be marked in shipping lanes so that ships don't run into them. We will have all this clean energy without even seeing where it is coming from.
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Just quickly, how will they be constructed? Almost certainly on land. I can tell you about some foolish attempts to construct in situ in the ocean.
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This is the way it will happen. You can lift them into the ocean. They can be floated into place or put on heavy lift vessels and taken to different places.
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That, as you might have gathered, is our Port Kembla parabolic-wall version-one plant.
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The International Energy Agency have done a very, very thorough study on the cost of 108 different energy technologies. There is a bell-shaped curve around 82 per cent, meaning that for every doubling of capacity the cost comes down to 82 per cent of what it was before. When one megawatt of a technology goes to two megawatts you expect the cost to go to 82 per cent. When it goes to four megawatts, 82 per cent of that again. Then eight, 82 per cent of that again. This means that going from 1 megawatt to 1,000 megawatts, which is not a lot for a new technology, you would expect a seven-fold reduction in price. If a wave project is currently producing at 35 cents a kilowatt-hour you could expect 5 cents per kilowatt-hour by the time 1,000 megawatts is installed. That's really competitive.
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So at 5 cents a kilowatt-hour the uptake rate is expected to be very high. Various estimates put 10 per cent of the world's electricity needs produced from waves within 50 years. We will see whether that happens; well, hopefully some of us will still be around to see it. The actual proportion is expected to be higher [for Australia] because we've got so much coastline. Three to five percent of [Australia's] energy needs in about 20 years, and a quarter by 50 years.
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What's needed? The biggest problem is getting from early stage to multiple unit projects. You need a lot of money to make that shift, to drive down the cost. Feed-in tariffs, where government guarantees a higher rate early on to get projects built, is the way that most people agree things should be. Such programs are in place in Portugal and will be in the UK soon. So a feed-in tariff is probably the most positive way to get new technologies happening.
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A couple more slides. What do we have to overcome? We use lessons learned by the offshore oil and gas industry about the harsh environment. They have spent billions learning how to keep structures in the ocean. We get a lot of those benefits for free now. Another thing to overcome is the high costs. The perverse thing is that the oil and gas industry now, with oil so high, or at least it was recently, has forced up some of these costs for us. And, of course, we need to acquire the necessary funding to produce large multiple unit projects that drive the cost down over time.
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Just to summarise, there's a varied and diverse range of wave energy technologies out there. Convergence is not clear at this stage; hopefully it will become clear fairly soon. Australia is well placed to be a large utiliser of wave energy, with possibly 5 per cent of our needs coming from wave energy within 20 years. It would be much faster, and we would have more, if there were feed-in tariffs introduced to motivate investors to get into the industry.
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So with a view of our Port Kembla plant from a distance I would like to thank you again for coming, and hopefully you've learned something.
Discussion
Chair (Professor Mike Dopita): Thank you for that excellent talk. I notice the emphasis of 'feed-in tariffs'. The same things we had in the photovoltaic area. If a politician asks your opinion on how to get renewable energy up just say, 'Feed-in tariffs. Feed-in tariffs. Feed-in tariffs.'
Question: I have a question relating to the use of - not so much wave energy but tidal energy, which you did allude to. Millions of tonnes of water flow through the Torres Strait and the Bass Strait probably every hour. What is the problem with using the technology we have for ships' propellers to use the DSE turbine and water flowing constantly in these ocean currents, because wave energy is spasmodic.
Tom Denniss: True. One thing about tides is that they are more predictable. In fact, they are highly predictable. They are spasmodic in the sense that there are cycles throughout the day. But at least you know when they are going to occur. I should point out though that wave energy, of the renewables besides tidal, is the most predictable. It is far more predictable three to four days out than wind, which sometimes they have trouble even for a few hours out.
You probably wouldn't use our turbine for these tidal applications because, whilst it's valid, particularly with reversing tides, reversing currents, because of the tides. There are turbines that have been developed over the years that are probably more applicable. The problem, I guess, is the cost of implementing something out in these straits well away from land. There is an environmental aspect, in that just as people worry about birds getting hit by wind turbines they are concerned about whales and dolphins being affected by these turbines. I think there are ways around that.
Probably the biggest hindrance at this time is simply the cost. Most people don't realise, and I certainly didn't until I got involved in this, just how costly engineering something in the ocean really is, particularly if it's well away from the shore. So I think it certainly can be done. I guess the tidal energy developers are just having trouble convincing the people who control the money to put something in.
They probably need to be closer to shore. This sort of tidal turbine – it is not just tidal currents but also things like the Eastern Australian Current, which is akin to the Gulf Stream, people are really starting to have a crack at that now. I think we will see some good developments in the next few years.
Question: Just a simple question about embedded energy. How long does your big machine have to run before it has generated the amount of energy it took to create it?
Tom Denniss: It depends on how we create it and whether it is made out of steel or all different materials that it can be made of. Of course, we will be trying to get that number down. If we can use the energy from one of our own plants to build future plants then obviously that cost or that extraneous cost goes to zero. At the moment I'm not quite sure. In fact, I'm employing an honours student over the summer to actually calculate the energy budget. I will know more about it when that's done, but probably in the order of six months or so at this point.
Question: I am better informed. Two somewhat related questions, please. We have sort of half heard the answer. Do the waves have any diurnal effect or any predictable as to when you have them or when you haven't, as solar does? The Sun is there or the Sun is not; the wind is there or the wind is not. Take that one and then can I follow?
Tom Denniss: There is no diurnal predictability of waves. Mainly because they are not – mostly the waves with a lot of energy - are not generated locally. In fact, they are generated well away, sometimes thousands of kilometres away. And there is no correlation between what's happening in your time of the day and when the waves might get there. So with solar, yes, you get a lot during the day. That may or may not be when it's needed, depending on where you are. If you are at a place where it is very hot you need it for air-conditioning; in places that are cold it doesn't match quite so well.
Wind tends to be diurnal to a large degree. It is greatest in the late afternoon, quietest in the early morning. It matches one peak but doesn't the other. With waves you don't have that predictability. It doesn't benefit a particular peak during the day. By the same token, it doesn't not benefit it. The correlation between wave and wind and solar is roughly zero, which means sometimes it is in sync and sometimes it is not, and is a major positive for the generators. It would be great if it was completely out of sync, so that when you had wind you didn't have waves and when you had waves you didn't have wind because then there would be a perfect matching and you could balance things out. It is not exactly the way it works. But there is some benefit.
Question: Thank you. To follow on, and you have half-answered what I am about to ask, a lot of us have been to a couple of these lectures now and will probably come to more. And we have seen presenters talk about their thing and push their wheelbarrow. That is entirely understandable. But in terms of reliable energy supply, do you have any thoughts on how we could link a lot of these technologies together to compete with coal or geothermal, or something that can produce base load power?
Tom Denniss: Certainly the trend is for decentralised energy. It is a very big positive. At the moment we have grids where energy is generated centrally and it goes out. That means that the grid in the extremities is very weak. What will happen certainly with wave energy is that you will produce at the extremities and generate in towards the middle. That's a positive. Ideally you have a lot of different sources, wherever and whatever is generated all feeds into the grid. If you have enough of this it all balances out and smears out the highs and lows and you get a very stiff solid grid.
That's really what needs to happen. We just need a lot more capacity installed from a lot of different sources. They will all tend to balance each other out. That will create a base load in itself, or at least a lot more like a base load than currently is the case.
If all our renewables came from wave energy, well, we would have times when we had great amounts and times when we wouldn't. That's fine if we want to store it. But storage has its own losses associated with it. Of course that means that the relative cost goes up. It still may well be very viable.
The ways to compete with coal as baseline is either to store it, get the cost so low that you can waste some in storage and still be competitive, or balance it out with all the others. But you would need a lot of capacity of wind, waves, tidal, solar, geothermal – all the different sources. If we had enough of it we would be fine because there is more than enough of it to go around.
Question: My question is related to the direction of the waves. I used to be a surfer when I was younger. Some days it is good when the waves are coming from one direction and some days not so good when they come from other directions. I suspect anyway that the parabolic technology that you used there is very sensitive to the direction of the waves. I'm curious as to whether or not your resonant frequency column would suffer from the same effect?
Tom Denniss: Well, you're right about the parabolic wall. But it was a very near-shore technology. Due to refraction because of the seabed, waves close to shore tend to straighten up and follow the seabed contours. That was a benefit there. But you are right, the resonant technology is much less sensitive to the directionality. In fact, we can have it out in the middle of the ocean where waves could be coming from all sorts of directions, although predominantly from the west more than anywhere else. It is reasonably insensitive. There is some directionality, but it is one of the benefits. Again, it has advantages over the parabolic wall.
Question: A simple question about the sitting of your machine. How do you deal with spring tides, very hide tides, or do you have to site it in places where you don't have a very big tidal difference?
Tom Denniss: If it is fixed to the seabed – we have different ways of doing this, sometimes floating, sometimes fixed to the seabed – then yes, big tidal ranges are a major issue.
Up to about four metres is not too bad. If it is floating it doesn't matter anyway, because it will rise and fall with the tide. You have some losses associated with the floating structure but there are other major advantages. We will probably be moving, in one way or another, towards a floating device in the future.
Question: What is the capacity factor of the one at Port Kembla? Are you oversizing it in the case of huge storms or does it have to work essentially like that?
Tom Denniss: The capacity factor generally is somewhere around the 25 per cent to 30 per cent at the moment. We expect that to go up. The capacity factor is a bit misleading with the renewable technology, because you can actually make it anything you want by defining your peak capacity. If you want to put a really big generator in there then you can say, wow, this thing generates a megawatt or two megawatts on some occasions. But the rest of the time it might be well below that, in which case your capacity factor is going to be very low.
Alternatively, you can put your generator in, which is sized to roughly the average, and you will of course then have a peak capacity that is a lot lower. But your capacity factor will be very high, maybe up around the 100 per cent. So really the aim is to get the most kilowatt-hours per year out of the device.
That is certainly a science, but there is a little bit of art in it as well – at least at this stage. And the indications are that a capacity factor somewhere in the vicinity of 40 per cent or thereabouts for wave energy – it is about 30 to 35 per cent for wind, mainly because wind is more variable – is probably the capacity factor that will lead to the maximum amount of output per year.
Question: Thank you very much. It has been a great talk. What number of these units would it take to replace one typical coal powered base station for example? So what we are talking about is 1,000 megawatts or something like that. How many units? How much area?
Tom Denniss: You are right. A typical coal-fired power station to be of the order of 1,000 megawatts. We can make these things various sizes. It is still not clear what the best size is. I mean, the best size will depend on the location. But we don't want to have to tailor-make all of these things to every different location. We need a bit of standardisation in the construction process.
So we will probably have certain sizes and they'll just have to fit the environment. I might be wrong here, but I can't really see them being much bigger than about 2 megawatts per device. The reason is, you can't make them unlimitedly large because you start to get destructive interference of the troughs and crests within the domain of the device. So you do need to keep them at a size that is appreciably smaller in their dimension than the wavelength itself, which is typically somewhere of the order of 80 to 100 metres. So they must be smaller than that. Two megawatts therefore, so probably 500 devices per 1000 MW.
Now, a one-megawatt device probably takes up an area – if you take not just that circular chamber but the surrounding area – something in the order of 20 by 20 metres. So 500 by 20 by 20.
Question: It gives a rough idea.
Tom Denniss: It is much less than a square kilometre. Much less.
Chair (Professor Dopita): I am afraid I will have to give the last two questions here.
Question: Thank you very much. Following on from some of the previous questions and cutting to the chase as to how this sort of thing might be deployed, from your map you showed early on it seems Tasmania is once again the hot spot.
Tom Denniss: Oh, yeah.
Question: I was wondering whether you had considered how these may be integrated with the wind power efforts going on down there, the hydro-electric power, the DC cable running across the seabed from Tasmania, and whether there really is something prospective there that could be pulled together on a fairly large scale?
Tom Denniss: Yes. Eventually. Absolutely. We have been in talks with Hydro-Tasmania. They are keen on the concept, particularly on King Island. That's where we have been discussing the technology.
The problem is that at the moment they are a utility that has to get the best price and the best outcome. They have wind turbines on the island that produce far more than they need at certain times and nothing at other times. So if we were completely in sync with the wind there would be no point being there, because they already have enough when that occurs. As you know we could operate when there is no wind at all. That is very advantageous to them. They would be willing to pay a lot for the power then. When we are producing, and they have wind, they are not willing to pay anything. So we still have to advance the discussions there. But eventually I would say not just on King Island but Tasmania itself. Tasmania has hydro as well. I think they are now a net importer of power. So let's see.
Question: But you could pump the hydro storage to effectively extend the hydro --
Tom Denniss: Yes, that's true. The problem with their hydro at the moment is that they are not getting enough rain and their dams are not full enough. So we could pump up – yes, that is a longer term, larger scale possibility.
Chair (Professor Dopita): I am sorry to all of those who had your hands up. I see there are a number of questions. I hope you are willing to take questions, Tom, afterwards.
Tom Denniss: I have a cab arriving in 10 minutes.
Chair (Professor Dopita): Okay, so one last question.
Question: You talk about 20 to 40 kilowatts per metre of wave front. Is that harvestable energy?
Tom Denniss: That's what's incident, as opposed to capacity factor, which we have just discussed, which is a proportion of the average output to the peak output. What I think you are alluding to is the conversion efficiency. In other words, how much of what is incident upon the device do we actually capture?
It can be a misleading term, because if we looked at what was incident upon our device, that's not actually how much we get in there because of this resonance. The resonance modifies the energy field and actually drags in more energy. So how much we drag in – the effective width that we're capturing even though the device might only be this wide – will depend on how well we can make it resonate.
But the simple way of saying it is, let's say we have got 30 kilowatts per metre and we have a 10-metre wide device, there is 300 kilowatts average incident. If we didn't have resonance we would have about 35 per cent conversion of that 300 kilowatts. So whatever that is, about 100 kilowatts on average; about a third. But we actually draw more in, if you are still only measuring it on the width, if we are drawing three times more in and converting a third of that then we are back to 100 per cent efficiency.
Like I say, it is a little bit misleading at times, the definition. If you understand that then it can be as high as 100 per cent or more.
Chair (Professor Dopita): I thank Tom for a very interesting talk. And clearly from the number of questions it has generated it has excited a lot of thoughts. I think what's needed here is a good organ technologist in order to devise the appropriate resonant pipe.
Tom Denniss: The pipe organ is another example.
Chair (Professor Dopita): It is very exciting to see here, at least, there is a technology where Australia is clearly right in the vanguard or in the leading edge. I wish this technology well and if it really can deliver this five or six cents a kilowatt-hour, it's incredibly competitive. I think it is rather good you have got it going off Port Kembla, just to show the dirty coal people what really can be done with a bit of clean energy.
Tom Denniss: Actually the coal loader off Port Kembla where we have it positioned have actually been quite helpful.
Once again, I would just like to apologise. It is impossible to come into something like this and not concentrate on your own technology because, as I said, it would be a fairly short talk otherwise. If you can forgive me for that.
By the time we get gown to 5 cents a kilowatt-hour, I should say, we will have probably of the order of 1,000 megawatts installed worldwide before we get down to that level. That's really a very, very small amount of power in the bigger picture. It will go well beyond that.
