Glen Paul: G'day, and welcome to CSIROpod, I'm Glen Paul. Ocean waves, tidal and ocean flows, collectively known as ocean renewable energy, are attracting increasing interest in Australia as a potentially viable source of electrical power supply. To investigate just how much energy may be waiting to be harnessed CSIRO has produced a report called Ocean Renewable Energy 2015 – 2050, which details maps of wave, tidal and non-tidal ocean flow energy distributions around the Australian coastline.
Joining me on the line to discuss it is CSIRO's Doctor Peter Osman. Peter, it is a comprehensive report, how did you go about pulling all this data together?
Dr Osman: First of all we got in touch with the companies who are working in the area to ask if they could supply information, and we did literature searches, and in particular we looked at the industry associations and the international energy agency reports that had been testing ocean renewable energy, because we were very interested in the practical applications, and the practical development of it.
Glen Paul: Now there are a number of forms of ocean renewable energy in the report – can you just take us through the main ones there and how they work?
Dr Osman: Yes. If we look at four of the bigger ones, we have tidal, that's the energy of the moon pulling on the ocean and filling our harbours and estuaries with water cyclically, typically twice a day, so that you can capture the movement of that water and allow that moving water to turn to a propeller on a generator and produce electricity, so that's one method.
The next one is wave energy, and anyone who's gone surfing will realise the enormous power that a wave can have, and what a wave is, it has that enormous power because winds have been blowing over thousands of kilometres of ocean to produce a wave, so it's concentrated wind energy that has been turned into a wave of water, and that wave of water can travel hundreds and thousands of kilometres without losing much of the energy, until it arrives at our shores and dumps all that energy on the shore. Well instead of dumping the energy on the shore, we can actually dump that energy into a machine and turn it into electricity, so that's wave energy, and there's a huge amount of it in Australia.
Ocean renewable energy also includes a couple of tricky ones. One is ocean currents, so the east coast of Australia, fishermen will know this well, off the east coast of Australia there's a very strong current that runs at about four knots. Trouble is, that that current moves all over the place, and you need very large propellers to capture the energy from the current, so it's not an easy one, and not at the moment commercially viable, still very much in the research area and may always be. And the other one is really interesting, ocean thermal energy, and there's just one spot in far north
Queensland near Cooktown where you can get to the very abyss of the ocean, about a kilometre down, without going too far offshore, and if you look at the temperature right at the bottom of the ocean, and the temperature at the top of the ocean, the difference in that temperature can be 20 or 30 degrees, and that allows you to run something like a reverse air conditioner to produce electricity.
But the ones that are of most interest to us, and the ones that are most likely to be practical, are tidal energy and wave energy.
Glen Paul: Well let's just refine it then, which of those two would be the most likely, or prove to have the most potential for Australia?
Dr Osman: Oh, now that's a hard question, because tidal energy has quite a proven track record, it's been around for a long time, and there are some big demonstrations of them, but in Australia there are only perhaps two areas where it would work well, one is in Banks Strait off the east coast of Tasmania, and the other is up in Broome, around that area of Western Australia. So we also don't really know if we extract energy from tides how that would affect the surrounding region, so a lot of research needed there, but the actual technology to turn tidal energy into electricity is quite well understood. Most of the research that needs to be done would be environmental.
Wave energy, that has huge potential – it's a very interesting form of energy because it could supply, in theory, five times Australia's energy needs. Now in practice you wouldn't do that, because it would make an enormous impact on various users of the ocean, and on the environment, but you could nevertheless without making so much impact on the environment or other users, you could quite readily extract ten or 20% for example of Australia's electricity requirements, and wave energy has the great virtue that it's much more available than wind energy for example. You can predict wave energy lasting for three or four days, compared to perhaps one day for wind energy, which tends to come and go more intermittently.
They're are about a hundred or so designs for machines that will extract wave energy around the world, and it's a really exciting time in the science of wave energy as people work out which of these machines are going to be the best.
Glen Paul: So wave energy gets a nice big tick next to it, but just getting back to tidal power, from my understanding you'd have to build a dam or something across a tidal basin, which obviously doesn't sound too appealing aesthetically or environmentally.
Dr Osman: Oh yes. Now that's the old fashioned way of doing things.
Glen Paul: Ah-ha.
Dr Osman: Building a dam, or what they call a barrage. There's one in La Rance in France, and there's another in Sihwa in Korea. But nowadays people are concerned that if you build a dam across an estuary it's going to restrict the movement of marine life, and it's going to change the way sand and silt moves around, and it could have quite serious environmental impact. So there's a new way of doing things, and it's the use of a thing called a tidal fence, or freestanding generators, where you put a pillar in the tidal flow, and you put a generator on the pillar, or you put a fence across the tidal flow with many, many gaps in it, more gaps than there are generators, so it combines the generation of electricity with allowing flow of marine life, and silt, and sand, a much less environmental impact.
The interesting thing though is that the building of dams isn't always a bad thing. There are some areas in the world where it can be quite effective, but mostly people are moving to tidal fences and to the freestanding turbines.
Glen Paul: What about infrastructure itself required to get the power into the grid from, you know, a remote shore, was that taken into account in the report?
Dr Osman: Yes, it was. Now the costings associated with all of this are at a very early stage indeed, because the state at which these technologies are is really just seeing how much energy they can produce, how to design the machines most effectively, but yes, the cabling that's associated with transmitting that energy to the shore, there's been quite a lot of work done on that internationally, particularly in Europe. It's a significant cost.
Glen Paul: On the back of this report then, Peter, how substantial then will ocean renewable energy be to Australia's future energy mix?
Dr Osman: Well that's a very difficult question to answer because there are a number of different scenarios. One of the key issues would be for the demonstration of a commercial scale wave energy unit, once that's in place then we would find it much more straight forward to project the future. But I can tell you where it could go – it could be that you could generate as much as 10%, or even 20%, of Australia's electricity competitively against other technologies. That's perhaps the most optimistic evaluation. The pessimistic is that we don't generate any at all. It depends on how quickly we move in this area, it depends on how well other technologies work.
One thing we are certain of though is that this area must be investigated, because it does have significant potential.
Glen Paul: Thanks very much for discussing it with me today, Peter.
Dr Osman: My pleasure.
Glen Paul: Doctor Peter Osman. And to find out more about the research being undertaken at CSIRO, and to follow us on other social media, go to www.csiro.au.