TCASE 9: Ocean power II – CETO

In TCASE (thinking critically about sustainable energy) #5, I analysed a currently deployed technology for harnessing wave energy – the Pelamis device. If you haven’t read TCASE 5 then please do so now, since it explains some of the basic physical properties of wave energy, the extend of the global resource, etc. In writing the following post, I’ll consider this to be assumed knowledge.

CETO, named after a Greek sea goddess, has been developed by Carnegie Wave Energy (an Australian company), and is described in detail on their website. It is based on a submerged, underwater buoy-like device, anchored to the sea floor, which pumps water to shore at high pressure (6,400 kPa). Read more about the technology here.

The list of advantages of CETO on the website are worth citing here, as they provide a useful target for analysis. Main ones are:

  • 60% of the world live within 60km (40 miles) of a coast, removing transmission issues.
  • Waves are predictable days in advance making it easy to match supply and demand. (Wind is predictable hours in advance at best.)
  • CETO units are designed to operate in harmony with the waves rather than attempting to resist them. This means there is no need for massive steel and concrete structures to be built.
  • CETO wave farms will have no impact on popular surfing sites as breaking waves equate to areas of energy loss. CETO wave farms will operate in water deeper than 15 metres in areas where there are no breaking waves.
  • CETO is the only wave energy technology that produces fresh water directly from seawater by magnifying the pressure variations in ocean waves.
  • CETO contains no oils, lubricants, or offshore electrical components. CETO is built from components with a known subsea life of over 30 years.
  • Wave energy can be harnessed for permanent base load power and for fresh water desalination. The ratio of electrical generation to fresh water production can be quickly varied from 100% to 0% allowing for rapid variations in power demand.
  • CETO uses a great multiplicity of identical units each of which can be mass produced and containerised for shipping to anywhere in the world.

For these reasons, wave power is certainly among the most attractive of the range of possible renewable energy technologies. Unfortunately, it is also one of the most nascent in its development cycle (along with engineered geothermal systems, which is probably even further behind — I’ll cover this in a later TCASE post). Wave power is also up against one of the most hostile environments that any man-made structure has to endure — the salty (corrosive) and capricious (exposed to occasional very high energy events) marine environment.

CETO is certainly an innovative technology: it appears to overcome some of the shortcomings of the Pelamis device, such as a reduced bulkiness with more modular construction and deployment possible, lower vulnerability to storm damage due to anchoring at 25 m, and an added bonus of providing a neat method for reverse osmosis desalination using mechanical rather than electrical energy. The latter seems to be its biggest selling point, as I explain below.

The anticipated output for CETO wave power is given on page 10 of this senate submission. At deep-water wave resource sites with 90% availability (i.e. times when the units can generate some power, even if below their peak), capacity factors are stated to be 40%, which agrees with experience from the Pelamis device. For instance, if all of Australia’s estimated resource of 572 GW could be harnessed, the annual yield would be 1.6 million GWh (we’re talking about theoretical limits here, not what is actually likely to happen).

Carnegie’s strategic plans look towards building a 50 MW peak facility using an a 300 buoy system at 180 kW peak per undersea buoy. The technical documentation says that 2 m wave conditions with a 6 sec period, a single CETO unit can produce 80 kW of power (i.e. 45% capacity factor) or 11 litres/sec of fresh water. Each CETO unit will extract 15 — 20 % of the wave’s incident energy, and they’ll be arrayed a few units deep.

The news story here, citing a CETO official, claims a 50 MW plant could produce 25 MW of electricity and 50 GL of fresh water per year. From the technical data (table 3.7), you can work out that if the 50 MW unit was dedicated just to desalination, it could output ~90 GL/year. Actually, at 11 l/sec average output, each unit would produce 350 ML of fresh water per year (on average), and a 300-unit field’s output would be 104 GL/year. So, a figure of 90 to 105 GL/year seems for a 50 MW plant seems to be right, if the technical report is to be believed.

Their first ‘commercial’ wave farm, however, is a more modest venture, at 5 MW peak (2 MW average at a 40% capacity factor). It is due to begin operating outside of Perth, Western Australia in 2011, at a cost of $50 million. That works out to be a capital cost of $25,000 per kW of average power. Assuming a loan for capital at 6% interest, repaid over 20 years, and O&M costs of 1-2 c/kWh, this works out to be a wholesale cost of electricity of ~28 c/kWh. If successful, a 50 MW plant is planned for 2013.

Even if they can achieve a sharply declining cost curve after their first-of-a-kind plant, it’s a long stretch to imagine them expanding to 1,495 MW (peak)  in the subsequent 9 years. Carnegie’s forecast is $7.5 billion for the 1,500 MW, which is $12.5 billion per average GWe, so a projected better than halving of total cost compared to the initial 5 MW demonstration plant. That sort of price reduction with scale-up actually seems conceivable to me — I just doubt their capacity to raise the capital without massive subsidisation (WWF is asking for special wave-power feed-in tariffs — in Ireland, Portugal and the UK they average 25 to 35 c/kWh).

Still, the desal costs look impressive — indeed, almost too good to believe. The 100 GL/year Port Stanvac RO desalination plant in Adelaide will cost $1.83 billion in capital costs, and then has to pay for its electricity. A direct-cost scaling-up of the 5 MW CETO plant to 50 MW, which is anticipated to produce ~100 GL/year (see above), is $500 million (a slightly lower figure is cited here), with no electricity costs (or greenhouse gas emissions). Am I missing something here?? If this fresh water production rate from CETO can be confirmed, then this seems like the ideal use of this technology, high-cost electricity be damned. Comments on this point would be appreciated.

WWF recently produced a glossy document which stated that we should be aiming for 12,000 MW of wave energy by 2050. They claim:

Wave energy is an ideal source of baseload power – it is highly predictable and reliable, particularly along the southern coastline of Australia where regular storms in the Southern Ocean deliver constant swells to the shoreline. Analysis indicates that waves from which CETO generates electricity exist over 97.5% of the time, making it a baseload resource.

They also say:

Carnegie forecasts that by 2020, approximately 1,500 MW of CETO wave energy capacity could be installed along the southern coastline of Australia, contributing around 4% of Australia’s forecast electricity needs – emissions-free. To achieve this, the combined area occupied by CETO wave energy facilities is less than 1,000 ha (3.2 km2).

There are two obvious sleights-of-hand here.

First, ‘availability’ is quite different to capacity factor. A 40% capacity factor (if that is achieved consistently – probably only in the high-energy locations) means sometimes it is delivering close to 100% of rated capacity, sometimes close to 0%, sometimes 10%, sometimes 70% etc. Cumulatively, it averages 40%, but the actual output is variable and not able to be controlled. Thus, as Peter Lang has explained in his many posts, to ensure system reliability, you have to have back it up — at least to the minimum system-wide output of a geographically dispersed deployment. It could conceivably be considered ‘baseload’ if you chose to rate the plants according to a 1 m wave height (see figure here), but that would blow out the costs of average power enormously compared to the already high costs cited above, and would also lead to massive ‘dumping’ when there were large swells across large stretches of coastline.

So, CETO power may be ‘predictable’ (many hours in advance), and even ‘reliable’ (i.e., there will always be some waves, generated some power, so the 97.5% figure cited above might be strictly true but not relevant), but ultimately, wave power is still variable and fickle, and therefore not suitable for cost-effective ‘baseload’ electricity (or dispatchable uses, such as intermediate or peaking power).

Second, with the area occupied figure (the claim of 1,000 ha for 1.5 GWe peak).  My calculations, as outlined in TCASE 5, suggest a requirement of 115 linear km of coastline, with the buoy-field occupying an area of about 700,000 ha. Even if a CETO facility is twice as efficient at trapping wave energy than Pelamis (a generous assumption), this figure is still 2 to 3 orders of magnitude larger than the Carnegie claim. Why the huge difference? I speculate that they’re using a statistical trick here that is similar to the Mark Jacobson’s habit of stating the area of occupied by wind farms by only counting the actual physical displacement of the turbine towers when packed together. You can do a similar thing with the 6.8 billion people on Earth and find that they can all fit, cheek-by-jowl, within the Isle of Man. Maybe so, but it’s hardly reflective of reality and is a silly and disingenuous distortion of the facts.

Still, it’s tough to pick apart the details of spin vs reality, especially from news stories and media releases (I emailed CETO to ask if they had any available operating data on their demo plant, especially with regards to annual output per unit, but they never replied). So if any of you have alternative interpretations to me on these data, I’d like to hear it.

Conclusion (preliminary): CETO is not cost-effective for electricity generation, it cannot be considered ‘baseload’ (it is certainly not dispatchable), and its lifespan in trying marine conditions is highly uncertain. BUT, its potential for low-cost, high-output mechanical desalination (based on high-pressure pumping to an onshore facility) seems enormous, if the preliminary reports can be confirmed.

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39 Comments

  1. If this fresh water production rate from CETO can be confirmed, then this seems like the ideal use of this technology, high-cost electricity be damned.

    If efficiencies of scale & technology refinements *cannot* in the long term bring the cost of CETO down to the ‘assumed’ price of nuclear, then I’d go along with this summary of the technology.

    Of course at this stage I remain agnostic as to whether or not they’ll be able to do so. Economies of scale and new materials can have radical effects on price.

    However, is it the best desal system?

    I’d love to see some cost & benefit comparisons with the Seawater Greenhouses, which also create the potential for fresh vegetable produce from deserts, as well as fresh water, desert reclamation and reforestation, especially energy crops combined with biochar energy systems.

    Some permaculture guru is going to come up with an industrial ecosystem where water, food, and liquid fuel energy (2nd generation biofuels) are all produced surprisingly cheap from the world’s deserts!

    http://www.seawatergreenhouse.com/

  2. I think desalination is the ‘killer app’ that will encourage acceptance of NP at coastal sites. It has been previously noted that the large NPP/desal complex in the UAE will only use reverse osmosis and not thermal methods such as flash distillation. I believe water from Adelaide’s Pt Stanvac RO desal will cost nearly $3 per kL and will be blended with reservoir water on an as-needed basis. Thus in a heatwave and drought the fossil fuel stations will work extra hard not only to supply water but also to power the air conditioners in the city.

    Isn’t 25 metres too deep for extended working by scuba divers? I think a CETO array would need a submersible for maintenance. If indeed CETO does produce useful electricity by 2011 it will have beaten dry rock geothermal despite the latter’s head start.

    Another reason to like RO desal as a task for relatively constant output NP is that more fresh water could be made during low external load conditions. If the water is sent to an elevated reservoir less effort will be needed later to pump through pipelines.

  3. Marine growth is likely to make ocean wave power impractical. The maintanance will prove to be to too expensive. Effective paints (such as lead based paint) to prevent marine growth are toxic. Less toxic materials like copper based paints are too expensive. I predict that barnacle growth will kill attempts to harness wave power on a wide scale for long periods of time unless some non toxic super paint can be found. If it is I would be the first to use it on my boat.

  4. If the desal numbers hold, this would be the ideal application for this technology IF the deployment numbers were found to be cheaper than other options AND it can be shown clearly that there is no negative impact on the littoral zone associated with the installation.

    I would not bother with attempting to generate electricity with this system – it would appear to be more trouble than it is worth.

  5. 1750 customers @ 4000kWh/a for the 5MW plant.

    It won`t be that hard to find 2000 or more people that will pay 40cent/kWh (thats 27€cent…thats about normal European tarrif) to get this CETO plant built.
    Tap into these WWF people…

  6. Barry,

    CETO is a near shore wave energy converter and the wave resource in deep ocean is likely to be different so using CETO as an example across the board in your post may not be that useful (Pelamis and the Anaconda Wave Snake are examples of deep ocean WECs). Your point about a device working with one meter waves and perhaps having to dump energy in larger waves is not strictly accurate as WECs such as Pelamis are ‘tunable’ for different seas i.e. the WEC can generate power across different wave heights and periods, changing its operating parameters for different seas. I think a different problem, than not having waves, is having waves that are too large at certain times of the year with the WEC going into survival mode with no power generated.

    The Southern ocean may be a better resource to think about because its long fetch of about 4,000 kms gives much more predictability but then the problem becomes the economics of transporting power back to land. As to how much area is likely to be taken up by a wave farm if we are thinking of trying to equal the output of a coal fired power station we don’t know because the only operational experience so far of a ‘farm’ were the three Pelamis units operating briefly off Portugal last year (till Babcock and Brown went under no pun intended). Everything else has been simulations of 10 or so units, not hundreds let alone thousands so we don’t know how much sea area might be needed and what the environmental effect of that could be inshore. Its been suggested that adjacent units could reinforce energy flow rather than cause a general attenuation of wave power flowing through a wave farm (its also been suggested that lots of units offshore could offer a ready made fishing sanctury).

    Its early days as evidenced by the huge number of designs (and also for construction from different materials such as cement and rubber e.g. the snake) so I’m not sure anybody can make more than general predictions about wave energy on a large scale.

    I think you would have to add Aquamarine’s Oyster and Oceanlinx’s oscillating water column device for desalination along side CETO and that made me wonder if a partial answer to your point about despatchability might be that such devices could pump water into a onshore reservoir located by the sea with turbines to generate power.

  7. It won`t be that hard to find 2000 or more people that will pay 40cent/kWh (thats 27€cent…thats about normal European tarrif) to get this CETO plant built.

    Not on Planet Heavyweather, perhaps.

  8. John Newlands said
    “Isn’t 25 metres too deep for extended working by scuba divers?”

    Depends on what you mean by extended – 25 metres allows about 30 mins no-deco time so normal scuba gear would allow a dive to use a full tank of air with a 10-15 min deco stop.

    Commercial divers could easily use gas mixtures and surface demand gear to extend that significantly

  9. “You can do a similar thing with the 6.8 billion people on Earth and find that they can all fit, cheek-by-jowl, within the Isle of Man.”

    Going off on a tangent:
    “And to close on, the Dept of Small Consolations. Some troubledome just figured out that if you allow for every codder and shiggy and appleofmyeye a space one foot by two you could stand us all on the six hundred forty square mile surface of the island of Zanzibar. ToDAY third MAY twenty-TEN come aGAIN!” (Stand on Zanzibar, 1968)
    So the future becomes the present.

  10. I don’t know where this attitude that a little bit more urban density is so evil comes from? We’ve lived that way for 10 thousand years, only recently did the car allow the monstrosity of suburban sprawl to erupt out over the landscape.

    We have no sense of place…. we drive through traffic to get to a little box where we work, and then drive an hour back home again to get to a little box where we sleep. Then we drive somewhere to do sport, go to church, go to the movies, take the kids to school… it is madness.

    1 million people in the blandness of suburbia = 400 square miles.

    1 million people in New Urbanism = 40 square miles.

    Which leaves more room for ecosystems to thrive, for local farmlands, for parks and promenades and nature?

    Anyone that was into conservation and the environment should know that the city environments we build is either our greatest threat or greatest hope. There’s still room for family homes with a backyard in New Urban town plans. Maybe they’re a little bit narrower, and there is less of them and more people living in terraced houses or town houses, but you get my point. It’s not like everything we like about suburbia has to disappear! But we can design urban environments where everything we like about the city is just outside our front door, with a greater sense of community and place and involvement and connectedness.

    So protests about density just sound… uninformed, to my ears.

  11. eclipsenow, 13 April 2010 at 8.50,

    I’m not sure where your urban density argument came from, but surely a more practical solution for “leaving more room for ecosystems to thrive” would be to drastically reduce our reliance on beef as a primary food source. We’d save several orders of magnitude more space than 360 (400-40) square miles per 1 million people if we could do that. Not to mention we’d be cutting our greenhouse gas emissions some 15% or more. Packing everyone severely into one spot sounds a bit silly in comparison.

    I’m not sure how likely either of these events happening are, but I’m gonna say that they’re “equally unlikely”.

  12. Well, eating red meat on a daily basis might not be that great an idea for health reasons anyway, but I’ve known vegetarians that can’t metabolise enough iron from vegetables even though they were eating all the right stuff, even stacks of Pop-eye’s Spinach. So maybe a bit less red meat, but I wouldn’t want to see it taken off the menu altogether.

    Packing everyone severely into one spot sounds a bit silly in comparison.
    I agree. Which is why they don’t make New Urbanism ‘severe’ as you put it. According to this science show episode, where do young adults most prefer to live these days? What trend is occurring across Western city cores?

    http://www.abc.net.au/rn/scienceshow/stories/2009/2571785.htm

    For that matter, where do we LOVE to go on holidays to appreciate cities with charm? Venice, Paris, Rome, London… oh yeah, all those cities that have a more traditional city plan, semantics in architectural form that make sense, and above all, *well planned* Density and Diversity of city form and function!

  13. Gene,
    ever lived in Paris? Ever lived a short walk from a beautiful ‘city room’, which us Aussies have a hard time imagining, which basically is a fully functional town square and public space beautifully framed by your favourite book shops, Cafe’s, Restaurants, local school, banks, Post Office, and other functions of the ‘town’… and yet all within walking distance.

    Sell your car, and by a Granny-trolley.

    Get fit.

    Get to know the neighbours. Enjoy knowing the names of the people you buy your groceries and coffee and books from.

    If all you know is McDonalds Drive-Thru and shopping at Westfield Malls, and the ‘freedom’ of driving across Sydney through peak hour traffic each day, then no wonder you can’t imagine life without a car.

  14. Well, I don’t live in Paris and don’t desire to. Anyway I don’t earn enough money to live in Paris. I would go nuts not being able to eat Tex Mex in Paris, which is my main diet here in Austin, not McDonalds, which is for kids and soccer moms. I don’t drive to work every day because I work out of my house. If I didn’t eat beef I could live on chickens I guess. But thats the main meat in Tex Mex food anyway. Fish is not eco friendly since it depletes the oceans and if grown in land, depeletes valuable water here in Texas. There have been water wars over growing catfish fish in ponds here – inland. I do hike and bike every day. I drive a hybrid electric car less than 10k miles per year.

    Basically I think the whole conservation ethic is going in the wrong direction. We need more supply and we need some kind of population control. Our new power sources need to be consistent with the environment. I don’t see how eliminating beef solves our energy problem. If I gave up my 2 acre lot I would not have room to put up my ham radio antennas. No, I see apartment living with no cars and no beef as a step backwards, not an improvments in living standards. You are not going to get Texans to buy into the no beef and no cars theory. Heck, we will build new nuclear plants before we do that.

  15. You are not going to get Texans to buy into the no beef and no cars theory. Heck, we will build new nuclear plants before we do that.

    Can’t we do both? Beef in substantial quantities is bad for you health and is extremely wasteful of nutrient, land and water. Supplied at commercial scale, it’s also extremely cruel — much crueler than what could happen with chickens.

    Cut out or severely reduce beef consumption and you are going to get less salmonella, and e-coli H10_O57. You’re also going to get less PCBs in the diet and less obesity. You radically reduce workplace injuries in those abbattoirs (many of them underpaid undocumented workers shipped in from south of the border) as well. What’s not to like about that?

    Let’s build good urban, suburban and interurban transport systems so people hardly need cars. Again, if you do that, not only does the demand for oil drop, (and thus the rpice of everything that oil is used to raise, transport or refrigerate), not only do GHG emissions decline, not only is every net-oil importing country better hedged against oil price volatility, not only are places people are bothered about like Iran and Saudi Arabia and Venezuela relieved of petro-dollars, not only are serious impooerters like the poorer countries in Africa and Asia relatively enriched because their import bill falls, but the number of road trauma victims (dead and seriously injured) declines, saving us money in the health system and in lost productivity.

    Again, what’s not to like about that?

  16. Hi Ewen,
    just to pick up some more on the points you raise about oil independence and other economic impacts…. this from our ABC on measurable Australian GDP impacts of driving instead of catching more trains.

    ****

    ” Citizens are saying, we want to pay for increased public transport. We see that in research by the Warren Centre where 70% of the citizens who were surveyed said yes, move my tax out of the roads budget and into public transport. Now that’s a resounding response…
    — and —

    …Robyn Williams: The cost of road crashes in Australia is $17 billion a year. The cost of traffic jams in America, according to The Economist is $100 billion a year, and that was in 1999. The cost of traffic jams in Australia was $12.8 billion in 1995. By 2015, long before 2024, it’ll cost us $30 billion a year – that’s six times what the Commonwealth spends on all scientific research. Can you afford it? Whatever the energy source, hydrogen, wind or whatever, we can’t, says Dave Rand, just hope to go greener and keep our vehicles.
    — and —

    Sally Campbell: Public transport systems cost less as a percentage of GDP than transport systems based mainly on roads. And we see that when they start to compare Europe’s current systems to the current systems in Australia and the US and it’s almost a third less in terms of percentage of GDP to operate a system mainly based on public transport. So there are massive cost savings to be had.

    Robyn Williams: You’re talking about billions.

    Sally Campbell: Yeah, we’re talking about billions of dollars, we’re talking about two, or three, or four a percent of GDP that we could be saving. This is huge amounts of money.”
    http://abc.net.au/rn/science/ss/stories/s1266965.htm

  17. Gene Preston,

    “I don’t see how eliminating beef solves our energy problem”

    It doesn’t. But it eliminates a huge chunk of GHG emissions, habitat destruction and ecosystem fragmentation (i.e. agriculture driven extinction).

    “I see apartment living with no cars and no beef as a step backwards, not an improvments in living standards”

    I disagree strongly with your belief, but agree that this is reflective of the belief of much of western society. Cars are particularly unlikely to go away, so we really need to get cracking with grid-powered vehicles so they’re not spewing out carbon constantly. Another reason we need more power, not less – we need nuclear power.

    “No beef” is very unlikely too, but I see at least a reduction as well within the realms of possibility.

  18. DV82XL, 12 April 2010 at 1.44

    “I would not bother with attempting to generate electricity with this system – it would appear to be more trouble than it is worth.”

    I’m not sure – if (hypothetically) they’re already down there for the purpose of desalination, what would be the capital cost on top of this to produce electricity as well?

  19. @TeeKay – It’s not just the cost to produce electricity, but the cost of the switching, transmission, and integration that has to be taken into account vs the return on the fresh water, which still needs to be transported, but can be stored at various places along the supply routes.

    Frankly I think this system in general is just another distraction, and I suspect that in the sizes of the installations that will be needed for commercial deployment, impacts to the environment will manifest that may not be trivial.

  20. I have a more open mind on the matter DV8. If it can produce cost-effective low emissions desal then let’s have it. This is not an alternative to NPP but as we are still a very long way in Australia from getting nuclear, and this would be approved by the populace without blinking, it becomes an alternative to the carbon footprint of desal.

    If there is also some way of switching between desal and electricity that is no more expensive than, say, gas then I’d say let’s do that too. I suspect this won’t be the case but as long as we’re looking at it, let’s give it the once over to at least exclude that. Perhaps it spends most of its time pumping desal and then if there is a slew, it switches? Again, as you say, the costs of all the connection switching equipment may not make it economic.

    In Australia though we do have a water problem, especially in the southern portions of the mainland.

  21. This is off topic and apologies for that, but I thought it interesting that at the current Washington shindig on safe and secure nuclear waste storage, Barack Obama mentioned plutonium stockpiling by the US of own and other countries waste as providing fuel for further nuclear power. Did he have 4th gen plants in mind I wonder? Maybe a future post topic? eg Who owns the submitted Pu now in safe US hands? Does this give the US a decided advantage?

  22. I looked at CETO with some enthusiasm some time ago but the more I looked at it the less convinced I became about whether it could achieve its stated outputs.

    Most of the schemes seeking government funding of some sort seem to me to be more like grandiose perpetual motion machines attempting to use a multitude of technologies.

    For all the schemes already subsidised by government funding with grandstanding by politicians, I have been unable to obtain any actual costs and production/generation figures. If I had a choice, I would not be paying another cracker until I had seen the results for the existing schemes.

    While I have no problems with people playing with various “renewable” technologies, I think the real step forward is with nuclear power and Australia should be developing the full nuclear cycle from mining, processing, electricity generation, reprocessing and storage of waste. Storage for the world’s waste nuclear fuel and even decommissioned weapons is a responsible and profitable enterprise. The fact that almost all of our politicians have declared that they will not look at this industry fully leaves me speechless.

  23. This just in:

    British Green Party Candidate Chriss Goodall accepts nucelar power in Mix, cites David Mackay with apporval

    Scroll down and check his comment in the body of posts responding to his original article.

    Like many of the readers of the Guardian web pages, I am a big enthusiast for Prof David MacKay’s rigorous approach to the issue of how we build a portfolio of electricity and other resources to provide the UK with 120 kWh a day per person. He thinks that we probably need nuclear and I don’t disagree with him. (For the avoidance of doubt, this is NOT Green Party policy and remains a minority opinion within the Party).

  24. Barry, it doesn’t much matter how many people live how close to the
    coast, because they only use … ~10% of the water. What matters is the
    proportion of food Calories produced close enough to
    the coast for CETO to supply the water, because that’s
    where you need the bulk of the water. Still if CETO can produce fresh
    water and perhaps also supply pumping energy for a useful
    distance, it could still be valuable. Just
    like solar hot water heaters … they don’t solve our energy problems, but
    reduce the scale of the problem we are left with.

  25. Pingback: The ways we choose our fact – the real tragedy of environmental ignorance « Moth incarnate

  26. Re: Barnacle and sea life growth. I really don’t think barnacle growth would really cause significant problems to the system. They grow, time goes by, you clean/replace. The parts that they would grow on would be very accessible and easy to maintain. 25M depths is really quite shallow.

    Re: Energy Production. Agree with most comments, Costs/reliability issues will be a major deterrent. However, subsidies are there, and reducing Green House gasses is on most political party agendas. Subsidized green energy programs are here to stay at least in the short-medium term. Can’t compete with coal or natural gas without help, but help is probably going to be available.

    Re: Water generation. Two Thumbs up. If only to subsidize an existing well or system it would still make sense to me. Even if only agriculture benefits, it would still make sense to me. If your a rich snob who wants to water his garden during a drought to make it looks prettier than next door it makes sense to me. If your a tourist town, and everything is all dried up and ugly, it makes sense to me.

    Water makes sense to me.

  27. It sounds like a form of wave power is going to run desal in the states, but I don’t think it is CETO.

    “The US Army Corps of Engineers has issued the first permit for a wave-powered desalination plant in American territory to a company called Independent Natural Resources. Waves will operate ‘Seadog’ pumps, which will lift water into the plant and onto a water wheel connected to a generator, which will create electricity to operate a reverse-osmosis desalination system. The permit runs for four years. Let’s hope they don’t harm the environment, permanently impact drilling operations, or give Rube Goldberg any crazy ideas…”

    Barry, why are you in favour of CETO for desal? Is it the bottom line that the mechanical energy from pumping all that water on shore seems cheaper than nuclear running desal? I wish we already had extensive industry experience of the Seawater Greenhouse concept to compare that as a technology for desal, because water is going to be the next big issue after oil.

  28. Ewen Laver says ‘IF there is also some way of switching between desal and electricity that is no more expensive than, say, gas then I’d say let’s do that too. I suspect this won’t be the case but as long as we’re looking at it, let’s give it the once over to at least exclude that. Perhaps it spends most of its time pumping desal and then if there is a slew, it switches? Again, as you say, the costs of all the connection switching equipment may not make it economic.”

    Ewen, Ceto claims that it is merely a matter of switching a valve to direct the flow of water from desal to turbines. What massive costs might there be in the switching equipment?

  29. Peter Ferguson – at least when I was referring to switching equipment up thread, it was that which would be required, along with the transmission lines to move the power generated to market, and the infrastructure to tie it into the grid. It had nothing to do with switching the system from one mode to the other.

    These delivery costs for the electricity, (I was postulating) might be so high that the desalinated water produced by this wave powered apparatus under discussion would have greater value. This is because the costs of transportation, and the costs of storing transient surplus output for water are much, much lower than for electric energy.

    Thus while an installation like this may be economical, indeed profitable for desal, I question if that would be the case foe co-generation of electric power.

  30. Pingback: Thinking Critically About Sustainable Energy #5 « Dylan Ratigan

  31. Pingback: Anti-nuclear cartoon book, 1978 – anything changed? « BraveNewClimate

  32. The key to success in renewables such as Wind, Solar, and Wave will be to incorporate cost effective energy storage solutions to buffer the volatile & unequal supply and demands of energy in these grids (especially in regional grids). There are new utitility scale battery technologies currently at or near commercialization that forgo the archaic means of energy storage which were highly taxing on the environment. Old tech used Sodium Sulfur (NaS) batteries which are dangerous and environmentally hazardous, there are more cleanly and recently developed Zinc Bromide (ZBB) Batteries, and there are the revolutionary Vanadium Redox Flow Battery (VRB) systems which could find widespread applications in the renewable energy space.

    NaS Batteries
    NGK Insulators, LTD. (TYO:5333)

    ZBB Batteries
    ZBB Energy Corp (AMEX: ZBB)

    VRB Batteries
    Prudent Energy (private co.)

  33. How is a zinc bromide battery less environmentally hazardous than a sodium sulfur battery? Anything that involves dealing with bulk amounts of elemental bromine should have a higher freakout factor than sodium-sulfur batteries. Not that I think a properly engineered system should present a risk, but saying a Va or ZnBr flow battery is cleaner or safer than an NaS battery sounds like a dubious claim to me.

  34. @rleberenz

    The Huxley Hill wind farm on King Island uses a ‘revolutionary’ Vanadium Redox Flow battery successfully since 2003. But it makes up only 3% of King Island’s small electric capacity despite its 55,000 litre capacity of electrolyte, acting as a buffer for wind’s volatility rather than ‘storage’ in the usual sense of the term. At AUD 20,000 per kW (compare under AUD 1,000 /kW for an OCGT), it will make expensive energy even more expensive. It provides a good example of what is technically possible with an unlimited budget, but a sober reminder of its limitations.

    http://en.wikipedia.org/wiki/Huxley_Hill_Wind_Farm
    http://www.hydro.com.au/system/files/documents/King_Island_Renewable_Energy_PK_2008.pdf

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