6 ms·

Salters Duck

84 points by atilev 12y ago

jfroma 12y ago
I've read another article about a similar device in Brasil: http://m.youtube.com/watch?v=GA_UgVm9bvU http://m.youtube.com/watch?v=GA_UgVm9bvU
chadpaulson 12y ago
Interesting overview of Edinburgh duck R&D. https://www.youtube.com/watch?v=_bdeNuRF-yE https://www.youtube.com/watch?v=_bdeNuRF-yE
deegles 12y ago
I couldn't find any pictures or videos of how this works.
- forgotpasswd3x 12y ago
  http://www.technologystudent.com/energy1/tidal7.htm http://www.technologystudent.com/energy1/tidal7.htm
- gus_massa 12y ago
  From Google Images: https://www.google.com/search?q=Salter's+duck&tbm=isch https://www.google.com/search?q=Salter's+duck&tbm=isch
rndn 12y ago
I like this concept in particular, because it has no mechanical parts in contact with the water: https://www.youtube.com/watch?v=gcStpg3i5V8 https://www.youtube.com/watch?v=gcStpg3i5V8 Edit: It seems however that tidal power is a more interesting research area [1]. I still find it's a neat idea, it also makes awesome noises: https://www.youtube.com/watch?v=IK65S0sPtsg https://www.youtube.com/watch?v=IK65S0sPtsg (loud) [1] https://en.wikipedia.org/wiki/Wavegen https://en.wikipedia.org/wiki/Wavegen
pavel_lishin 12y ago
"DUCK EFFICIENCY on COMPLIANT AXIS" is a great title for a graph. It would make for a pretty amusing piece of art. http://i.imgur.com/NR34IOt.jpg http://i.imgur.com/NR34IOt.jpg
- joezydeco 12y ago
  Wasn't it the title of an ELP album from the 1970s?
krylon 12y ago
It sounds like a brilliant idea, how come these things aren't all over the North sea?
- sethrin 12y ago
  Because waves don't transfer that much energy. There's a reason why ships had sails, even though winds were highly variable and waves somewhat less so. Also, maintenance on anything you put in the ocean tends to be high.
tootie 12y ago
Tidal generators are in production. There's a pilot program installing them in NY harbor. They're fully submerged and I don't think they're ducks.
- knodi123 12y ago
  this is not about tidal power
wxm 12y ago
A friend of mine worked with Prof. Salter. He's an incredibly brilliant, smart and kind scientist. Unfortunately, much of his research was 'blocked' due to someone miscalculating the cost by twice the amount, starving the research field of funding until recently. There are quite a few related spin-outs (e.g. Pelamis Wave, website currently down). Edinburgh also just got a huge wave tank for more experiments (http://www.bbc.co.uk/news/science-environment-27702506 http://www.bbc.co.uk/news/science-environment-27702506).
atilev 12y ago
What's more interesting is that Salter was Studying AI at the university of Edinburgh
guelo 12y ago
That's the problem with cheap oil, like we have now with fracking, it kills all market incentive to develop clean energy. If we're ever going to get serious about climate change we need a dynamic carbon tax that keeps the price of fossil fuels stable and high. If we had such a carbon tax right now, that kept gas price at the previous price of $4/gallon, it would be a huge windfall that could be used to spend on clean energy incentives as well as low-income energy subsidies.
- mangecoeur 12y ago
  well no, because most renewable energy sources aim to produce electricity. Very little electricity is generated using oil, so the oil price should have little impact on most renewable energy production. The culprits are cheap gas and coal - especially coal, which really should be heavily taxed because of the huge health and environmental impacts from mining and burning coal.
  - dredmorbius 12y ago
    A few corrections. Within the US, little electrical generation comes from oil (about TK%), but outside the US that level's rather higher -- something I only learned recently myself when trying to rebut the statement that oil was significant in electricity generation elsewhere. Hrm. Still not all that big. 256 Mtoe per the IEA in 2012, of 6,497 MTOE, about 4% - 6% depending on how you read net global imports / exports. (How does the world import/export to itself?) http://www.iea.org/Sankey/index.html http://www.iea.org/Sankey/index.html Though in many parts of the world, electricity comes from gasoline or diesel generators on small scale rather than central generation plants. There's also the fact that renewable energy can produce liquid or gas fuels via the Sabatier process (resulting in natural gas) or Fischer-Tropsch fuel synthesis (liquids). These aren't used in bulk now, but could be, and represent a possible carbon-neutral gas and liquid hydrocarbon fuel source in future.
  - guelo 12y ago
    It's all linked because fracking produces both gas and oil. But I agree coal is the biggest culprit. That's why the tax should be on carbon, not a specific fuel. But the tax should be designed to be dynamic somehow to act as a stabilizer to keep prices from going to high or to low too fast.
mangecoeur 12y ago
http://en.wikipedia.org/wiki/Pelamis_Wave_Energy_Converter http://en.wikipedia.org/wiki/Pelamis_Wave_Energy_Converter The Pelamis, based on technology evolved from the Salters Duck at the Edinburgh labs, was installed in pilot installations for a few years through the company has sadly since gone bankrupt
dredmorbius 12y ago
Total available wave energy relative to present human energy consumption is minuscule. Realize: wave energy is solar power twice removed. First solar heating converted to wind energy, then wind to waves. If you can capture the initial solar flux, you're better off. Wind is your second-best option, and where that's locally high, the EROEI (energy returned on energy invested) is quite high. Marine installations are notoriously high maintenance. Water, salt, corrosion, marine life, snagging, navigations hazards, and other factors, all play a role. Few man-made (or natural) materials survive well, and those which do tend not to play a big role in power generation. Even tidal energy, with both more available power and greater concentration than wave energy, has at best limited potential. As an example that may be relateable to HN, the energy avaiable from daily fluctuations in the San Francisco Bay, at the Golden Gate. In 2006, EPRI (the Electric Power Research Institute) established that the Golden Gate has a tidal energy potential of 35.5 megawatts of total extractable average energy power (852 MWh/day, 310 GWh/year), of which 15 to 17 GWh might be practically exploitable at costs comparable with current wind and natural gas projects. The total tidal energy represented at the gate is 237 MW (average). Capturing the entire amount would require blocking the Bay to any and all shipping traffic, or installing locks or other means to allow shipping in and out of the Bay. The total daily energy (5,688 MWh) is still well below the 18,000 MWh consumed by San Francisco daily), though it is a healthy fraction at 32%. Note that that's the power draw _of San Francisco alone_. Not the greater Bay Area. Yes, all that water flowing in and out of the bay daily and the "immeasurable energy" it represents? About 1/3 of the City of San Francisco's electricity usage. Human beings use a LOT of energy. http://www.sfenvironment.org/article/hydro/tidal-energy http://www.sfenvironment.org/article/hydro/tidal-energy http://oceanenergy.epri.com/attachments/streamenergy/reports/006_CA_06-10_-06.pdf http://oceanenergy.epri.com/attachments/streamenergy/reports...
- msandford 12y ago
  What waves and tidal energy represent, though, is something which might be a lot more capital efficient. Yes you're much closer to the power source using photovoltaics but they're only 20% or so efficient right now commercially. Further, the sun only shines on where I live between 8 and 16 hours a day, depending on the season. The useful average power I can expect to extract on average is about 3-4 hours per day. Waves, on the other hand, are an excellent store of energy and they persist for a long time. Easily overnight and actually over many days. So if you can reliably produce power from waves for the same capital cost per watt installed, you might get 3x-5x the energy production from the wave plant versus the solar plant. And that's before you take into account the storage necessary for solar! In other words you might be able to spend 10x on a wave power plant as a solar plant and break even. If it only costs 2-3x as much per watt, well, you're saving money. And the batteries (the ocean) are free.
platz 12y ago
Does it generate DC or AC? I think there are losses if you want to transport and connect the power generated up to the grid
- jacquesm 12y ago
  It generates pulses of AC power, but that can be overcome by feeding those pulses into a flywheel or superconductor based short-term storage system.
jacquesm 12y ago
Wave energy is one of those ideas that 100's of clever people have had independently over the years and not a single one has been able to make it work reliably and cost effectively. We've seen a wide variety of prototypes, some even made it to net power out but absolutely nothing came close to winning the prize. (Though that didn't stop the government from pumping large amounts of subsidy into some of these.) When you compare 'wind' to 'waves' (or tides, for that matter) the environment is even more hostile, the power transportation problem more acute and the engineering challenges incredibly more formidable and the maintenance headaches harder still. Having mostly stationary waterborne structures is hard enough and commands skills that are rare and very expensive (think oilrigs). Now change that to dynamic structures which drive generators, add in storms, salt water and interference with shipping and you're looking at a very expensive and complex mixture. It will take extremely deep pockets to pull this off successfully, with the inbuilt assumption of a number of false starts and resulting re-engineering. Elon Musk will likely walk on Mars (or die on impact) before we will see widespread adoption of tidal energy for electricity generation on Earth. Which is a pity, because it seems such a good idea.
- wgx 12y ago
  This one is in use in Scotland: http://en.m.wikipedia.org/wiki/Islay_LIMPET http://en.m.wikipedia.org/wiki/Islay_LIMPET
  - jacquesm 12y ago
    500 KW (now derated to 250KW), it's neat but that's piddly little bits of power for an installation that size. A single present day wind turbine will produce up to 3 MW continuously rather than pulsed. Pity I didn't know about it when I toured Scotland a couple of years ago looking at their renewable energy installations. This one was by far the most impressive: http://pics.camarades.com/v/jacques/trips/scotland08/dscf1585.jpg.html http://pics.camarades.com/v/jacques/trips/scotland08/dscf158...
- alephnil 12y ago
  The problem with wave energy is not to make a device that makes energy from waves, but to make one that can withstand the storms that invariably are present wherever there is wave power resources, and at the same time remain efficient. Most wave power prototypes have ended up as wreckage during the pilot period.
wiml 12y ago
A lot of wave and tidal motors were built along the California coast in the late 1800s and early 1900s. It's an interesting history. Cheap fossil power made them uneconomical, though. http://bldgblog.blogspot.com/2009/05/wave-motors-of-california.html http://bldgblog.blogspot.com/2009/05/wave-motors-of-californ... http://www.outsidelands.org/wave-tidal.php http://www.outsidelands.org/wave-tidal.php
Shivetya 12y ago
Still never understood why they don't concentrate on using areas where currents are well known, for Europe that would be the Straight of Gibraltar. There is energy in the outflow from the Med into the Atlantic at the bottom layers, surely capturing energy like that is not as difficult as surviving the forces waves put out.

84 points by atilev 12y ago

I've read another article about a similar device in Brasil: http://m.youtube.com/watch?v=GA_UgVm9bvU http://m.youtube.com/watch?v=GA_UgVm9bvU

chadpaulson 12y ago

Interesting overview of Edinburgh duck R&D. https://www.youtube.com/watch?v=_bdeNuRF-yE https://www.youtube.com/watch?v=_bdeNuRF-yE

deegles 12y ago

I couldn't find any pictures or videos of how this works.

forgotpasswd3x 12y ago
http://www.technologystudent.com/energy1/tidal7.htm http://www.technologystudent.com/energy1/tidal7.htm
gus_massa 12y ago
From Google Images: https://www.google.com/search?q=Salter's+duck&tbm=isch https://www.google.com/search?q=Salter's+duck&tbm=isch

rndn 12y ago

I like this concept in particular, because it has no mechanical parts in contact with the water: https://www.youtube.com/watch?v=gcStpg3i5V8 https://www.youtube.com/watch?v=gcStpg3i5V8 Edit: It seems however that tidal power is a more interesting research area [1]. I still find it's a neat idea, it also makes awesome noises: https://www.youtube.com/watch?v=IK65S0sPtsg https://www.youtube.com/watch?v=IK65S0sPtsg (loud) [1] https://en.wikipedia.org/wiki/Wavegen https://en.wikipedia.org/wiki/Wavegen

pavel_lishin 12y ago

"DUCK EFFICIENCY on COMPLIANT AXIS" is a great title for a graph. It would make for a pretty amusing piece of art. http://i.imgur.com/NR34IOt.jpg http://i.imgur.com/NR34IOt.jpg

joezydeco 12y ago
Wasn't it the title of an ELP album from the 1970s?

krylon 12y ago

It sounds like a brilliant idea, how come these things aren't all over the North sea?

sethrin 12y ago
Because waves don't transfer that much energy. There's a reason why ships had sails, even though winds were highly variable and waves somewhat less so. Also, maintenance on anything you put in the ocean tends to be high.

tootie 12y ago

Tidal generators are in production. There's a pilot program installing them in NY harbor. They're fully submerged and I don't think they're ducks.

knodi123 12y ago
this is not about tidal power

wxm 12y ago

A friend of mine worked with Prof. Salter. He's an incredibly brilliant, smart and kind scientist. Unfortunately, much of his research was 'blocked' due to someone miscalculating the cost by twice the amount, starving the research field of funding until recently. There are quite a few related spin-outs (e.g. Pelamis Wave, website currently down). Edinburgh also just got a huge wave tank for more experiments (http://www.bbc.co.uk/news/science-environment-27702506 http://www.bbc.co.uk/news/science-environment-27702506).

atilev 12y ago

What's more interesting is that Salter was Studying AI at the university of Edinburgh

guelo 12y ago

That's the problem with cheap oil, like we have now with fracking, it kills all market incentive to develop clean energy. If we're ever going to get serious about climate change we need a dynamic carbon tax that keeps the price of fossil fuels stable and high. If we had such a carbon tax right now, that kept gas price at the previous price of $4/gallon, it would be a huge windfall that could be used to spend on clean energy incentives as well as low-income energy subsidies.

mangecoeur 12y ago
well no, because most renewable energy sources aim to produce electricity. Very little electricity is generated using oil, so the oil price should have little impact on most renewable energy production. The culprits are cheap gas and coal - especially coal, which really should be heavily taxed because of the huge health and environmental impacts from mining and burning coal.
- dredmorbius 12y ago
  A few corrections. Within the US, little electrical generation comes from oil (about TK%), but outside the US that level's rather higher -- something I only learned recently myself when trying to rebut the statement that oil was significant in electricity generation elsewhere. Hrm. Still not all that big. 256 Mtoe per the IEA in 2012, of 6,497 MTOE, about 4% - 6% depending on how you read net global imports / exports. (How does the world import/export to itself?) http://www.iea.org/Sankey/index.html http://www.iea.org/Sankey/index.html Though in many parts of the world, electricity comes from gasoline or diesel generators on small scale rather than central generation plants. There's also the fact that renewable energy can produce liquid or gas fuels via the Sabatier process (resulting in natural gas) or Fischer-Tropsch fuel synthesis (liquids). These aren't used in bulk now, but could be, and represent a possible carbon-neutral gas and liquid hydrocarbon fuel source in future.
- guelo 12y ago
  It's all linked because fracking produces both gas and oil. But I agree coal is the biggest culprit. That's why the tax should be on carbon, not a specific fuel. But the tax should be designed to be dynamic somehow to act as a stabilizer to keep prices from going to high or to low too fast.

mangecoeur 12y ago

http://en.wikipedia.org/wiki/Pelamis_Wave_Energy_Converter http://en.wikipedia.org/wiki/Pelamis_Wave_Energy_Converter The Pelamis, based on technology evolved from the Salters Duck at the Edinburgh labs, was installed in pilot installations for a few years through the company has sadly since gone bankrupt

dredmorbius 12y ago

Total available wave energy relative to present human energy consumption is minuscule. Realize: wave energy is solar power twice removed. First solar heating converted to wind energy, then wind to waves. If you can capture the initial solar flux, you're better off. Wind is your second-best option, and where that's locally high, the EROEI (energy returned on energy invested) is quite high. Marine installations are notoriously high maintenance. Water, salt, corrosion, marine life, snagging, navigations hazards, and other factors, all play a role. Few man-made (or natural) materials survive well, and those which do tend not to play a big role in power generation. Even tidal energy, with both more available power and greater concentration than wave energy, has at best limited potential. As an example that may be relateable to HN, the energy avaiable from daily fluctuations in the San Francisco Bay, at the Golden Gate. In 2006, EPRI (the Electric Power Research Institute) established that the Golden Gate has a tidal energy potential of 35.5 megawatts of total extractable average energy power (852 MWh/day, 310 GWh/year), of which 15 to 17 GWh might be practically exploitable at costs comparable with current wind and natural gas projects. The total tidal energy represented at the gate is 237 MW (average). Capturing the entire amount would require blocking the Bay to any and all shipping traffic, or installing locks or other means to allow shipping in and out of the Bay. The total daily energy (5,688 MWh) is still well below the 18,000 MWh consumed by San Francisco daily), though it is a healthy fraction at 32%. Note that that's the power draw _of San Francisco alone_. Not the greater Bay Area. Yes, all that water flowing in and out of the bay daily and the "immeasurable energy" it represents? About 1/3 of the City of San Francisco's electricity usage. Human beings use a LOT of energy. http://www.sfenvironment.org/article/hydro/tidal-energy http://www.sfenvironment.org/article/hydro/tidal-energy http://oceanenergy.epri.com/attachments/streamenergy/reports/006_CA_06-10_-06.pdf http://oceanenergy.epri.com/attachments/streamenergy/reports...

msandford 12y ago
What waves and tidal energy represent, though, is something which might be a lot more capital efficient. Yes you're much closer to the power source using photovoltaics but they're only 20% or so efficient right now commercially. Further, the sun only shines on where I live between 8 and 16 hours a day, depending on the season. The useful average power I can expect to extract on average is about 3-4 hours per day. Waves, on the other hand, are an excellent store of energy and they persist for a long time. Easily overnight and actually over many days. So if you can reliably produce power from waves for the same capital cost per watt installed, you might get 3x-5x the energy production from the wave plant versus the solar plant. And that's before you take into account the storage necessary for solar! In other words you might be able to spend 10x on a wave power plant as a solar plant and break even. If it only costs 2-3x as much per watt, well, you're saving money. And the batteries (the ocean) are free.

platz 12y ago

Does it generate DC or AC? I think there are losses if you want to transport and connect the power generated up to the grid

jacquesm 12y ago
It generates pulses of AC power, but that can be overcome by feeding those pulses into a flywheel or superconductor based short-term storage system.

jacquesm 12y ago

Wave energy is one of those ideas that 100's of clever people have had independently over the years and not a single one has been able to make it work reliably and cost effectively. We've seen a wide variety of prototypes, some even made it to net power out but absolutely nothing came close to winning the prize. (Though that didn't stop the government from pumping large amounts of subsidy into some of these.) When you compare 'wind' to 'waves' (or tides, for that matter) the environment is even more hostile, the power transportation problem more acute and the engineering challenges incredibly more formidable and the maintenance headaches harder still. Having mostly stationary waterborne structures is hard enough and commands skills that are rare and very expensive (think oilrigs). Now change that to dynamic structures which drive generators, add in storms, salt water and interference with shipping and you're looking at a very expensive and complex mixture. It will take extremely deep pockets to pull this off successfully, with the inbuilt assumption of a number of false starts and resulting re-engineering. Elon Musk will likely walk on Mars (or die on impact) before we will see widespread adoption of tidal energy for electricity generation on Earth. Which is a pity, because it seems such a good idea.

wgx 12y ago
This one is in use in Scotland: http://en.m.wikipedia.org/wiki/Islay_LIMPET http://en.m.wikipedia.org/wiki/Islay_LIMPET
- jacquesm 12y ago
  500 KW (now derated to 250KW), it's neat but that's piddly little bits of power for an installation that size. A single present day wind turbine will produce up to 3 MW continuously rather than pulsed. Pity I didn't know about it when I toured Scotland a couple of years ago looking at their renewable energy installations. This one was by far the most impressive: http://pics.camarades.com/v/jacques/trips/scotland08/dscf1585.jpg.html http://pics.camarades.com/v/jacques/trips/scotland08/dscf158...
alephnil 12y ago
The problem with wave energy is not to make a device that makes energy from waves, but to make one that can withstand the storms that invariably are present wherever there is wave power resources, and at the same time remain efficient. Most wave power prototypes have ended up as wreckage during the pilot period.

wiml 12y ago

A lot of wave and tidal motors were built along the California coast in the late 1800s and early 1900s. It's an interesting history. Cheap fossil power made them uneconomical, though. http://bldgblog.blogspot.com/2009/05/wave-motors-of-california.html http://bldgblog.blogspot.com/2009/05/wave-motors-of-californ... http://www.outsidelands.org/wave-tidal.php http://www.outsidelands.org/wave-tidal.php

Shivetya 12y ago

Still never understood why they don't concentrate on using areas where currents are well known, for Europe that would be the Straight of Gibraltar. There is energy in the outflow from the Med into the Atlantic at the bottom layers, surely capturing energy like that is not as difficult as surviving the forces waves put out.