[Zeiter]

This looks extremely promising. These power stations are relatively small, cheap, and ecologically friendly (no chopped up fish getting caught in turbines). http://news.bbc.co.uk/1/hi/sci/tech/1032148.stm

I hope this isn't just a re-post of this article. It's 4 years old, but I didn't find any threads dealing with wave power, so I assumed that this hasn't been covered yet.

[savethehumans]

Yeah, Zeiter, the UK is really big on wave/tidal power (and why not? They ARE an island, after all!). In fact, some grumblers are already complaining that not so much effort should be made in developing wind power, and the focus should be on wave/tidal

I don't understand this logic, myself. The UK is an island; that means lots of shoreline, which means lots of wind. Given what's about to come down on this planet, I'd think people would want to develop as many alternative energy sources as possible! But maybe that's only me, huh?

[Andy]

Interesting article. Wave, tidal and OTEC (The marine renewables) are the sleeping giants where renewables energy potential is concerned. We are being very tardy with their research and might pay dearly for it. I hope not but I guess we will see.

[born2respawn]

That system's been supplying the national grid for a few years now: BWEA information.

They're apparently working on a much larger system to generate 100MW in the Faroe Islands, which would be about 12% of what wind power generates in the UK. So fingers crossed.

I'd really like to stand near it when it's operating, the sound must be fantastic.

[Zeiter]

Wow, 0.5 MW from that tiny little thing? Isn't that a fairly respectable number? It says in the article that it generates enough power for a local community. That's 2/3 of what the Pelamis system generates, and I'd wager that the Pelamis system is a good deal more expensive, no? Anyways, both projects need to be pushed along, ASAP. They can be adapted to utilize energy from different environments: LIMPET on the coastlines, Pelamis out at sea. And if a group of countries with interconnected grids all worked to develop this kind of technology, calmer waves due to calmer weather in one area would be countered with rough waves due to rougher weather in another area, balancing out the production and making the supply more consistent.

Yep, the oceans are definitely a vast untapped resource. Considering this, would it theoretically be possible to live in floating cities in the open ocean? For food, one could fish or even grow food, depending on the size of the floating island. You could collect rainwater for drinking water. And you could get energy by having your floating city rigged with a bunch of Pelamis wave generators. That would be kewl...Although I think I'm getting ahead of myself. First, we'll need to get ourselves through the nightmares of Peak oil before we consider any of these fantastical contraptions.

[Zeiter]

Actually, on second thought, those floating cities probably wouldn't be a good idea. If people knew that we could populate the world's oceans, who knows how high our global population would skyrocket. No, we need to use the land we have now better, instead of trying to create new land. And also, I read somewhere that there aren't all that many fish in the open ocean, and that most are concentrated near the continental shelves. In that case, these floating cities might run into a bit of a food problem. Also, if there was ever a dry spell...not good. Yeah, we better stick to being landlubbers.

[backstop]

Zeiter - In case your not up on the background, here are some points that may help in comparing the many devices under development.

The scale of the resource : as a rule of thumb a storm-wave of over 6 metres hight is carrying an energy flux of around 1.0MW per metre of wave-front collected. This provides a potential for the EU15 (according to a report it commissioned in the '80s) of getting 80% of its total electricity from its western seaboard.

Plainly each design will have its own performance envelope either side the average wave on the intended site, and conversion efficiencies vary widely between them.

Beside construction, installation and maintanace costs, three major limitations govern the comparative viability of the various designs :

a/. The degree of wave force that the device can survive (the UK has already lost two major shore-based prototypes, and Norway one).

b/. The width of wave front it can collect for conversion;

c./ The ability to swing on a mooring to face the incoming waves (or, with 360 degree function, near vertical mooring is possible).

d/. The area of coastal waters within that mooring's radius, divided by the wave-front that it converts (i.e. area dedicated per unit yield)

In my view we need very large Offshore devices able to supply significant city scale power, grouped in moored fleets with an internationally agreed exclusion of shipping.

While we have a great many empty ship-building docks around the world that could readily be re-instated, such has been the corrupt sidelining of this option over 25 years that I'm not confident that it will be developed on a significant scale while society still has the capacity to do so.

I should perhaps make clear that I don't see this or any other energy technology buying us a ticket 'beyond the limits' to allow the present system of 'economic growth' to continue. What it could do is greatly ease the process of change.

regards,

Backstop

[Andy]

Agreed Backstop, there are always the Limits. We simply must reduce our footprint by reducing our numbers, energy use and materials use. What the Marine renewables in combination with the terrestrial promise is at least the potential for some reasonable quality of life that is not vicious, brutish, barbaric and short.

[Devil]

I feel we should differentiate between the three exploitable marine energies:
1. wave
2. tidal
3. current.

Wave energy is very variable in any given place, ranging from non-existent to ultra-violent, depending on the weather (even thousands of km away). As such, it can be used only as a complementary renewable source, in the same category as wind and solar.

Tidal energy, on a reasonable scale, usually demands damming of estuaries. It is much more predictable, with some weather variations, but there are always four slack periods per day (also predictable, but changing in time each day). Can cause great disruption to shipping and can ruin estuary shorelines and especially tidal marshes necessary for waders and other marine life.

Current energy is the most promising more-or-less constant energy source. Imagine giant submarine "windmills" in the Gulf Stream. Problems: extreme cost, extreme cost and, in case I forgot to mention it, extreme cost plus seasonal variations in the position of max current flow.

Let's keep each category well separate in our thinking and not confuse the issue.

[frankthetank]

Underwater submarine windmills in the Gulf stream, say off the coast of Florida? The flow of water through there is something like 300 times the volume of the Amazon River.

That would produce some electric current, and would also screw Europes mild climate, if not the worlds.

Those floating islands already exist, I call them cruise ships.

[bentstrider]

I at least now know what to power the phaser strips on the island with.
Turn an ICBM into a column of ash in seconds.

[mikela]

$this->bbcode_second_pass_quote('Devil', 'T')idal energy, on a reasonable scale, usually demands damming of estuaries.

[born2respawn]

$this->bbcode_second_pass_quote('frankthetank', 'U')nderwater submarine windmills in the Gulf stream, say off the coast of Florida? The flow of water through there is something like 300 times the volume of the Amazon River.

That would produce some electric current, and would also screw Europes mild climate, if not the worlds.

[mikela]

I stumbled onto a good overview of wave power technologies written this past June by grad students from my alma mater, the University of Washington. Thought I would share 'em.

Renewable Power from the Sea

The appendix describes 35 competing wave power designs from around the globe, from oscillating water column (OWC) devices such as the Limpet in Scotland and reservoir systems like the Danish Wave Dragon to a variety of relative motion devices, including the Pelamis in Scotland and the AquaBuoy in the U.S: Renewable Power from the Sea, Appendix A

There is such a variety of designs that it's going to take some time and consistent funding to shake out the better ones. Unfortunately for me it doesn't look like that funding will come from the U.S. anytime soon, as the government doesn't give much support to renewable energy (wave energy isn't even classified as renewable energy) and private investors with sufficient capital (mutual funds, utilities) consider it too risky. Not to mention the myriad government and local agencies that make permitting unnecessarily difficult and expensive.

As we've seen with wind energy, governments that sufficiently fund renewable energies see their investments pay off in time. Denmark has made great efforts to perfect its wind turbines and now they are the most cost effective in the world. I believe (can't confirm) that Vestas Wind Turbines (of Denmark) is supplying more wind turbines to the U.S. and Canada than any other manufacturer, to the consternation of U.S. Wind Farming, General Electric, and other U.S. wind companies.

[Frank]

I helped build the horizontal-flow generators for the Annapolis Royal tidal power station circa 1980. We thought the design would be more popular and maybe its time has arrived.

http://www.nspower.ca/AboutUs/OurBusine ... Power.html

[born2respawn]

What the ecological impact of that kind of thing? I'd expect the effect on sammon and the like to be pretty big if you block a river they need.

There was, some time ago, talk of something simillar going up in the UK's River Severn esturary. Place has a massive tidal variation, but of course since privitisation the amount generators can sell electricity for has plummeted and a big project like that is out of the question.

Of course, there are plenty of other renewable projects that are being worked on, it's just a matter of them being cost effective. MCTs still seem like a great idea to me, especially as you can hook them in to existing off-shore generation fairly cheaply. (Or so I read.)

[big_rc]

I came across this company as I was reading about some of the ideas that the US military is currently funding. To be honest, I really like this concept better than most other wave/tidal concepts that I have seen. Anyway check it out and see what you think. Yes, I know it is not a perfect oil replacement but it is a interesting way to generate electricity rather cleanly.

Ocean Power Technologies

P.S. - It will be interesting to see what kind of ideas start to spring up when the hunt for alternative energy generation methods really starts to heat up.

[FatherOfTwo]

bumping this thread back up.

Devil mentions the extreme cost for tidal energy generation... is this because there aren't many of these systems in place (eg. no cost benefits achieved yet from mass production) or are the cost issues more fundamental?

[Starvid]

I don't belive for a second those red sausage wave plants are going to be the next big thing. That doesn't mean wave power won't get big though. There is another (Swedish ) technology.

http://www.shipgaz.com/english/magazine ... tikel2.asp

Wave power is good in all the three relevant areas price, potential and ecological hazard.

Price: 45 öre/kWh, equals about 3.5 US cents/kWh. More expensive than coal or nuclear (which are 30 öre/kWh), but still adequate. On par with wind power.

Potential: $this->bbcode_second_pass_quote('', 'T')he wave energy potential in the EU has been estimated conservatively as 120–190 TWh/year offshore and an additional 34–46 TWh/year at near shore locations.

However, these estimations depend on assumptions of technology and energy cost. The actual resource could be a magnitude larger.

[Andy]

$this->bbcode_second_pass_quote('Starvid', 'F')or a comparison Swedish energy use is 450 TWh/year, of which electricity is 145 TWh. We have very electricity intensive industry
(steel, pulp) so I figure average in Europe is 10 TWh electricity per 1 million people and year. With an EU population of about 500 million electricity use should be roughly 5000 TWh a year. In the most optimistic scenario wave power could supply half of that! In the most pessimistic scenario it will still be 3-5 %, vastly more than wind power will ever contribute.