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The Heavyweight Sea Snail
Roland Piquepaille writes "Scotland, like many European countries, must comply with regulations requiring that a mandatory percentage of the energy it uses comes from renewable sources. For Scotland, this percentage will be 18% in 2010 and 40% by 2020. One of the programs in development is Ian Bryden's sea 'Snail' program. The Snail is a 30-ton anchoring device which uses hydrofoils -- wings that 'fly' in the water -- to generate enough power from tidal waves to service 10,000 homes by 2007. This overview contains more details and a picture of a prototype of the Snail with its six wings." There are several mentions of this in UK newspapers and the Scottish government webpages.
Let's hope it does better than the Salter's Duck. The development project was cancelled in the 1980's after UK government departments grossly over-estimated (by a factor of 10) the cost of the electricity it was going to produce. Cock-up or conspiracy?
According to this site:
"Currently, although the technology required to harness tidal energy is well established, tidal power is expensive, and there is only one major tidal generating station in operation. This is a 240 megawatt (1 megawatt = 1 MW = 1 million watts) at the mouth of the La Rance river estuary on the northern coast of France (a large coal or nuclear power plant generates about 1,000 MW of electricity). The La Rance generating station has been in operation since 1966 and has been a very reliable source of electricity for France. La Rance was supposed to be one of many tidal power plants in France, until their nuclear program was greatly expanded in the late 1960's. Elsewhere there is a 20 MW experimental facility at Annapolis Royal in Nova Scotia, and a 0.4 MW tidal power plant near Murmansk in Russia. "
I also recall having seen articles talking about attempts in Norway to capture wave/tidal energy for electricity generation.
I'm always a fan of renewable energy. I just wanted to point out that this is more an attempt to do something in a new way than to do something new.
Things to do today: See list of things to do yesterday
It's not socialism, it's simply a mandate to cover everyone's asses. As non-renewable sources are depleted (or grow more expensive), it will be better to have an extra decade or so of development - not to be desperately scrambling for a solution.
I don't know much about the initiative in question, so please don't read this as an unqualified endorsement. However, one factor that needs to be borne in mind when looking at the "affordability" of an alternate power source is its sustainability.
Energy from petrochemicals is not sustainable. It might be cheap - right now - but it's not going to last. Moving to sustainability while we have cheap petrochemicals to help us get there makes sense. I think it's high time that environmental costs, lack of sustainibility, and other "externalities" were factored in when comparing "affordability". Cheers!
Corruptissima re publica plurimae leges.
While they don't say so in the article, it would appear from the picture of the device that there is a medium diameter horizontal axis generator on the dorsal surface, and the six foils are going to generate the downforce required to anchor the device to the bottom.
This is just from looking at it, obviously not from the plans. One of the challenges they would face with any form of tidal or current energy device is how to keep the thing in place. With the foils, I can see issues with keeping it in position, but it does seem like that's what they're trying to do.
There's probably also a hard mooring to keep it from drifitng away at slack tide, which would also allow it to change facing when the tides change direction or the currant shitfs.
Never attribute to malice what can as easily be the result of incompetence...
Over what period of time?
You're (at least in the US) usually billed in kilowatt-hours (kWh). I'm no expert, but I doubt most homes use more than 0.5kWh at anything other than peak times (weekday evenings and weekend afternoons).
Appliances (again, in the US) all come with a sticker saying how many kWh they use in a year. A refrigerator is usually around 1000. That's a little less than 3 kWh a day, or 0.125 kWh (period... in an hour). That's only 1/4th of your constant usage allowance. How many other household appliances run 24/7? Probably none.
A good storage mechanism would store that unused energy for use at peak times. A poorly designed system would just fail over to a traditional power grid at peak times. In any event, it still reduces the load on the main grid.
Of course, my experiences are from my house in the USA... maybe Scotland is full of wasteful, electricity-hungry, even-worse-than-American people... but I doubt it.
In this case it's not oil that we are dependent on but COAL. Now while we mine coal right here in the US remember that coal mining is by far the most dangerous occupation in the US, for each coal plant in the US one coal-miner is killed each year in an accident. This doesn't count the long term healt and psychological effects that mining has on a person. Nor does it take into effects the polution generated by a coal plant. Sorry, but oil fuels some of our energy needs (heating and automobiles) but very little oil is used in electrical power generation.
This is a staggering over-simplification of the international oil economy. I just spent a semmester studying the economies of the middle east and north africa, and that was just a broad overview. This is a complicated problem.
While the United States and other countries that don't produce enough oil to run their economies would obviously like the price to be as low as possilbe (and I agree that internalizing the enviornmental, military, and foriegn aid costs of oil would greatly drive up its price), the idea that the price of oil is where it is because the US forces it to be so is just plain bad economics.
The Sauids (and not just Bush's buddies the House of Saud, but whatever theoretical government might be in place there) have a lot more oil than anyone else and a much larger time frame for extraction. So, they fight with the rest of OPEC to keep the price in an acceptable range (lower than other members would want) and use their massive capacity to flood the market when others get out of line. This is precisely so that oil doesn't get so expensive that people start looking elsewhere. Furthermore, this type of behavior is inherant is the nature of oil (rentier) economies, not a result of anyone's policies.
Now, I am far from an expert in these matters, but those who express admiration for "natural market processes" shouldn't also demonstrate such complete ignorance of how those processes work.
These seemed like valid concerns at first glance, but the numbers just don't add up. It's something we often deal with in physics; it's very hard for humans to compare quantities which are very very large.
The amount of energy we're extracting from the water is miniscule. Take the 5MW sea power station. Water weighs 1 gram / cc, which means 1000kg per m^3. 5 MW in 1 second is the kinetic energy (using E=(1/2)m(v^2)) in 100 cubic meters of water moving at 10 m/s: E=(1/2)(1000gm)(100m/s)^2 = 5e6 joules. 100 cubic meters, even once a second, is NOTHING compared to the rest of the sea. 7/10 of the Earth's surface is covered by water; the seas have an estimated volume of 1.4*(10^18) cubic meters!
Huge solar plants will abosorb their energy from our sun. That energy would have heated our soil, been absorbed by plants, been reflected back into the atmosphere...
The amount of land affected is exactly that in the shadow of the solar array. No more, no less. Even the power we "extract" from that shadow returns to the environment in the form of heat, after it's used in the grid. Remember, energy is always conserved.
Geothermal generation will cool our planets core faster
This one really set me off. Come on people, the Earth is a GIANT BALL OF MOLTEN ROCK. The crust, with all the seas, life, solid rocks and mountain chains, is a few miles on top of it. The radius of the Earth is 4000 miles = 6400km. It has a volume of 1.1*(10^12 cubic KILOMETERS)! You could literally pour every ocean on Earth (10^9 km^3) into the mantle, boil it off into space, and barely make a dent in the temperature. There's a reason it takes billions of years for planets to cool.
Think about replacing a nuclear power plant with a tidal generator. You are sucking an entire nuclear power stations energy output from the ocean! Don't you think that might have some sort of consequences? And that's just one nuclear power plant. There are dozens!
This seems really logical, because to humans a nuclear power plant generates an enormous amount of energy, i.e. many orders of magnitude more than it takes to run your electric razor. But the power in the oceans (7/10 of the Earth covered by VERY dense material moving about) makes those power plants look like coin cells by comparison.
The only solution is to be more efficient, not to try and generate more power.
On this point I agree with you in spirit, but have to point out that it will simply never work. Google for "The Tragedy of the Commons" if you want to know why. Simply put, any person/organization which tries to consume less energy puts himself at a competitive disadvantage. It sucks, but it's the way economics work.