People have been working on shrouded wind turbines for decades. Over and over again, the shrouds end up costing more than the cost of extending the blades and tower enough to capture the equivalent amount of wind.
I won't say that it will never work, but the list of failures is so long that anyone who mentions shrouded wind turbines without mentioning their history of failure should be suspected of being clueless. Inventing a new name for them, like "wind lens," makes them even more suspect.
("The abandoned [Oliver] turbine remained at the top of San Gorgonio Pass for almost two decades until it was dismembered for its scrap metal during World War II.")
I'm doing my own renewable energy startup right now, with our own innovations in turbine design. And while the engineering is critical, it is not the problem with the industry.
Energy startups fail primarily due to a lack of appreciation for the intensive capital required to make renewable energy work.
This is an industry where every project will cost millions of dollars, hundreds of millions, or even a billion for truly large-scale operations.
And that is EVERY project. You do not just come up with a design, test it, then repeat it 500 times. Each site has its own unique properties, each turbine need to be manufactured and shipped, connected into a grid, operated and maintained.
So you need a permanent source of massive amounts of cash to operate. Your standard VC firm normally is not an option because the ROI is likely to be 10 years out, and that is too long for most investors.
When the ROI does come in, it is massive. But this is a high-risk, long-term play, and it just doesn't match the interest of most VCs.
We have built our first production units, field tested them, and are ready to roll, but have spent the last 3 months lining up finances because we do not want to be another failed company added to the list.
Plus, you get power when the wind blows or the sun shines -- and none when they don't. Given the mean and standard deviation of cash flows, you can figure the proper debt to equity mix. But how well does the industry support that information for a particular project? Natural gas plants have very stable output so are more easily levered up. In a capital intensive industry, that's a very serious financing disadvantage.
This financing problem reflects a real economic problem. Risk -- cash flow variability -- is a real economic quantity. Failure to manage it causes real economic hardship and loss. If 50% of the power supply is wind, and it's down due to weather, someone on the grid is going down. Economically, the financing problem signals the importance of addressing that contingency. So this isn't just bankers being mean.
Actually with wind you also don't get power when the wind blows too hard, meaning you're at risk of being in a blackout for a lot of hurricane and tornado season.
What I don't understand is that these areas they refer to as natural wind resources are incidentally the areas that have had the highest instances of major tornadoes and hurricanes. I'm sorry, but erecting a structure purposefully designed to maximize wind drag in a storm zone is pretty stupid.
Nuclear power is the only viable method to go carbon-neutral before we hit the next century. It's also not likely to colossally fuck up our environment (see: Weather response to management of a large wind turbine array.), IE warning that it could shift the movement of cyclones in the atlantic.
Are you taking into account the extensive carbon emissions that come from mining fuel, transport, containment, etc. for nuclear power? As the supply of uranium and quality uranium decreases, the emissions will only get higher.
This is an area where I think government should provide generous grants and investments. Innovation for this type of problem is possible, but it takes more than 2 guys in a basement. Plus, as you mentioned, few VCs will want to wait a decade to see the results. Government can wait, however.
I'm not in the field, so I'll naively ask: Is the US government, or any government for that matter, doing anything about it?
Energy production is one of the purest of the wealth producers. If the energy producer can't break even on their own strength, then needing government subsidy (especially indefinitely) is all but a mathematical proof that the subsidized energy production method is a net loss to society as a whole; were it not, they would be profitable and not need the subsidy. See also corn-based ethanol.
Yes, I am aware of subsidizing R&D but that has diminishing returns too, and given the amount already poured in around the world and the rather dismal returns, I'm underwhelmed by the proposition that pouring even more in will turn things around. You can always claim that if you just keep pouring the money in it'll all turn around; it's a null argument when it comes down to it. (We'd almost certainly be better off pouring equal funds into getting nuclear going instead.)
Energy production is one of the purest of the wealth producers.
Extractive energy production where you can dump negative externalities onto the public or hide your subsidy in a part of the budget that is not directly traceable to you (e.g. Marines in Iraq and destroyers in the straits of Hormuz) is surely one of the purest wealth producers, but if forced to actually compete on its own the equations would look a bit different...
It would still be radically net positive. Oil is a stonking great deal; you put in one joule and get something like 10 to 30 back. (Note how I phrased that in energy terms this time, that's an important point.) You can't actually subsidize something of that size to profitability, because the energy industry is on of the bases of the economy; if oil is a net loss, the whole edifice comes crumbling down regardless of what you do. You can't subsidize the oil industry into net energy profitability with wealth taxed away from dry cleaners and accountants, and it doesn't matter what games you play with dollars if you aren't making a true net energy profit at the base of the economic structure.
Wind and solar both generally barely break even or barely above if you take a full accounting of their energy inputs and costs, biofuels are often a net loss (depends on the crop, but I think the balance of the argument has corn ethanol as a net loss, cane sugar seems to be a net gain, but...), and the problem is they're competing with things that easily get tens of times of returns on energy expended with the fossil fuels and nuclear power.
One of the things you rarely see correctly computed is what it would truly take to power our entire society with renewable energy, including the sudden new energy expenditures necessary to keep our purely-renewable infrastructure maintained with replacement gear. As the net energy benefit of the average piece of gear approaches 1x, the necessary expenditures approach infinity. Replacing 10-25x sources with 1.5-3x sources requires yet again far more resources than the naive multiplications and divisions would imply, if you don't make the mistake of assuming free infrastructure that never decays, or one-time-cost infrastructure that never decays.
(Incidentally, this is why cheap solar, in the sense of truly cheaper without government subsidy solar, is exciting. A solar panel that can make back 5-10x the expenditure to make and install it, and isn't a massive expenditure of metal and glass and silicon is a big deal, it makes things practical that weren't before. Or a solar installation consisting of lots of cheap reflectors concentrating the energy on a centralized station. I still think we might be able to go both net positive and practical on solar. Wind I'm less optimistic about, it's difficult to see what we can cut out of our wind generators and still have wind generators the way we can cut down on the mass/energy footprint of a solar installation with clever engineering. In the limiting case, a reflector is a sheet of foil and an amortized central station; a wind generator is an entire wind generator.)
The US government is doing a lot to fund renewable energy R&D since the creation of ARPA-E in 2009: http://arpa-e.energy.gov/ I suspect, but do not know for sure, that China is doing more of this sort of investment, particularly in wind.
If I were John Boehner (leader of the US opposition), I'd take money from corn and oil subsidies and use it to fund more R&D, but I'm not (or at least I won't admit to being him in this public forum).
Yes, many governments (including the US) are setting up funds to support renewable energy projects. However, we are finding more support from developing nations, who are not as entrenched in fossil fuels as the US.
As we are in the midst of funding talks, we don't have much public info to share on a blog right now. Once we close on funding, I intend to increase our social communications.
Investment requirement for each project is huge.
Check.
ROI is 10 years out.
Check.
When (if?) ROI comes in it is huge.
Check.
Hmm...sounds a lot like the oil business.
Wind power seems to be an area where the usefulness inversely correlates with spreading of a piece of news.
3 times the power of a conventional turbine? Albert Betz would like to have a word with these Japanese inventors. http://en.wikipedia.org/wiki/Betz_law
If anybody's interested in improving wind turbines, they should look at what is costly in current turbines. It's surprisingly the steel tower that's the most expensive part.
Shrouds do two things: 1) they improve the efficiency by reducing tip vortex losses; 2) they increase the effective diameter of the turbine, so Betz' law is circumvented to SOME degree.
I worked for a time on shrouded propellers for ship propulsion and studied ducted propellers for aircraft. These are more efficient than unshrouded propellers - but in each case the difference is under 10% - this is combined gain from reduced losses and larger apparent diameter. With turbines, things are a bit more complex, because with a well designed duct you achieve an effective diameter actually larger than the duct itself, and capture the additional wind energy from that extra area. Taking things to absurdity, I am fairly sure (without doing the math...) that you could have a relatively small turbine inside an enormous duct, and achieve 3x the power of an unshrouded turbine of that diameter. But this is a poor solution, because the large duct will surely cost a lot more than a larger conventional wind turbine.
Yes, they are within 20% of the Betz' limit. But you must understand that the Betz' law refers to "available power", and the "available power" is higher for a shrouded turbine due to its larger apparent diameter.
Please excuse me, I am not well educated on wind turbines, however, wouldn't it be beneficial, once you have extended the blades and tower as much as possible, to still use a shroud? After all, there is a finite amount of space between turbines and the ground, and you cannot make the towers infinitely tall.
Please correct me if I am wrong, but it seems to me that as long as the shroud or "wind lens" costs less than the price of building a second tower, it would seem that a 2x or greater increase in power output would be preferable to building a second tower, once you have increased the blade and tower height to the maximum efficient length.
As much as possible would probably mean a 600 m high turbine with 300 m blades made of pure carbon fibre or something like that. That could cost hundreds of millions and would be a useless monument.
Look, it's a simple cost trade - currently the most economical turbines are in the 1 to 3 megawatt range and roughly 100 m rotor diameter.
Tower cost is probably exponentially related to height for example. so the things balance out at that point.
Tower cost is probably exponentially related to height
Exponentially? So that every additional 50 feet, say, doubles the cost? I seriously doubt it. I would expect a quadratic relationship: the incremental cost to make it taller is proportional to the current height. Maybe I'm missing something and the relationship is cubic, but it's certainly not exponential.
(I know, maybe you didn't mean "exponentially" literally. But we're engineers here :-)
In a traditional shrouded turbine every additional foot of tower height would require, at a minimum, 2*pi feet of additional circumference to the shroud (in the case of the design that started this discussion it appears that the shroud is the main structural element so it is a bit different, but similar principles apply.) The shroud has weight. As the shroud circumference increases it will require both a stronger tower and stronger internal supports to handle the ever-increasing weight of the shroud. It is not hard to see that as the weight of the shroud increases most of the tower and most of the structural mass of the shroud becomes dedicated to holding up the shroud itself and an ever increasing proportion of the tower/shroud mass is dedicated to holding up the extra mass that is only necessary to keep the rest of the shroud from collapsing (e.g. structural mass to hold up the structural mass that is keeping the shroud up), with an appropriate increase in the cost of the tower. The exponent is probably closer to 1.1 than to 2 or more, but exponential is the proper term here.
Let's say you need 1000 kg for 10 meters of tower supporting another 1000 kg of load. A mass ratio of 2.
To extend that another 10 m, you need to support the above 2000 kg, so you need more beefy stuff for the next 10 m below, 2000 kg of tower.
Now you have 4000 kg to support for the next 10 m so you have to use 4000 kg of tower, 8000 for the next etc.
That's exponential.
Of course, in reality the base is less than two every 10 meters, steel is stronger per weight than that.
Though yes, on the other hand, the bending moment grows linearly only with height, and different buckling things are only power things. I don't know then if structural frequencies etc start coming in at some point.
I'm confused with the math used here. I think exponential is something like you double the height, and quadruple the costs. And that doesn't sound unrealistic to me.
I'm sure nontechnical people use the term "exponential" loosely, but this being HN, I think clarification is in order.
Consider the function
f(x) = x ^ 2
(where the caret stands for exponentiation, of course). This is called a quadratic function. Here are some example values:
0 1 2 3 4 5 6 7 8 9
0 1 4 9 16 25 36 49 64 81
This is the kind of relationship you have described: when x is doubled, f(x) is quadrupled.
Now consider this function:
f(x) = 2 ^ x
This is an example of a function that is properly called exponential. Here are some example values:
0 1 2 3 4 5 6 7 8 9
1 2 4 8 16 32 64 128 256 512
Here, every time x increases by 1, the value is doubled. See how much faster it grows?
In very practical terms, the difference between a "power law", as functions of the form x ^ k are called, and an exponential, of the form k ^ x, is massive. I grant that the terminology may be a little confusing, but this is not a pedantic distinction!
I'm sorry I didn't get that right. I should studying where I study.
Anyhow I don't think "50 more and double the cost's" is exponential?
// And I still would not think exponential is impossible function for the cost's. When you get about one kilometer high, the stuff just gets shit expensive. I mean humankind-scale expensive.
Nope. When something is exponential, a fixed increase in the input causes a multiplier in the output. So, for example, if I have the exponential y = 2^x, an increase of 1 in x, from x to x+1, increases y by a factor of two.
I won't say that it will never work, but the list of failures is so long that anyone who mentions shrouded wind turbines without mentioning their history of failure should be suspected of being clueless. Inventing a new name for them, like "wind lens," makes them even more suspect.
For a weak census of recent attempts, see Google Image Search: http://www.google.com/search?q=ducted+wind+turbines
1868, Ernest Bollee in France: http://en.wikipedia.org/wiki/%C3%89olienne_Boll%C3%A9e
1926, Dew Oliver, San Gorgonio Pass in California, USA: http://books.google.com/books?id=7M9C1Adp0yQC&pg=PA46...
("The abandoned [Oliver] turbine remained at the top of San Gorgonio Pass for almost two decades until it was dismembered for its scrap metal during World War II.")
2005, Enflo turbine, still trying in 2011: http://www.enflo-windtec.ch/
2007, FloDesign: http://fdwt.com/ $56M in funding so far.
2008, Marquiss Wind Power: $1.3M Series A in 2008, now dead: http://www.marquisswindpower.com/
To be fair, Enflo and FloDesign haven't failed yet, or at least their websites are still up.