Wind Power Without the Mills
forbes.com
forbes.com
Operation & Maintenance expense is my biggest issue with new technology. I have met many design engineers that have never been inside of a nacelle or even visited a wind farm. In the real world generators and blades break, hurricanes, lightning, shit happens. Cranes are extremely expensive and a 2MW "mast" that can compete with today's technology is going to be crazy tall. How to repair a lightning cable? Cranes are over $10k per day and cables take a few days to fix.
Today there is a 26 story ladder in the interior of the support tower that people climb up to fix hardware in the nacelle. To inspect the blades we then rig our anchors to the generator, pop out the top hatch and repel over the nose cone and down onto a blade in the "down" position. The only specialized hardware needed is anchors, carabiners, ropes, harness and helmet.
Vortex Bladeless would be impossible to inspect and repair using this method, yes drones are great for inspection, but what about repairing a stress crack on the tip? You would need a crazy tall crane that is even more expensive and with cranes the wind speeds need to be a fraction that of Industrial Rope Access. This means your available repair days are even less and the turbine has to be shut down for longer for the fix to occur.
I am all for new technology and crowd financing, but there are many practical obstacles this team needs to overcome in the design phase to build a product that can actually scale in the real world.
Also, feel free to AMA if you have specific wind turbine questions.
(Or if you want to sound fancy, "abseil")
I wonder about how the power generated scales as the size increases. It's 100W at 9', and 4kW at 40'. At ~4.5x the height there's 40x the power generated. It's foolish to assume the same exponential gains apply continuously, but given the reduced footprint, is it possible that laying out five of the 40' units is sufficient for 2MW (edit: wait, I totally fudged that math, so this point doesn't really make sense), and at that size, you might be able to just use a bucket truck for maintenance?
We shouldn't assume just because it's a new technology that the same problems don't need to be addressed, but we also shouldn't assume the same problems need to be addressed in the same manner. This article doesn't do a lot to explain the details, and as you've explained I've heard that maintenance of wind turbines is where a lot of the money to run wind farms goes, so it's interesting to look at new designs from the standpoint of how it may radically change maintenance, not just scale with the current methods.
That said, you obviously have more experience with this than me, so hopefully you'll be able to provide some more perspective on the ideas here.
P.S. Something that occurs to me is that I have no idea how they stop the oscillation caused by the wind for maintenance on those. You can lock the turbine blades, but I'm not sure how you prevent something made to oscillate naturally in the wind from doing so, easily.
P.P.S I totally messed up my math because I wasn't thinking straight, 5x4kW is not even close to 2MW. I'll leave this here for historical purpose, but much of my point lacks any weight now...
Yes, there are two factors, wind speed and blade swept area.
Height: "Energy in the wind is not linear. Double the wind speed and the energy increases not by double but by a factor of 8. As speed increases the power is increased by a cube factor."[0] You want to capture that higher elevation wind to maximize power output while also factoring in the cost of the tower heigh and stability. Most 2MW turbines have a tower height of between 60 and 100 meters depending on the local wind profile.
Blade Swept Area: "Energy captured by the rotor is linear. If you double the swept area, you double the amount of energy it can capture."[0] If you can double the length of a classic wind turbine the swept area increases by a factor of 4!
This is where the problem lies. Even if there was the cost efficient method of building a 2MW Mast turbine the swept area would only be a fraction that of a classic wind turbine, say only 45 degrees in each direction. This makes the height necessary just unrealistic. Just thinking about an entire farm of these these wobbling back and forth makes me giggle.
> we also shouldn't assume the same problems need to be addressed in the same manner.
Totally agreed! But these fiberglass "Masts" are still in the outdoor environment. They still get struck by lightning, they still need generators replaced, they still have electronics, etc. This is why I have moved away from my believe system that wind energy will make up a huge factor of our energy production needs and have become very bullish on solar. Mechanical electricity generation requires maintenance and moving parts increase complexity exponentially. Wind energy is no longer a technical problem to be solved, we have already done that with three bladed turbines, it's a financial and incremental improvement problem.
In the end, it may be that the better use for these is indeed the 40' 4kW version for the back yard. I could see that pairing with a bunch of chained Tesla powerwall units to good effect.
Modern wind turbines have a cut in wind speed of maybe 3.5m/s and my guess is that these wind masts don't have a cut-in speed. So in low wind resource regions they may be effective at capturing market share because they can produce electricity with only a slight breeze.
> I imagine scaling these up you have some pretty crazy engineering problems to overcome, like how to deal with the repeated strain at the base.
Modern turbines have plenty of vibrations that the tower and foundation have to deal with. I was in the nacelle of a wind turbine when a surprise small tornado came to town, we were full on rodeo mode with the tower swaying back and forth. That being said on a day to day basis most of the forces are countered with the rotating mass (someone else can explain this better than I) so the turbine doesn't transfer much horizontal load to the foundation.
With the wind mast there would be most horizontal load on the foundation as there is not another blade or two to counteract the motion and thus it would require a larger foundation.
If you want to buy a 4kw turbine you can find one used for under $7k which is much less than this new technology. As better 3 bladed tech comes online there will be a larger second market for used turbines and thus might be a better economic option then buying unproven new wind mast technology. Pairing used or new wind tech to batteries can really benefit the offtaker depending on the marketplace.
But I agree that for places on earth close enough to the equator to have plentiful solar irradiance, also in the winter, solar looks like it is going to win hands down.
Yes! They are very cheap compared to coal fired power plants. During University I helped prepare one of the first wind turbines (call the wind furnace[0]) ever built to be shipped to the Smithsonian. This initial prototype turbine was built in 1972. Now 43 years later we have massive adoption of the technology and we are still ironing out the bugs. Big O&M cost are blade repair, gearbox and generator swapout and yes they are getting cheaper, but most of the these costs are the cost of the crane coming in.
Modern turbines are fairly new to the market and we are still collecting data on how the components last over time. Most manufacturers, Siemens, GE, Gamesa, etc provide a 3-5 year warranty. Their incentive is to produce as many cheap components as possible that last the 3-5 years so they don't have to replace the parts under warranty.
Wind turbines are very complex feats of engineering, solar panels on the other hand are simpler to make than sheetrock and as we scale that technology and come up with creative financing options that guarantee savings market penetration is going to be even greater than wind even in regions far away from the equatorial region.
creative finance is the key to clean energy scale and adoption, not technology.
That said, their web site makes them out to be idealistic dreamers (I know that sounds judgemental but it is the impression I got from it). If Google were still running the RE<C initiative I'd suggest they put a couple of test units next to the data center at The Dalles (its on the Columbia River and was always windy whenever I visited there). If they can build a 4 - 10kW one and its something you can stick in your backyard, I would expect that they can build a small business out of that to develop the expertise to build the big ones. I worry that if they try to do too much too soon they will become overwhelmed.
[1] Caveat the amount of energy you can pull out of a moving mass of air at STP is finite.
Having 500 4kw systems cuts into harvest revenues as do 10 20kw systems as the equivalent square footage lost to generate 1MWh is an order of magnitude larger.
Also, wind turbines blades in colder climates tend to accumulate ice in the winter and thus are permitted to be located away from populated areas. Some big chunks of ice have been flung hundreds of meters. The larger the blade the further the distance you need to put your structure for safety reasons. These masts shouldn't be put on buildings (vibration) or near populations (ice).
I am attributing larger footprint usage to trying to generate a similar power output given current wind mast technology. 10 wind masts alone don't take up the same space as 10 classic turbines, but the the number of wind masts necessary to generate the equivalent output of 10 classic turbines is greater that 1:1 due to wind swept area per turbine.
The primitive model is a tabernacled mast on a sailboat.[1]
I'm a big sailer too. I used to crew on racing boats and classic schooners.
Let's say we have a cantilevered mast and can swap it out "quickly". For 2MW worth of generation that would be a massive engineering feat and would mean that you have inventory not being utilized stored in the warehouse. Not just a generator or blade, but an entire system unutilized sitting around! Also most sailing masts are fairly light (aluminium) and short (30'). A 2MW wind mast would be 10x a sailing mast and hold all of the generator and electronics, not just a hollow tube that needs to be structurally sound. also masts are designed to be rigid and are held in place using shrouds and stays. A wind mast designed to move can not be held in place using guy-wires as that defeats the purpose of the dynamic wind mast.
Workers on these wind farms are making between $10 and $25 each and every hour. Some specialized workers are making double that at times, but let's keep the average of $20/hr.
It doesn't make economical sense even if you didn't need a crane to swap it out. And yes you would need a crane as this would be a multi-ton structure.
There are constantly amazing technologies just around the corner that will definitely totally be awesomely better than existing 3 bladed horizontal axis wind turbine technology. And they'll always be less expensive than current technology somehow. Trust me, getting the cost right at this stage of the technology curve is almost impossible, and founders and technology developers are notoriously optimistic.
Yet they are always a few kW (this one is 4 kW) rather than 2 or 3 MW (a factor of 1000), and are always "just a few years away". And will never be a commercially successful product outside, perhaps, small scale demonstration and greenwashing projects.
We didn't get to the standard model of wind turbine by accident. It took decades of engineering and refinement. And yes, we still have a lot to learn. And yes the current technology has problems.
However, there are animations that show it wobbling.
This implies that it's made of a flexible substance. I'm not being so pedantic as to suggest that the fibres or crystals etc. of the substance are moving parts (though surely there is friction between them), but I do have a query:
In my completely anecdotal and limited experience of household bendy objects vs. household hinges; hinges win the longevity battle every time, even without regular application of lubricants. Also, when a bendy object fails, the whole thing needs to be replaced. On the other hand, when a mechanical part fails, I can replace the part and keep the rest of the object.
Can these things therefore really be cheaper to maintain than a mechanical wind turbine?
So I'd say it's at least plausible that these generators could be built.
There are airplanes and boats that use this technique too: http://en.wikipedia.org/wiki/Rotor_ship , http://en.wikipedia.org/wiki/Flettner_airplane , http://en.wikipedia.org/wiki/Alcyone_(ship) , http://en.wikipedia.org/wiki/E-Ship_1 ,
Wind mills and green energy is great, so go for it - just don't try to patent the "Magnus effect".
On the other hand, this sort of unit might be interesting for the use you suggest. Even if the manufacturing cost isn't a big win, if the MTBF is enough of an improvement by design, it might have some application in small remote sites where maintenance is a pain.
For a 4kW sized solar system, you'd be looking at ~$6K-8K USD before your 30% federal tax credit (plus state incentives, if available). Your solar system would have significantly less maintenance requirements, consisting of rinsing the panels with a hose 1-2/year.
http://www.renewableenergymagazine.com/article/the-power-of-...
Regarding the practical matters, it looks like they are three orders of magnitude from being on par with the three-blade vertical design.
So while this idea may be worthwhile in some niches like mentioned in the article, it's currently not a replacement for the giant, towering, 3 MW and up turbines erected these days.
And just like other wind-turbine replacement ideas (like kites or vertical-axis designs, but there are many more, just check Wikipedia), they probably never will. As I understand it, part of the beauty of the three-blade design is that by scaling the blade length linearly, you get a quadratic gain (pi r^2 area swept) in energy harvested.
As for the parent design, could be interesting. I cannot imagine a possible justification for not building it out given the urgency of renewable power to our present needs.
> If you've never driven past trees in the morning or evening, the flashing is incredibly irritating.
Shadow flicker is a siting and operations problem. It's based on geometry (sun angles and turbine locations), wind conditions (turbine direction) and weather conditions (cloudiness). If we consider residences, schools, churches, and so on as discrete shadow receptors, flicker can be minimized through careful siting of the machines, and eliminated at those sites through programmatic controls (curtailment).
I wonder what's the size of their prototype? Hard to tell from the picture.
I suppose using this system means blocking the wind with something akin to a forest, with a small space between "artificial trees".
Assuming that we were to compare it to natural gas, for which you may have used oil as a proxy, this provides some substantiation to your claim: - http://www.theoildrum.com/node/1863
But the calculations here don't reflect that peak power generation doesn't reflect peak demand. So, we've looking at adding in battery's costs too.
At the end of the day, if a greedy capitalist can make a bigger buck (with or without government subsidies) with wind than they can with coal or natural gas, they will.
Given that the efforts to bring new capacity on-line fluctuate (dramatically!) with the comings and goings of government subsidies, my guess is that they aren't quite the competitive economic wonder, at this point, that they are touted to be.
YMMV.
Numbers from an unverified source: http://science.howstuffworks.com/environmental/green-science... (other sites seems to agree on the cats vs turbine numbers)
Alternatively, from a source you might expect to be very biased in favour of birds: http://www.rspb.org.uk/forprofessionals/policy/windfarms/
http://en.wikipedia.org/wiki/Ecosystem
Enjoy the next three days of reading.
A less selfish reason is that bad things happen to the rest of the ecosystem when you mess around with apex predators.
The tower waggles and is made of piezoelectric materials, so the electricity comes from the deformation of the tower.
Edit - I got sideswiped by marketing. The current one is electromagnetic, the future ones are proposed to use piezoelectrics, but they do not have the materials available to do this.
ie vortex shedding. There are moving parts, but the movement is much smaller and more confined.