Invest carefully: wind energy innovations are rarely kosher

Published by Barnard on Wind. View the original article

Wind energy is a big business world-wide, with billions of dollars flowing around at various levels. And as in any large and growing market, a wide variety of people are attracted to it.  Most are solid, competent professionals. Some are superstars.  A slightly larger percentage than in other fields are engaged in part because it’s the right thing to do, not just something they can do well and make money.

Along with all of the professional people, there is a physically optimal design that the vast majority of wind generators have converged to: the three-bladed, horizontal-axis wind turbine. This is the most efficient design due to pure physics: the blades are always flying in clean air, at the optimal angle to the wind, at the height of strong wind and have the added component of aerodynamic lift as another vector of force.

There are over 200,000 of them worldwide in sizes ranging from a few kilowatt capacity to 7 megawatt capacity both onshore and offshore, in rural and urban areas. They are generating all but a tiny fraction of a percentage of the electricity harvested from the wind in the world. They are undergoing constant incremental improvements in design including:

  1. Low-wind vs high-wind models
  2. Variable pitch blades
  3. Gearless vs geared nacelles
  4. Slight variants of blade design for aerodynamic efficiency
  5. Leading edge coatings
  6. Tower design
  7. Base design – rock-anchor vs concrete-base vs tethered floating vs. bottom-mounted offshore
There are, of course, people who don’t fit into the above categories in one way or another. Perhaps they aren’t particularly intelligent or competent. Perhaps they aren’t professional enough to carefully assess prior art to see if their great idea has actually been fully assessed and declared unworkable 15 times before. Or perhaps they just see the opportunity to make a fast buck off of people who think that a disruptive new wind generation technology will be worth a lot of money.A subset of these people come forward with ‘innovative’ and ‘new’ wind energy technologies which they claim solve the mostly non-existent problems associated with the current leading technology.  There are a few dozen designs in play at any given time, which have perhaps tens of thousands of instances with very small generating capacities world wide. These include variations of savonius windmills, darrieus wind turbines and a variety of flying or compressing designs.  Almost none of them are producing electricity right now anywhere in the world at anywhere near utility scale; most of the ones that are producing any electricity are for off-grid applications such as sailboats or local-residence supplemental electricity (both of which are very well served by small scale horizontal axis wind turbines or HAWTs). Some of the savonius designs are pumping irrigation water as that’s what they are good for due to their high-torque and low speed.Sandia Labs, the pre-eminent wind generation test facility in the world, got out of thebusiness of testing and developing vertical axis wind turbines (VAWTs) in the 1990′s due to their proven ineffectiveness compared to horizontal axis wind turbines.  They are re-opening their historical research to see if some of the design characteristics of VAWTs might make them more suitable for offshore wind generation, where the different compromises might be economic, but it’s unlikely that VAWTs will capture more than a tiny fraction of the market compared to HAWTs even if they prove to be equivalent for offshore wind. Kickstarting a new technology and new supply chain for one niche when that niche is well served by existing technologies that also work on land is likely not optimal. This is a counter-example to the rest of the examples below; it’s thoughtful, it’s being done with full knowledge of prior art, it’s being done by a top notch organization with a long history in wind energy and it’s being done because they think that the compromises might favour VAWTs for a specific niche. It’s a stretch, but no one is spending big bucks on this yet, just enough money to dust off the research and think through applicability to the niche.

Then there are the others. As a thought exercise, look at the picture of a simple savonius windmill below and guess reasons why it’s never going to be as efficient as a horizontal axis wind turbine.

The challenges include the drag of the concave surface rounding into the wind, the lack of an aerodynamic component to the force, the limitation of speed of rotation to maximum of the speed of the wind, cyclical change in load on the bearings as the unit rotates, the lack of optimal angle of attack for their scoops the majority of the time and the sheer volume of material needed to harvest energy from a volume of wind. At that, however, it’s a very cheap, high-torque unit that a farmer can make and maintain themselves out of materials at hand to pump water. That’s about all the savonius wind turbine is really good for; that’s its niche. It’s moderately foolish to try to make it more than it is.Yet one ‘inventor’ created a version of this that used injection molded fiberglass with dimples for aerodynamics on the leading concave edge, magnetic levitation and a handful of other ‘improvements’ that merely resulted in it being a very expensive ineffective generator of electricity. He even claimed that wind would somehow fill the inside of the hollow structure generating additional force. And he was actively peddling this intellectual capital for sale. The only good thing about this situation was the business niche that was being targeted: charging backup batteries for remote communication towers using low-maintenance renewables instead of diesel generators. This is a design point and market that could be worked toward using existing solar and wind generators, and there might be a nice small business in there.
savonius

A higher profile ‘innovation’ is Saphon, which actually got a TED spot for something that is so obviously deficient that any one remotely related to the wind industry would have laughed it off the stage. Professionals’ comments regarding it are invariably brutal.

Its failures include inability to scale due to mass of the conical device they use, no ability to feather the cone so it will likely fall over in high winds and a mechanical piston actuator that also won’t scale and introduces massive inefficiencies.The patent it claims represents its breakthrough is actually for a different device than the one they are promoting.  They explicitly call out many of the myths denigrating wind generation as real in their promotional video and then claim their design solves these almost non-existent problems. The two principals have no background in wind energy, but one is a former investment banker who specialized in getting people to invest money in companies. Is there a niche where their product is better than a tri-blade HAWT? It’s extremely unlikely in our physical universe, yet this doesn’t stop them from seeking new investors, creating prototypes and getting a remarkable amount of fawning press including being shortlisted for an African innovation award recently. The principals are much better at PR than engineering.

An idea what won’t stay buried is shrouded or cowled wind turbines, where a bulky external shroud concentrates air flow on a smaller wind turbine.  This idea is challenged in ways similar to the Saphon, in that scaling up produces a massively heavy and shear susceptible bulk on top of a tall, relatively slender pole. Effective harvesting of wind requires getting the generator up into the air where the wind is stronger and having a broader surface area to harvest from. All the shrouding does is reduce efficiency of a three-blade HAWT with the same diameter as the shroud. Yet this is re-invented with prototypes being funded regularly, as if no one in the history of wind energy has ever in the past thought to apply the Venturi effect to wind generation.

Many of these innovations claim to have found a way to exceed Betz’ Limit of 59.3% of potential energy harvested from a volume of wind.  None have stood the test of third-party, independent testing. Some claim that Betz’ Limit doesn’t apply to VAWT technology and then point to Sandia Labs documentation which clearly says that it does. Virtually none have performed ISO standard full lifecycle cost assessments, published them and had them audited by independent third parties.

Most claim to be quieter, although virtually none publish side-by-side noise evaluation tests with similarly scaled HAWTs to prove it.  Many claim to kill no birds, although there is no proof of that claim either (and of course utility scale wind generation is the best form of generation for birds from a species perspective.)  Some anti-wind lobbyists have internalized these claims without understanding them and actively promote the idea that there is a better alternative for their pet concerns.

Then there are the situations where there doesn’t even appear to be a physical product of any sort. A firm in the western US received $4 million up front a handful of years ago from the municipality to build a factory for savonius-style wind turbines. It has delayed breaking ground on its factory for four years, doesn’t have a working website and is saying delays are due to bird tests (not true according to the agency that was performing them), a completely unrelated scandal many states away and the need for more money in the bank. It appears to be nothing more than a large scale scam that has already netted them around $4 million and they are hoping to get $10-11 million more. All for a conceptual variant on that barrel split in two above.

There are minor niches where alternatives to tri-blade horizontal axis wind turbines are effective.  There is a vertical axis design, for example, that self-stalls in high-winds, making it effective for remote locations with regular very high winds, e.g. Antarctica.  There are a few darrieus variants that are remarkably attractive kinetic sculptures that happen to generate electricity as well, where the aesthetic value makes the high cost per KWh palatable.

So, how can you inoculate yourself against putting money into a bad wind energy product?  Ask these simple questions and if any of the answers are Yes, be very suspicious:

  1. Do they claim to exceed Betz’ Limit?
  2. Do they disparage other wind generation technologies to establish their technology’s superiority?
  3. Do they have backgrounds entirely in fields unrelated to wind energy?
  4. Are they claiming that their variant of a savonius or darrieus wind turbine is actually a new technology?
  5. Are they claiming that their product will replace utility-scale three-blade wind turbines?
  6. Are they starting from a product as opposed to a specific and tightly targeted market niche?
  7. Is their product just a design concept as opposed to at least a working and tested prototype?
  8. Are the only test results from tests that they have performed as opposed to independent, third-party labs?
  9. Are claimed patents for devices other than the one they are demonstrating?
  10. Are they claiming greater efficiency than existing generation technologies based on anything other than an ISO standard full lifecycle accounting that has been independently assessed?
  11. Are they claiming to integrate storage into their wind generation device? (Special case: GE is allowed to do this because it has proven it knows what it is doing and the market.)

The wind industry is disruptive because it is supplanting fossil fuel generation at a reasonable cost. That reasonable cost is due to decades of incremental innovation and major supply chain and business innovations, not radical technical innovations. The most effective technology was chosen a few decades ago, and it’s been getting steadily better ever since.

The wind industry isn’t going to be disrupted by someone with an idea and a Powerpoint pitch. If someone is approaching you with a great investment opportunity based on a ‘new’ wind generation technology, be aware.

6 thoughts on “Invest carefully: wind energy innovations are rarely kosher

  1. Here are some of “Nearly non exising problems with 3 bladed design” http://www.windbyte.co.uk/safety.html
    Next If Betz limit is based on V2/V1 ratio, which cannot be other than INEFFICIECY coeficient because V2 conains energy that went unused trough turbine, it clash with formula for “Extractable Kinetic energy from wind” which states maximum is 1/2 of total energy present, assuming 100% eficient turbine, etc.
    In any case every formula is corect if all assumptions are present (save for Betz Limit which postulates turbine with “limitless number of blades” which cannot exist, and would boz work if it would exist since there would be no space between blades for air to pass) and if some assumptions are missing or something else exist replacing them, then sometimes formula canot be applied.

  2. Excellent summary of the wind energy evolution so far, though I think the background conclusion is too bold since it does not seriously consider future innovation. A couple of sentences at the end of the article say: “The most effective technology was chosen a few decades ago, and it’s been getting steadily better ever since […] The wind industry isn’t going to be disrupted by someone with an idea and a Powerpoint pitch”. It’s truethat we all must be cautious with scams, but the history is full with recurrent disruptive innovations. I obviously recommend investors do take care in order not to “bite the bait”, but I would never be so emphatic with our next future. An example, think of the earliest stages when combustion engines were being born. Gas against diesel, and gas engines were the winners for automobiles. A couple of decades ago some manufacturers wanted to get back and deepen new alternatives for diesel engines. Some tuning made the rest and everybody knows today that turbodiesel engines are a real alternative to gas ones. HAWT vs VAWT? Who knows. Three blades classical HAWT vs 6 blades or twin rotor? Who knows. I’m sure the evolutionary innovation by constantly improving the classical 3 blades HAWT design is coming to its limit. A revolutionary design is about to come. It’s the only way to dramatically reduce the cost of energy and boost the competitiveness of wind energy.

  3. Hello, very good point but one thing current technology applies for cut-in at somthing like 3 m/s with 0 power to somthing like 23 or 25 m/s for the rated power. Rated power is reached at about 12 m/s.
    What if we consider to adapte the turbine design to wind speed range ?
    Specially for low wind speed sites looking for some design fitting to 1 m/s to something like 15 or 18.
    Regards

  4. I’m all for future innovation but it is not for want of trying that vertical axis machines haven’t come of age.
    The reason has to do with angular momentum.
    Check the structure.
    With a horizontal machine, the mass of the fan at the periphery is negligible.
    The mass is close to the axis. It can develop speed.
    (Power is proportional to the cube of the wind speed and the machine needs to get up to speed as well).
    With the vertical device, the mass is all at the circumference.
    These things can’t get up to sufficient speed to develop power!
    Great for torque but that’s all.
    It’s physics.

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