SunPlower Wind / Solar Energy Device
ABUNDANT CLAIMS of Supposed Energy-Harvest Market Disruption Tech
For any of my readers that have a decent background in mathematics, engineering, physics, and a general inclination towards science and the reality of how things work, as soon as you read the claims made on the SunPlower.de website (yes, that is how they spell it; apparently trying to gain some name-recognition advantage for nearly copying the name of the large American solar company SunPower). Just one quick look at the "SunPlower" device, which I first saw demonstrated at the Lisbon, Portugal Web Summit 2019, and you will instantly see why the company claims regarding "breakthrough" power-generation (implied efficiency) are completely absurd and utterly misleading for many reasons.Here are some quotes from their website:
"SunPlower's (patent pending) world’s first Inclined Axis Wind Turbine (IAWT) propeller uses both lift and drag efficiently and reduces expensive & heavy masts costs. In addition to that propeller's blades are flat, which can be used for installing solar panels."
"Breakthrough in Fluid propulsion of both air and water more efficiently and effectively with SunPlower propeller."
"As the pitch of the propellers is synchronously varying while rotating, dust on blades with solar panels is self-cleaned. Its world’s first true Hybrid Solar + Wind technology, along with self-cleaning & self-cooling solar cells reducing maintenance costs."
Those are some rather wide-ranging and bold claims, implied and direct, and, given what was shown at Web Summit 2019 (a device which was a motor turning a windmill-like device whereby a set of gears simultaneously altered the blade angles), these claims are are highly unlikely, if not utterly impossible, to prove out in any controlled test environment (e.g., a wind tunnel).
Why these types of Claims are Problematic
There are many science blogs on the web that have tackled devices like this in the past and exposed obvious problems every time a new "disruptive" or "patent-pending" (not that a patent means anything with regard to efficiency, even if it were granted) or similar new wind-power technology — though, this one wants to call itself wind and solar power in one, or, as their home-page even goes further to state "Harvesting renewable energy using wind, solar hydro and tidal energy leveraging breakthrough technology", which sounds rather amazing.Without diving too far into details, let's start by the simple fact that this and any other such device must respect:
- Betz's law, which indicates the maximum power that can be extracted from the wind, independent of the design of a wind turbine in open flow. Every time anyone claims they have created some "breakthrough" in a wind-power device that defies this law, by directly stating so or by implication, it is certainly an instantly dubious device!
- Bernoulli's principle, which, in fluid dynamics, states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy — i.e., used to relate the velocity of the flow of air to the pressure difference across the turbine.
- Mechanical efficiency, in general, especially with regards to loss throughout a mechanical device due to friction and gears and so forth.
The device demonstrated at Lisbon Web Summit 2019 was fraught with problems and design issues that will certainly prevent it from being any "breakthrough" with regards to power-generation efficiency (whether wind and/or it's combined solar-on-blades idea, with dubious self-cleaning claims) or being produced with any sort of price/generated-watt advantage over many other existing technologies. First of all, simply put, it is overly complex mechanically and complexity = likely for failure, just as a simple rule of mechanics. There is considerable mechanical efficiency-loss due to internal gearing that alters blade angle as the overall prop-mechanism rotates.
Keeping the Betz Limit in mind, consider the following equation that represents the theoretically available kinetic energy (in Watts) in the wind flowing through an area:
½pSv3
(where p = ~1.23kg/m3 density of air, S = swept area which is πr2 with r being the turbine blade-length in meters , v=air velocity in meters/second; also keep in mind that you cannot extract all that power or the wind would stop, and thus your wind-turbine would stop, and because of this, the maximum available power is ~59% of the number arrived at with above formula — modern turbines may reach only 35-45% in reality, and that is before loss in gears, bearings, power-transmission, etc)Thus, the max power attainable by a turbine is known.
So, this little SunPlower device shown at the Web Summit did not even have blades of half a meter, and the swept diameter was perhaps not even half a meter. This means very, very low power potential. I'll keep this rough-out easy though and assume the firm may eventually build a one-meter-diameter-sweep device. So, max-theoretical-power that thing could produce at 10m/sec wind (which is a brisk and rather unlikely 22.4mph average sustained wind speed) would be:
~ .35 (efficiency extracted) x ½ x .25 (πr2, square-meters swept area) x 1.23 (air density) x 103
... or, .35 x .125 x 1.23 x 1000 ... or, 53.81 Watts!
THIS IS NOTHING! We can get so much more out of a simple solar panel! A SunPower brand ( NOT to be confused with this SunPlower thing) 405W solar panel outputs 200W per square meter! And, unlike this overly-complex SunPlower device, the solar-panel is warranted for 25 years and has no moving parts; pair it with a simple Enphase IQ Microinverter, and the panel can be easily mounted near a cell-tower and you're all set. Furthermore, the solar panel alternative is not going to be creating potential cell-tower signal interference like a spinning wind-rotor (especially if those blades were truly coated with solar-cells!).
Of course, my "red flag hype alert system" went off as soon as the developer began talking about how this device could be placed on some 4 billion (or whatever) cell-phone towers to power. Sure. As could many existing, proven, and simpler technologies like a simple single solar-panel which is an already proven, affordable, mainstream solution. And, make no mistake: the tiny solar-panels on the rotating blades of this SunPlower (proposed) device are not going to produce any appreciable amount of electricity in the same overall footprint as a simple static solar panel, nor will it make much diff when combined with the wind-power (also, bear in mind, it's not like any solar-cells on the blades are all aiming the sun at once and capturing the power, especially given how the WIND is what will dictate which direction the supposed device is pointing).
I admire any attempt to come up with new green-tech, but please, remain aware of the limits imposed by science and the fact that hype cannot overcome such laws. If this supposed breakthrough/disruptive-tech can prove they have overcome existing laws (like Betz), then bring it on! Get it proven in lab conditions and you'll have achieved the formerly impossible; but, good luck at that!
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