When it comes to measuring the efficiency of a device, especially one that creates clean and green energy you have to be cautious. One should only compare efficiency on a like versus like basis. What I mean is that it’s not an accurate representation to compare the efficiency of biodiesel engine with the efficiency of a wind turbine. At best the only real comparison between the two that could be made is the rate of improvement seen in each medium. To rate the efficiency of one wind turbine you can only compare it to another wind turbine. Anything else would be basically meaningless.
What is Efficiency?
We use the term efficiency to judge physical concepts, poetic concepts, and even human efforts. The concept is very loose, and with human efforts, and artistic endeavors there is no set formula for efficiency. You can say a worker is efficient at their job, but what is the mathematical formula you use to describe such a thing? Is a good movie efficient because it told you an excellent story in two hours? How do you scientifically and mathematically quantify that?
With physical concepts you can judge the efficiency using mathematical formulas that is clearly defined throughout an industry or subject of study. In fields of engineering and science these formulas are invaluable to industry when designs are being planned. These formulas are derived from data derived from an ideal model of efficiency. There isn’t just one type of efficiency formula, as the efficiency formula for a solar panel is different than the formula for wind turbine efficiency. The only thing universal about these efficiency formulas is that they are all different, and machinery, computers, and engines all have their unique formulas.
A wind turbine’s efficiency rating is a good way to find the best wind turbine for specific needs. The most efficient wind turbines may not be perfect for everyone due to the increased price it will demand. However, with an efficiency formula you can judge a turbine’s efficiency for its price to get the cheapest per kilowatt price. Once the turbine is in place the energy is technically free, however due to the cost of the system we divide the cost by the kilowatts it can produce to arrive at this number.
Now if efficiency is a scale that is based on an ideal standard, then we judge a wind turbine we are judging its efficiency versus a perfect wind. What is a perfect wind turbine? Well, the job of a wind turbine is to convert wind power into electrical power. So the perfect wind turbine will convert 100 percent of the wind into electricity. There will be zero electricity lost in the conversion from rotational energy as it converts into electrical energy. At an efficiency rating of 100 percent there would be absolutely zero wind power that is not converted into electricity. This perfect turbine is theoretical of course, and is actually an impossible achievement. Wind turbines are roughly 50 percent efficient on average with current technology.
This is a drastic improvement over wind turbines of old. In just a few decades we were able to raise efficiency from a mere 25 percent to 50 percent. That number will continue to grow as technology improves. The technology for wind turbines increases piece by piece.
Since the system relies on a wide variety of different machinery there isn’t a simple answer here. Engineers start with one part and expand from there, making the entire system more efficient.
One thing done to double wind turbines efficiency was increase the rotor size from 70 to 100 meters. This was the first step in producing better blades, which could in fact make the wind turbine eve more efficient. Blade design is not a simple thing, it’s robust, dynamic and carefully done to maximize torque and reduce thrust. When designing a blade every inch of it is planned out to maximize efficiency and reduce efficiency killing vibrations. To maximize efficiency the blades are thinnest at the tip, which is necessary to maintain fluid dynamic contact with the blade regardless of the wind speeds. The tip of the blade is actually the fastest moving portion of the blade and leads the rest of the blade in rotation.
Computer simulations and 3d printing are the leading edge in developing more efficient wind turbines. With modern computers engineers can predict what will happen to a turbine in certain winds, how design changes will affect the turbine, and really what the future of turbine efficiency looks like.
Design and the components used to build turbines play a large role in efficiency. When you begin mixing different generators with different rotors you can have a wide variety of different effects. Using a small generator with a large rotor is perfect for harvesting wind energy at low speeds. Placing these turbines in low wind areas is an excellent idea, but these turbines will not be as efficient as possible when faced with rapidly moving winds. It will still produce electricity, but it will be wasting tons of wind. On the opposite end of the spectrum a larger generator with a large rotor is perfect for harvesting faster moving winds.
Since there is not a set size for generators and rotors computer simulations can predict what size of each is perfect for the average wind conditions in a certain area. This location based efficiency is another factor that can aid in generating as much bang (AKA electricity) for your buck. When you talk about total turbine size, including the tower, rotor and blades, and all of it put together you may think you get more efficiency from a bigger tower. You get more power from a bigger solar panel right? Well, remember turbines aren’t solar panels. A massive turbine placed in an area where a smaller model will work is incredibly inefficient.
Maximizing efficiency is a dynamic concept when it comes to wind turbines. There is no one best answer. Instead you have to look at each individual question and find a solid, undeniable answer for each situation. Like the wind, the answer is always changing.