While solar PV could be hogging all the limelight owing to the National Solar Mission, wind industry is by far the most important renewable energy sector in India as of 2010, comprising over 70% of the total renewable energy installed capacity (excluding large hydro). It will thus be interesting to know what inventions and innovations could shape this industry in future.
Those analyzing the renewable energy industry would surely have come across statements that say that wind is a mature industry. To some extent, it is true. We keep hearing about many “breakthrough” inventions in solar PV and solar CSP almost every second day; the number of such breakthroughs we hear about are far less frequent in wind energy.
In theory, wind farms have existed for over a hundred years, but they have been used to generate electricity only for the past about 40 years. For instance, the wind farm at Altamont is considered to be one of the oldest “modern” wind farms in the world – this was constructed in the early 70s. So that makes the wind power a 40-year old industry. That could qualify as a fairly mature industry.
If you consider solar PV, a quick reading of the industry will tell you that there have been dramatic cost reductions with innovations and improvements in technology. Since the early 1980s, capital costs for solar PV have fallen by about 90% – yes, the capital cost today just about 10% of what it was in the early 1980s. In the last couple of years alone, costs have fallen by over 30%.
Well, wind energy costs have fallen as well. In 2004, wind energy cost a fifth of what it did in the 1980s, and some expected that downward trend to continue as larger multi-megawatt turbines were mass-produced. However, the cost reduction in wind energy (per MW of power or per kWh of energy) has not been as regular and steady as it has been for solar PV, with some years in the period 2004-2007 actually experiencing significant cost increases, mainly owing to the shortage of wind turbine supplies.
OK, so most of us would readily admit that solar (both PV and CSP) have much higher chances of disruptive innovations down the line than does wind. This does not however imply that there are no major innovations or efforts to increase the efficiency of wind farms or to decrease the costs of components.
The development of electricity production efficiency, owing to better equipment design, measured as annual energy production per square meter of swept rotor area (kWh/m2) at a specific reference site, has improved significantly in recent years. With improved equipment efficiency, improved turbine siting and higher hub height, the overall production efficiency has increased by 2-3 per cent annually over the last 15 years. That’s something to write home about indeed.
I am providing some of the latest research and commercial efforts in the context of wind energy innovations. I am categorizing them into Fundamental Innovations and Incremental Innovations.
The truth is, there have not been way too many “fundamental” or “original” innovations in wind for many years. Using kite-shaped designs at high altitudes for exploiting higher wind speeds is one of the few remember as being memorable.
A couple of other wind energy ideas that I thought were original, I’m mentioning below.
Gearless Wind Turbines
In regular wind turbines, the gearboxes are highly complex mechanisms, which require a lot of time and money to repair in case of a failure. Some companies are trying it out with gearless wind turbines. An example is CWind. A Candian company, CWind has developed a prototype for a new class of gearless wind turbines.
The new “friction drive,” as experts at the company call it, runs more efficiently and reliably than existing devices, and also promises numerous financial saves. The innovation, if applicable, could translate into a new class of turbines that will endure for longer, and that will not need to be shut down for several days each year for maintenance. The approach uses a shaft to propel a large metal flywheel inside the nacelle. The flywheel is surrounded by eight smaller, secondary shafts, which are in turn connected to eight 250-kilowatt generators. Each of the secondary shafts is covered with special tires, which grip onto the surface of the flywheel. “We’re using friction. It’s not mechanically hard-coupled,” a CWind engineer explains. If the wind suddenly speeds up, which is the main cause why gearboxes fail, the tires simply slip from the surface of the flywheel, preventing any damage to the ensemble.
FloDesign’s Jet Engine-inspired Wind Turbine
A small Massachusetts-based start-up, FloDesign Wind Turbine ( http://www.flodesignwindturbine.org/ ) has been working on a “shrouded turbine” design that it says can generate three to four times more electricity than today’s hulking wind turbines. The company’s design draws on its jet engine expertise from parent company, aerospace engineering firm FloDesign. The turbine design takes a radically different approach than the rotor-based wind turbines that dominate the market now. FloDesign Wind Turbine’s design resemble a jet engine, an approach that allows it to capture much more wind energy while taking up less space than traditional turbines. When wind hits a turbine, it’s constructed so that different air flows create a rapid-mixing vortex. A fin directs it to face the direction of the wind to maximize the amount of energy it receives. See an illustration of the turbine here to see why it is so dramatically different from the current design – http://www.devicedaily.com/wp-content/uploads/2008/12/flodesign-wind-turbine-03.jpg
Adam Fuller’s Vertical Axis Wind Turbine for Utility Scale
While other inventors have been dabbling in the idea of small vertical wind turbines for home use, Adam Fuller has been developing a large utility scale vertical wind turbine with a very unique design. (see the picture here to see how different it looks – http://www.greentechgazette.com/images/fuller-verticalwindturbine.jpg .
One can also see that this machine is unique even among other vertical axis wind turbines. The structure that Fuller has built is approximately 12 ft. wide by 36 ft. tall and features 8 rows of 4 scoop units revolving around a single axel. As one can see the design is bird friendly since birds can actually see this turbine rather than the swift blades of a horizontal design. Fuller calculates that if his design was scaled up to around 120 ft. tall, it would produce between 30,000 and 75,000 kilowatt hours per month or enough to power 30 to 75 average homes.
Now, I am not suggesting this is as fundamentally unique as the FloDesign idea, but you can see that folks could come up rather creative and hopefully much more efficient designs. It is too early to say whether Adam Fuller’s design or FloDesign’s concept could make dramatic efficiencies happen at large scales. But you never know! At least a few important folks have believed in FloDesign as it has landed a $35 million equity funding earlier this year.
Not-so-Fundamental (Incremental) Innovations in Wind Energy
Innovations needs not be original or disruptive. In fact, many of the critical innovations in our history have actually been incremental than disruptive. Thankfully, there are a number of such incremental innovations happening in the field of wind energy. I am providing details of some of them.
Some of the key innovation efforts in wind turbine towers are towards reducing the amount of materials used in the towers.
For instance, Greenward Technologies’ patent pending “ISO-e” tower technology reduces the steel component in the tower by at least 50%. If applied, this would result in a significant decrease in tower manufacturing cost. At the same time, the development would also make the turbine less vulnerable to buckling failure. The design decreases steel usage by making it the tower’s thin inner shell. The steel shell is combined with an outer concrete-polymer jacket which is over six times the thickness of conventional pressurized steel. More on this here – http://greenward-technologies.com/iso-e.htm
Innovation in Generators
Most innovators had not bothered to touch the generator in order to increase the efficiency of wind turbines; rather, they had tried to play around with the blade designs that maintain an almost constant rate. But some companies are trying to change the transmission to the generator itself.
Take this new design by ExRo, a start-up. The company has revamped the generator by abandoning mechanical transmission in favor of an electrical transmission. This new design promises up to 50 percent more efficiency and lower production costs. Ordinary generators have an optimal rate tuned to local average wind conditions. When the wind blows faster or slower than average, efficiency significantly decreases, a major cause of why wind power is more expensive than coal, which burns in plants with turbines that turn at steady rates, maintaining a high efficiency. Some have tried blades that change pitch to catch more or less wind and maintain a steady pace. Others have used mechanical transmissions. However, cost and maintenance is pricey, and these are of limited use. The new generator scraps the mechanical transmission for an electrical one. The new transmission still requires a bit of blade pitching with extremely high winds. However, it can significantly extend the peak efficiency range, balancing gusts and lulls to produce up to 50 percent more power over the year. More on this @ http://bit.ly/aJY5I8
Well, I must admit that the above innovation is not exactly incremental!
Innovation in Blades
While rotor blades, gearbox and generator all are major components of a wind turbine, the blades usually define how proficient a wind turbine is going to be. There has been of late a notable innovation in the traditional blade set wind turbines’ blade technology. Ideal wind speed is what decides the efficiency of a wind turbine. It needs to be tuned for a certain type of wind to be efficient and smart. A recent design uses shape-shifting blades designed by researchers at Purdue University and Sandia National Laboratories, which, having sensors and computational software to monitor forces exerted on wind turbine blades, constantly manage the blades to keep rotating at a uniform speed that is the most ideal. The shape-shifting blades have sensors that tout control surfaces with simple flaps and are responsible for changing the aerodynamic traits of the rotor-blades.
And Finally, the Challenge of Intermittency has Still Not Been Confronted
While the innovations mentioned above tackle a number of interesting issues, they do not tackle the most important of all: Intermittency.
Tackling the intermittency of wind both while it is waning as well as when it supplying excess power is perhaps the single most critical challenge facing the industry today. Well, the obvious solution is to have storage technologies. If only life were so simple! Storage technologies today are terribly expensive and can increase the cost of producing electricity from wind by over 100%!
To give you an idea of costs of storage for renewable energy, a recent report estimated that the potential costs of building the storage necessary to allow renewable energy to expand to supply just 20 percent of US energy needs would be enormous – more than $340 billion to develop some 912 billion watt-hours of storage capacity.
Conventional lead-acid batteries are too costly and have poor durability. Instead, researchers are turning to batteries with unusual chemical combinations, such as sodium-sulfur as well as the more familiar lithium-ion. But it is too early to say whether these technologies will be able to provide affordable storage.
Hope you found this article useful. Your feedback is welcome.
ISpecific productivity – kWh/sq m for Wind Turbines have not increased by 2-3% annually. There is no technological innovation in India except for the Gearless technology. Increase in swept area/ hub height are not innovations.
Introduction of hydrodynamic torque converter has not been mentioned. Friction drive, Flodesign may be concepts yet to be field proven.
Pumped storage hydrpower continues to be the lowest cost storage technology even today. Tamil Nadu has 550 MW established long back !