Posting in Design
Vortexes spun by vertical-axis turbines may have two types of windmills sharing the same ground. Mixing it up could increase a farm's efficiency and reliability.
Horizontal-axis windmills, with their traditional daisy design, are more efficient than their vertical counterparts, which resemble the beaters of an electric mixer.
But one company is hoping the two styles will complement each other.
Wind Harvest International aims to plant their vertical-axis windmills in groups of three among horizontal turbines to possibly double the farm's energy yield.
Vertical windmills are better for capturing the gusty winds that are closer to the ground. Overall however, a single vertical turbine lacks efficiency. Some of its blades are always positioned against the wind, which results in drag.
But placing three of them right next to each other—with their blades turning in alternate directions—creates a vortex. The small tornado generated between the turbines raises wind speed. Rotors on both side quicken, torque increases, and energy output grows.
Greentech Media reports:
Boosting the performance of existing turbines would further help ameliorate wind's chronic problem: unpredictability, resulting in wind turbines that only generate power about 30 percent of the time. By increasing the power output when the wind blows, the capacity factor could creep up. Reliability could also potentially increase: in high wind conditions, wind farm owners could shut off their horizontal turbines but still harvest power from the vertical ones.
Whether the vertical trios might even bring higher winds to the larger horizontal turbines remains to be seen. But the squat, cyclone-spinning windmills could also aid the wind industry's real estate concerns. After huge investments in infrastructure (roads, zoning, fencing), the farms could boost their windmill holding capacity.
Commercial production for the turbines is slated for 2011.
Mar 24, 2010
The risk to birds with these catenary windmills is real. Every day, everywhere, millons of birds die (mostly at night), flying straight into the ground or ocean, under the influence of red lights on buildings and tv and radio towers, meant to warn pilots of hazards in their path. There have been some very successful efforts to stop the bird kills at offshore oil rigs by switching to other colored lights, which pilots can see but which don't disorient birds for whom red is a very special color. Birds also see things at different wavelengths from humans. Rather than have them crash into windows on skyscrapers (another deadly problems for birds flying through cities), some buildings are being equiped with films stuck to the windows, which make them visible to birds as obstacles in their path, rather than a clear way to fly. The patterns remain invisible to humans. If you were fortunate enough to read SmartPlanet articles for as long as I have, you would already know this.
While this is a rather interesting way to utilize a wind farm's footprint, there are certainly more important and longer reaching considerations that deserve greater attention. Namely, the oil and coal industries are being federally subsidized while their harmful effects on local and global environments continue to be ignored. The wind energy industry, meanwhile, has to scramble for credits. Adequate transmission lines from wind rich regions to metropolitan areas also need to be placed, or more research needs to be done on the bigger problem of energy storage instead of "unpredictability". The excerpt from Greentech makes it sound like a little more efficiency will solve wind's "chronic problem" but what is called for is more political will than technological gadgetry and efficiency. By "unpredictable" what they mean is that the wind blows whenever the wind blows. By careful sighting and a fairly simple understanding of basic fluid dynamics, any good engineer can figure out how much potential energy a particular site is capable of on a rather consistent annual basis. The daily wind patterns change, but the yearly outputs are actually rather consistent. The problem is often much more of distance and/or energy storage. Windy sites are usually not very well populated and quite distant from large metropolitan areas: the Dakotas compared to Chicago, for example. Secondly, the wind blows on its own schedule, not at humankind's peak rush hour. You may have a glut of energy when nobody needs it or a lack of wind when there is great demand. These vertical turbines do utilize a more integralist design (whether deliberately known or not) and so can grab a few more drops of energy by being put in the cracks of a wind farm, whose design needs adequate space between turbines. But as cool as Wind Harvest International's idea sounds, what will really benefit us all - create good jobs & clean energy, and allow local residents to work together to utilize the land integrally - is the political interest and will to make real changes.
Yes I mentioned this because i remembered hearing on NPR about scientists who came up with a way to deter bats from flying into the wind turbines: http://www.npr.org/templates/story/story.php?storyId=113435504
Reality is that birds do get whacked by wind turbines, but according to these statistics it's a relatively small # compared to other manmade structures, and the figures can be inflated using examples like the Altamont wind farm. http://www.focusonenergy.com/files/Document_Management_System/Renewables/windturbinesandbirds_factsheet.pdf http://science.howstuffworks.com/wind-turbine-kill-birds.htm/printable Stats and solutions from the American Bird Conservancy: http://www.abcbirds.org/conservationissues/threats/energyproduction/wind.html