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Dense Packing Increases Efficiency for Wind February 17, 2010

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While it’s generally understood that horizontal wind turbines are more efficient than vertical blade turbines, the effect of the blade catching the air tends to slow that air down, meaning each turbine needs a significant separation from one another to reach that efficiency.

Students at Caltech were looking for ways to improve wind turbine efficiencies, and have found a way to increase the power efficiency per foot of land area by studying the way fish swim. 

When in a school, fish swim in an offset pattern that creates what’s called a Kármán vortex street.  In fluid dynamics, a Kármán vortex street is a repeating pattern of swirling vorticies (whirlpools) that are formed when a fluid (which could include water or air) passes over objects.  Under the right conditions, the separation and recombining of the fluid is what causes the effect.

When air passes around an object – especially circular cylinders, like power plant cooling towers, it tends to move to one side, which creates a low pressure on the other side, pulling the air back in a wave pattern.  These eddies are shed continuously from each side of the body, forming rows of vortices in its wake.  The further it gets from the object, the smaller the oscillation, and eventually the regular pattern disappears.  But in the first few feet past the object, it can cause havoc.  It’s especially troubling when the object is moving through a relatively slower fluid (like an airplane flying through the air).

This effect also has positive effects. Their interaction helps keep schools of fish synchronised and reduces the total propulsive power needed per fish. A similar effect reduces the fuel consumption of vehicles travelling in a platoon.

What the students did was arrange the turbines in a way to catch the vortices.  that drove them to vertical blades, since the eddies would dissipate in a traditional horizontal blade wind farm.  But by installing vertical turbines in a Kármán vortex street, the turbulance from one helped power the next.  And because they were closer together, more of them could be mounted on smaller patches of real estate, and support structures could be combined for more efficient transmission.

According to the researchers, “these configurations significantly reduced the land use for vertical axis wind turbine wind farms, resulting in array power density increases of over one order of magnitude compared to operational horizontal axis wind turbine wind farms”

Patents have been filed.

sources: 

http://www.technologyreview.com/blog/arxiv/24813/

http://en.wikipedia.org/wiki/Von_Karman_vortex_street

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Note: the comment to the article mentioned  a Russian company, ‘SRC Vertical’, whose wind turbines are marketed in the USA by a company called ‘Wind-sail’, that was funded by the U.S. Department of Energy to build VAWT’s, has built VAWT’s with an efficiency of 38%, which is up there with the best HAWT’s, and they reckon they can increase the efficiency up to 45%.

NASA Data Could Boost Wind Production December 9, 2008

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NASA has a long history of spinning off cool technology for non-NASA purposes.  Coatings, insulation materials, safety improvements, and Tang.

Recently, NASA released the results of their QuikScat satellite.  QuikScat was launched in 1999 and uses a microwave radar instrument named SeaWinds to track the speed, direction and power of winds near the ocean surface. Data are also used to predict storms and enhance the accuracy of weather forecasts. Those results reveal ocean areas where winds could produce energy.

Wind energy has the potential to provide 10 to 15 percent of future world energy requirements, according to Paul Dimotakis, chief technologist at JPL. If ocean areas with high winds were tapped for wind energy, they could potentially harvest up to 500 to 800 watts of wind power per square meter, according to Liu’s research. Dimotakis notes that while this is less than peak solar power, which is about 1000 watts per square meter on Earth’s surface when the sky is clear and the sun is overhead at equatorial locations, the average solar power at Earth’s mid-latitudes under clear-sky conditions is less than a third of that. Wind power can be converted to electricity more efficiently than solar power and at a lower cost per watt of electricity produced.

Ocean wind farms have less environmental impact than onshore wind farms, whose noise tends to disturb sensitive wildlife in their immediate area. Also, winds are generally stronger over the ocean than on land because there is less friction over water to slow the winds down — there are no hills or mountains to block the wind’s path.

Areas with large-scale, high wind power potential also can be found in regions of the mid-latitudes of the Atlantic and Pacific oceans, where winter storms normally track.

source:  NASA’s Jet Propulsion Lab

Wind Turbine Efficiencies Offered November 10, 2008

Posted by OldGuy in energy conservation, Wind Power.
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Virginia-based Catch the Wind has an innovative solution for improving wind turbine efficiency— laser beams. The company’s fiber-optic laser system gives turbines up to 20 extra seconds to adjust to changes in gusts and wind direction. That may not sound like much, but Catch the Wind claims that its system can improve turbine output by 10 percent.

source:  cleantechnica.com

Catch the Wind, Inc is based in Manassas, VA

Solar Updraft for Energy Production September 13, 2008

Posted by OldGuy in solar, Wind Power.
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There’s an interesting but still untried approach that combines solar power and wind power.

The principle of Solar Updraft is that a solar collector is laid down across an open field, such as a desert wasteland.  In the center is a tall hollow tower.  The result is an updraft inside the tower.  If one or more wind turbines is placed inside the tower, the constant wind can generate a steady stream of electrical energy, with virtually no carbon footprint once the tower is finished construction.  (Carbon payback on construction is generally 2-3 years.)

Some have suggested the collector field can be fitted with solar storage mechanisms, such as tubes of liquid, which heat during the day and generate a secondary heat source after the sun has gone down.

Unfortunately, most of the concepts involve very tall towers.  A prototype plant with a 200 meter-tall  tower built in Manzanares, Spain in the early eighties, and was operated successfully for several years.  However, a production plant was never constructed, in part because the finished tower will be almost a mile high (1.5km) and 280 meters wide.  And it will take a large amount of land, as currently designed.  The prototype plant included a 44,000-m² collector; the production unit uses a 37 square km collector field.

Of course, you don’t need to leave the collector field empty.  The solar tower proposed for Nambia includes a design to use that collector field as a greenhouse.

It’s an interesting concept.  I’m a little concerned about how they would construct a tower that is nearly 5 times taller than the Eiffel Tower (325 m).  It would be twice as tall as the world’s tallest building, the Burj Dubai in downtown Dubai (still under construction), which will be 688m (160 floors) when finished.

The expected power output – 400MW of energy – is impressive, but I wonder whether it might be better to stick with more, smaller towers, even if they generate less  energy each.

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sources:

http://www.inhabitat.com/2008/09/10/solar-updraft-towers-in-namibia/

http://www.sbp.de/en/html/solar/aufwindkraftwerk.html

http://en.wikipedia.org/wiki/Solar_updraft_tower

Oregon Wind Farm Gets Go-Ahead August 18, 2008

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The Oregon Energy Facility Siting Council has approved construction of what will be one of the world’s largest wind energy generation plants.

The Shepherd’s Flat Wind Farm, which stretches into both Gilliam and Morrow counties in north-central Oregon, is planning 303 wind turbines.  At peak capacity, the new plant will be capable of generating 909 megawatts, more than all other wind-generated plants operating in Oregon today (889 megawatts).  Until it is finished, the Horse Hollow wind farm will hold the title of largest operating wind farm in the United States, operating at 736 MW.  (Texas oil and gas magnate T. Boone Pickens has plans to build a wind farm in Texas by 2014 that would reach 4,000 MW.)

The project is being developed by Caithness Shepherds Flat, LLC of Sacramento, Calif.

(This report from the Portland Business Journal, 28 Jul 08)

Energy alternatives for Africa August 17, 2008

Posted by OldGuy in Alternatives, energy conservation, Wind Power.
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“Africa is fast becoming an important player in cleaner energy sources. If only 0.3% of sunlight falling on the Sahara and Middle Eastern deserts can potentially provide all of Europe’s energy needs because of its intensity, how about everything else?”

With these words, Sam Aolo Ooko (a writer for Green Options), introduced a bold idea – switch Africa from eco-costly investments into planting and developing biofuels, but instead jump-start more developed continents by developing alternative energy sources and innovating conservation measures. He continues:

“How much wind blows from Nouakchott to Natal, and how much of this is ever utilized as an alternative energy source? How much water flowing in the Zambezi is used to power villages in Zambia and Zimbabwe; and how much more of the great Nile waters that flow into the Mediterranean can sustainably be harnessed to run corn mills in Nakuru and cotton ginneries in Jinja and Khartoum or fisheries in Cairo?”

Ooko quotes Ester Nyiru, a respected African economist, as saying “African countries are not using alternative power supplies since international combines do not encourage the switch; indeed, the use of such technologies may damage their business.”

Ooko is on to something. There are vast deserts with abundant sun and wind. In those regions, there is little reason to use oil and coal to generate electricity. Africa has vast coastlines and many rivers capable of producing hydro- and tidal generation.

Ooko’s future is hopeful: “Every single village in Africa can have cheaper, cleaner, sustainable energy and we can re-write every book that proclaims the end of poverty. Forget oil, alternative energy is the way to go for Africa.”

150 gigawatts of wind power by 2020 August 17, 2008

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A recent report from Emerging Energy Research says that, given current trends in the rate we are building wind plants in the US, we could be generating 150 gigawatts of wind power by 2020.

By comparison, the average coal plant generates 800 megawatts of power.   That means that if the report is true, by 2020, wind could do the work of 180 coal-fired generating plants.

There’s a lot of ifs between now and then.  You’ve read my posts on the problems with siting.  In most cases, where the power is needed (cities) is not good for wind-based power plants, and there is always some loss in transmission.  Then there’s the loss of the energy tax credits, which makes the cost of construction that much more expensive.

And then there are the production delays over at General Electric.  According to EcoGeek, the backlog is up to two years for the generation turbines.  (Note that these are the large turbine blades, with a spinning diameter larger than the wingspan of a 747.

To make the EER report valid, GE’s 40% growth in the rate of production has to continue (not likely sustainable).  But we will see.

Small Wind Machines help solve a national energy problem August 9, 2008

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“In theory, small-scale wind energy has the potential to generate 41.3 TWh of electricity and save 17.8 MtCO2 in the UK annually.”

Thus begins an informative report on the use of small wind turbines at individual home sites to address the national energy problem in the UK. And although the focus, and the examples, are British, the solutions offered are universal. This is no puff piece with cliche answers. The solutions are realistic enough to adequately discuss the needs and options in laymen’s terms.

For example, in discussing methodology of calculating savings, it suggests that the biggest cost driver is the costs of turbine installations. “Since the costs of maintaining turbines tend to be low, upfront capital costs are the primary drivers of costs of energy, and capital cost reductions are most likely to lead to cost of energy reductions.”

The report helps with siting considerations. Turbines work best when they are out by themselves, or upwind of a single building. There is a good description of the effects of building spacing on wind turbulence and how the buildings slow the strength of the wind forces – a good thing in the city, but bad for generating electricity efficiently. This is one reason why there are nine times more wind turbines in rural areas than in cities. The study found that “small turbines in rural locations may achieve capacity factors of around 15-20%, but urban turbines are likely to have significantly lower factors, with less than 10% being common.”

The report also describes the carbon savings potential with implementing small turbines throughout England. Imagine the savings if this were implemented in the USA, if worldwide!

Read this report and you can pretend to be an expert. It is well-written with substantive research and solid recommendations. Find it here.

Predictions for Wind Energy August 6, 2008

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A new report from the Department of Energy suggests that Wind Energy has the potential for being a major factor in meeting our nation’s energy needs.

The report is called “20 Percent Wind Energy by 2030” and suggests that use of this clean and readily available source of energy.  Wind energy, they say, could also avoid 7.6 cumulative gigatons of CO2 by 2030; it could save 825 million metric tons in 2030 – and every year thereafter.

Today, the US produces 16.8 gigawatts (GW) with wind energy.  Not shabby, but nowhere near the estimated 304 GW the DOE thinks we will be generating by 2030.

The U.S. wind energy industry invested approximately $9 billion in new generating capacity in 2007.  This has helped the industry grow with a 30 percent annual growth rate over the last 5 years.

But for the US to reach this 20% goal, several things must happen.  The US transmission infrastructure will need to be upgraded, to limit transmission losses from wind-prone areas to areas where the energy is needed.

And there will need to be more wind farms.  The number of generating facilities must increase from approximately 2000 in 2006 to almost 7000 in 2017.  OF course, that means process improvements are needed to streamline siting and permitting for new transmission lines.

The goal will also require improvements in reliability and operability of wind systems.

This report presents an in-depth analysis of the potential for wind in the United States.  It identifies opportunities to bring the US to produce 20 percent of the nation’s electricity mix by 2030.

To write the report the DOE drew on the expertise of the American Wind Energy Association and Black and Veatch engineering consultants, and the report reflects input from more than 50 energy organizations and corporations.

The pdf of the report is available from the DOE website.

Make your Fortune in Wind Power August 4, 2008

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The Department of Energy has a great little publication for download on its website that you can use to set up your own green energy generation company.

The report is called “How to Build a Small Wind Energy Business: Lessons from California.”

The goal of the DOE is to have small businesses across the country – but especially in wind-prone areas – setting up capacity tied to the national energy grid. The energy producer listed in the report, Joe Guasti, owned two wind turbines as an adjunct to his construction company.

He chose the 10 kW generator from Bergey Windpower Company, and qualified for California energy tax credits – as soon as he got past the local regulatory officials! In Riverside County, for example, the process may take a year or longer and cost upwards of $6,000. Small wonder there are few turbines there.

But where the local officials are amenible, the processes are fairly well defined, and easy to negotiate. And in areas where electricity is expensive (such as parts of California), single turbine installations can reduce home electricity bills from as much as $400 down to less than $50 a month.

And for Guasti, the business is not just in energy savings. His construction company will put up the tower and connect it to the house for energy usage, and to the local electrical grid to sell back the excess power.