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Giant Turbines Propel Boom in Wind Energy

The wind industry is growing, literally。 American wind developers are installing increasingly large turbines, capable of generating twice as much power as their predecessors and opening up new areas of the country to wind development。 The trend arrives at a … #windturbine #wind

critical time for the industry. The production tax credit, a federal subsidy, is set to end at the end of the year. But unlike in previous years, when wind development ground to a halt when subsidies dried up, industry representatives are predicting only a modest slowdown.

“We are confident we will remain one of the most competitive forms of energy,” said John Hensley, vice president of research and analytics at the American Wind Energy Association (AWEA), a trade group.

Among the reasons for the sunny outlook: improved turbine technology. Today, only six land-based projects with a combined capacity of 767 megawatts employ turbines with a generating capacity of 3.5 MW or higher. The majority of today’s turbines have a capacity between 2 and 3 MW.

Turbines with a capacity of 3.4 to 3.6 MW accounted for 14% of all installations in the second quarter. And orders for larger turbines are starting to add up, according to AWEA’s most recent . Some 22 projects boasting a combined capacity of 3,907 MW reported buying turbines with a listed capacity of 3.5 MW or greater in the second quarter of the year, a 35% increase over the first three months of 2019.

斗地主达人Developers in the United States only first started ordering 4 MW machines in the third quarter of 2018。 Orders for those turbines increased to 2,190 MW in the second quarter, AWEA reported。

The advantages of larger turbines are several。 Larger turbines mean fewer towers are needed to generate the same amount of electricity, decreasing projects’ costs and the size of their footprint。 That opens areas of the country like the Great Lakes, Mid-Atlantic and West Coast, where open land is at a premium, to wind energy, Hensley said。

“The 4。5 MW turbines can power twice as many homes as the average turbine in the last few years,” said Celeste Wanner, a senior analyst at AWEA。

Overall, the pipeline for new wind projects continues to grow。 Roughly 41 gigawatts of new wind capacity was under construction or in the advanced stages of development during the second quarter of 2019, an industry record。

Texas continues to lead America’s wind-building boom. The Lone Star State already boasts 25.6 GW, and the local grid operator recently reported that turbines there had generated more electricity than coal through the first half of the year (, July 23). AWEA’s figures show that even more wind is on the way. Another 7.6 GW is under construction in Texas, while 1.4 GW is in advanced development.

斗地主达人The question for the industry is how much growth levels off after the production tax credit terminates. The impact of the subsidy’s end likely won’t be immediate, as many companies will still be able to qualify for the federal money, provided they began construction before the end of the year.

AWEA is projecting a short-term slowdown but expects other factors will ultimately boost the industry。 They include falling costs and strong consumer demand。 Corporate power purchase agreements represented slightly more than half of all wind contracts in the second quarter。

Ultimately, the industry has benefited from the recent policy certainty, with the PTC laying the foundation for the industry to reduce cost, Hensley said.

“We’re seeing the fruits of our labor coming to fruition in the next couple years,” he said。

Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at .

How Does Wind Energy Work?

斗地主达人How do wind turbines convert wind into electricity? And can living near one really affect your health? Everyday Einstein explains.By Sabrina Stierwalt, PhD, 

Wind turbine farm.

In the U.S.  comes from wind turbines—that’s more than any other renewable resource—and wind power has more than tripled over the past decade. More than half of that capacity comes from just five states: Texas, Iowa, Oklahoma, California, and Kansas. According to the , there are over 56,000 wind turbines across the country that provide a capacity of ~96,000 megawatts, enough to power more than 15 million homes. The Department of Energy projects that by 2050, that wind capacity will increase to more than . 

How can you get in on this growing wind energy action? Many electric utilities allow you to tap into wind—and other renewable—sources of power if you pay a little bit more for . More consumers signing up for green energy means those utilities will work to procure more of it. Let’s take a look at how wind turbines work and some of the potential pros and cons. 

How Do Wind Turbines Work?

Wind power actually starts with the Sun. In order for the wind to blow, the Sun first heats up a section of land along with the air above it. That hot air rises since a given volume of hot air is lighter than the same volume of cold air. Cooler air then rushes in to fill the void left by that hot air and voila: a gust of wind. 

Wind power actually starts with the Sun. In order for the wind to blow, the Sun first heats up a section of land along with the air above it. 

斗地主达人The Office of Energy Efficiency and Renewable Energy describes a wind turbine as “.” Simply stated, the turbine takes the energy in that wind and converts it into electricity. So how does it do that? 

First, the wind applies pressure on the long slender blades, usually 2 or 3 of them, causing them to spin, much like the wind pushes a sailboat along its path through the water。 The spinning blades then cause the rotor, or the conical cap on the turbine, and an internal shaft to spin as well at somewhere around 30 – 60 revolutions per minute。 

The ultimate goal is to spin an assembly of magnets in a generator which will, well, generate voltage in a coil of wire thanks to electromagnetic induction. Generators require faster revolutions, however, so a gear box typically connects this lower speed shaft to a higher speed shaft by increasing the spin rate to around 1000 to 1800 revolutions per minute. These gear boxes are costly as well as heavy, so engineers are looking to design more “direct-drive” generators that can work at the lower speeds.

So wind turbines take the kinetic energy in the wind (that’s the energy due to the motion of the particles in the air) and turn it into mechanical power. That power can be used directly (for example as it often is in windmills for doing things like grinding grain or pumping water) or the generator converts it into electricity. Check out the great  on the U.S. Department of Energy’s website that walks you through the process. 

斗地主达人Wind turbines take the kinetic energy in the wind (that’s the energy due to the motion of the particles in the air) and turn it into mechanical power. 

To maximize efficiency, turbines have a wind vane that measures the direction of the wind so the turbine can orient itself to be most directly in the wind’s path. The blades also sit at 100 feet or more above the ground so they are subjected to the faster winds found at higher altitudes. Most turbines further require winds of 8–16 miles per hour to operate and have a shut off function to prevent them from operating at wind speeds higher than  because they could be damaged.

Wind power is also more space efficient than solar power。 Just one large wind turbine can power , a task that would require a much larger spread of solar panels。 The space between wind turbines can also be used for other purposes。 

What Happens When the Wind Stops Blowing?

When we turn on our televisions or start running the A/C, we get that energy from an interconnected grid, which pools together the electricity generated by many turbine locations, rather than a single wind farm. So the wind doesn’t have to be blowing in your own backyard, it just has to be blowing somewhere that’s contributing to your grid, whether that be Iowa, Texas, or California. 

However, the wind is unpredictable. The wind does blow at night, which is an obvious advantage of wind over solar power, but at least we know the Sun will rise again in the morning. The wind will always blow on our planet. We are just not always sure of when or where. This unpredictability is one of the biggest barriers to using wind power exclusively and also why your utility company doesn’t rely completely on one energy source. Most use a mix, including natural gas. 

Do Wind Turbines Affect Your Health?

There is a large amount of anecdotal evidence, mostly in the form of complaints from those living nearby, that wind turbines can cause health problems due to the low frequency noise they produce. Those complaints include reports of everything from  to  to nausea to vertigo. (Notably, this list does not include .) However, no scientific studies have been able to draw a clear link between wind turbines and health. And they’ve tried. 

The Australian government established a Select Committee on Wind Turbines which reported in 2015 that there was a  to link any of the reported illnesses to the wind turbines. The  agreed with them. In an article published in the Journal of Occupational and Environmental Medicine titled “Wind Turbines and Health: A Critical Review of the Scientific Literature,” the authors combed the archives for existing studies and the worst they found was an association with “annoyance.” They further concluded that “infrasound near wind turbines does not exceed audibility thresholds.”

Further research into the claims of adverse health effects of living near wind turbines is needed to explain their strong anecdotal support. And developments of carefully interspersed and well-connected grids of wind farms would clearly be needed if we were to increase our dependency on wind power. High upfront investment costs are also a barrier to increasing our use of this clean, renewable, and sustainable resource. Because fossil fuel rates are so much lower, estimates claim it takes anywhere from  on a newly constructed wind turbine. 

The return on that investment, in the form of the potential reduction in , however, is priceless. 

Until next time, this is Dr. Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of  or  where I’m . If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com

 image courtesy of Shutterstock.

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Reinventing the Small Wind Turbine

A wooden rotor and tower greatly increase the net energy output over the lifetime of a small wind turbine. Many commercially available small wind turbines with plastic blades and steel towers are infamous for their low reliability, high embodied energy, and limited power output. #windenergy #renewableenergy #windpower #windturbine

Building them out of wood can addresses these issues.

Because of their aesthetic appeal, and thanks to the ability to produce them locally, small wooden wind turbines can also improve the public acceptance of wind power。 Furthermore, innovation in tower design facilitates the installation of small wind turbines, reducing the need for concrete foundations and heavy machinery。

Low Performance

Tests have shown that many commercially available small wind turbines  to compensate for the energy that was needed to produce them.

There are three reasons why this is so. First, there are the laws of physics. The energy yield of a wind turbine increases faster than its height and rotor size, meaning that as a wind turbine becomes smaller, .

Second, wind turbine blades are commonly made from fiberglass reinforced plastic, which is energy-intensive to produce (). This energy needs to be “paid back” during the lifetime of the wind turbine, which can be challenging for machines with small rotor diameters.

Third, the maintenance of small wind turbines depends on the ability of the manufacturer to remain in business and provide its customers with spare parts. Unlike solar panels, wind turbines have a lot of moving parts and are thus more likely to need repairs. However, suppliers of small wind turbines tend to have an even shorter life expectancy than their products. 

Hand Carved Wood Blades

The laws of physics can’t be changed, but on their own they don’t make small wind turbines uneconomical and unsustainable. It’s the other two factors that are decisive, and these can be addressed. In fact, they have been addressed for more than two decades by Scottish engineer Hugh Piggott, who builds small 1-2 kW wind turbines with 2-4 meter rotor diameters using solid wooden blades. 

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Image: Hand carved wooden blades. Source: 

The blades are hand carved locally with basic woodworking skills and tools. In contrast to fiberglass blades, little or no energy is used to produce them. This increases the chance that the wind turbine will produce more energy over its lifetime than was needed to make it.

Defying the usual focus on efficiency, Piggott’s wind turbines sacrifice peak power for more reliable operation. The machines use a furling system which limits the turbine input at winds of 8 m/s (Beaufort 5), while most commercial models keep working up to higher wind speeds. This increases reliability, because the faster the machine spins, the quicker its parts will wear out. 

Local Manufacturing

A comparison of Piggott’s wind turbines with commercially available models concluded that the increased energy yield generated by the latter at wind speeds above 8 m/s is largely wasted, because most of the extra power is generated when the batteries are already full. The study also revealed that Piggott’s design is about 20% cheaper, taking into account both capital and operational costs. 

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Image: Wooden wind turbines in Nepal. Source: 

Piggott’s open source design has spawned thousands of small DIY wind turbines all over the world. It also became the basis for several wind-based rural electrification initiatives in Mongolia, Nepal, Peru and Nicaragua. 斗地主达人 In “developing” countries, the ability to manufacture and maintain the turbines locally is a great advantage over the use of commercial wind turbines or solar panels.

Commercial Wind Turbines with Wood Blades

The use of solid wood blades,  for , has seen renewed interest lately.  Most notable is the success story of the Dutch company , founded in 2014 by four young windsurfers. The firm, which now has over 40 employees, sells wind turbines with solid wooden blades to farms and energy cooperatives in the region. With a rotor diameter of 12 meter and a power output of 10 kW, the turbines are about five times larger than Piggott’s machines.

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Wind turbine with wooden blades, built by EAZ Wind.

The blades are made from solid wood beams that are glued together and then sanded to obtain their shape. They are then covered with an epoxy coating to protect them from humidity, while the sharp side of the blade gets a strip of fiberglass reinforced plastic to make it more durable. According to the manufacturer, the wind turbines — installed on 15 m tall towers — produce roughly 30,000 kWh of electricity per year, which corresponds to the power use of ten Dutch households. A machine sells for 46,000 euro, which makes it cheaper than a solar PV system (4,600 euro per household, or less than half the price of a solar PVsystem). The financial payback time – in the windy northern Netherlands – is 7 to 10 years.

Public Acceptance

Interestingly, EAZ Wind’s choice for wooden blades is not driven by the aim to lower the embodied energy of the wind turbine. Rather, the company’s mission is to make the countryside – especially farms but also small villages – self-sufficient in terms of power production by designing more beautiful and locally produced wind turbines that people don’t complain about. As in many other countries, large wind turbines – and the transmission lines that go with them – raise a lot of opposition from local residents in the Netherlands.

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Image: Installing a wind turbine with wooden blades. Image: EAZ Wind.

The approach seems to work. When a farm installs a wind turbine, its neighbours are usually the next customers. EAZ斗地主达人Wind has sold more than 400 wind turbines by now. Public acceptance of wind power seems to be encouraged by two factors. First, wind turbines with wooden blades have a more natural look, increasing their aesthetic appeal. Second, the machines are produced locally, meaning that the purchase of a wind turbine supports the local economy. The wood for the blades comes from a nearby province and is processed by companies in the region.

Wooden Towers

The turbins from EAZ斗地主达人 Wind have wooden blades, but steel towers. The Swedish company  takes a different approach: its wind turbines have a wooden tower, while the blades are made from plastic. The 12 m or 20 m tall towers are of a unique design, composed from small wood modules that can be bolted together on the ground in a few hours.

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Image: InnoVentum’s wooden wind turbine tower.

The multi-leg towers require  and they can be erected without the use of a crane, using a rope and a winch instead. Around fifteen have been installed since 2012. Like EAZ斗地主达人 Wind, the company aims to create a new aesthetic level that may help to increase the acceptance of wind turbines.

!image

Image: InnoVentum’s wooden wind turbine tower.

Of course both approaches could be combined, resulting in small wind turbines with wooden blades, tower and other structural parts. A small wind turbine that’s almost completely built out of wood – minus the gearwork and the generator – further decreases the energy that’s needed to produce it, thus making it more economical and sustainable over its entire lifetime. In terms of carbon emissions, a small wooden wind turbine can even be considered a carbon sink, because the wood sequesters CO2 that the trees have taken from the atmosphere.

Combining Wind and Solar

The newest products from both EAZ Wind and InnoVentum incorporate solar panels at the basis of the structure. Because the wind turbine and the solar PV system can share the same support structure, electrical system, and energy storage, this approach saves money and resources. The combination of solar and wind also increases the chances of sufficient power output at any time, reducing the need for energy storage – which is the .

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Image: InnoVentum.

In the hybrid solar-wind model from EAZ Wind, the capacity of the wind turbine is double the capacity of the solar PVpanels, reflecting the local climate (windy but not very sunny). The addition of solar panels increases the power yield to 45,000 kWh per year, which corresponds to the power demand of 14 Dutch households. However, the use of solar panels , so that it may no longer be a carbon sink.

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Image: InnoVentum。

Decentralised Power Production

Small wooden wind turbines offer additional benefits that are inherent to all decentralised power sources. The fact that they’re paid for by the same people that enjoy their benefits, increases their public acceptance. They also eliminate the need for transmission lines, and the more power is produced and used locally, the less challenging it becomes to integrate unpredictable wind power into the central grid. Last but not least, the connection between energy use and demand .

Kris De Decker

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