Navigant Research Blog

Wind Energy Innovation: Vortex Generators

— July 15, 2014

The wind energy industry has doggedly pursued higher energy yields and lower costs of energy with each successive generation of wind turbines.  As a result, the wind energy industry has lowered its costs by over 40% in just the past 4 years.  Innovations in wind turbine design, materials, and the sub-component supply chain are continually yielding advances – sometimes from the smallest places.

The mature aerospace industry has provided many complementary solutions to the wind industry in terms of design, materials, manufacturing, and the operation of large rotors.  Among these is the relatively recent introduction of vortex generators (VGs).  These small, simple fins, usually less than 8 centimeters tall and wide, energize airflow directionally around a blade when applied in multiples and keep it from erratically scattering as it passes over the blade surface.

The image below, from LM Windpower, the largest global independent blade manufacturer, shows the difference in airflow over a blade during recent testing.  The benefits are most pronounced close to the thickest section of the blade, near the blade root.

(Source: LM Windpower)

Lower Speed, More Energy

Lessons learned long ago in aviation show that planes with wings equipped with VGs are able to reach slower speeds before stalling out, as the VGs helped increase lift on the wings.  Wind blades operate similarly to aircraft wings, in that wings capture passing wind to create loft for flight, and blades capture passing wind as loft for mechanical turning power of the rotor.  The effects proven in aviation are also more pronounced at lower air speeds, when wing flap angles are more aggressively angled toward the passing wind.

Similarly, the effects of VGs appear to increase the productivity of a wind turbine more during medium and low wind speeds versus high wind speed environments.  This is complementary to the fact that, in recent years, the majority of new turbines installed in the mature markets of North America and Europe are designed for lower wind speed environments.

No wind blades presently are manufactured with VGs attached out of the factory, but a robust retrofit business has evolved among some independent service providers (ISPs) to install VGs during blade maintenance and inspection.

UpWind Solutions, an ISP based in North America, says it has installed 22,000 VGs across multiple wind turbine models and found that assumptions around a General Electric (GE) 1.5 MW turbine, with a power purchase agreement of $50/MWh and operating at a 40% annual capacity factor, would see an increase in annual energy production (AEP) of around 2.2% and recoup the cost of VG installation in 20 months.

From the Factory, Soon

Siemens has discovered the value of VGs and other aerodynamic add-ons and has incorporated these into aftermarket power curve upgrade services, similar to UpWind’s applications.  In early 2014, Siemens added VGs as a retrofit upgrade to the existing 175 wind turbines at the 630 MW London Array offshore wind project.  Siemens says the aerodynamic upgrades will yield about a 1.5% increase in AEP.

Independent blade manufacturer LM Windpower also offers VGs as an add-on service to blades.  With ISPs, turbine vendors and blade manufacturers offering VGs as add-on aftermarket services, it’s only a matter of time before vendors begin offering VGs with their standard blade offerings.

After all, they are already standard offerings on your average mallard duck.

 

Old Technology Fuels New Energy Boom

— May 12, 2013

With U.S. oil imports hitting a 17-year low, the mainstream media has awoken to the fact that, as I pointed out in a Fortune.com article 3 years ago, peak oil is not happening anytime soon.  Charles Mann’s excellent cover story in this month’s Atlantic, “What If We Never Run Out of Oil?” focuses on an obscure though potentially vast source of energy: methane hydrates, or crystalline natural gas trapped below the seabed.  If early exploration ventures by Japan and other countries succeed, this gas “could free not just Japan but much of the world from the dependence on Middle Eastern oil that has bedeviled politicians since Churchill’s day.”

An Associated Press story last week reached a similar conclusion about “unconventionals” in general: companies are opening huge deposits of shale gas, “tight oil,” and other hard to reach petroleum sources that will essentially flip the energy world upside down, as the United States regains its status among the world’s largest exporters of petroleum.

Both of these stories, though, share a common misconception, captured in the AP article’s headline: “New Technology Propels Old Energy Boom.”

In fact, the technologies underlying today’s petro-boom are not new at all; they are innovative applications and refinements of technology that has existed for decades.  The boom’s core technology is hydraulic fracturing, or fracking.  And drillers have been fracking wells for nearly 60 years.  More than 1 million wells have been developed using fracking since the 1940s, according to EnergyFromShale.org, an industry-supported website.

The early use of fracking to get at reserves previously thought of as unrecoverable, emerged in the early 2000s after exploration companies began examining geologic formations using x-ray computed tomography, or CT scanners.  The CT scanner was invented in 1967.

Tinker Imaginatively

What’s happening today is not a new-technology revolution; it’s an evolution of new applications for existing technology.  We are doing things that we’ve been doing for decades more efficiently, more effectively, and in much wider applications.

That may sound like a fine distinction, but it’s an important one: Silicon Valley has for years invested in sexy new technologies, from smartphones to social media to exotic solar power materials.  The cleantech industry itself has not benefited from a fascination with the new, the exotic, and the high-tech.  The technology for embedding sensors in a drill head so that technicians on the surface can map a formation as they drill is not all that sexy, and it didn’t come from a VC-funded startup in a Mountain View garage.  It came from drilling engineers in the field figuring out, incrementally, how to do things better, cheaper, and smarter.  Often, as in the case of the 21st century oil and gas boom, imaginative tinkering can be more fruitful than reinvention or laboratory R&D.

Leaving aside, for the purposes of this blog, the question of how we can move toward a carbon-free energy system in a world suddenly awash in hydrocarbons, the next phase of technology will almost certainly focus on how to better store, transport, and distribute the seemingly limitless supplies of natural gas now becoming available.  The difficulty and expense of liquefying and transporting natural gas have been a drag on the wider use of the relatively clean fuel for many years, particularly in the transportation sector.  In 2012, GE Oil and Gas introduced its Micro LNG plant to power remote industrial locations and fuel long haul trucks and locomotives, and last month the company debuted its LNG In A Box system for small-scale retail fueling stations.  The Norwegian gas producer and distributor Gasnor in 2009 launched the world’s first specialized, small-scale LNG carrier, the Coral Methane, designed to deliver fuel to remote ports along Norway’s coastline.

These are not “new technologies,” and they’re not being developed and funded as such.  But they’re exciting innovations.  And they are helping to power an energy transformation that will shape the world’s economy and its geopolitics through the rest of this century.

 

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