An answer to green energy could be in the air

Dec 19, 2010 by Jim Hodges
NASA aerospace engineer Mark Moore in his office. Moore is part of the first federally-funded research effort to examine airborne wind capturing platforms. He's developing methods the government can use to fairly evaluate competing ideas on how to capture and use wind energy efficiently. Credit: NASA/Sean Smith

(PhysOrg.com) -- In Mark Moore's world, long nanotubes reach into the clouds, serving at once to tether a turbine-vehicle flying at 2,000 feet, or 10,000 feet, or 30,000 feet (610, 3,050 and 9,150 meters); and also to conduct the power that vehicle can harvest from the wind back to Earth.

Aloft might be a funnel-shaped blimp with a turbine at its back; or a balloon with vanes that rotate; a truss-braced wing; a ; a kite. Any and all of them are ideas being considered by nascent renewable industry that is flexing its imagination.

Moore, who works as an aerospace engineer, centering his focus on advance concepts in the Systems Analysis Branch at NASA's Langley Research Center, is using a $100,000 grant from the federal government to research what it will take to judge the value of any of those ideas.

"It's the first federally funded research effort to look at airborne wind capturing platforms," Moore said. "We're trying to create a level playing field of understanding, where all of the concepts and approaches can be compared -- what's similar about them? What's different about them, and how can you compare them?"

He likens the development of wind-borne energy to flight itself, adding that "this is like being back in 1903. Everybody's got a dog to show. Everybody's got a different way of doing it?"

But the Wright Brothers didn't have to deal with a crowded sky and the laws regulating it when they took off at Kitty Hawk. When they invented the airplane, they also created competition for airspace that makes creating air-borne much more difficult.

"Airspace is a commodity," Moore said. "You have to be able to use airspace without disrupting it for other players. Smaller aircraft are still going to need to fly around. Larger airplanes, you can't expect them to fly around every wind turbine that has a two-mile radius as a protected flight zone."

It's another issue in considering air-borne power generation, which Moore hastens to say it not THE answer to clean energy but deserves consideration in a mix that includes solar power, ground-based , algae and the other solutions both realistic and exotic that are being worked upon by scientists and engineers.

None have approached the cost of fossil fuel energy for thrift, but Moore argues that cost takes on a new dimension when all of its factors are considered, including the amount of land used in generating that power and its impact upon the atmosphere.

Tethers for airborne wind generation assets don't require a lot of ground space, nor are they labor intensive. And they don't pollute.

"They could stay up a year, then come down for a maintenance check and then go back up," Moore said. "Or they could be reeled in in case of a storm. Or one operator could watch over 100 of these."

Wind power is nothing new. Wind turbine farms have dotted the landscape for more than a generation. So why is this different?

"At 2,000 feet (610 m), there is two to three times the wind velocity compared to ground level," Moore said. "The power goes up with the cube of that wind velocity, so it's eight to 27 times the power production just by getting 2,000 feet (610 m) up, and the wind velocity is more consistent."

Send turbines farther aloft, into the 150 mph (240 kph) jet stream at 30,000 feet (9,150 m), and "instead of 500 watts per meter (for ground-based wind turbines), you're talking about 20,000, 40,000 watts per square meter," Moore said. "That's very high energy density and potentially lower cost because of the 50-plus fold increase in energy density."

So why isn't it being done? Or at least, why isn't it being researched more expansively?

One answer involves the vehicle to be flown. Another involves where to fly it.

"All you have right now are small companies doing the research, and all you can expect of them is to focus on one little piece," Moore said. "They have enough trouble just analyzing their concept without worrying about geography, about 'where should I mount these so that the wind is optimal?' "

The ultimate answer could be the federal government itself.

"In my mind, it's crazy that there isn't federal investment in this area, because the questions are just too great for small companies to answer," Moore said.

It's one of the reasons he has undertaken the wind-power study, which actually, he maintains, should be two studies. One involves the technology and geography. The other involves the interaction between those elements and other competitors for airspace.

That means dealing with current Federal Aviation Administration regulations and with those that might be necessary to accommodate an airspace that includes manned aircraft, the unmanned aircraft in the future, plus wind-borne energy turbines.

But first things first.

"It's important to understand the concept without regulatory constraints because it lets decision-makers and investors understand the topology of the solution space," Moore said. "We don't want to just look at the problem with regulatory blinders on, but we don't just look at it with no blinders on, either. We have to look at it both ways."

He offers another option that can help the FAA in its decision-making.

"Offshore deployment of these airborne systems probably makes the most sense in terms of both airspace and land use, because there is little to no demand for low altitude flight over oceans 12 miles (19 to 20 km) offshore," Moore said.

"Also, unlike ground-based turbines, there is almost no additional cost for airborne systems offshore because huge platforms are not required to support the structure or resist large tower bending moments.

"NASA Wallops could have an important role as an airborne wind testing center with access to offshore wind profiles in controlled airspace."

What all this has to do with NASA goes beyond the agency's commitment to help the nation with clean energy solutions. It also involves some of the core capabilities of the agency in aeronautics, composite materials and air space management.

"We've shown in the past that NASA's expertise can help broker and bring an understanding to the FAA as to how these technologies can map into constructive purposes," said Moore, who has met with wind power energy industry leaders, as well as officials from the National Laboratory and Department of Energy in undergoing this project.

"They welcome this study because they've never dealt with flying systems and NASA has," Moore said. "You can't come up with advanced concepts until you understand the requirements well, and frankly, I don't think anybody understands the requirements well."

It's why he's undertaking the project: to bring a sense of what's going to be necessary to harvest power from the wind.

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User comments : 14

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Quantum_Conundrum
1.3 / 5 (6) Dec 19, 2010
Aloft might be a funnel-shaped blimp with a turbine at its back; or a balloon with vanes that rotate; a truss-braced wing; a parachute; a kite. Any and all of them are ideas being considered by nascent renewable energy industry that is flexing its imagination.


I wonder how many times I've made similar proposals, and someone like FBM or some other atheists on this site insults me because of it?

The power goes up with the cube of that wind velocity

tricky but true.

In meteorolgy, if you double wind speed your actually also doubling the mass of the fluid passing any given point.

So then the mass of the air passng a point in a given time frame is a related rate and must also be expressed as a function of the velocity, and this explains the "cube" value given above, because Kinetic Energy is:

Ek = (1/2)mv^2

IN this special case;

m = f(v) = density air * v * time * area of turbine

m is mass of the horizontal tube of air orthogonal to the turbine.
Quantum_Conundrum
5 / 5 (4) Dec 19, 2010
However, his formula is true only for constant air pressure and constant air density.

He neglects the fact that air pressure and density decreases with altitude.
ubavontuba
2.4 / 5 (5) Dec 19, 2010
Can you say, "Aviation hazard."

If appied at large scales, I wonder, might it significantly disrupt the weather?
Quantum_Conundrum
2 / 5 (3) Dec 19, 2010
If appied at large scales, I wonder, might it significantly disrupt the weather?


Of course.

There's heat waste and entropy in any interaction, particularly those based in friction, which turbines are.

Just look at the buildings of a city, for example. they test building designs in wind tunels and shake tables to find out how they influence the environmental wind, and how they behave in a storm or quake, and how turbulence is produced by wind interactions. You also have urban heat islands, etc.

The same sort of issues would arise from a large enough, tall enough, and dense enough wind turbine farm or solar panel farm.

The Red Wood forests in California are large enough to alter local climate, because each tree absorbs thousands of gallons of water from the air every day.

Still, turbines and solar panels are a lot cleaner than coal or oil/gasoline power.
solar2030
Dec 19, 2010
This comment has been removed by a moderator.
Lord_jag
5 / 5 (5) Dec 19, 2010
I wonder how many times I've made similar proposals, and someone like FBM or some other atheists on this site insults me because of it?


How does someones belief in religion or lack there of have any relevance on this story?? Does one need to believe in God to believe in wind energy???

It sounds like a neat idea, but how do
you keep the transmission line from weathering or keep multiple units from tangling/tugging/lowering on other buildings?
Quantum_Conundrum
2 / 5 (2) Dec 19, 2010
how do you keep the transmission line from weathering or keep multiple units from tangling/tugging/lowering on other buildings?


Have you ever seen a dual-tether kite? I saw a guy playing around with one many years ago at the beach when I was maybe 7 or 8 years old. I don't go to beach much so... Was fascinating at the time. It allows a bit more control of the range of motions.

Also, if you were to use the idea of an airship floating with a turbine, then there is little worry about it falling to the ground. Just tether it with 2 or 3 tethers that have just enough slack to keep it in place without breaking.

To allow for higher altitude and minimize issues like loss of land, it would potentially be good to either do this at the tops of sky scrapers or tops of mountains, whenever that is both possible and useful for local power grids.

For ocean usage, I think west coast makes more sense than east. Major hurricanes would be a serious problem, I think.
Quantum_Conundrum
not rated yet Dec 19, 2010
The thing about an airship is that it is more stable than a kite, particularly if there is going to be a tether anyway.

However, an airship probably costs more money in materials than a kite, because of the price of Helium.

However, and don't laugh, if the airship is hoisting wind turbines for electric power, you could just use HOT AIR from a heating coil, powered by a small amount of the electricity to keep the air hot...helium problem solved. (Patent pending?!)
nag_asam
not rated yet Dec 19, 2010
Is the power transmission going to be wireless? To such long distances??? I don't think we can have cables for power transmission there.
One more doubt, if the thing is floating, the wind that is flowing mostly uses it's energy to push the floating thing, other than rotating our turbine, how are we achieving efficiency here?
blazingspark
not rated yet Dec 19, 2010
if the airship is hoisting wind turbines for electric power, you could just use HOT AIR from a heating coil, powered by a small amount of the electricity to keep the air hot...helium problem solved. (Patent pending?!)
Hmm it might work but I don't know if hot air balloons can get these turbines to the required height. As you said earlier the air is thinner as you go higher so the lift generated from hot air would drop and the temperature differential would increase (it's really cold up there). Insulation would add more weight and the turbine is already pretty heavy so hot air might not work well enough. Then again.. what do I know? :/
antialias
5 / 5 (1) Dec 20, 2010
Wireless transmission using blimps/airships/baloons is not an option. They'd just drift with the wind and the generated power would be next to nothing (additionally your powerplant would drift all over the place - away from the receiving station. Keeping station would rquire more power than you could generate)

Kites and other anchored solutions have other problems. One lightning bolt would melt through any cable (and such cables make exceptionally good lightning rods - especially during rainy weather). You'd need to restrict their use to exceptionally arid regions (e.g. deserts).
JES
not rated yet Dec 20, 2010
Proper blue sky research!
Eikka
not rated yet Dec 20, 2010
He neglects the fact that air pressure and density decreases with altitude.


Doesn't pressure also decrease with velocity, which is how pitot tubes on airplanes work?
Newbeak
not rated yet Dec 25, 2010
I wonder how many times I've made similar proposals, and someone like FBM or some other atheists on this site insults me because of it?


How does someones belief in religion or lack there of have any relevance on this story?? Does one need to believe in God to believe in wind energy???

It sounds like a neat idea, but how do
you keep the transmission line from weathering or keep multiple units from tangling/tugging/lowering on other buildings?

I don't believe he is talking about religious belief-he is referring to the naysayers.
sender
not rated yet Dec 25, 2010
Harnessing eddie currents which form laterally to a beam of plasma or lasers could yield high ionization and compressibility inherent to the turbine generation process hence increasing yield. Wonder if they've worked it out yet.