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#1 2012-02-28 08:51:12

Glandu
Member
From: France
Registered: 2011-11-23
Posts: 106

Wind power : possible ?

HERE some frenchmen discuss about the colonization of Mars.

on its second post of the page, GIWA makes a very interesting calculation from the Betz Formula(Pmax = (16 /27). (1/2).ρ .S. V 3), with windspeed on earth 20km/h & 80km/h on Mars.

( VMars /V Terre )3 = 64 et PMars /P Terre = (0,02 /1,3) x 64 # 1

where #means roughly equals. A wind of 80 km/h on Mars gives nearly as much power than a 20km/h wind on earth. If one can identify a "wind corridor" on mars, using windpower would be possible.

ideas? Reactions?


"I promise not to exclude from consideration any idea based on its source, but to consider ideas across schools and heritages in order to find the ones that best suit the current situation." (Alistair Cockburn, Oath of Non-Allegiance)

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#2 2012-02-28 11:05:27

Rune
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From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Wind power : possible ?

Well, if ρ is about 100 times lower (and it is), then yes, you need a wind speed 100^(1/3) times bigger, or ~4.64, for the same power. The thing is, solar is about half as efficient on Mars as on Earth, and it is already dubious you would choose it over nuclear options. Plus, wind power is pretty much on the top of it's theoretical efficiency on earth already (>85% of theoretical Cp), so not much room for improvement. Some niche application is of course entirely possible.


Rune. Oh, and v^3 is much more clear (IMO) than v 3, if what you mean is velocity cubed. Made me look it up. ^^


In the beginning the universe was created. This has made a lot of people very angry and been widely regarded as a "bad move"

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#3 2012-02-28 20:21:10

louis
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From: UK
Registered: 2008-03-24
Posts: 6,871

Re: Wind power : possible ?

Rune wrote:

Well, if ρ is about 100 times lower (and it is), then yes, you need a wind speed 100^(1/3) times bigger, or ~4.64, for the same power. The thing is, solar is about half as efficient on Mars as on Earth, and it is already dubious you would choose it over nuclear options. Plus, wind power is pretty much on the top of it's theoretical efficiency on earth already (>85% of theoretical Cp), so not much room for improvement. Some niche application is of course entirely possible.


Rune. Oh, and v^3 is much more clear (IMO) than v 3, if what you mean is velocity cubed. Made me look it up. ^^

Wind power may not be the most efficient power source but it makes sense to utilise it during dust storms when solar power is low (and when servicing of nuclear plants may be difficult).


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#4 2012-02-29 13:59:22

Rune
Banned
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Wind power : possible ?

I don't really want to get into the same old argument... but I will wink Nuclear powerplants on Earth need servicing only every couple of years per reactor (In powerplants with more than one reactor, they alternate every year). A couple of months offline, too, to swap cores and check all the inaccessible areas during operation. While you are at it, install upgrades and such. That is on Earth. The designs proposed to be used on Mars run their entire service lives as closed boxes with cables coming out, buried and forgotten until a replacement/backup has to be brought on line.

Anyhow, the main point is wind power would be tremendously uneconomical, even compared to other, similarly low-density energy sources like solar. And to have that, at that cost, just for backup? Wind turbines are not exactly mechanically simple, or light, these days. Neither are they easy to produce locally compared with say, solar thermal powerplants.


Rune. Did I really just argued for solar thermal back there? ;P


In the beginning the universe was created. This has made a lot of people very angry and been widely regarded as a "bad move"

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#5 2012-03-13 16:16:41

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Wind power : possible ?

I think this really depends on what stage the colonization effort is in with respect to manufacturing capability.  For imported powersources, Nuclear is at this point clearly the best*, but when we're building the generators in situ, I think that concentrated solar power is the best choice, even given the possibility of importing nuclear material (I admit, this is debatable, I believe Rune is in favor of imported Uranium), until we can produce fissile material from the resources available on Mars. 

Anyway, Wind power provides an interesting counterbalance to any form of solar in one of solar's weakest points:  A dust storm can reduce power generated down essentially to zero, especially for solar thermal systems.  The question in this case becomes if it is worth building the wind towers or storing energy in some other way, such as chemical or pressurized gas, which is definitely competitive with chemical storage even if you let the heat escape.  I don't know if it's worth it, but I suspect that it probably isn't, especially because this doesn't solve what is in many ways a worse failing of solar power, which is that it can't provide power outside of the brightest ~8 hours of the day.

Is it bad that my arguments for why CSP might be better than nuclear are starting to convince me that it might be worth importing fissile material?

Sorry for my few weeks of absence, by the way.  I had quite a lot of schoolwork to do and didn't have the spare time to keep up with Newmars.

*I should add, though, that I am actually quite impressed with some of the developments on the photovoltaic front.  It is possible that in a few years PV will become advanced enough that it will come out ahead of space nuclear reactors designed in the 90s.  I believe that given equal resources put into the technologies nuclear would have some far more impressive developments, since the technology is inherently easier to improve upon (Imagine something like a nuclear betavoltaic generator, or in the farther future a micro-nuclear reactor like the ones Asimov talks about in the foundation series).  Instead of working towards that, research at this point is focusing on lighter and more efficient PV panels, which of course means that nuclear technology is not improving to its potential relative to Solar PV.


-Josh

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#6 2012-03-13 19:23:12

Rune
Banned
From: Madrid, Spain
Registered: 2008-05-22
Posts: 191

Re: Wind power : possible ?

JoshNH4H wrote:

I believe Rune is in favor of imported Uranium

Well, I am in favor of refueling the imported reactors for as long as they work. That is, I believe if you are going to import any powerplant (and to establish a first settlement you will have to), nuclear power is the most efficient and robust way to go. And I mean big, badass, tens of MW's and bigger powerplants to have a robust energy base to fiddle with ISRU in a big scale. Plus, keeping a reactor going is ludicrously cheap in terms of fuel mass, and said mass is only needed every couple of years (happy coincidence, the time between launch windows). Now, by the time the first imported reactors are ready to be decommissioned, maybe 50 years down the line, and replaced as the main powersource, the whole argument about whether building new reactors or solar thermal (or wind, or PV, or whatever) powerplants is not that easy of a decision. That's probably when martians start building proper martian cities and all of that, so lots of new decisions to be made based on different premises. In fact I'm not sure it would not go the way I argue against, when the final pro/cons analysis is done, in most cases. But it's a timeline thing, every thing at its proper time, and for the proper applications. Hope that clarifies my position.

JoshNH4H wrote:

Is it bad that my arguments for why CSP might be better than nuclear are starting to convince me that it might be worth importing fissile material?

Dude, you are not the only one with a similar problem. My take is it's healthy to look at things from the other side of the fence every now and then.


Rune. I hadn't thought about Asimov's belt-worn reactors in years. Thanks for the reminder! (They must have been inspired by RTG's, is my take on them)

Last edited by Rune (2012-03-13 19:26:30)


In the beginning the universe was created. This has made a lot of people very angry and been widely regarded as a "bad move"

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#7 2012-03-13 19:53:59

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 23,122

Re: Wind power : possible ?

The solar may be easier than we think by time we get to go with these types of advances.
Spray-on solar may be future for green energy

Mitsubishi Chemical is the first company to create prototype spray-on solar cells, which at present have a practical conversion level of 10.1 percent of light energy into electricity.

The new solar cells utilize carbon compounds which, when dried and solidified, act as semiconductors and generate electricity in reaction to being exposed to light.

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#8 2012-03-13 22:59:12

JoshNH4H
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From: Pullman, WA
Registered: 2007-07-15
Posts: 2,526
Website

Re: Wind power : possible ?

The problem with organic solar cells in the context of a martian colony is that they have a tendency to be degraded by the ultraviolet and X-ray radiation which is so prevalent there, as well as by the oxidative regolith if any happens to get through the coating.  But there is definitely a significant future for solar cells if development continues while development for forms of nuclear power continues to... not continue.


-Josh

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#9 2012-04-04 13:09:58

RGClark
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From: Philadelphia, PA
Registered: 2006-07-05
Posts: 534
Website

Re: Wind power : possible ?

SpaceNut wrote:

The solar may be easier than we think by time we get to go with these types of advances.
Spray-on solar may be future for green energy
Mitsubishi Chemical is the first company to create prototype spray-on solar cells, which at present have a practical conversion level of 10.1 percent of light energy into electricity.
The new solar cells utilize carbon compounds which, when dried and solidified, act as semiconductors and generate electricity in reaction to being exposed to light.

Thanks for that, Space. Given that they expect to reach the same efficiency level as usual solar cells, this will mean that the mass of the solar cells needed for a certain power level will be about 1/10th of that currently needed. Since current cells are about 100W to 200W per kilo, we might get up to the 2,000 W per kilo range.
This page suggests a lunar base might only need 100 kW to 1 MW power and a Mars base 1 MW:

Lunar Production of Solar Cells.
http://www.asi.org/adb/02/08/solar-cell-production.html

Then this might be only 50 kg to 500 kg that needed to be transported to the Moon or Mars for the power for the base. It would also be easy to transport since it could be sent in liquid form.
Also, in regards to the VASIMR plasma propulsion system Robert Zubrin has raised some points to question its feasibility since it requires high power at lightweight, which was proposed to be nuclear. Zubrin argued nuclear plants at the power level required, in the range of 1,000 watts per kilo, were not likely to be achieved in the near future:

VASIMR and a new war of the currents.
by Chuck Black
Monday, August 1, 2011
http://www.thespacereview.com/article/1896/1


But these new solar cells might be able to provide the power at the lightweight required.


   Bob Clark


Nanotechnology now can produce the space elevator and private orbital launchers. It now also makes possible the long desired 'flying cars'. This crowdfunding campaign is to prove it:
Nanotech: from air to space.
https://www.indiegogo.com/projects/nano … 13319568#/

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#10 2012-04-05 15:46:06

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,586
Website

Re: Wind power : possible ?

VASIMR is a variation on the ion drive.  All the electric propulsion schemes,  including VASIMR,  will have vehicle accelerations measured in milli-gees or less.  Some much less.  The burn is definitely not a short impulsive burn,  by any standards.

If your burn is impulsive,  meaning delivered over an extremely short time,  not a large percentage,  relative to travel time,  then you have no gravity losses relative to what we normally compute for the rockets and orbits we are familiar with. 

Minute acceleration levels make you burn through a large percentage of your travel,  incurring gravity losses during the entire burn.  Your effective specific impulse is nowhere near as high as you would compute from a bench or static test. 

These electric things do help quite a bit on very long trajectories,  but the shorter the trip,  the "crappier" they look relative to plain old high-thrust,  very-impulsive rockets.  Mars is not far away enough for it to look good.  Itokawa was. 

GW

Last edited by GW Johnson (2012-04-05 15:47:21)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#11 2012-04-05 16:00:39

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,586
Website

Re: Wind power : possible ?

The original topic was wind power on Mars.  The maximum achievable energy capture of a windmill I once read to be around 59% of what kinetic energy rate (kinetic power) there was in that portion of the wind stream tube intercepted by the mill.  I don't remember how that limit was derived,  but no real windmills actually recover that much.  Sort of like a Carnot engine in thermodynamics,  you can't really build anything quite that good. 

Now,  the KE rate (kinetic power) of a windstream is essentially 0.5 mass flow rate * velocity squared.  Mass flow rate is density*velocity.  So the kinetic power available is 0.5*density*velocity cubed.  You will recover about half or so of 59% of that stream power in a good mill;  say about 25%. 

Density on Mars is quite low relative to density on Earth,  and wind speeds are comparable.  So the velocity-cubed factors are similar there and here.  Temperatures are colder on Mars,  which act to increase density by inverse proportionality,  while pressures are lower,  which act to decrease density in direct proportion.  Say 233K there versus 288K here,  and 7 mbar there compared to 1013 mbar here. 

The density ratio there to here is then (7*288)/(1013*233) = 0.0085 or thereabouts.   Wind power potential there is a bit less than 1% of wind power potential here,  at similar speeds.  Twice the speed there vs here would give you power potentials 8 times higher (about 6.8% of here).

Myself,  I'd be looking harder at solar PV,  solar thermal,  and nuclear,  than wind.  The "air" is just too thin there. 

GW

Last edited by GW Johnson (2012-04-05 16:02:55)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#12 2012-04-05 17:32:19

Terraformer
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From: Logres
Registered: 2007-08-27
Posts: 3,362
Website

Re: Wind power : possible ?

Are gravity losses an issue when you're already on a trajectory - say using a chemical burn for TMI, then using VASIMR for drastically reducing the transit?

Do remember that a milligee gets you to about 36m/s each hour - 864m/s in a day, 26km/s in a month. Quite impressive really, and if you can get 10mg...


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#13 2012-04-05 18:57:21

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 4,586
Website

Re: Wind power : possible ?

Yep,  it matters. 

Days or weeks or months of micro-acceleration are incompatible with the delta-vees one computes under the impulsive (pretty near zero burn time) assumption. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#14 2012-04-13 11:42:42

RGClark
Member
From: Philadelphia, PA
Registered: 2006-07-05
Posts: 534
Website

Re: Wind power : possible ?

RGClark wrote:
SpaceNut wrote:

The solar may be easier than we think by time we get to go with these types of advances.
Spray-on solar may be future for green energy
Mitsubishi Chemical is the first company to create prototype spray-on solar cells, which at present have a practical conversion level of 10.1 percent of light energy into electricity.
The new solar cells utilize carbon compounds which, when dried and solidified, act as semiconductors and generate electricity in reaction to being exposed to light.

Thanks for that, Space. Given that they expect to reach the same efficiency level as usual solar cells, this will mean that the mass of the solar cells needed for a certain power level will be about 1/10th of that currently needed. Since current cells are about 100W to 200W per kilo, we might get up to the 2,000 W per kilo range.
This page suggests a lunar base might only need 100 kW to 1 MW power and a Mars base 1 MW:

Lunar Production of Solar Cells.
http://www.asi.org/adb/02/08/solar-cell-production.html

Then this might be only 50 kg to 500 kg that needed to be transported to the Moon or Mars for the power for the base. It would also be easy to transport since it could be sent in liquid form.
Also, in regards to the VASIMR plasma propulsion system Robert Zubrin has raised some points to question its feasibility since it requires high power at lightweight, which was proposed to be nuclear. Zubrin argued nuclear plants at the power level required, in the range of 1,000 watts per kilo, were not likely to be achieved in the near future:

VASIMR and a new war of the currents.
by Chuck Black
Monday, August 1, 2011
http://www.thespacereview.com/article/1896/1


But these new solar cells might be able to provide the power at the lightweight required.

Just saw this discussed on NasaSpaceFlight.com:

Scientists develop spider-silk solar batteries.
By Charlie Osborne | April 4, 2012, 4:22 AM PDT
"One gram of the solar battery produces 10 watts of energy. The efficiency of conversion from solar power to electricity is 4.2 percent, substantially lower than typical solar panels. However, the new battery can function without conversion rate drops when folded or bent. According to the team, the spider-silk soar batteries can also be made cheaply."
http://www.smartplanet.com/blog/smart-t … ries/25079

For the free, full text, research article:

Nature Communications | Article Open
Ultrathin and lightweight organic solar cells with high flexibility.
Martin Kaltenbrunner, Matthew S. White, Eric D. Głowacki, Tsuyoshi Sekitani, Takao Someya, Niyazi Serdar Sariciftci & Siegfried Bauer
Nature Communications 3, Article number: 770, Published: 03 April 2012
http://www.nature.com/ncomms/journal/v3 … s1772.html

A specific power of 10 watts per gram is 10,000 watts per kg. This is about a hundred times better than current space solar cells(!) If they do get the conversion efficiency up to that of current cells at about 20%, then the specific power would be 50,000 watts per kg.


  Bob Clark


Nanotechnology now can produce the space elevator and private orbital launchers. It now also makes possible the long desired 'flying cars'. This crowdfunding campaign is to prove it:
Nanotech: from air to space.
https://www.indiegogo.com/projects/nano … 13319568#/

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#15 2020-11-22 20:49:23

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,122

Re: Wind power : possible ?

Here is a paper for DESIGN AND RESOURCE REQUIREMENTS FOR SUCCESSFUL WIND ENERGY PRODUCTION ON MARS

Mars air is thin so to get surface area force we need volume of air. The solar chimney would increase due to heating the amount of air pressure that would be a force increase to allow for air to create power.

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#16 2020-11-24 16:29:53

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 1,154

Re: Wind power : possible ?

I like the idea of the wind fed solar chimney.  I don't think the chimney needs to be a completely vertical structure in order to work.  We could run a tube up the side of a mountain say.

One interesting feature of the Martian atmosphere close to ground level - its temperature is beneath the triple point for CO2 (217K) at most locations and for most of the day throughout the year.  Very little compressor work is needed to compress the cold CO2 into liquid.  The wind speed is useful for driving the gaseous CO2 into the compressor, although it is doubtful that it would have sufficient power density to drive the compression.  A nuclear reactor could function  like a gas turbine on Mars, drawing CO2 into a compressor, liquefying it, superheating the liquid and using the hot vapour to drive the turbine.  In this way, no radiator would be needed, as the hot CO2 exhaust can be vented into the atmosphere.  The turbine could even create its own shielding by filling a shield tank with liquid CO2.  Just face the compressor into the wind.


Interested in space science, engineering and technology.

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#17 2021-04-12 19:35:34

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,122

Re: Wind power : possible ?

Seeing the Helicopter can fly on Mars makes wind power a possibility as well.

Happened on the above link by http://www.marspapers.org/paper/James_1999.pdf again....

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#18 2021-07-14 08:08:40

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,347

Re: Wind power : possible ?

https://www.yahoo.com/news/california-p … 14877.html

While floating offshore wind farms are becoming a commercial technology, there are still technical challenges that need to be solved. The platform motion may cause higher forces on the blades and tower, and more complicated and unsteady aerodynamics. Also, as water depths get very deep, the cost of the mooring lines, anchors, and electrical cabling may becomes very high, so cheaper but still reliable technologies will be needed.

Expect to see more offshore turbines supported by floating structures in the near future.

This article is republished from The Conversation, a nonprofit news site dedicated to sharing ideas from academic experts. It was written by: Matthew Lackner, University of Massachusetts Amherst.

Read more:

Glad to see this report of innovative thinking to increase harvesting of offshore wind.

***
Tossing this question out for the engineers in the crowd ...

Water has greater mass than air.

A floating platform can be held in place (with respect to the Earth) by fixed cables (as described in the article).

A floating platform (such as a ship) can be held in place (with respect to the Earth) by applying force to the water.

The question: Is there a difference between the force applied by the wind to move a platform, and the force applied to the water to hold it steady?

The difference may be large or it may be small.

The movement of the current around the platform would also be a factor.

I would imagine the engineers who designed cables for floating platforms have a pretty good idea how much force is involved.

The difference between energy collected from wind, and invested in holding position, is the "profit" of the platform.

(th)

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#19 2021-07-14 09:34:12

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 7,347

Re: Wind power : possible ?

For all with posting privileges ...

The post above, about floating wind platforms, stimulated this question ...

Premise: About 30% of energy can be extracted from a moving fluid under optimum circumstances (this is a figure from a PhD study.)

[The source of the study referenced above is available upon request ... I made a 3 ring binder to hold the printout]

Let us suppose the floating wind platform is practical, and that it is implemented on a global scale.

Energy would be extracted from the momentum of the atmosphere, which itself is stimulated by input of photons upon the Earth's surface.

Removal of a significant percentage of energy from the atmosphere (reduction of momentum) ** should ** have an effect upon weather patterns.

Related question ... is it possible to harvest wind energy before it grows large enough to become a hurricane?

Are there locations on Earth where large scale harvesting of wind would have a beneficial effect by regulating severe weather?

Are there locations on Earth where large scale harvesting of wind would have a detrimental effect, by reducing needed flows of water laden air?

If there are readers who are NOT members with posting privileges, and who would like to contribute to this topic, please Read Post #2 of Recruiting and drop a line to the NewMars Portal.

(th)

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#20 2021-07-14 19:46:29

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 23,122

Re: Wind power : possible ?

With water and wind the wave has the mass momentum which can accumulate into larger waves to push on the exposed structure which is riding in the wave height to contend with.

Its that wave cycle which is being looked at for power extraction with anchored buoys and other platforms.

here is one of those topics Power of Earths Oceans

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