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chaloobi
SFN Regular

1620 Posts

Posted - 02/26/2008 :  11:17:26  Show Profile  Send chaloobi a Yahoo! Message Send chaloobi a Private Message  Reply with Quote
Biofuels are basically just solar power with an organic intermediary. They take carbon out of the air and the fuel produced fits well with our existing infrastructure, making them an attractive quick hitter in the climate change battle. However, they compete with food crops which will likely lead to deforestation to free up more crop land, which would be a net increase in carbon in the atmostphere and a reduction in biodiversity. Not good.

Solar power, however, generates electicity directly from sunlight. It does not have to compete with food crops and works best on land that can't be used for agriculture. It is good for replacing coal and oil fired power plants, assuming you can store enough power to get through night and adverse weather, but not so good for transportation. We either have to use electric vehicles or transform the electric power into some kind of fuel, like electrolysis of water to create hydrogen. That or give up cars altogether and re-engineer our civilization for mass transit. Big design and infrastructure costs in all three cases, not good considering our short sighted government and fickle electorate.

The biggest disadvantage to both of these energy sources is that there isn't enough available land to replace the energy we get from fossil fuels. Yeah, we could get serious about energy efficiency, but I'm not so sure we could get that efficient. Probably the best approach in engineering future energy infrastructure is to design around replacing our existing energy demands.

Really, the land thing is a moot point. The best place to generate solar power is in high orbit where vast areas of solar cells can generate power continuously and require no land at all. Of course here the infrastructure cost is enormous, but so are the benefits, which are not just limited to clean energy. (Spin offs, man.)

Just wondering, does anyone know the relative efficiency of the best available biofuel crop - switchgrass? - vs the best available solar cells? Which produces more usable energy per land unit?

-Chaloobi


Edited by - chaloobi on 02/26/2008 11:18:11

Dave W.
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USA
26009 Posts

Posted - 02/26/2008 :  12:10:02   [Permalink]  Show Profile  Visit Dave W.'s Homepage Send Dave W. a Private Message  Reply with Quote
"A Solar Grand Plan" gives us massive drops in fossil-fuel usage over the next 42 years, and probably more to come after that, as it looks (from the authors' data) like there's plenty more land to be used.

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Dr. Mabuse
Septic Fiend

Sweden
9677 Posts

Posted - 02/26/2008 :  12:14:00   [Permalink]  Show Profile  Send Dr. Mabuse an ICQ Message Send Dr. Mabuse a Private Message  Reply with Quote
For starters, how do you define "best available" solar cells? The most efficient ones are very expensive and contains a lot of environmentally hazardous materials.
There are more eco-friendly ways to build solar cells: they are much less efficient, but may also be more cost effective. The lower conversion rate however, will require larger areas.

Edited spelling.

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Edited by - Dr. Mabuse on 02/26/2008 16:42:07
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chaloobi
SFN Regular

1620 Posts

Posted - 02/26/2008 :  15:31:41   [Permalink]  Show Profile  Send chaloobi a Yahoo! Message Send chaloobi a Private Message  Reply with Quote
Originally posted by Dr. Mabuse

For starters, how do you define "best available" solar cells? The most efficient ones are very expensive and contains a lot of environmentally hazardous materials.
There are more eco-friendly ways to build colar cells: they are much less efficient, but may also be more cost effective. The lower convesrsion rate however, will require larger areas.
I recall reading recently about a 'break through' in thin film solar cells by some Japanese company. They weigh less, are much cheaper to make (probably due to so much less material) and are much more efficient than the previous generation. I don't recall reading about pollution from the manufacturing process. I guess I'll have to look that up somewhere. Can't be hard to find.... Anyway, that new tech is what I was thinking about in best available.

-Chaloobi

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chaloobi
SFN Regular

1620 Posts

Posted - 02/26/2008 :  15:35:57   [Permalink]  Show Profile  Send chaloobi a Yahoo! Message Send chaloobi a Private Message  Reply with Quote
Originally posted by Dave W.

"A Solar Grand Plan" gives us massive drops in fossil-fuel usage over the next 42 years, and probably more to come after that, as it looks (from the authors' data) like there's plenty more land to be used.
I actually read that article when it came out. It's not nearly as sexy as orbital power, which I hear the Pentagon is seriously researching (there's a web site if I can find it...). The only issue I can think of with solar is the huge foot print it requires. What happens to a desert, or any, ecosystem when you cover up a significant percentage of thousands of acres with mirrors? It can't be without consequences.

-Chaloobi

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HalfMooner
Dingaling

Philippines
15831 Posts

Posted - 02/26/2008 :  19:39:18   [Permalink]  Show Profile Send HalfMooner a Private Message  Reply with Quote
I've had a lot of changes in heart, based upon what I see as the primary global problem of our age: Warming due to greenhouse gasses. Solar is probably the greatest new source of energy that we should be exploiting, along with building new fission-driven electrical generating plants, exploiting wind and geothermal power, and trying to get practical fusion power started.

Going to biofuels is among the worst of options, as it produces no net reduction in CO2, and strains global food supplies. I seriously worry about third world countries putting food crop land into biofuel crops to feed the gas tanks of autos in developed countries. We're already beginning to see the beginning of this effect in Brazil. This would be especially bad as low lying coastal croplands disappear under rising seas.

We also desperately need a big breakthrough in battery technology (or anything analogous to batteries, including ultracapacitors, flywheels, fuel cells, etc.), which will allow "green" electricity to power vehicles.


Biology is just physics that has begun to smell bad.” —HalfMooner
Here's a link to Moonscape News, and one to its Archive.
Edited by - HalfMooner on 02/26/2008 19:40:29
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Dude
SFN Die Hard

USA
6891 Posts

Posted - 02/26/2008 :  20:19:10   [Permalink]  Show Profile Send Dude a Private Message  Reply with Quote
The problem with biolfeuls is the carbon balance isn't neutral or that much better than fossil feuls. This is due to several factors, including fertilizers, land clearing, and processing. There was a paper out a month or two back on this topic, and hell if I can find it now.... heh.

What needs to happen in biofeuls is efficient cellulosic ethanol. This could use the stalks, stems, roots, etc of food plants (the part farmers leave to rot in the fields after harvest) and the entire plant of non-food plants. Until this tech gets better, biofeuls will be of minimal use in reducing carbon emissions.

I'll see if I can find a link to that paper... not looking good now though.


Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
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bngbuck
SFN Addict

USA
2437 Posts

Posted - 02/26/2008 :  20:34:00   [Permalink]  Show Profile Send bngbuck a Private Message  Reply with Quote
Chaloobi....

I have understood, but have not researched the information, that the energy required to process various biofuel sources into the appropriate alcohols for utilization as fuels, is greater, joule for joule; than the energy than the finished fuel product will yield. Do you, or anyone (Dave?), know if this is true or is perhaps a red herring caught and served to the gullibly hungry public by the petroleum interests of the world?

With regards to solar power.....
The best place to generate solar power is in high orbit where vast areas of solar cells can generate power continuously and require no land at all. Of course here the infrastructure cost is enormous, but so are the benefits, which are not just limited to clean energy. (Spin offs, man.)
I assume this would refer to orbiting solar panels producing electricity in near space, a few hundred miles up.

No land or cloud worries, 24 hour power production, etc. But I can't seem to visualize the high voltage transmission system to the surface? Perhaps high tech batteries or capacitors yet to be developed to be charged and carried back and forth on a space shuttle? I may just not be up to snuff on this proposed future technology, but if you know or can refer me to what has been suggested, I would appreciate it!

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Dave W.
Info Junkie

USA
26009 Posts

Posted - 02/26/2008 :  21:58:32   [Permalink]  Show Profile  Visit Dave W.'s Homepage Send Dave W. a Private Message  Reply with Quote
Originally posted by bngbuck

But I can't seem to visualize the high voltage transmission system to the surface? Perhaps high tech batteries or capacitors yet to be developed to be charged and carried back and forth on a space shuttle? I may just not be up to snuff on this proposed future technology, but if you know or can refer me to what has been suggested, I would appreciate it!
Beam it down in the radio spectrum at whatever wavelength the atmosphere is most transparent to (when I first heard this idea 20-something years ago, it was microwaves). Big antennas on the ground capture it and convert it to useful electrical power. Biggest technical problem on the orbit-to-Earth side is aiming, and that's not much of a problem anymore.

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Dude
SFN Die Hard

USA
6891 Posts

Posted - 02/26/2008 :  22:23:13   [Permalink]  Show Profile Send Dude a Private Message  Reply with Quote
Of course, we are overlooking the potential of wind. There is enough wind energy available to power the planet almost forever. We just have to build the infrastructure to tap it.

This site is a little biased, but this is the technology for wind I think has the most potential.

Of course, there are 72terrawatts of wind power available at 80m (300feet), which is the hub height of modern ground based turbines. In 2000 global electricity use was ~1.8terrawatts.

Wind power, imo, should be our primary focus for electrical generation. There is enough to power us for a long long time, and it could enable hydrogen production (for fuel cells) as well.

Seems like a no brainer.


Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson

"god :: the last refuge of a man with no answers and no argument." - G. Carlin

Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth
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bngbuck
SFN Addict

USA
2437 Posts

Posted - 02/27/2008 :  00:23:00   [Permalink]  Show Profile Send bngbuck a Private Message  Reply with Quote
Dave.....
Beam it down in the radio spectrum at whatever wavelength the atmosphere is most transparent to (when I first heard this idea 20-something years ago, it was microwaves). Big antennas on the ground capture it and convert it to useful electrical power. Biggest technical problem on the orbit-to-Earth side is aiming, and that's not much of a problem anymore.
Well, from the little that seems to be available regarding this neo technology, it is still definitely in the experimental stage.
Radio and microwave
Main article:

Microwave power transmission

Power transmission via radio waves can be made more directional, allowing longer distance power beaming, with shorter wavelengths of electromagnetic radiation, typically in the microwave range. A rectenna may be used to convert the microwave energy back into electricity. Rectenna conversion efficiencies exceeding 95% have been realized. Power beaming using microwaves has been proposed for the transmission of energy from orbiting solar power satellites to Earth and the beaming of power to spacecraft leaving orbit has been considered.[16][17]

Power beaming by microwaves has the difficulty that for most space applications the required aperture sizes are very large. For example, the 1978 NASA Study of solar power satellites required a 1-km diameter transmitting antenna, and a 10 km diameter receiving rectenna, for a microwave beam at 2.45 GHz. These sizes can be somewhat decreased by using shorter wavelengths, although short wavelengths may have difficulties with atmospheric absorption and beam blockage by rain or water droplets. Because of the Thinned array curse, it is not possible to make a narrower beam by combining the beams of several smaller satellites.

High power
Wireless Power Transmission (using microwaves) is well proven. Experiments in the tens of kilowatts have been performed at Goldstone in California in 1975[18][19][20] and more recently (1997) at Grand Bassin on Reunion Island.[21]
Wiki (Link below)

"Tens of kilowatts" is experimental quantification.

Nicola Tesla dreamed of creating such phenomena, and did indeed transmit electrical power to a considerable distance largely to barbed wire fences) in the vicinity of Colorado Springs back in 1899-1900. But to my knowledge, this technical feat is still largely theoretical, certainly as it might apply to sending useful amounts of power (1000's of megawatts) wirelessly over distances of hundreds of miles!

Dave, if your unparalled ability to ferret out information can find evidence that anyone, or any company, or any country, has succeeded in wirelessly transmitting commercially viable amounts of electrical power (megawatts) over several hundred miles, via microwaves, (or anywhere in the EMS for that matter), please give me a referent! I am intensely interested in this idea, and I instantaneously become a futurist when the subject of wireless power transmission comes up!

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chaloobi
SFN Regular

1620 Posts

Posted - 02/27/2008 :  05:54:55   [Permalink]  Show Profile  Send chaloobi a Yahoo! Message Send chaloobi a Private Message  Reply with Quote
Regarding Wind and Wave power - waves are driven by wind and wind is driven by the sun. They, like biofuels, are just different forms of solar. In fact fossil fuels are just stored solar. Tidal power I suppose has it's source in both solar and gravitational interactions with the moon.

In a Sciam article last year they suggested mounting wind turbines on giant tethered kites which would sail very high up. This would address the problem of wind turbines massacring the local bird populations and presumably the winds higher up are more constant. Not sure what that would do with aesthetics - can't be much worse than contrails.

Regarding Orbital Solar: You don't have to build the collectors a few hundred miles up, you could go out to geosynchronous orbit or even out to the langrange points. It sounds like a way-out idea but SciAm ranked it as more feasible than Fusion power in an article last year, for whatever that's worth. And like I said above the military is interested in Orbital Solar Power, presumably because the logistics of supplying electricity to troops deployed in remote areas are expensive and difficult. Here's a link to the web site:

http://spacesolarpower.wordpress.com/the-national-security-space-office-study/

<
About the Study

The National Security Space Office is conducting a study to determine the feasibility of space solar power as a source of clean energy that may be able to broadcast power to deployed forces, supplement national power grids, and other smaller applications.

The study got underway on 20 April 2007 at the direction of the Director of the National Security Space Office, Major General Jim Armor, who designated his Chief of Future Concepts, Lt Col M.V. “Coyote” Smith, the director of the study.

The stimulus for this study was a briefing given to General Armor in March by Lt Col Mike “Green Hornet” Hornitschek, the ring leader of the “Space Solar Power Cabal.” The Cabal is a small group of Air Force officers and civilian scientists and engineers who have other jobs, but are true believers in space solar power and have advanced the concept inside the Washington Beltway in their spare time. Lt Col Pete “Lips” Garretson, John “The Evil Dr” Mankins, and Lt Col M.V. “Coyote” Smith are at the core of the Caballeros. The Green Hornet and Lips are designated co-leaders of the National Security Space Office study. There are over ninety volunteers serving as members of the study. They have widely diverse backgrounds but all have a passion for space, energy, commerce, public policy, or any combination thereof.

The National Security Space Office study is laid out like this:

Our Vision

Security in the form of clean energy independence for America, its Allies, and the World

Our Mission

Determine the political, scientific, technical, logisitical, and commercial feasibility of space-based solar power collection and distribution in the 21st Century as a contributing source of clean energy to national power grids and smaller niche applications. Discuss significant capabilities, limitations, and alternatives. Identify challenges that must be overcome, and suggest a research and development investment plan that incrementally retires risk on the path to fielding an operational system. The final report shall not exceed thirty pages and is due to the Director of the National Security Space Office no later than 15 September 2007.*

* Mr Joe Rouge, the Deputy Director of the National Security Space Office (becoming the Director on 30 September upon General Armor's retirement), directed on 6 September that no final report will be issued. Instead an interim report will be issued, tentatively on the 10th of October at a National Press Club event sponsored by the National Space Society. The study will continue and will focus more intently on certain areas.

-Chaloobi

Edited by - chaloobi on 02/27/2008 06:47:13
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chaloobi
SFN Regular

1620 Posts

Posted - 02/27/2008 :  06:44:09   [Permalink]  Show Profile  Send chaloobi a Yahoo! Message Send chaloobi a Private Message  Reply with Quote

-Chaloobi

Edited by - chaloobi on 02/27/2008 06:45:57
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Dr. Mabuse
Septic Fiend

Sweden
9677 Posts

Posted - 02/27/2008 :  08:59:23   [Permalink]  Show Profile  Send Dr. Mabuse an ICQ Message Send Dr. Mabuse a Private Message  Reply with Quote
Originally posted by bngbuck
I assume this would refer to orbiting solar panels producing electricity in near space, a few hundred miles up.
A few hundred is the boundary between Low Earth Orbit and Medium Earth Orbit, ~2hrs orbital period. Not much time to dump the energy, and then you've got to hit your target during the fly-by.

I think a Geostationary Orbit is the way to go, while 35786 km above the Equator, both the satellite and the receiver station can be considered stationary targets. Also, the Orbital Station would very rarely hide in the shadow of Earth, only a few hours every equinox, as the geostationary orbit aligns with Earth and the Sun.


No land or cloud worries
Except the orbit-to-earth beam may be affected by weather, depending on what frequency is used for the transmission.


24 hour power production, etc.
See above.


But I can't seem to visualize the high voltage transmission system to the surface?
That would also require a tether going all the way up to geostationary orbit.
http://en.wikipedia.org/wiki/Space_elevator


Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3

"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse

Support American Troops in Iraq:
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Dave W.
Info Junkie

USA
26009 Posts

Posted - 02/28/2008 :  15:09:07   [Permalink]  Show Profile  Visit Dave W.'s Homepage Send Dave W. a Private Message  Reply with Quote
Scary turbine (HT: PZ).

- Dave W. (Private Msg, EMail)
Evidently, I rock!
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Dave W.
Info Junkie

USA
26009 Posts

Posted - 02/28/2008 :  15:48:32   [Permalink]  Show Profile  Visit Dave W.'s Homepage Send Dave W. a Private Message  Reply with Quote
Originally posted by chaloobi

However, they compete with food crops which will likely lead to deforestation to free up more crop land, which would be a net increase in carbon in the atmostphere and a reduction in biodiversity. Not good.
Be careful, or you'll hurt the farmers' feelings.

- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too.
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