Backyard Aquaponics
A place to discuss aquaponics

Kilgore,

You need to acquaint yourself with PolyWell Fusion Technology. It would be clean, and a technology that cannot we weaponized. Initial work was done by Dr. Bussard, now deceased. In less than a decade they have solved multiple technical issues and are probably one design generation away from break even.

I appreciate the attention. In return, I'll spend more time doing some research. As a student, it's what I'm most accustomed to doing anyway.

My heart is set on the Sun as our fuel supply, but if there's a closer promise, then my heart can love another.

To a better tomorrow. I'll post again when I get a little smarter, and I'll do some work on making my numbers more presentable.

Kilgore,

You have the interest, that's being smart as a beginning.

You might want to also read Gerard K. O'Neil's stuff from back in the late 70's. He spearheaded very early analysis in building space based power. He was also the PI on the development of the mass driver for delivering loads without rockets.

A GW is a gigawatt or 10^9 or a billion watts and is a rate of flow, like gallons per hour. That means that if you had it orbiting the earth to always be in sunlight, placed it in a spot where gravity would hold it (one of the Lagrange points), or another place where it would get 24/7 sunlight that it would produce enough power to keep 10^7 (10 million) 100-watt light bulbs running.

The 41,670,000,000watts (let's just call it 41GW) has to me an error. The energy required for a shuttle mission would be an amt of energy (like gallons or watt*hrs) rather than a flow (like watts.) Perhaps the actual number should be 41GW*hrs per mission, but I'm not bothering to look up the numbers and don't see them in the Wiki article.

Does anyone else here have an issue with people who quote numbers like "this change alone would save us 89billion barrels of oil" without telling you the time period? Is that savings over the lifetime of the earth or what? Numbers like that are absolutely meaningless and useless and I see them all the time in debates over various policies.
This is not a comment on you, Kilgore, just on one of the numbers you posted. Is there a corrected one?

As far as placing the collectors farther away, this would lead to problems such as different orbital period (what happens when it is on the other side of the sun?), far greater transmission losses at that distance, and maintenance issues.

Some Clarity...

As far as "meaningless numbers", I am always in favor of the facts--graphs and data models that portray the rhetoric. A similar example recently in the news is the Chromium VI in our drinking water. Environmental Working Group (EWG) has made claims over Cr(VI) in a number of cities at levels that are cause for concern, but they haven't presented any of their analytical methods or raw data, but even more troubling is here in Tallahassee, the technicians run for total chromium, and assume its the safer chromium(III). My lab group at FSU plans to run analyses this semester to resolve the issue, at least in our city.

With that said...

A watt is a measure of power, not energy. 41 Gigawatts (GW) was the justification for each $2Billion dollar mission, assuming the 6 cent per kilowatt-hour. So it would be 41GW for one hour. 41 GW*hr is the net energy return that would justify the cost in my scenario.

My previous calculations called for about 29,000,000 m^2 (5385mx5385m) for 41GW (instantaneous) at 100% efficiency. Drop down to 10%, and that calls for 290,000,000 m^2 of surface area at the distance of the Earth, where the solar constant is about 1.4kw/m^2.

Alternatively, if the energy transmission rate is 1MW*hour, then to break even, we would need that transmission to exist for 41,000 hours=1708 days=4.7 years.

So, at 1.4kw/m^2, then the area of collection for 1MW would need to be 714 m^2 at 100% efficiency. Realistically, we can expect up to 25% efficiency. Let's be earnest and call it 10%. This now requires a satellite to collect over an area of 7140 m^2 (84mx84m).

The theoretical aspect might be fun, but how realistic is it really. When transmitting that much energy, no engineering in the world can protect from the consequences of catastrophic failure. Would anyone here volunteer to have one of those collectors in their backyard, near town, or even in the state? Heck - I would not want one in the same hemisphere. It would seem to me that with the kind of money your talking about, PV panels could be put on almost every roof in the country. And how about the environmental impact of blocking out that much sun? Someone is bound to start sueing because their farm is less productive, or rain patterns change...the consequences could be far reaching. Perhaps entire species are lost because the migratory path gets them all zapped. I for one just cannot take it seriously.

I too was kinda wondering about the size of the shadow something like that would cast

Always good to have accurate representations of the facts, but as (Twain?) said, "there are lies, damned lies, and statistics". One can mislead with numbers, too.


OK, but there is no requirement for the missions to cost that much or use so much manpower, materials, dollars, and energy. And out here I'm paying about $0.40 per KW*hr....

We should not use shuttles to lift panels as we are lifting them from a deep energy well and the power use is horrible, especially if we need to lift the shuttle and all it's fuel as well. A magnetic drive here on earth (other than some issues with engineering, sonic booms, etc) or laser drive (with the laser on earth would be far far more efficient, using only electricity.


As far as shadow size, if the world uses 15*10^12 watts and we can collect 100w/m^2, the array will measure sqrt(15*10^12/100) or a bit under 4x10^5 meters, square (40 kilometers square). In geosynch orbit, this would shadow any one spot on the surface of the earth for a max of 2 minutes. In the Lagrange positions or on the moon there would be no shadowing effect.

Now that is an excellent point.

But consider this (maybe OT): All of the billions/trillions we've poured into the banks haven't solved the underlying problem of bad assets in their vaults. The banks are still insolvent if they have to mark their assets at fair value.

Instead of of pouring money into the banks, the fed/gov could have paid off everyone's mortgage & the banks would be solvent. What's the difference? Moral hazard either way.

Maybe everyone would have had to pay the fed/gov back overtime or something. Or the gov could've let the banks go belly up and then used the bailout money to start brand new solvent banks.

Not advocating any of this (I don't have a mortgage, I own my home free & clear).

My point is putting PV panels on every roof would never pass through congress (OMG socialized energy) but a sexy spaced-based solar thingy would.

Well, it may simply be the sexiness of big projects, but they might have a more practical reason for space-based power sats: easy to surreptitiously power up a killer laser system! Not that they would ever do that...

According to http://www.nrel.gov/docs/fy09osti/44073.pdf, we could produce about 20% of our total electricity (NOT total energy) from rooftop PV. With systems dropping in price, this will soon be break-even. If we charge for carbon it will be break-even even sooner. tax and refund, anyone? I'll plow my refunds into PV panels...

The problem with solar on roofs is that it only produces when it is 1) clear and 2) sunny. And having panels on roofs takes away economies of scale. Still, it avoids the technological hurdles of space-based power and avoids the transmission losses of space-based or mega-solar setups. If we can be more frugal and can find a really good storage solution (smart garage?), then it could be a huge part of the solution. But it will not fulfill the dreams of the sci-fi geeks (guilty!) who'd like a realistic way for humans to move into space..

Why is it that we continually look up for answers to our energy problems.

Geothermal doesn't have power storage problems like solar, no bad weather problems, no major power transmission problems, it's sustainable and permanent. But.... I guess it's a bit more boring....

Is that a pun?

I guess so....

Gee, EB, I thought we spent the last couple centuries looking down for energy: coal, oil, methane, uranium. Still, some (like dry rock geothermal) looks promising (thus Google's interest).


Speaking of the big G, I've read that for every $ spent to build a data center (I assume that is the building and all) that the companies spend about $1/2 for power to run the thing? And that for every watt used to run it they often need 2 to cool it? If they simply looked for more efficient servers they could dramatically drop power use at very low or even no cost (there is no good reason that servers need to be so power hungry, it is simply a matter of no market for it as no one is looking at life cycle costs).

This is incredibly common in every aspect of our civilization.

We could all make little changes that would make a big difference: eat less beef (incredibly water and carbon intensive), quit eating pork (in this country, at least, industrial pork producers are unwittingly working on the next pandemic flu virus), quit buying stuff that needs to be refrigerated and get a tiny, really efficient one just for the essentials: ice, beer, cheese.


Sorry about going off like that. My mission at 20 was to "live live lightly on the world".....my recent review has given me a failing grade....20-year-old me is not happy with older me and has been kicking my butt...

Eat grass fed beef! Much less carbon & water intensive.

Buy non-industrial pork from a local farmer! For a whole or half-pig the price is about the same as yucky industrial pork. Same price break for buying 1/2 or 1/4 of a cow.

If you're anti-beef, you ought to be anti-dairy as well.