There are no means of power generation that involve getting more power out than is put in.
Which is trivially true, but also fairly meaningless unless you're trying to argue with perpetuum mobile nutjobs.
In all other cases, you're looking at how much _usable_ power you get out of a process, and how much power in addition to the fuel you need to feed in.
Hence, a fusion reaction would be energy-producing if (electric output power) > (electric power input needed to keep the fusion reaction going)
All Fusion reactions (hot or cold) need is a catalyst which increases the efficiency (lowers activtion energy, increases yield, affects rate, etc) of the reaction.
Err... so far we've found only one catalyst for fusion reactions, and that's muons. Not really all that helpful. And you usually don't want anything other than your reaction fuels in hot fusion, because anything else will act more as a pollutant than anything else and increase the likelyhood of unwanted interactions.
Is it reasonable to assume that all the materials on earth came from a single supernova, or is that overly simplistic?
That would be overly simplistic.
The solar system is roughly 5 billion years old, the universe is roughly 13 billion years old. The early universe contained more supermassive stars than today's universe, and these giants only had lifespans in the tens of million years. So a lot of them popped before our solar system formed. It is believed that our solar system formed in the vicinity of several earlier supernovas.
So, the Wright brothers should not have been able to invent the airplane because they were incapable of building a Boeing 747 in their little cottage?
FAIL.
You can build a perfectly working airplane that fits on a kitchen table. Granted, it might not transport a person, but it's otherwise completely functional and airworthy.
Here's an honest question: where do our iron deposits come from?
Um... from dead stars that had enough mass to produce iron (as well as even heavier elements) as they died. This means stars that were much more massive than our little sun.
We're talking about *consuming lots of water in a desert* -- enough to power vehicles around the world. What the heck kind of plan is that?
If you're discounting all the other problems, then you may as well assume that the process can use straight seawater. We have plenty of that (just stick a pipe in the nearest ocean and build a long pipeline), and it doesn't compete with anything that requires freshwater (agriculture, human consumption, etc).
have to disagree here. I did the math a couple weeks ago and came up with about 7 pounds per mile for lithium based batteries currently used in cars and total battery weights between 1/2 ton and a ton.
There's another name for a contraption that is supposed to move at high speeds and hold people and a half-ton lithium battery: death trap.
Artificial hydrocarbons? My recent research into alternative technology for automobile propulsion didn't reveal any approaches that look feasible in the near-term (by which I mean Obama's proposed 10 year window). If I missed something, could you please provide a cite?
Well, the technology itself is almost a century old (Fischer-Tropsch process and Sabatier process), the only real problem is finding a source of carbon or (relatively pure) carbon dioxide that's not a fossil fuel in the first place or requires prohibitive amounts of energy per unit of C/CO2 produced.
I assume that hydrogen could be used to augment the yield of existing biomass-to-liquid processes, since biomass probably contains a carbon surplus. Especially if the BTL process aims to produce short hydrocarbons.
Hydrogen has many - the cost of producing hydrogen, the cost of compressing or liquefying the hydrogen, the impermanence of liquid hydrogen ("venting"), the safety concerns of carrying around enough hydrogen to power a car without a "Hindenburg effect", and the cost of a new infrastructure to transport megatons of hydrogen to fueling stations scattered across your country.
Or find an efficient way of extracting CO2 from the air or from seawater, and use that and hydrogen to make liquid fuels that are entirely compatible with the existing infrastructure.
Liquid fuels will always be easier to handle than gaseous fuels. And of the latter, hydrogen is one of the more problematic ones.
Another use for this technology would be a sort of energy pack that goes on the roof. A water line goes in, hydrogen comes out and is stored in a fuel cell which powers the house.
Fuel cells don't store hydrogen - they use it as fuel. Hydrogen storage is a can of worms entirely separate from the fuel cell that has its own challenges.
Problem is what to do with all the waste oxygen.
Um, what problem ? You either store it, too, and use it when your fuel cell generates electricity, or you just release it into the atmosphere.
Yes, they do. It's a simple matter of the laws of optics and quantum mechanics. They can't be circumvented with a little bit of engineering.
CCDs are constantly getting better and smaller,
If they get smaller, they usually get worse. Making them smaller (and/or increasing the pixel count) means that there's less light falling on each pixel, while the noise per pixel stays the same (sorry, almost no way around that except using liquid nitrogen to cool the thing). Hence, you'll get more noise per pixel.
and lenses are constantly improvivng.
It's not a lens issue (and we've been able to make pretty good lenses for quite a while now), it's an issue with the basic inner workings of a CCD.
You may be surprised with just how good some of these are.
I just bought a Sony DSC W300. Yes, it has 12 Megapixels, but it also has a larger CCD chip (I think 1/1.7"... the usual size is 1/2.5" or even 1/3.0" for really crappy cameras).
Let me show you a picture I took with my Nikon Coolpix 7 megapixel camera that is a year old
There you say it: That camera only has 7 megapixels. That's pretty close to the ideal number for compact cameras - 6 megapixels.
Get any of the 10+ megapixel cameras with 1/2.5" CCDs, and you'll find that they'll take large, but not really good, pictures. 6 Megapixels would be enough, but explain to a customer why he should by the camera with the smaller number... ?
I just carry a simple point-and-shoot camera with a great lense and high mega-pixel count.
High megapixel counts on compact cameras are a marketing trick to lure clueless people into buying them. Compact cameras don't have enough space to accomodate CCDs that are large enough to allow for high pixel counts while at the same time keeping the noise down. So all that high-megapixel, small sensor compact cameras will do is take crappy pictures that take up _way_ more space on the storage medium than they should. Hey, the camera makers probably get paid by the SD-card makers.
In what the hell jurisdiction does a security guard have the right to arrest somebody?
In any jurisdiction that has something similar to a citizens arrest clause. However, you'd have to be committing an actual crime for this to be applicable.
Or confiscate their property?
That's a "nowhere". If anything, they can hand you over to the police.
More energetic light, such as x-rays tear these bonds apart.
Ok, but we're assuming a star here that doesn't actively sterilize its planets through solar flares.
Lower energy light, such as from infra-red on down is insufficiently powerful to "tie" the elements together into compounds needed for life.
Well, things we consider stars usually don't radiate a lot of xrays (compared to their output at lower frequencies), and usually do radiate quite a bit of visible light (else they wouldn't really be stars). The spectrum might be different, but there's light that can be used for photosynthesis.
The spectrum of the parent star must well matched to the energies involved in photosynthesis.
Err... I would believe it's the other way round. The life forms with the photosynthesis mechanism that is best adapted to the light of their star will be the most successful, given enough time.
Why on earth is there a presidential veto in the US?
It's a common thing that some member of the executive actually has to sign laws for them to take effect. I think something to that effect is in place in Australia, too, but it's probably used less often and less politically than in the US.
Slashdot Mirror
There are no means of power generation that involve getting more power out than is put in.
Which is trivially true, but also fairly meaningless unless you're trying to argue with perpetuum mobile nutjobs.
In all other cases, you're looking at how much _usable_ power you get out of a process, and how much power in addition to the fuel you need to feed in.
Hence, a fusion reaction would be energy-producing if (electric output power) > (electric power input needed to keep the fusion reaction going)
All Fusion reactions (hot or cold) need is a catalyst which increases the efficiency (lowers activtion energy, increases yield, affects rate, etc) of the reaction.
Err ... so far we've found only one catalyst for fusion reactions, and that's muons. Not really all that helpful. And you usually don't want anything other than your reaction fuels in hot fusion, because anything else will act more as a pollutant than anything else and increase the likelyhood of unwanted interactions.
That would be overly simplistic.
The solar system is roughly 5 billion years old, the universe is roughly 13 billion years old. The early universe contained more supermassive stars than today's universe, and these giants only had lifespans in the tens of million years. So a lot of them popped before our solar system formed. It is believed that our solar system formed in the vicinity of several earlier supernovas.
So, the Wright brothers should not have been able to invent the airplane because they were incapable of building a Boeing 747 in their little cottage?
FAIL.
You can build a perfectly working airplane that fits on a kitchen table. Granted, it might not transport a person, but it's otherwise completely functional and airworthy.
Next?
And why would you need oil if you have enough energy to synthesize any hydrocarbon of your choice on an industrial scale ?
Here's an honest question: where do our iron deposits come from?
Um ... from dead stars that had enough mass to produce iron (as well as even heavier elements) as they died. This means stars that were much more massive than our little sun.
Which isn't a problem if we don't try too hard to keep the waste heat from escaping into space.
Heck, any human-generated amounts of heat on Earth are dwarved by the 1.275*10^17 Watts of solar irradiance Earth receives anyway.
We have plenty of fusion power.
Yes, but the reactor design sucks big time. Let me explain:
We've got a 1.989e30 kg fusion reactor producing approximately 386 billion billion megawatts of power.
1. The thing is way too big. We can't move it or take it with us.
2. The specific power per volume or mass sucks really big time. I mean, 27 Watts per m^3 ? 20 Milliwatts per kg ? This is a ridiculous waste of space.
If you're discounting all the other problems, then you may as well assume that the process can use straight seawater. We have plenty of that (just stick a pipe in the nearest ocean and build a long pipeline), and it doesn't compete with anything that requires freshwater (agriculture, human consumption, etc).
Metals are usually heavy.
Safe and extremely dense.
Maybe dense as far as volume goes, but what about stored energy per unit of weight ?
The metal in you gas tank would still be worth $50 or so,
I think you're missing a k there. $50k. Palladium is expensive.
have to disagree here. I did the math a couple weeks ago and came up with about 7 pounds per mile for lithium based batteries currently used in cars and total battery weights between 1/2 ton and a ton.
There's another name for a contraption that is supposed to move at high speeds and hold people and a half-ton lithium battery: death trap.
Artificial hydrocarbons? My recent research into alternative technology for automobile propulsion didn't reveal any approaches that look feasible in the near-term (by which I mean Obama's proposed 10 year window). If I missed something, could you please provide a cite?
Well, the technology itself is almost a century old (Fischer-Tropsch process and Sabatier process), the only real problem is finding a source of carbon or (relatively pure) carbon dioxide that's not a fossil fuel in the first place or requires prohibitive amounts of energy per unit of C/CO2 produced.
I assume that hydrogen could be used to augment the yield of existing biomass-to-liquid processes, since biomass probably contains a carbon surplus. Especially if the BTL process aims to produce short hydrocarbons.
Is there enough energy in sunlight to make it a worthy opponent of non-renewable energy that is sitting around the planet?
Yes. But that's not the question. The questions are:
How do we efficiently get this energy to where it's needed ?
How do we efficiently turn this energy into a form that we can store and take with us ?
Hydrogen has many - the cost of producing hydrogen, the cost of compressing or liquefying the hydrogen, the impermanence of liquid hydrogen ("venting"), the safety concerns of carrying around enough hydrogen to power a car without a "Hindenburg effect", and the cost of a new infrastructure to transport megatons of hydrogen to fueling stations scattered across your country.
Or find an efficient way of extracting CO2 from the air or from seawater, and use that and hydrogen to make liquid fuels that are entirely compatible with the existing infrastructure.
Liquid fuels will always be easier to handle than gaseous fuels. And of the latter, hydrogen is one of the more problematic ones.
Another use for this technology would be a sort of energy pack that goes on the roof. A water line goes in, hydrogen comes out and is stored in a fuel cell which powers the house.
Fuel cells don't store hydrogen - they use it as fuel. Hydrogen storage is a can of worms entirely separate from the fuel cell that has its own challenges.
Problem is what to do with all the waste oxygen.
Um, what problem ? You either store it, too, and use it when your fuel cell generates electricity, or you just release it into the atmosphere.
Yes, they do. It's a simple matter of the laws of optics and quantum mechanics. They can't be circumvented with a little bit of engineering.
CCDs are constantly getting better and smaller,
If they get smaller, they usually get worse. Making them smaller (and/or increasing the pixel count) means that there's less light falling on each pixel, while the noise per pixel stays the same (sorry, almost no way around that except using liquid nitrogen to cool the thing). Hence, you'll get more noise per pixel.
and lenses are constantly improvivng.
It's not a lens issue (and we've been able to make pretty good lenses for quite a while now), it's an issue with the basic inner workings of a CCD.
You may be surprised with just how good some of these are.
I just bought a Sony DSC W300. Yes, it has 12 Megapixels, but it also has a larger CCD chip (I think 1/1.7" ... the usual size is 1/2.5" or even 1/3.0" for really crappy cameras).
Let me show you a picture I took with my Nikon Coolpix 7 megapixel camera that is a year old
There you say it: That camera only has 7 megapixels. That's pretty close to the ideal number for compact cameras - 6 megapixels.
Get any of the 10+ megapixel cameras with 1/2.5" CCDs, and you'll find that they'll take large, but not really good, pictures. 6 Megapixels would be enough, but explain to a customer why he should by the camera with the smaller number ... ?
Unfortunately, for everyone of you there's a hundred dumb tourists who don't even know that they can turn off the flash of their compact camera.
High megapixel counts on compact cameras are a marketing trick to lure clueless people into buying them. Compact cameras don't have enough space to accomodate CCDs that are large enough to allow for high pixel counts while at the same time keeping the noise down. So all that high-megapixel, small sensor compact cameras will do is take crappy pictures that take up _way_ more space on the storage medium than they should. Hey, the camera makers probably get paid by the SD-card makers.
In what the hell jurisdiction does a security guard have the right to arrest somebody?
In any jurisdiction that has something similar to a citizens arrest clause. However, you'd have to be committing an actual crime for this to be applicable.
Or confiscate their property?
That's a "nowhere". If anything, they can hand you over to the police.
If you're a criminal in the first place, there are other ways to get an SLR than spending a fortune.
meaning if you catch any copyrighted work in your photo,
1. Copyright sky.
2. Profit !!!!
(Note the complete lack of "???")
Ok, but we're assuming a star here that doesn't actively sterilize its planets through solar flares.
Lower energy light, such as from infra-red on down is insufficiently powerful to "tie" the elements together into compounds needed for life.
Well, things we consider stars usually don't radiate a lot of xrays (compared to their output at lower frequencies), and usually do radiate quite a bit of visible light (else they wouldn't really be stars). The spectrum might be different, but there's light that can be used for photosynthesis.
He now owes the local police department $700.
If they can't find a tracking device, then it wasn't much good at tracking in the first place.
The spectrum of the parent star must well matched to the energies involved in photosynthesis.
Err ... I would believe it's the other way round. The life forms with the photosynthesis mechanism that is best adapted to the light of their star will be the most successful, given enough time.
It's a common thing that some member of the executive actually has to sign laws for them to take effect. I think something to that effect is in place in Australia, too, but it's probably used less often and less politically than in the US.