Actually, it says the THEORETICAL limit (which is what Carnot was talking about) is 95%.
The practical limits is PROBABLY around 86% given the current materials.
We already have cells that are 45% efficient however they are exceptionally expensive and are only used for satellite power etc. These super efficiency cells are some of the few cells that still consume more power to make than they are expected to produce (part of this is the harsh radiation/meteor environment of space).
The techniques used in these cells (multi-gap, ultra purity, frequency isolation etc) are getting cheaper and are starting to make there way into the consumer grade equipment.
It is not unreasonable to expect a 50% efficiency in consumer cells in the next 10-15 years. In addition the price for cells across the whole solar cell spectrum will drop, as will power storage and potentially even inverter/controller costs. As the price drops and efficiency increases the range of applications solar is appropriate for will grow. Eventually I would not be surprised if solar cells became standard on new residential construction over the next few decades.
While local temperatures don't effct the PV Carnot efficiency, the surface temperature of the sun does.
The sun is about 6000K. Locally we are 300K calculate it out and you get a maximum efficiency of about 95% (my mistake...off by 3)
However 80% is a much more realistic end point for consumer grade equipment. Even 50% would bring the cost down to less than ANYTHING out there and provide power for all residential uses plus power a couple of nice electric cars rather well.
Argue with my electric bill.... I pay 10.5 cents per KWH and I am slightly better than my state (Georgia).
Coal prices vary but the average has NEVER been below 7 cents a KWH (adjusted to today's dollar) before distribution costs. Those that are that low are typically from non-profit co-op type organizations.
For profit power companies charge anywhere from 8 cents up to 15 depending on market forces (again average).
Finally even is you WERE right and it did cost 4-6 cents before distribution costs, we are talking about power at the wall and pricing for residential off-grid solar. the 4-6 cents then gets line maintenances and transmission losses which together can be substantial.
In the end, financially Solar is still not a viable option for MOST people. However if you live in a sunny are where central power is relatively high solar is ALREADY a financially viable option. As the technology improves, and it is improving quickly, solar becomes cost effective for more people. Right now I am about even financially purchasing power vs generating power with solar. In 2-3 years it probably won't be a contest and I will gradually move off grid. (Probably solar water heater on year then grid tie solar the next and finally fully off grid).
As efficiency goes up and price goes down more people will move towards solar and away from centrally generated power.
However with nanosolar's thin film cells the price can drop to about 1.5X coal (although space could become an issue).
Currently the payback period for a full off-grid residential solar system is on the order of 7-10 years. (Cited all over the place) This is in line with the roughly 4X for conventional silicon cells.
But the cost of power is based on more than cell efficiency.
For instance, nanocell solar cells are proven and produce power at 0.15 cents a KWH. this is done at about 7 percent efficiency. Coal power typically costs about 0.10 cents a KWH. This is possible because the cells are so cheap and can be placed in "useless" areas like residential siding and roofs. This tech is expected to reach rf percent efficiency at the current price point in 5-10 years.
There is enough unused space on roofs etc to provide several times our power usage right now AND do it at about a third the price of coal plants.
Remember, caol plants are already close to thermodynamic top efficiency at 40 percent efficient.
In a few decades you may be able to buy a gallon of PV paint that will cover a wall with 50 percent efficient cells at $20 a gallon (I am exaggerating on the price since I don't know and it really doesn't matter).
Remember we have an avearge of 4 KWH falling on every dquare meter every day. Even 50 percent efficiency on the wasted space would provide all our energy needs for the predictable future.
The primary benifit to solar thermal is that it is a mature technology and is about 40 percent efficiency plus we are decent at storing heat energy without loss.
The downside is that we are unlikley to improve much because of Karnat restrictions.
PV has a Karnat limit of about 98 percent. Therefore while at the moment thermal is better for large power plants, PV will eventually pass thermal. We are already pretty close efficiency wise to storing electricity cost effectivly.
Currently availible non-specialty cells (the cells used for space etc are not used for general power) are typically between 5 and 15%.
Therefore getting to the 80-90% range would result in a 5-18X improvment.
Since solar is currently 4X, that means it will drop to.2-.8X of CURRENT power costs.
Now remember that hydro is essentially 100% tapped. Wind has a much more limited range and is already approaching the likley maximum efficiency. Nuclear is great but will take some time to spin up. Oil/natural gas prices are climbing rapidly and coal is becoming more expensive to mine and or clean.
Solar PV provides a great load matching power source that will help reduce an individuals demand on the system even if it doesn't complely remove the need for other power sources as well.
The Roswel aliens that were stranded on earth brainwashed some NEC employees who planted the code in all fax machines to send the fax to fermilabs who then posts it on the internet (which would be invented in 40 years) and thereby transmitted to mars...
I maintain you are making assumptions that reach well beyond what we know about OUR universe, let alone gods plane.
For instance, string theory predicts a "greater" universe of M-Branes. These are, by necessity of the observations in our universe, eternal having neither a creation nor an end point yet by your definition they have time because periodically they collide which is what created the big bang.
I dispute your contention that change mandates an end and therefore a beginning. Time can also be defined in terms of a reference beginning point which in an endless universe does not exist ergo no time (something of a tautology I know but still a valid definition of time)
The existence of space-time in the god-universe also implies the existence of entropy working in the same manner as the entropy of our universe, albeit with a different mechanism and materials. If entropy does not exist in a universe, then nothing could be created in it: any creation would be randomly destroyed. Actually, it is entropy itself that causes the random destruction. What if there was no trend? What if an atom stayed in place unless acted upon by a consciousness? There is actually nothing that precludes this scenario and that easily allows for creation without mandating terminals for the universe. Actually, some physicist think that OUR universe was only caused by the presence of our conscious ability to interpret it. Due to the separation of cause and effect, since we were GOING to be here the quantum supposition in our area collapsed creating the universe within our view (defined by about 15 billion light years.) Outside this area the universe is a standing wave and has not condensed at all. All this is very esoteric and I won't pretend to understand it much at all but all these theories are based on observations of OUR universe. We have already proven that temporal infinity does not preclude change outside of our universe.
As for Indiana Jones, what is the difference if I am watching it for the first time with my kid on the couch? I may have the fast forward button but I choose not to know what is going to happen. It is still a surprise to me (god) just like it is a surprise to my child (people) when Indy and whats her name got tied up and all the Nazi's got melted. Since there is no one else around who knows more about the plot, there is no material difference.
If you want to look at it your way than even if god DIDN'T exist there would be no free will. We can predict the future with arbitrary accuracy based on our current knowledge. Given a great enough knowledge we could predict everything that will happen to you till you die. Having a generous god is the ONLY way we could possibly have free will.
However even in our own universe, causality is not mandated. Some of the interesting features of quantum mechanics is that it can actually disconnect the cause from the effect. This even allows you to experience the effect BEFORE the cause has happened. It is only through a gradual summation of these strange effects do we get the universe we experience....and this is all in a universe with very sane and predictable rules (ours).
Current theories show that a universe with our laws (which allow for our type of life) are no more likely than any other combination.
There is no reason to expect that the "universe" god exists in is mandated to follow the laws of causality as we experience them. There is no reason to expect that the 2nd law of thermodynamics applies. As such, god could certainly have existed for all of time (there may not be time anyway) and at the same time created our universe. This is not a proof of god rather it is disputing your proof.
This is all based on current physics much of which is already exploited in some technology (therefore more than well proven).
Your argument as stated does not seem to have merit. Please update it if you like.
As for your statement about free will. This was not part of the original discussion but still a fun thought experiment.
#1 you are basing the statement on the assumption that we have free will from gods perspective. We may, we may not however we DO have reasonable free will from our perspective.
#2 From a position of faith I personally believe that god has granted us true free will. The reason is actually biblically based, we are asked to choose Christ and without free will there can be no choice. Therefore how can this be? While I concede that an all powerful god has the ability to short circuit free will, this does not mean that free will WILL be short circuited. Free will is a gift from god and is provided by god specifically NOT looking at our futures. This does not mean he is not all knowing, only that he hasn't already observed the result. Like quantum theory states, so long as you don't observe it you don't FORCE a result.
Free will for us means a sacrifice for God. I hope you use your gift well.
We are basing this on the concept that each of us has an immortal component (call it a soul).
The soul is a reflection of God. The soul is the "image of God."
To use a technological/sci fi analogy, you are not your brain in your body. Your consciousness could (in sci fi/future tech) be transfered into a computer. YOU would still exist...your body wouldn't. Your form would change but the portion of you that is fundamentally you would remain the same.
As for Christianity and religion, I suggest you try researching the history with out pre-conceived prejudices. Christianity has more historical proof behind it than most secular organizations (like ancient Egypt or other river delta civilizations). In addition the internal logic is absolutely consistent and is actually a remarkable support for scientific exploration.
If you can put down your pre-conceived ideas and actually do a real, scientific examination of the history and associated data you would find that a Christian type God IS the logical conclusion. The way it has been practiced is often messed up but the fundamentals stand on the tests of logic.
I claim you don't understand through a flaw in your above logic....
True we are in a universe that is winding down (entropy) and will eventually end.
True, for god to have ultimate power over this universe he must be greater and or outside the universe.
Question: Why must we assume that the place god interacts from MUST have had a begining?
Now I agree, I can't comprehend what that would be like...but my personal inabilities DOES NOT mean that it can't be true. (Talk to most people about the specifics of quantum mechanics and you will find a similar sort of opinion)
If god is omnipotent than he(she/it) can appear in any form (say a burning bush).
Therefore god must have created us in the image of the only part of him that doesn't change. His morality, his way of thinking and his personality. We have a dim image of this immutable portion of god.
Therefore aliens COULD look very different but still be created in his image.
The only remaining question is how did they get so many light years from eden?
The context for the power "Source" is always "when it becomes availible for the application."
Therefore with a trully self-contained system that is disposable and time-limited to the very short term, under those conditions you MIGHT be able to call a battery a power source.
However thoes situations are exceptionally rare. Nothing quoted in our conversation comes close. Maybe the voyager probes would work...the power source being the plutonium on board.
But if you intend to use a device for longer than the initial charge, you can't honestly call the battery a power source.
You are correct that an electron with a specific voltage will act the same regardless of the motive force. But the electron is not the SOURCE of the voltage, it is only the carrier.
Absolutely, the only TRUE power source would be the big bang.
HOWEVER when I and most people refer to a power source, they are referring to the point at which the power becomes accessible to us.
So for oil, it is when we pump it up. For agriculture and photovoltaics it is when the photons hit the earth.
Batteries may be an immediate source of power but they are not the point at which it first becomes available to us.
Other than dictating the time before refills/recharges, we don't care anything about the last step in the power chain.
We care about when the energy becomes available and of course how expensive it is when it FIRST becomes available. If you can find me a battery mine...or even an electrolyte lake, or how about a natural H2 cavern I will be happy to include that as hydrogen as the SOURCE of power.
Actually, the POWER comes from the chemicals used to create the battery or is supplied in the form of electricity when the battery is charged.
Saying you are using Hydrogen as a power source makes as much sense as saying I am using a rock as a power source.
Put the rock on the ground and watch it power something....you might want to get some food first since it will be a long wait.
Now pick up the rock and throw it at something...say a certain Rakishi and we will watch said rock make chunky salsa...
The rock itself is only a storage medium for the power NOT the source. Same with hydrogen. If you add energy to it you can later take it out but WHERE does the ernergy come from in the first place?
Very true...it always bugs me when people start talking about using Hydrogen as a power source...
But the one issue is that we are VERY unlikley to find things that react together on an asteroid.
Even in space on a solid object chemical reactions still take place. over the last few billion years any high energy reaction will probably have happened already. Since they are talking about using the water ON the asteroid for power, we won't find lots of sodium or other oxidizer on the same rock.
There are only a few reactions that would react with water to release hydrogen. Florine for instance.
However then you have excess Hydrogen and no oxidizer, unless you bring it with you. But you could always use your Flourine with your oxidizer directly and get more energy.
Short of nuclear reactions (fusion) you are not going to be able to get more chemical energy out of water than you put in. Therefore you MUST provide an external energy source and crack water to store it.
This asteroid is close to earth so we will assume insulation like earths. Roughly 1500 watts/ meter ^2. Current cells used by NASA operate at about 45% efficiency. Therefore they will produce about 750 watts/ m^2, at 24 hours a day that is 18 KWH per day per M^2. Therefore a 3 month mission each solar cell can produce about 1620 KWH PER M^2.
Finally, remember that you don't need a huge amount of fuel to get moving in the right direction. You can then use gravity to assist.
Finaly, this looks like it is intended to be a proof of concept. I doubt the mision will depend on any fuel from the asteroid...
Slashdot Mirror
Actually, it says the THEORETICAL limit (which is what Carnot was talking about) is 95%.
The practical limits is PROBABLY around 86% given the current materials.
We already have cells that are 45% efficient however they are exceptionally expensive and are only used for satellite power etc. These super efficiency cells are some of the few cells that still consume more power to make than they are expected to produce (part of this is the harsh radiation/meteor environment of space).
The techniques used in these cells (multi-gap, ultra purity, frequency isolation etc) are getting cheaper and are starting to make there way into the consumer grade equipment.
It is not unreasonable to expect a 50% efficiency in consumer cells in the next 10-15 years. In addition the price for cells across the whole solar cell spectrum will drop, as will power storage and potentially even inverter/controller costs. As the price drops and efficiency increases the range of applications solar is appropriate for will grow. Eventually I would not be surprised if solar cells became standard on new residential construction over the next few decades.
Sorry about that...I sent the message on a palm pilot with not checking :-)
take a look here http://www.ese.iitb.ac.in/aer2006_files/papers/086.pdf
While local temperatures don't effct the PV Carnot efficiency, the surface temperature of the sun does.
The sun is about 6000K. Locally we are 300K calculate it out and you get a maximum efficiency of about 95% (my mistake...off by 3)
However 80% is a much more realistic end point for consumer grade equipment. Even 50% would bring the cost down to less than ANYTHING out there and provide power for all residential uses plus power a couple of nice electric cars rather well.
Argue with my electric bill.... I pay 10.5 cents per KWH and I am slightly better than my state (Georgia).
Coal prices vary but the average has NEVER been below 7 cents a KWH (adjusted to today's dollar) before distribution costs. Those that are that low are typically from non-profit co-op type organizations.
For profit power companies charge anywhere from 8 cents up to 15 depending on market forces (again average).
Finally even is you WERE right and it did cost 4-6 cents before distribution costs, we are talking about power at the wall and pricing for residential off-grid solar. the 4-6 cents then gets line maintenances and transmission losses which together can be substantial.
In the end, financially Solar is still not a viable option for MOST people. However if you live in a sunny are where central power is relatively high solar is ALREADY a financially viable option. As the technology improves, and it is improving quickly, solar becomes cost effective for more people. Right now I am about even financially purchasing power vs generating power with solar. In 2-3 years it probably won't be a contest and I will gradually move off grid. (Probably solar water heater on year then grid tie solar the next and finally fully off grid).
As efficiency goes up and price goes down more people will move towards solar and away from centrally generated power.
And growing 20% annually with some companies hitting 50%http://www.washingtonpost.com/wp-dyn/content/article/2007/05/04/AR2007050402466.html
I was quoting the parent of my comment.
However with nanosolar's thin film cells the price can drop to about 1.5X coal (although space could become an issue).
Currently the payback period for a full off-grid residential solar system is on the order of 7-10 years. (Cited all over the place) This is in line with the roughly 4X for conventional silicon cells.
Yet Germany, which is one of the worst for solar, still generates a huge amount of it's power from currrent solar tech and the percentage is growing.
Germany produces more power from solar than the whole US.
You are correct..You did say Wind power.
But the cost of power is based on more than cell efficiency.
For instance, nanocell solar cells are proven and produce power at 0.15 cents a KWH. this is done at about 7 percent efficiency. Coal power typically costs about 0.10 cents a KWH. This is possible because the cells are so cheap and can be placed in "useless" areas like residential siding and roofs. This tech is expected to reach rf percent efficiency at the current price point in 5-10 years.
There is enough unused space on roofs etc to provide several times our power usage right now AND do it at about a third the price of coal plants.
Remember, caol plants are already close to thermodynamic top efficiency at 40 percent efficient.
In a few decades you may be able to buy a gallon of PV paint that will cover a wall with 50 percent efficient cells at $20 a gallon (I am exaggerating on the price since I don't know and it really doesn't matter).
Remember we have an avearge of 4 KWH falling on every dquare meter every day. Even 50 percent efficiency on the wasted space would provide all our energy needs for the predictable future.
The primary benifit to solar thermal is that it is a mature technology and is about 40 percent efficiency plus we are decent at storing heat energy without loss.
The downside is that we are unlikley to improve much because of Karnat restrictions.
PV has a Karnat limit of about 98 percent. Therefore while at the moment thermal is better for large power plants, PV will eventually pass thermal. We are already pretty close efficiency wise to storing electricity cost effectivly.
Thermal is great for now.
personally I would love to see throium reactors until fusion actually shows up.
While I am not a "tree-hugger" I am a "tree-shacker-hander"
Currently availible non-specialty cells (the cells used for space etc are not used for general power) are typically between 5 and 15%.
.2-.8X of CURRENT power costs.
Therefore getting to the 80-90% range would result in a 5-18X improvment.
Since solar is currently 4X, that means it will drop to
Now remember that hydro is essentially 100% tapped. Wind has a much more limited range and is already approaching the likley maximum efficiency. Nuclear is great but will take some time to spin up. Oil/natural gas prices are climbing rapidly and coal is becoming more expensive to mine and or clean.
Solar PV provides a great load matching power source that will help reduce an individuals demand on the system even if it doesn't complely remove the need for other power sources as well.
So long as they came with their handy dandy bipedal humanoid repair agents...
And Bush says..
Global warming, what global warming? (Paper shredder noises in the background)
The Roswel aliens that were stranded on earth brainwashed some NEC employees who planted the code in all fax machines to send the fax to fermilabs who then posts it on the internet (which would be invented in 40 years) and thereby transmitted to mars...
Makes perfect sense!
For instance, string theory predicts a "greater" universe of M-Branes. These are, by necessity of the observations in our universe, eternal having neither a creation nor an end point yet by your definition they have time because periodically they collide which is what created the big bang.
I dispute your contention that change mandates an end and therefore a beginning. Time can also be defined in terms of a reference beginning point which in an endless universe does not exist ergo no time (something of a tautology I know but still a valid definition of time) The existence of space-time in the god-universe also implies the existence of entropy working in the same manner as the entropy of our universe, albeit with a different mechanism and materials. If entropy does not exist in a universe, then nothing could be created in it: any creation would be randomly destroyed. Actually, it is entropy itself that causes the random destruction. What if there was no trend? What if an atom stayed in place unless acted upon by a consciousness? There is actually nothing that precludes this scenario and that easily allows for creation without mandating terminals for the universe. Actually, some physicist think that OUR universe was only caused by the presence of our conscious ability to interpret it. Due to the separation of cause and effect, since we were GOING to be here the quantum supposition in our area collapsed creating the universe within our view (defined by about 15 billion light years.) Outside this area the universe is a standing wave and has not condensed at all. All this is very esoteric and I won't pretend to understand it much at all but all these theories are based on observations of OUR universe. We have already proven that temporal infinity does not preclude change outside of our universe.
As for Indiana Jones, what is the difference if I am watching it for the first time with my kid on the couch? I may have the fast forward button but I choose not to know what is going to happen. It is still a surprise to me (god) just like it is a surprise to my child (people) when Indy and whats her name got tied up and all the Nazi's got melted. Since there is no one else around who knows more about the plot, there is no material difference.
If you want to look at it your way than even if god DIDN'T exist there would be no free will. We can predict the future with arbitrary accuracy based on our current knowledge. Given a great enough knowledge we could predict everything that will happen to you till you die. Having a generous god is the ONLY way we could possibly have free will.
Your argument is based on causality.
However even in our own universe, causality is not mandated. Some of the interesting features of quantum mechanics is that it can actually disconnect the cause from the effect. This even allows you to experience the effect BEFORE the cause has happened. It is only through a gradual summation of these strange effects do we get the universe we experience....and this is all in a universe with very sane and predictable rules (ours).
Current theories show that a universe with our laws (which allow for our type of life) are no more likely than any other combination.
There is no reason to expect that the "universe" god exists in is mandated to follow the laws of causality as we experience them. There is no reason to expect that the 2nd law of thermodynamics applies. As such, god could certainly have existed for all of time (there may not be time anyway) and at the same time created our universe. This is not a proof of god rather it is disputing your proof.
This is all based on current physics much of which is already exploited in some technology (therefore more than well proven).
Your argument as stated does not seem to have merit. Please update it if you like.
As for your statement about free will. This was not part of the original discussion but still a fun thought experiment.
#1 you are basing the statement on the assumption that we have free will from gods perspective. We may, we may not however we DO have reasonable free will from our perspective.
#2 From a position of faith I personally believe that god has granted us true free will. The reason is actually biblically based, we are asked to choose Christ and without free will there can be no choice. Therefore how can this be? While I concede that an all powerful god has the ability to short circuit free will, this does not mean that free will WILL be short circuited. Free will is a gift from god and is provided by god specifically NOT looking at our futures. This does not mean he is not all knowing, only that he hasn't already observed the result. Like quantum theory states, so long as you don't observe it you don't FORCE a result.
Free will for us means a sacrifice for God. I hope you use your gift well.
Actually, this falls in line PERFECTLY.
We are basing this on the concept that each of us has an immortal component (call it a soul).
The soul is a reflection of God. The soul is the "image of God."
To use a technological/sci fi analogy, you are not your brain in your body. Your consciousness could (in sci fi/future tech) be transfered into a computer. YOU would still exist...your body wouldn't. Your form would change but the portion of you that is fundamentally you would remain the same.
As for Christianity and religion, I suggest you try researching the history with out pre-conceived prejudices. Christianity has more historical proof behind it than most secular organizations (like ancient Egypt or other river delta civilizations). In addition the internal logic is absolutely consistent and is actually a remarkable support for scientific exploration.
If you can put down your pre-conceived ideas and actually do a real, scientific examination of the history and associated data you would find that a Christian type God IS the logical conclusion. The way it has been practiced is often messed up but the fundamentals stand on the tests of logic.
I claim you don't understand through a flaw in your above logic....
True we are in a universe that is winding down (entropy) and will eventually end.
True, for god to have ultimate power over this universe he must be greater and or outside the universe.
Question: Why must we assume that the place god interacts from MUST have had a begining?
Now I agree, I can't comprehend what that would be like...but my personal inabilities DOES NOT mean that it can't be true. (Talk to most people about the specifics of quantum mechanics and you will find a similar sort of opinion)
If god is omnipotent than he(she/it) can appear in any form (say a burning bush).
Therefore god must have created us in the image of the only part of him that doesn't change. His morality, his way of thinking and his personality. We have a dim image of this immutable portion of god.
Therefore aliens COULD look very different but still be created in his image.
The only remaining question is how did they get so many light years from eden?
This is a common gene that is added to explore the control mechanism of specific protein...
Like when and where they are produced.
The context for the power "Source" is always "when it becomes availible for the application."
Therefore with a trully self-contained system that is disposable and time-limited to the very short term, under those conditions you MIGHT be able to call a battery a power source.
However thoes situations are exceptionally rare. Nothing quoted in our conversation comes close. Maybe the voyager probes would work...the power source being the plutonium on board.
But if you intend to use a device for longer than the initial charge, you can't honestly call the battery a power source.
You are correct that an electron with a specific voltage will act the same regardless of the motive force. But the electron is not the SOURCE of the voltage, it is only the carrier.
Absolutely, the only TRUE power source would be the big bang.
HOWEVER when I and most people refer to a power source, they are referring to the point at which the power becomes accessible to us.
So for oil, it is when we pump it up. For agriculture and photovoltaics it is when the photons hit the earth.
Batteries may be an immediate source of power but they are not the point at which it first becomes available to us.
Other than dictating the time before refills/recharges, we don't care anything about the last step in the power chain.
We care about when the energy becomes available and of course how expensive it is when it FIRST becomes available. If you can find me a battery mine...or even an electrolyte lake, or how about a natural H2 cavern I will be happy to include that as hydrogen as the SOURCE of power.
Actually, the POWER comes from the chemicals used to create the battery or is supplied in the form of electricity when the battery is charged.
Saying you are using Hydrogen as a power source makes as much sense as saying I am using a rock as a power source.
Put the rock on the ground and watch it power something....you might want to get some food first since it will be a long wait.
Now pick up the rock and throw it at something...say a certain Rakishi and we will watch said rock make chunky salsa...
The rock itself is only a storage medium for the power NOT the source. Same with hydrogen. If you add energy to it you can later take it out but WHERE does the ernergy come from in the first place?
Very true...it always bugs me when people start talking about using Hydrogen as a power source...
But the one issue is that we are VERY unlikley to find things that react together on an asteroid.
Even in space on a solid object chemical reactions still take place. over the last few billion years any high energy reaction will probably have happened already. Since they are talking about using the water ON the asteroid for power, we won't find lots of sodium or other oxidizer on the same rock.
Point conceded....barely
There are only a few reactions that would react with water to release hydrogen. Florine for instance.
However then you have excess Hydrogen and no oxidizer, unless you bring it with you. But you could always use your Flourine with your oxidizer directly and get more energy.
Short of nuclear reactions (fusion) you are not going to be able to get more chemical energy out of water than you put in. Therefore you MUST provide an external energy source and crack water to store it.
Don't know but lets look at the math...
This asteroid is close to earth so we will assume insulation like earths. Roughly 1500 watts/ meter ^2. Current cells used by NASA operate at about 45% efficiency. Therefore they will produce about 750 watts/ m^2, at 24 hours a day that is 18 KWH per day per M^2. Therefore a 3 month mission each solar cell can produce about 1620 KWH PER M^2.
Finally, remember that you don't need a huge amount of fuel to get moving in the right direction. You can then use gravity to assist.
Finaly, this looks like it is intended to be a proof of concept. I doubt the mision will depend on any fuel from the asteroid...