PeakOil is You
Antimatter Breakthrough Could Lead to Starships
Re: Antimatter Breakthrough Could Lead to Starships
by radon » Sat 20 Nov 2010, 06:29:59
$this->bbcode_second_pass_quote('OilFinder2', '')$this->bbcode_second_pass_quote('', 'W')e *could* use it for power if we had enough of it, but I'm going to be very surprised if it doesn't take way more power to make than you'd ever get out of it.
From the article:
$this->bbcode_second_pass_quote('', 'F')urther into the future, Kaku believes we may be able to use antimatter as the "ultimate rocket fuel," since it's 100 percent efficient – all of the mass is converted to energy. By contrast, thermonuclear bombs only use about 1 percent.
When an anti-matter particle collides with a matter particle, they emit a photon and disappear - the process know as annihilation. A single photon carries energy of circa 1 quintillionth Joules http://answers.yahoo.com/question/index?qid=20061014185218AAWxqel For reference to the names of large numbers view http://en.wikipedia.org/wiki/Names_of_large_numbers.
In order to keep your 40 watt spot lamp lit for a tenth of second (the time that the anti-particles were managed to be held stable), you will need a quintillion packs of 40 (or 38 for that matter) photons, or a quintillion Large Hadron Colliders working simultaneously. This is assuming that we are able to harness the photons' energy without losses.
The area of the Collider is about 230 km2 http://en.wikipedia.org/wiki/File:Location_Large_Hadron_Collider.PNG. The total land area of the Earth is 150 m km2. The entire land surface will thus be able to accommodate about 650 thousand Colliders - let's say a million for simplicity.
This means that we will need about a TRILLION Earths covered by Colliders in order to keep light in a 40 watt bulb for a tenth of a second at the current level of the technology development. You need to invest energy in building these Colliders, maintaining them, generating the anti-particles, harnessing the photons' energy. To get a 40 watt light flash. This gives the idea about the potential energy efficiency of the process at the current stage.
No need to produce all those numbers though. The entire argument by reference to the "100% efficiency" in the article is logically flawed from the outset. The energy input into synthesizing the fuel (anti-matter) is in no way dependent on the efficiency of the output process. Moreover, the input energy may not be lower than the output energy, as otherwise we would have created a perpetuum mobile and declining entropy. If this was the case it would be easier then to synthesize petroleum and use it to drive our contemporary oil-dependent economy, instead of drilling holes in the ground in searches for more oil. This contradicts the laws of thermodynamics as they stand at the moment - a topic discussed on this forum on numerous occasions.
In light of this the only way to practically address the energy starvation issue is to try to find storages of the anti-matter that the universe might have already created for us over the course of its billion-years evolution. Those similar to the oil fields beneath the ground. For some reasons, unknown to the scientists yet, the anti-matter is far less common in nature than the matter, and is anyway difficult to store as it annihilates instantly when contacted with the matter. So it is more a science fiction at the moment than any practical prospect to address our energy needs.
- radon
Re: Antimatter Breakthrough Could Lead to Starships
by radon » Sat 20 Nov 2010, 08:04:26
$this->bbcode_second_pass_quote('steam_cannon', 'T')his is so stupid. I expect better then this from peakoil.com
Magic space travel?
This is the stupid part. Antimatter is not any magic key to star ships or space flight. This won't magically levitate a spacecraft. And this isn't even a good way to store energy.
Magic space travel?
This is the stupid part. Antimatter is not any magic key to star ships or space flight. This won't magically levitate a spacecraft. And this isn't even a good way to store energy.
This is not stupid at all. EU showed above that the photon's engine is hypothetically able to propel a spaceship to 10% of c (30 000 km per second) within 10m seconds, and Plantagenet calculated that this is a 45 mins travel to Mars. A qualifier is that 10m secs is about 116 days. But nevertheless, the modern spaceship engines propel spacecrafts to no more than several km per second. Due to the supreme efficiency of the fuel-to-energy conversion process, the photon engine is the best potential technology, currently known, for the spacecraft propulsion.
Also as EU wrote above, the 10% of c speed would be achieved when the mass of spacecraft is m0/e. Proton's rocket mass is about 700 tones, and it is able to bring to the orbit 20 tones at a speed of a few km per second. A 700-tone photon rocket would propel 260 tones of the spacecraft to 10% of c. So using anti-matter looks potentially like a very efficient way to store energy.
The subject's article does not address the world's energy scarcity issues. It addresses the potential for creation of highly efficient/effective engines for space-vehicles and alike. These are absolutely different problems that OF2 seems to have failed to discern, and that led to a general confusion.
The modern space rockets (or even airplanes) use extremely energy-efficient fuels. Meaning, the ratio of the emitted energy to their mass is very high. Nevertheless, these fuels are not used in car vehicles or in electricity generation. Because the amounts of energy inputs required to produce these fuels are very significant. The EROEI of these fuels should be appallingly low. (Besides, the space liquid fuels are very toxic). However, these does not prevent them from being very energy efficient in performing their ultimate task of bringing the spacecraft to the orbit. It all seems like a question of definitions and terminology.
$this->bbcode_second_pass_quote('', '[')b]Regarding this as a weapon or for producing energy?
You put in x amount of energy creating your antimatter. At most you might get 2X in energy reacting with matter. However this isn't likely since you have likely spent an aircraft carrier in momentum to create your first atom. On reaction your atom makes a little pop. Ultimately it is more efficient to throw aircraft carriers at enemies with catapults. Regarding using this in a reactor, it's got a long way to go to get a positive EROEI.
Yes, as long as you use the Large Hadron Collider to produce the anti-matter. You may similarly employ the Large Hadron Collider or alike device to synthesize petroleum. You will get a similar result. But instead, you may drill a hole in the ground and get the oil from there at EROEI of 10:1.
Again, as discussed above, these are two distinct issues:
1. Maximizing EROEI from the available resources - this one is that po.com seems to focus on.
2. Maximizing energy concentration at an arbitrary EROEI cost - the primary concern of the scientists in the article.
$this->bbcode_second_pass_quote('', '[')b]But what if antimatter could be produced efficiently and this had a positive EROEI?
Then it would not be used for space travel.
1. First it would be orders of magnitude less safe as an energy source then a nuclear reactor strapped to a tank of liquid hydrogen propellant.
So what? Liquid space fuels are extremely toxic and unsafe, but they are nevertheless used to propel rockets. Nuclear plants are potentially very dangerous but nevertheless used to generate energy.
$this->bbcode_second_pass_quote('', '2'). The only way antimatter could be useful for space travel is if the antimatter could be produced on the fly and reacted with matter ..
Not necessarily. An alternative would be a search for the anti-matter containment mechanism to store it. Similarly to the attempts to find containment for plasma used in fusion reactors, but perhaps far more difficult than that.
$this->bbcode_second_pass_quote('', '3'). If it was possible to produce antimatter for less energy then was consumed in the production, then it is likely countries could use this produce nuclear bombs without having to refine uranium or other isotopes. An antimatter nuclear bomb alternative would be very dangerous for the world. Such an energy source might be used to send people into space; with mushroom clouds. If antimatter production was easy and efficient, it would not be a good thing. Luckily we live in a universe where it is neither easy or efficient to produce.
