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okay, so that works out to about 2kW per person. given that you don’t get full sunlight all day, let’s say this is equivalent to a 8 kW panel, which costs ~$40k but supposedly operates for 25 year.
.. overall $133/month.

to make this 100% renewable, you want to bootstrap the technology: energy required to make and maintain and dispose of panels would all have to be renewable as well.

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seems i am not the first to propose this.

http://e360.yale.edu/content/digest.msp?id=2054

“The costs of building and running reverse-osmosis plants for desalination and transporting the water would be about $2 trillion per year.”

Focus fusion could reduce the cost of energy for this project

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Brian H wrote:

That is great to heard a comment so early.

Actually we are living in USA, and in US if the Americans able to just alter there traveling habit specially the areas in which i pointed out, then surely there will be great savings for us .

Regards

Zavier Francis.

It’s appropriate only in small towns and cities, and in the right weather, and with very limited cargo. Very unlikely to have much effect. The US is too large to become a bicycle commuting nation.

Expansion of public transit would tend to unburden the energy expenditure for commuters. The trouble with that, in the U.S., is that many places were designed with the assumption that people will drive a car, even to cross the street, to get to the local mall, instead of walk through a tunnel, or take a bus or train. Manhattan is an exception, of course, and exemplary of urban planning that makes efficient use of space.

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zapkitty wrote:
The limitation, of course, will be that you can only run the DPF intermittently.

Let the station heat rejection system chill the heat sink back down, and repeat.

But, unlike my previous 1 MWe low-power concept, during this power cycle you can run the reactor at whatever power setting gives the greatest efficiency.

Full-tilt boogie… be it 5 MWe or 11 MWe.

bursts of large power could have advantages, for placing your delta-v closer to where you need it. but i don’t know if the gain from that would cover the the mass penalty.

contrast this with: running radiators hotter lets you make them smaller. and heat rejection by venting plasma into the exhaust nozzle might cover all of it: giving extra thrust, at lower Isp, with all of the needed heat rejection.

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Aeronaut wrote:
I used the word fiction in that case to mean that which has not yet been proven. Predicting surface conditions of a gas giant is science fiction.

nope. different animal.

it is quite possible to predict some aspects of ‘surface conditions of a gas giant’, relying on what we know of the physical principles at play, without venturing into fiction. we just have to be careful how we discuss it. scientific synthesis builds its castles, not on sand, but on firm bases. if gas giants have a surface, then we can discuss probable pressures and temperatures, compositions, chemistry, heat flows, and such, at this surface, with suitable models in hand for the physical processes. we can duplicate those conditions in a lab, and verify pieces, all without needing to journey there, ourselves. it is speculative, theoretical modelling, yes. and we don’t get the whole picture, this way, but we do stay out of the realm of fiction.

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psupine wrote: As I understand it, one of the techniques used in electron tubes (aka valves) to reduce electrode erosion is to a maintain a negative potential on the “target” electrode. This decelerates the free electrons (that had been accelerated by the grid potential) so that most of the energy has been taken out of them and the electrons impact the plate at low energy. This is a bit like a lunar lander game played out on a very small scale.

Electrons travel through the vapourized decaborane, heating up the vapour to plasma on their way from the cathodes to the anode. The anode must be positively charged in order to attract the electrons, but the electrons give lots of their energy to the plasma. If 90% of the energy in a 45 keV electron were to go to the plasma, then the electron would be travelling slowly when it hits the anode (but i dont know the actual percentage). This process begins around the outside edge of the anode, where the cathodes are closest to it. The charge of the anode drops considerably as the electrons hit it and the plasma tendrils climb up.

The tendrils climb up and over the edge and become the plasmoid; so the parts of the electrodes most-exposed to heating vary through this pulse. All this happens on the order of nanoseconds, therefore skin effect will be important: the charges will be confined to the surfaces of the electrodes almost exclusively.

My understanding of the superiority of Beryllium is that it is much more transparent to x-rays, so it wont heat as much as copper. But otherwise its heat capacity and thermal conductivity counteract its higher melting temperature. It seems necessary to use a thin coating of a much higher melting temperature, thermally conductive material. (eg: graphite? single-walled nanotubes? )

But if, after the shot, the anode is turned slightly on its axis, then the next shot will contact a different, perhaps cooler, part of the surface.

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Aeronaut wrote: Perhaps we should clarify that FF-1 is science fiction for the moment, as it is testing hypotheses and theory.

Disagree. “fiction” means “not true, or not real”. There is real science being undertaken in these experiments, real hypotheses being tested, and independently-reproducible results being generated. Clearly, this is not fiction.

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The desire to have your power plants far away from your cities stems from the present condition of society: the collective belief that power generation must be massive, expensive, polluting, and dangerous. The public is so convinced that this must be true, that people are willing to invent diseases, in order to blame even wind turbines. Erode those misconceptions, and you’ll be selling.

A role-playing game around the various power technologies that involves perceived threats by public, accidents, and consequences, as well as success or failure of marketing/propaganda would be very educational.

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oh wow, that was a whole lot weaker a response than i had imagined was possible. how depressing. i’d sign that DNR waiver, but i’m inclined to believe that the whole species is at stake, here.

if we are not worthy, we can pay penance by immsersing ourselves in non-fiction, brushing up on maths an science topics by answering a thousand questions on http://answers.yahoo.com/ , selecting a research direction for a masters degree,
and attempting to give quantitative answers in our posts here.

please, someone, at least tell me what are the next hard problems to solve, this month, for Focus Fusion?

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It’s a fun game to seek fusion references in film –however, a successful campaign to bring onboard fans of sci-fi may only serve to undermine the fusion campaign effort.

I think it’s accurate. “Fake fitness” being the key term.
— http://seedmagazine.com/content/article/why_we_havent_met_any_aliens/

As recent, general traffic on the forum site seems to be covering the AGW debate, and movies, and games, better than real progress toward exceeding unity, I’m finding myself suddenly deeply dissatisfied.

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Yes, external magnetic fields do influence the DPF if they are strong, but Focus Fusion will have its own field generator, and is otherwise magnetically isolated. In an ordinary situation of power generation, this will not produce thrust, since you can have a barrier to stop the alphas after they pass through the coil.

A VASIMR VF-200 is made from two 100 kW engines, strapped together with opposite magnetic polarity. So 250-500 W/kg from a solar array will weigh in at 400-800 kg for each VF-200. Yes, if you want to strap a dozen or so of engines together for a faster flight, a 5MW focus fusion reactor will beat the solar array.

The hotter you can run the reactor, the smaller your radiator.

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epimenide wrote:
Waiting for comments and suggestions!

the poll-taking script on http://www.paolomanna.com/ appears to be broken (on both chrome 5.0 browser, and IE 6.0).

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Don’t get me wrong; i do love the idea of using antimatter, it’s just that it seems a little technologically disproportionate, here.

Hmm…

What if a bulk condensate of spin-polarized positronium can absorb stably into a light metal, the way hydrides do?
Let’s try using lithium, and keep it really cold.

Oh wait, those are Star Trek dilithium crystals! 😉

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Seeing as no one has, as yet, found a way to make or contain antimatter in sufficient quantity to use it for propulsion, let’s plan to go with something that has a chance of being feasible sooner.

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Estimated depletion, of both oil and coal, seems to match. Looks like ~54 years, or so, is all you get, from both.
— http://en.wikipedia.org/wiki/Proven_oil_reserves#Estimated_reserves_by_country

If demand softens, because alternatives become competitive, then this time frame extends.
But if extraction becomes cheaper, then the price drops, demand strengthens, and the time frame contracts.

As fusion is deployed, it will meet energy demand increases first, so i don’t see the above numbers changing a lot, near term.

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