Why 10-25 times net power?

[djmelfi]

Article on the "Piston" fusion device states needs 10-25 times output gain to be viable.

I am a neophyte but have been following the fusion blogs avidly.

If a device had a 25% net power gain and was cheap enough to operate less energy costs, it would make enough power to sustain itself and have a surplus for the "GRID". As long as the value of net output could cover the cost of opertion and amortize the construction costs over 25 years or so, why would we need 10-25 time gain? (ADD IN CAP AND TRADE CREDITS )

By my reserch the average gas fired electric plant produces about 700 MW for 500 million dollars construction costs.

[MSimon]

You get a factor of 3 loss from converting steam to electricity.

To be viable as an energy producer a power plant needs to have a net power gain of 5 to 20 (or more).

That says that the fusion reaction must have a power gain of 15 to 60.

In addition the power plant costs are jacked up by the power conversion eqpt. - heat exchangers, boilers, turbines, pumps, auxiliary eqpt., etc. In fact the conversion eqpt. is where most of the costs lie.

[chrismb]

That says that the fusion reaction must have a power gain of 15 to 60.

I think that is a bit of a misleading answer. Generally, that sounds reasonable from a commercial perspective, given all the other associated costs and radioactive materials handling issues, and I wouldn't've thought anyone would pay too much attention to anything less whilst cheap fossil fuels abound.

But the original answer raises a perfectly valid point - how little energy 'gain' do you want to have to put up with to get a 'change' in your energy source. If you put 100MW in and get 303MW out and after converting that 301MW you get 101MW power again 100 of which goes back into the machine, then you've got a net of 1MW.

whoppee.

That's all.

Work out how efficiently you can convert the output energy back into 'high quality' electrical energy to feed back in. You only need to be greater than that to get an energy over-unity gain. And that pitance of energy output may be enough to justify running it. Better than nothing. You'd be glad for 1MW net power if you were stuck on a moon base or something!

Just generating heat is no great function for such a power source, it has to [be able to] generate electricity. You can get a Q=2.5 energy gain just by running a reverse cycle air conditioner to generate heat, 1kJ in, 2.5kJ heat out (energy that is sucked in from the colder outside).

You can also power air conditioning cycles with heat directly - like the old gas powered fridges. Someone should get around to designing and commercialising a domestic boiler that also drives an external heat extraction engine to get more heating energy out of that gas.

[djmelfi]

I thought the boron fuel process would generate electricity direct to grid, directly capturing free electrons, and bypass steam conversion and dosnt have radioactive issues either. That would bypass the 3-1 power loss in steam conversion issues. (I havn't verified that figure, but accept it)

If you started fuel input for reaction with fossil generated energy, then switched to your own energy (direct captured free electrons) and produced a net 100%, lets say 200mgw from a 100mw input with direct electron capture that would give you a net 100mw fossil free and radioctive free energy, why isnt that a viable target for a "commercial" plant. That would power a small community. If the cost would approach $200million or less it would seem this approaches viability at "Green Economy" level costs. Intuition says that operational costs of direct electron capture would compete more than favorably with steam conversions.

[djmelfi]

My objective here is merely to try to define the low end of what is commercially viable. Obviously a 20 fold increase is better than 10 and 10 is better than 2. A 20 fold increase converted directly to free electron capture would change the world immediately.

But what is the lowest end where we could produce commercially viable clean energy, where maybe the only bonus is "CLEAN" for the price of "FOSSIL".

This would still change the world abeit a bit slower. This would take energy off of the COMMODITIES market and make it a fixed constant. Energy would cost would be the same 30 years after these plants were built.

[djmelfi]

My understanding that DR. B was shooting for direct electron capture, he proposed that reactors could be placed in existing steam plants that already had invested in conversion infrastructure as a relatively easy drop-in conversion, but that wasnt his final solution.

[MSimon]

Chris,

I believe I covered your point:

You get a factor of 3 loss from converting steam to electricity.

It is not just a matter of net power. It is a matter of economics.

[djmelfi]

It is not just a matter of net power. It is a matter of economics.

Thats the issue what is the lowest denometer for a commercially viable plant.

My reconning isn't anywhere near what the replies are stating. If I started up with fossil fuels and then switched to my own generated energy, the fossil consumption stops and I am now generating NEW energy constantly as this continues WITHOUT ANY FOSIL FUEL INPUT, the energy I produce and recylcle is not part of the COST. My 25-100% gain eventually represents 1000s% gains over the fossil fuel input which has ceased.

If I started up with $10,000 worth of energy and eventually produced $10,000 worth of energy the subsequent energy produced is economically 100% profit.

I think the economic model works at lower multiples, it seems no one understands the break even point and wants to project the start up model ad infinitum.

[MSimon]

It is not just a matter of net power. It is a matter of economics.

Thats the issue what is the lowest denometer for a commercially viable plant.

My reconning isn't anywhere near what the replies are stating. If I started up with fossil fuels and then switched to my own generated energy, the fossil consumption stops and I am now generating NEW energy constantly as this continues WITHOUT ANY FOSIL FUEL INPUT, the energy I produce and recylcle is not part of the COST. My 25-100% gain eventually represents 1000s% gains over the fossil fuel input which has ceased.

If I started up with $10,000 worth of energy and eventually produced $10,000 worth of energy the subsequent energy produced is economically 100% profit.

I think the economic model works at lower multiples, it seems no one understands the break even point and wants to project the start up model ad infinitum.

Uh. No. I will now explain to you why engineers get paid the big bucks.

If it costs you $100 million to produce $10,000 worth of energy a year it is not going to happen. Unless the $100 million is yours and making energy is your hobby.

Because even parking the money in a place that returns only 1% on investment will get you a profit of $1 million. Which is 100 times $10,000, if I did the math right.

You see there are opportunity costs.

And now you know why engineers get paid the big bucks.

[djmelfi]

[/quote]And that pitance of energy output may be enough to justify running it. Better than nothing. You'd be glad for 1MW net power if you were stuck on a moon base or something![/quote]

If I had a startup energy cost of 100mgw for 1 hour, then produced 1mw for 20 years I have 175200 (-100) hours of 1 mgw power net gain. that is a 1752 times net gain in energy.

[MSimon]

Better than nothing?

How about 1 milliwatt hour net for $100 million.

See me. I can give it to you for much less.

In fact if you send me $1,000 I will send you 10 watt hours of electricity Fed Ex.

And if you get a couple of your buddies together I can give a discount. If you order 100 watt hours I can sell it to you for $5,000. Half price. Delivered to one address. And if you buy in that quantity with a signed contract I can let you have it for only 1/3rd down. $1,666.66 and you can keep the penny as a sign of my good faith.

[chrismb]

Chris,

I believe I covered your point:

You get a factor of 3 loss from converting steam to electricity.

It is not just a matter of net power. It is a matter of economics.

OK, I'll buy the argument. I rekon it will commercially pay if you can show just a x2 power increase though at 100'sMW output - it would be energy out for next to nothing in. The only question would be real-estate prices for the power generating site!

But there again, if we swallow all we are fed on how much power a little polywell could put out, it would take up a heck of a lot less space that a coal-burning furnace.

Direct coversion of ions to electricity, yeah, sure, let's see a prototype powering a light bulb first. Theoretically seductive... practically nonsense. It's easy enough to fire an ion gun at whatever configuration of screens you might choose for such a hairbrained scheme, so has power transfer in this way been proved yet? Let's stick with the reality of thermal energy extraction until this is demonstrated. Too many other hurdles to focus on for now to worry about sci-fi ideas.

[MSimon]

chris,

Tell me why wind electricity isn't free? After all the power doesn't cost anything. Or for that matter why isn't solar the king? Free power there too.

By your reckoning every roof in America should have been covered in solar cells by 1970 or 1980. After all we had solar cells in 1962. And the power is free.

Why should capital costs count for anything if the energy is free?

In fact I will go further. Why don't we heat all our hot water with solar energy? Solar hot water heaters were common in Florida in the 1920s. By 1940 all of America should have been using solar hot water heaters. After all - the energy is free.

[djmelfi]

MSIMON

With all due respect, and admiration for all of your wealth. I don't think you read my post correctly, the $10,000 was a break even point covering the cost of the fossil fuel startup, and has nothing to due with overall output. After startup costs are reccovered , all net output is a net gain. The issue of plant costs is a matter of scale, can you scale net output to cover that over a 20 year cycle. (net means to grid) My understanding is a net output of 100mw to 200mw would be competitive at a $200 million "Green Economy" investment. if the reactor produced 500mw gross and we could net 200mw (40% not 40X) this should be a viable investment. I don't think you are opening your mind to this!!! Using Boron II direct electron capture a 40% net gain could be commercially viable. Lectures on enconomics isn't an engineer's forte, no matter what the remuneration..

You all keep saying 40x fuel outpput to fuel input conversions, this model assumes a continuing fuel cost and steam conversions which just isnt part of the model I am presenting, when you have a net gain the Reactor can power itself and those costs end. The remaining costs are plant and operational. A 500mw gross power reactor with a 200mw net to grid (300mw to run) should be viable investment. My understanding Boron II is one of most available sustances and should never be a "Commodity" per se.

This wouldn't blow away energy costs, but it would produce competitive "Green" energy which is a viable goal.

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Portlan OR Gas Plants

The plant would produce 240 to 350 average megawatts, enough electricity to power as many as 230,000 homes. PGE would not disclose the price tag, but energy experts peg construction costs for a plant that size at roughly $200 million.

[MSimon]

dj,

You don't get it. You have to have net output AND cover your capital costs plus a profit.

Read this:

http://iecfusiontech.blogspot.com/2007/ ... posia.html

And the Vincent Page presentation linked and then get back to me.

It is not a matter of opening my mind. It is a matter of net present value.

As I said: engineers get paid the big bucks because:

Engineering is the art of making what you want from what you can get at a profit.

And to make a profit you have to include the cost of money. Or opportunity costs if you prefer. And to make a profit you need fusion gains of 15 to 60 when you run a steam plant because otherwise the ROI doesn't work out and 60 is better than 15.

It is not just physics. It is money. Which is why engineers typically get paid more than physicists. They have to make decisions where big bucks are riding on getting it right. Not just make it work (the physicists job), make it work at a profit.

A BFR running pBj only makes economic sense with direct conversion. Otherwise D-D or D-T if you are going to run a steam cycle.