Fusion Power Plants

[robject]

The figure of 50 kW is stupidly high. Something with the same activity level as a human will use about 1W/kg mass on a sustained basis...

Then the question in my mind is, is that a typo? Because it seems strange that Greg Porter could be off by that much.

As a test, has anyone built Battle Dress using EABA Stuff!?

Addendum Well, his "Powered Armor" section of EABA Stuff! looks like it agrees -- the average human uses about 1 kW when in sustained activity.

 

[Anthony]

Then the question in my mind is, is that a typo? Because it seems strange that Greg Porter could be off by that much.

Why? Lots of other stuff in FF&S2 has stupidly high power consumption.

Addendum Well, his "Powered Armor" section of EABA Stuff! looks like it agrees -- the average human uses about 1 kW when in sustained activity.

1 kW, at typical human metabolic efficiency (25%), is equivalent to 3,450 Calories/hr; a more plausible 500 Calories/hr works out to 145W. In addition, I might point out that 1 horsepower is only 745W. I hope that Mr Porter does not think that humans have higher power output than horses.

 

[Wol]

Why? Lots of other stuff in FF&S2 has stupidly high power consumption.

1 kW, at typical human metabolic efficiency (25%), is equivalent to 3,450 Calories/hr; a more plausible 500 Calories/hr works out to 145W. In addition, I might point out that 1 horsepower is only 745W. I hope that Mr Porter does not think that humans have higher power output than horses.

Horses ???:file_21:

I think battle dress could be big enough and powerful enough to be fitted for/with a power supply for FGMP etc. They might need to be specially constructed perhaps - again more like small craft.
As for power usage

Pah! My toaster is 1.5KW, My ford escort (yep 1973) makes nearly 35KW (50hp), and that would fit in the backpack on a piece of battledress.

 

[Anthony]

I think battle dress could be big enough and powerful enough to be fitted for/with a power supply for FGMP etc.

Oh, sure. 1+ kW/kg is perfectly doable with a fairly small power plant. However, nothing about normal movement requires all that much power, and there's a severe limit to how much you can augment BD movement before you start ripping the wearer apart, so a half-ton suit of BD is unlikely to use more than 1 kW on any sustained basis.

 

[Wol]

I think you may be right in terms of normal use. However, I suppose the thought here is that (forgive the pun) Battledress could provide a vehicle for fusion guns - even though battledress without fusion guns would not require anything like so much power. It would be fairly easy to carry it.

cheers

(sorry Horses in Battle dress):file_21:

 

[TheEngineer]

Sorry, but my engineering sense tells me, that this 1 KW for a 500 kg battle dress is perhaps really not enough.
Digging in my former experience with industry robots (at the moment the only thing I can think of, which is somehow related to a BD and generally a highly dynamic device with a bunch of electronics, servos and hydraulics) we had power requirements from 10 up to 80 KW (automobile manufacturing).
We should not forget, that the human body is an exceptionally energy efficient thing (just try to loose a bit body weight and you will notice).
And, you never really know what kind of devices and techniques are used in a BD, which actually consume power.

So I could think more of 50 KW (another cooling issue as of just a humble 1 kw like a hair dryer

regards,

TE

 

[atpollard]

Sorry, but my engineering sense tells me, ...

Watch out, his "Engineering Senses" are tingling.

Could that be a new Psi discipline for the working classes?

(PS. I agree with your points. A machine that allows a man to lift and move cars will need to consume more energy that just a normal man and mechanical systems are less efficient than biological systems.)

 

[robject]

So then, supposing the power requirement for TL14 battledress were 10 kW. Add on the 90 kj plasma gun, which can fire every other round, add 5% slop, and you need a 20 kW powerplant.

As Wol suggests, such a powerplant would be backpack-sized.

How long would a battery pack last?

How long should battle dress last? I'm thinking 2 days maximum. But, is it more like 2 days at an average drain of (guesstimate) 25% power? i.e. An actual duration of 12 hours at full power?

 

[Anthony]

Digging in my former experience with industry robots (at the moment the only thing I can think of, which is somehow related to a BD and generally a highly dynamic device with a bunch of electronics, servos and hydraulics) we had power requirements from 10 up to 80 KW (automobile manufacturing).

Industrial robots do an enormous quantity of work in comparison to a human, and often include extremely energy-intensive components such as cutting torches. I was only addressing the power consumption of the actual motive system.

Plenty of household appliances use far more power than a human can produce. If you don't believe me, get a pedal-powered generator and try to run one of them off of your own power.

 

[TheEngineer]

Hi !

The power consumption of the industry robots I refered to only were equipped with motion and moving systems (no torches).
Here is a link to the spec of one medium sized robot:
http://www.kuka.com/NR/rdonlyres/86E32754-1305-4D39-80F3-A8BBF4E57363/0/spez_kr100comp.pdf
This one uses at least 20 KW power.
Here the spec of a bigger one:
http://www.kuka.com/NR/rdonlyres/790AE8B4-F5EB-41E1-9B12-A88B18F8F612/0/spez_kr3602.pdf

Ok, for basic motion 50 KW appears a bit high, so perhaps robjects number of 10 KW is a good compromise for a TL13 device..

Oh, and regarding pedal powered stuff. In the gym I'm humbly able to produce perhaps 200W on this fake bicycle for about half an hour - but then I need a doctor

regards,

TE

 

[robject]

Here's some input, about 4 hours old, from Marc.

Energy Use...

A human uses about 100 watts.

in a day, that's

= 2.4 kwh = 8.64 Mj = 8195 BTU

= 26 cuft of H2 at stp +atmospheric oxygen
= .07 gal of gasoline +atmospheric oxygen
= 147 pound lead-acid battery
= 0.5 kg sugar carb protein metabolism =food +atmospheric oxygen
= 2 liters compressed H2 at 700 bar. = +atmospheric oxygen
= 1 liter liquid H2 in a special tank.+atmospheric oxygen
= 1 liter hydrocarbon (methanol) in a fuel cell. +atmospheric oxygen

http://www.infinitepower.org/calc_watts.htm
http://en.wikipedia.org/wiki/Energy_density

Let's extend that...

if human is the benchmark, then
an android is 2X and
a robot is 4X and
powered armor is 4X

finally, the relative minimum size for the handwavium Fusion Plus is 16 x 16 x 32 cm stripping off all unnecessary stuff.
I suppose that assumes it runs constantly, feeds power directly to the consuming processes, and has no "storage or buffering."

Appx 10 kW for robots and powered armor.

To me, this means that Fusion+ is still quite powerful and still can be quite small, although I hope that at low volumes it's less efficient.

 

[Anthony]

Appx 10 kW for robots and powered armor.

How do you get 100W x 4 = 10 kW? Incidentally, 100W for a day is 2065 Calories, and I was talking about power output, not power input. Power input for robotic systems will be (power output) / (motive system efficiency), and fuel intake will be (power output) / (motive system efficiency) / (power plant efficiency). For a human, the motive system and the power generation system are combined and between them have about a 25% efficiency. For a robot the power plant efficiency can be calculated from fuel consumption (and is fairly irrelevant for fusion+), and the motive system efficiency is likely to be more than 50%, so on average a robot doing human-level work might need less than 50W from its power plant.

 

[robject]

Ah, so that's 10 kwh, not 10 kw.

 

[atpollard]

Just a quick point. We keep dealing with the average power requirements for a man, a robot or a battledress, but the system actually needs to provide enough power for the PEAK demand. A sprinter running his fastest with a heavy backpack will require many more watts than I require to sit here typing.

Think about your car. It can cruise at 50 mph with the engine running at only 2000 rpm. But accelerating from a start requires closer to 6000 rpm out of that same engine. So the car engine must be sized for the power requirement of the acceleration rather than the average power used over 24 hours.

The same will be true with battledress. The power plant will need to be capable of very high output for brief periods of time and a lower sustained level of output. [Unless you design it with large, heavy, expensive “batteries” to store excess power and release it in bursts as needed.]

 

[Scott Martin]

Actually for powered armour, as long as the "sprint" times are fairly short (minutes) then a battery system makes a lot of sense: storage of a few kiojoules is pretty compact (even for extant battery systems) and the cost differential between battery storage and a nuclear plant designed to handle fullload all the time would push strongly towards the battery system.

Remember that cars are a special case, since they are using a mechanical driver and *cannot* use an auxilary power source. If you look at the concepts for hybrid electric vehicles instead you will note that they are moving towards the "engine" simply recharging the battery and the battery providing the peak load output for accelleration etc. This is disconnecting the drive system (electric engine) from the power source (internal combustion engine) and there is a company in the lower mainland (Vancouver BC Canada area) that is making a lot of money by building diesel electric delivery vans with the diesel plant optimized for fuel efficiency (it only runs at a single RPM) powering batteries which are used to actually mocve the vehicle. Aparrently this results in significant (I have heard numbers greater than 50% reduction) improvements in fuel efficiency.

Heck, I have *starships* designed this way, with jump drives kicked off by battery banks powered by a "trickle" fusion plant, but they certainly aren't likely to appear in the OTU any time soon (although with cargo at Cr 1,000/dT I'm pretty sure that I can make a J-4 version profitable on cargo alone at TL -13)

Scott Martin

 

[Anthony]

Just a quick point. We keep dealing with the average power requirements for a man, a robot or a battledress, but the system actually needs to provide enough power for the PEAK demand. A sprinter running his fastest with a heavy backpack will require many more watts than I require to sit here typing.

For burst power (up to a couple minutes) batteries are probably your best option. The power plant should handle anything beyond that. I'd want about 3W/kg (equivalent to ~750 Calories/hr for a 75 kg adult) sustained output.

 

[robject]

Hmmm, perhaps that backpack on the PGMPs is mostly batteries...

 

[atpollard]

For burst power (up to a couple minutes) batteries are probably your best option. The power plant should handle anything beyond that. I'd want about 3W/kg (equivalent to ~750 Calories/hr for a 75 kg adult) sustained output.

How long do you need to sustain "burst power" under combat conditions? That will determine the range of a BD combat charge against an enemy position. The CT assumption is that the battledress augmentation is of virtually unlimited endurance.

I agree with the points raised about batteries. I just wanted to point out the game implications of this discussion.

 

[Wol]

How long do you need to sustain "burst power" under combat conditions? That will determine the range of a BD combat charge against an enemy position. The CT assumption is that the battledress augmentation is of virtually unlimited endurance.

I agree with the points raised about batteries. I just wanted to point out the game implications of this discussion.

My thoughts too, I can see versions of battle dress more like Starship troopers on the bounce, and others more like an augmented vac suit.

 

[Anthony]

How long do you need to sustain "burst power" under combat conditions?

Probably only a few seconds. 3W/kg is a very high base power level (get on an exercise cycle which shows power output and try to generate that much; it's doable, but not for long). In any case, burst power doesn't need to last longer than human anaerobic effort limits.