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vampire2948
2008-07-28, 05:47 PM
hey all,


I'm gonna be playin' in a high-technology campaign, and i was looking into ways of producing power using magical means.

So, naturally, I set about working out how much energy I could make with castings of spells.

I started with fireball.

After some maths, catgirl funerals, and cake, I found that:

Fireball Energy Produced (by spell) < Fireball Energy Required (to produce the temperature required, and the other effects such as light and sound)


Any ideas on how to work out the energy produced by spells such as fireball?

I ended up with the result that for a Fireball spell to work, it would cause the same amount of damage as 2.9 tons of TNT. Which isn't shown in the spell's stats.


Thanks!


Vampire2948,

tyckspoon
2008-07-28, 06:06 PM
Well, let's see.. Fireball's spell entry says it can melt metals with a 'low' melting point, like lead, copper, silver.. and gold. Which has a melting point of approximately 1064 C/1337 K/1947 F. So Fireball releases enough energy to heat a 20-foot radius sphere to near 2 thousand degrees in an instant. It's been a while since I took anything physic-y so I don't remember the relevant math, but I'm sure somebody could use that information and the statistics of the standard reference bit of air to figure out exactly how much energy is being released. 'tho Fireball's not very good for actually harnessing as power.. I suppose you could try to create a gigantic internal combustion engine with them, but Fireball explicitly says it has little to no pressure.

For actual power generation, the standard item is a Decanter of Endless Water. Combine it with something enchanted with Heat Metal for an eternal boiler, or just use it to power a waterwheel for something lower-tech. There's tons of wind spells if you want to try for wind power- try a permanent Gust of Wind. Control Winds and Wind Wall would be even better, but those aren't on the default list of things you can use Permanencey on.

vampire2948
2008-07-28, 06:13 PM
In 'The Origin of PC's' it says that Fireball is 1850 degrees celsius, this fits with the melting points of the metals mentioned, so it is what i used for my calculations.


Water Wheels do not produce the kind of power I was looking for.

I shall have to look at other spells...fireball poses a problem in that it has no pressure.


Any suggestions as to a spell?


Vampire2948,

vampire2948
2008-07-28, 06:15 PM
1,000 kg of TNT = 4.184 GJ

0.454 kg of TNT = 3d6 damage

therefore:

0.454 kg of TNT = 1899536 joules


3d6 Blast Damage = 1,899,536 Joules of energy.

If the above value for 3d6 blast damage is taken as the maximum damage, (i.e. a result of three sixes on the damage roll for the explosion of 1 lb of TNT) Then a fireball cast by a tenth-level arcane caster would have a maximum yield of (1,899,536/3)*10=6331787, with a result of 10 sixes.

So 60 points of damage = 6,331,787 joules

1 Point of damage = 105,530 joules



One khw = 0.00000027778 joules

So, for example, a 40 kwh bulb would produce light (and a % of heat dependent upon it's efficiency) for 379,904,960,760 hours per point of damage, if all the energy were turned into electricity and used to power said lightbulb.


It seems that the people who created D&D did not intend for their damage rolls to be converted into joules, as it is not feasible that weapons such as a greataxe should produce as much energy per point of damage.

However, the above calculations work for blast-type effects, such as a fireball.

One joule is the amount required to heat regular air one degree.

In 'The Origin of PC's', Roy tells us that a fireball has an approximate temperature of 1,850 degrees Celsius (the temperature at which the skin of undead vaporises, apparently). This is further supported by the statement that fireballs can melt metals such as lead, copper and bronze, all of which have melting points lower than 1,850 degrees celsius.

This would require 1,850 joules to heat one gram of air to this temperature from 0 degrees celsius. Not counting for the cooling due to radiation and conduction to the area surrounding the fireball.

At IUPAC standard temperature and pressure (0 °C and 100 kPa), dry air has a density of 1.2754 kg/m3.

A fireball spell covers a spherical area, 20 ft in radius.

20 ft = 6.09 m

Pi*r2 = Circle Area
Pi*6.09^2 = 117m^3 (rounded up)

117*1.2754=149.2218 kg of air.

149.2218 KG = 149,221.8 g of air.

1,850*149,221.8=276,060,330 joules

6,331,787 < 276,060,330

Therefore...fireballs cannot exist when cast by a level 10 caster, or even a level 20 caster.

12,663,574 < 276,060,330

At Room Temperature, air density is 1.2041 kg/m^3

This still results in the Calculated Produced Energy < Calculated Required Energy for the fireball.


So...unless fireballs produce more energy than TNT does per point of damage, they can't happen.

To exist they would need to produce 4,601,005.5 approx. joules of energy per point of damage, and that is without the energy released as light and sound. As they are obviously visible (they emit light) and the spell description mentions a 'low roar'.


This means that to exist, they would need to produce roughly 44 times the amount of energy/point of damage that TNT does.
Which clearly isn't reflected in the game mechanics, as a fireball (10th level caster, 10d6 damage) would do the damage of 2903 kg of TNT.

The effects of 2.9 tons of TNT are quite different from a 117m^3 fireball, and would cause a lot more damage to whatever it is directed at.


So...yeah...DIE CATGIRLS! DIE!




There is the maths I used.

Collin152
2008-07-28, 06:16 PM
Reverse Gravity?
I mean, you monkey with a fundamental aspect of physics, it's bound to generate some energy.

Emperor Tippy
2008-07-28, 07:22 PM
Make a Steam Engine.

Make an Adamantium box with foot thick walls and an internal volume of 20 cubic feet. Have 1 Decanter of Endless Water per square foot inserted into the floor and horizontally have 10 walls of fire (stacked one on top of the other). Have a small opening in the top of the box for the steam to get out of.

How much damage in needed to turn 300 gallons of water per round into steam is debatable but 20d6+200+20d4 should be enough.

How much power a steam engine generates is really a function of how much pressure the steam is under, which depends on how much pressure the walls can contain.

---
And you can always use the old Kinetic Energy Weapon trick as a power generator.

Or you can create a fusion reactor.

Or do matter/antimatter reactions.

aaron_the_cow
2008-07-28, 07:33 PM
why not just lightning bolt a rod of some sort like in the latest comic?

JeminiZero
2008-07-28, 07:53 PM
I'm gonna be playin' in a high-technology campaign, and i was looking into ways of producing power using magical means.


Use minor creation to create plant oils for burning/fueling an engine.

Reserve Feats may help. I once suggested sticking metal rods into water and passing storm bolt through them to generate hydrogen + oxygen.

Permanancied spells might also help. Permanancied Gust of Wind to drive wind mills. An alternative to the multiple walls of fire in Emperor Tippy's steam box is permanancied heat metal. And if your fortress/airship/mecha needs air-conditioning, use permanancied chill metal.

Or you could just link a decanter of endless water to a turbine.

Chronos
2008-07-28, 07:55 PM
Reverse Gravity?
I mean, you monkey with a fundamental aspect of physics, it's bound to generate some energy.Oh, that's easy. Cast Reverse Gravity. Make it permanent, if you want. Mount a flywheel on the edge of the field. One half of the flywheel is pulled down, the other half is pulled up, and so it spins. There's no limit to the amount of energy you can get out this way.

TheDarkOne
2008-07-28, 07:58 PM
The decanter of endless water certainly makes things easier, but it's not really necessary, as it's really just acting as a source of water(you aren't getting your energy out of it). You could just use the use the wall of fire as the heat source for a closed cycle heat engine.

Where decanters of endless water could be useful is in hyrdo-electric generators.

nargbop
2008-07-28, 08:16 PM
High technology? I played an engineer-turned-adventurer in a recent game, and my DM and I bantered about substantiating the world for a while before playing the game proper. BTW, everyone should try that - all players meet individually with DM for several hours over the weeks before the game, creating the world together. What's the government? How prevalent the magic? etc. etc.
We envisioned a Leonardo Da Vinci level of technology, wherein his designs were sucessfully implemented by magically-assisted standardized parts. I put Decanters of Endless water high above waterwheels for motive power in dry areas, and put a giant adamant ring with multiple permanent reverse gravity spells on it near the capital city. Wizz a couple heavy weights around tied to the axle inside the ring, and massive motive power was provided for the inhabitants. We decided NOT to go electrical in this world.

UglyPanda
2008-07-28, 08:21 PM
Animate Objects + Permanency + Dynamo = Perpetual Energy Machine = Profit

That is the least complicated way of producing energy through magic that I can think of. It's possible at level 11, so a more complicated solution might be better.

holywhippet
2008-07-28, 08:23 PM
In 'The Origin of PC's' it says that Fireball is 1850 degrees celsius, this fits with the melting points of the metals mentioned, so it is what i used for my calculations.



I thought Roy stated that he needed fire spells cast which were at least that temperature since thats the temperature at which necrotised flesh will burn (not sure if the 1850 value is correct, haven't read the book in a while). As such, a fireball has to be at least that temperature if thats what he was talking about. However, that means a fireball can be in excess of that value - which makes sense since the caster level affects the damage level of the spell so presumably a higher level mage casts hotter fireballs.

1850 would seem to be excessive though. Boiling water is only 100 degrees C at sea level.

Collin152
2008-07-28, 08:25 PM
I'm quite certain that's 1850 Farenheit, dear.

Randel
2008-07-28, 08:40 PM
Raise Shocker Lizards or something else and harvest electricity from them.

Steam power generated from permanently heated magic items or a permanent wall of fire sounds like the easiest bet, its basically like having a coal power plant but not putting in fuel.

Not sure just how well you can harvest electricity from lightning, I don't doubt its possible but having the equipment that can handle that kind of load might be a problem.

The permanent reverse gravity thing sounds pretty good. You could have a hydroelectric dam and then set up an upside-down waterfall on one side that makes the water flow back into the reservoir.

Use plant growth to grow crops for food or biofuel.

Irreverent Fool
2008-07-28, 11:46 PM
WON'T SOMEBODY PLEASE THINK OF THE CATGIRLS!

Fire Trap mentions in its description that if it is triggered underwater it creates a large cloud of steam. I'm sure you could do something with that.

kamikasei
2008-07-29, 12:33 AM
I'm quite certain that's 1850 Farenheit, dear.

It was 1850 K, which is about 1577 C.

Hal
2008-07-29, 12:41 AM
There's a cantrip that does 1d6 electrical damage. Just get yourself an item that does it at will or permanently.

Probably expensive, but there's your electrical current.

BizzaroStormy
2008-07-29, 12:49 AM
See there is one explanation for it...it just magic. I know its a cop-out but sometimes magic is just magic.

It also brings up the question of how something could survive a fireball. Such intense heat would be akin to a nuclear blast and would reduce those caught in its radius to vapor regardless of whether or not they make their reflex save unles that save magically teleports them outside the range.

But enough of that, back to my main point. Magic is just magic. It is specifically described as telling the laws of time and space to sit down and shut up. High enough level means you could create half-fish, half-beaver, half-other fish monsters that reproduce by shooting microwaves from their anuses at pine trees.

Cast lightning bolt on a battery, use Gust of Wind on a windmill, make Uranium with Major Creation, hell, summon a celestial hamster and have it run on a wheel.

*twitch twitch*

vampire2948
2008-07-29, 06:01 AM
Thanks for all the great ideas!
I'll use them...especially the reverse gravity one.


However : The idea of this was not to work out ways of producing energy, it was to work out the amount of energy produced, in joules.


I can probably do something with the gravity-dynamo thing though :) thanks!


- Vampire2948 -


p.s. long time no see, Randel.

Zeta Kai
2008-07-29, 07:16 AM
Magic is just magic. It is specifically described as telling the laws of time and space to sit down and shut up. High enough level means you could create half-fish, half-beaver, half-other fish monsters that reproduce by shooting microwaves from their anuses at pine trees

That's the best description of magic that I've ever heard.

Pronounceable
2008-07-29, 07:34 AM
half-fish, half-beaver, half-other fish monsters that reproduce by shooting microwaves from their anuses at pine trees.

I like that monster.

PanNarrans
2008-07-29, 10:34 AM
I'm impressed, but it doesn't really hold together.
Firstly, the 'damage dealt : heat energy released' conversion is flawed, as TNT also deals force damage, and there's a lot of other variables.

As to the actual numbers, in Origin, Roy states that he requires 'a thermal signature no less than 1850 degrees Kelvin... because it is the minimum level at which necrotized epidermis has been proven to combust'. Firstly, it's Kelvin, not Celsius, so you're 273.15 degrees out to start with. Secondly, that's a minimum value. Although I suppose that actually gives a boost to your argument that it generates more power than you expected.
Also, I don't really follow these workings:

''Pi*r2 = Circle Area
Pi*6.09^2 = 117m^3 (rounded up)''

It looks to me like you've used a circle: a fireball is spherical. But I could just be misinterpreting your notation.

Anyway, I really wouldn't start trying to quantify these things. The fact that a Rogue can dodge the damage while being in the area suggests that there are areas of higher and lower temperature within it, and the fact that it deals the same damage to all creatures in the area, regardless of how many of them there are, rather than distributing a set total of dice over them, suggests that the rules weren't designed to reflect a set amount of energy being released.

On to the discussion of energy generation, anyone read the new Discworld? Making Money? Think golems. Except that D&D also has elementals, summoned creatures, undead... any number of critters you can get to do work for free. So I'd go with PirateJesus' Celestial Hamster suggestion.

Another_Poet
2008-07-29, 11:26 AM
In order to keep the energy-producing properties of maic consistent with existing spells, I'd start by looking at the Light spell.

Light is a 0th level spell that generates a small light for 10 min/level.

Therefore, I'd propose this new spell:

Battery
Level: Brd 0, Clr 0, Drd 0, Sor/Wiz 0
Components: V, M/DF
Casting Time: 1 standard action
Range: Touch
Target: Electric appliance or circuit touched
Duration: 10 min./level (D)
Saving Throw: None
Spell Resistance: No

This spell causes the target object to receive enough electricity to power a single 60w incandescent light bulb or similar small, low-voltage electric appliance. Any circuit can be charged this way and continues to receive electricity for the duration of the spell. The effect is immobile and does not account for resistance if conducted over very long power lines. It can, however, be cast on a movable object like a boom box.

Arcane Material Component
A small scrap of copper or a wedge of lime.

From there you could scale it up:

Greater Battery
Level: Brd 1, Clr 1, Drd 1, Sor/Wiz 1
Components: V, M/DF
Casting Time: 1 standard action
Range: Touch
Target: Electric appliance or circuit touched
Duration: 10 min./level (D)
Saving Throw: None
Spell Resistance: No

This spell works just like Battery, except that the target object receives enough electricity to power a single industrial electrical device or a series of up to four low-voltage electric appliances.


etc.

You could keep scaling this up to a 2nd level spell that basically powers 1 small building, or a 5th-tth level spell that gives the caster total conrol over all circuits in a large radius.

ap

Dannoth
2008-07-29, 11:28 AM
Sure, go play warhammer 40k's version of D&D.

PanNarrans
2008-07-29, 07:26 PM
Is there any way to make a portable portal? Without any sly circumlocutions involving different frames of references. As per RAW.
If so, just use portals to the Elemental Plane of Fire. It's an infinite plane of infinite energy.
If not, it still works on large scales. Plus, think of the adventure seeds! Dealings with djinni, stamping out rogue fire elementals that slip through, and so on.

AstralFire
2008-07-29, 07:31 PM
Control Flames is probably the best method I can think of for easily figuring out energy generation:

http://www.d20srd.org/srd/psionic/powers/controlFlames.htm

Or you could google how much energy is in a tornado and use Control Wind.

http://www.d20srd.org/srd/spells/controlWinds.htm

Randel
2008-07-29, 08:07 PM
p.s. long time no see, Randel.

Yeah, its been a while. Nice to see you again.

Serania
2008-09-10, 10:00 PM
Maybe this counts as sorta necroticy.

But this got me thinking, and I wondered, what if you set say, a Gate or a Portal or something, Ring Gates wouldn't work as they have a weight limit, into the ocean floor way way down low, like oceanic trench deep. Wherever you put the other end there's now a massive geyser of water, caused by the ridiculous pressure when you get that deep. Ideally you'd use the water and either have it like, drain out to some other portal set into the floor below the one the water flows from, or maybe just set this contraption on the ocean as a whole. If you could get a portable portal, then you've just beaten the decanter of endless water.

This also opens up all sorts of ideas for manipulating ocean currents. Could I make a whirlpool with this I wonder? If I set one portal a hundred feet below sea level, suspended in place, and then set another one a thousand below that facing up, would I eventually create like an up to down flow? It's interesting. Anyway...

Ent
2008-09-10, 10:10 PM
I'd work on Constructs or Undead. That seems like a pretty inexhaustable source of energy.

Gribsdawg
2008-09-10, 10:36 PM
You could take the very simplistic approach and say

A bolt of lightning has 300 GJ (reference wikipedia, positive lightning).

Since the magic that go into creating a lightning bolt and a fireball are equal,

the energy output of the fireball also = 300GJ. Now 300GJ would be a little much for your garden variety Lightning Bolt, but the reasoning is plausible.

Dervag
2008-09-10, 11:11 PM
Real life lightning bolts are miles long. Therefore, they have to punch the current across a bigger air gap, which costs more energy.

D&D lightning bolts are shorter, and would be less energetic by a few orders of magnitude.

Gribsdawg
2008-09-10, 11:18 PM
Now 300GJ would be a little much for your garden variety Lightning Bolt, but the reasoning is plausible.

I agree, and i made the same point myself, just without spelling it all out...

Pronounceable
2008-09-10, 11:48 PM
Put a portal at the bottom of a lake (or sea). Put the exit portal few meters above the lake's surface. Set up the turbines and we're good to go.

Permanentify continual light. Set up solar panels around it.

Use golems.

Frosty
2008-09-10, 11:51 PM
Given the number of Decanters of Endless Water, why hasn't the Material Planbe been flooded yet?

DigoDragon
2008-09-11, 08:22 AM
There is the maths I used.

Egads. :smalleek:
Well... if the math holds it would explain why spellcasters haven't brought about an industrial age yet. :smallsmile: If one thinks about it, all this magic should have been able to produce dynamos and engines without too much worry on fuel needs. Yet, most campaign settings I've played in would have magic around for centuries and little progress in the general tech level of the world. Something has to be stagnating the advancement of machinery. I think Ebberon is one of the farthest though, having a magically powered train system of a sort.



WON'T SOMEBODY PLEASE THINK OF THE CATGIRLS!

Uh, let's see math kills catgirls right? So... would philosophy heal them?
Let's then take out the math and expand on my above thoughts. Perhaps magic and technology don't get along. For some crazy reason that only the gods know (And they won't talk about) trying to build a motor using magic to power it fails to produce any work. Maybe magical energy and technological energy are opposing forces and having one active in a given area would exclude the other from working. They simply don't follow the same rules.

It's like having a field of baseball players go up against a soccer team. They both score points in the end, but how they score 'em are totally different. :smallsmile:

It can make for an interesting campaign premise and I've been working on just that for a few weeks now. :smallwink:

bosssmiley
2008-09-11, 09:11 AM
Given the number of Decanters of Endless Water, why hasn't the Material Plane been flooded yet?

Easy. Using a decanter of endless water creates not one, but two, planar micro-breaches. One allows water to flow from the decanter per the item description, the other (generally found in some deep ocean trench or other such off-screen area) allows water to flow back to the Elemental Plane of Water. And thus is the Balance maintained. :smallwink:

We now return you to your regularly scheduled catgirl butchery.

Tokiko Mima
2008-09-11, 09:34 AM
I think Ebberon is one of the farthest though, having a magically powered train system of a sort.

And earth elemental powered overland carts, floating cities, water elemental powered sailing vessels and let's not forget the setting does have air/fire elemental airships. They go to a lot of trouble to make these difficult to manufacture and/or use when all they need to do is cast a permanent animate object or phantom steed.

GolemsVoice
2008-09-11, 05:48 PM
Hmm, can you just animate a turbine or a dynamo to make it turn itself? That would be easy energy, since the device doesn't need to stop. Ever.


Oh, let's see math kills catgirls right? So... would philosophy heal them?
Let's then take out the math and expand on my above thoughts. Perhaps magic and technology don't get along. For some crazy reason that only the gods know (And they won't talk about) trying to build a motor using magic to power it fails to produce any work. Maybe magical energy and technological energy are opposing forces and having one active in a given area would exclude the other from working. They simply don't follow the same rules.

It's like having a field of baseball players go up against a soccer team. They both score points in the end, but how they score 'em are totally different.

It can make for an interesting campaign premise and I've been working on just that for a few weeks now.
The computer game Arcanum: Of Steamwork and Magick Obscura did that. At the beginning of the handbook, three experiments are described (the technology level is about 1850, maybe). One is an electric current with a battery and a lightbulb. When a magic amulet is brought near the current, the light begins to flicker and goes out in the end.
Second experiment is a surface where things slide down (damn, you, lacking English vocabulary, but at 00:57 I'm too lazy to look it up). An object is placed on it so that it just does not slide down. Again, a minor magical item is brought, and the object begns to slide, unsteadily, downwards.
Lastly, a pendulum swings, and when our trusty amulet appears, the pendulum just stops in midair, and then swings again, stops again, so on..

So, magic has a desastrous effect on the natural laws of physics, thus incapacitating or even destroying technological devices, while technology disturbs the magical field, making spells fail and giving wizards headaches.

Tokiko Mima
2008-09-11, 06:30 PM
Hmm, can you just animate a turbine or a dynamo to make it turn itself? That would be easy energy, since the device doesn't need to stop. Ever.

Animate the turbine/dynamo, apply permanacy and command it to attack the air. :smallwink:

AstralFire
2008-09-11, 06:48 PM
Animate the turbine/dynamo, apply permanacy and command it to attack the air. :smallwink:

Have I ever said I like the way you think, Ms. Mima?

'cuz 89.476% of the time, I -really, really- do!

DigoDragon
2008-09-12, 07:43 AM
And earth elemental powered overland carts, floating cities, water elemental powered sailing vessels and let's not forget the setting does have air/fire elemental airships. They go to a lot of trouble to make these difficult to manufacture and/or use when all they need to do is cast a permanent animate object or phantom steed.

Yes and those things as well. Thanks! :smallsmile: But I concur on the puzzlement on why these things seem so difficult to come by. If I recall there aren't any rules in Ebberon to build/own your own airship. You'd think that there would be at least one nutty wizard who could figure out mass production of magic items to sell to the public.



The computer game Arcanum: Of Steamwork and Magick Obscura did that. At the beginning of the handbook, three experiments are described (the technology level is about 1850, maybe). One is an electric current with a battery and a lightbulb. When a magic amulet is brought near the current, the light begins to flicker and goes out in the end...

Yes, that does seem to follow my idea quite nicely!! I should look into that game. Thanks for the tip! :smallsmile:

Tokiko Mima
2008-09-12, 10:55 AM
Have I ever said I like the way you think, Ms. Mima?

'cuz 89.476% of the time, I -really, really- do!

Thanks! I like you, too! :smallsmile:

You know how police investigators always tell you that the simplest explanation for a given situation is almost always the truth? I try to think of myself as a sort of hilarity investigator, where the funniest possible answer should be the truth. And is, in my crazy imagination that is now imagining that Thomas the Tank Engine as an animated construct with a mission to destroy the planet's atmosphere one cubic liter at a time.

Is the other 10.524% encompassing the thing I did with the noodles (http://tvtropes.org/pmwiki/pmwiki.php/Main/NoodleIncident)? :smallwink: