A Player's Guide to Redpower 2 Blutricity

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Omicron

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Nope. One solar panel produces 200 W during the day, and that only if it is at 100 V. With the blulectric engine grabbing all the power it can get, the voltage will drop to around 60 V and the output of the solar panel will fall to 120 W.

The engine converts 1000 W into 1 MJ/t; if only 120 W is available, it will produce 0.12 MJ/t, which is about two and a half redstone engines worth.
 

Nommy9

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I realize this is a little old now, but a search didn't show any more relevant threads so...

14.) There is no such thing as distance based energy loss in blutricity. However, there is distance based power loss, due to electrical resistance...
I'm not sure I understand this correctly. I was measuring with the voltmeter and got results like this: windmill (5000 watts) -> wire -> Engine (4000 watts). So, that means more energy is going in than coming out, since watts represent energy/tick, right? Which must mean energy is lost in the cable, yeah? Or does a wattage drop mean something else? Maybe someone can clear this up for me because I'm a little confused right now.

Also, any tips on how to set up windmills or solar farms? Like, is there any point putting in extra cables just to keep the voltage at the generators high, or is this just wasted effort since the voltage will be lower at the other end anyway?

Cheers
 

Omicron

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Guides don't get old unless the mod updates so much that they become irrelevant. And even then, the guides can be updated ;)

You confusion stems from how close the terms power and energy are in the minds of many people, who use them completely interchangably in everyday life. Watt is the unit of power. It is true that it represents energy over time, but losing power does not mean you lose energy. The energy never goes away or somehow disappears; you simply transfer more or less energy in the same time.

Often, analogies to flowing water are made to help explain the flow of electrical current, and resistance in particular. Try thinking of it like that. Think of the voltage differential needed to allow power to flow as a physical difference in height. Instead of going from 100 V down to 90 V, think of going from a water container 1 meter high above the ground, down to the ground. Imagine the water flowing down a ramp. You could have a very short ramp at a very steep angle, causing the water to rush down at great speed; or you could have a very long ramp with a very gentle slope, causing the water to flow calmly and take much longer to reach the ground. However, no matter how short and steep or long and gradual your ramp is, the water will always arrive at the end. All of it will. None gets mysteriously lost along the way.

It is the same with electrical power. You can have a large voltage differential, compared to the distance traveled, that supports a very high amount of power to rush through, carrying energy very quickly; or you could have a very small voltage differential, compared to the distance traveled, that supports only a small amount of power, meaning that energy will only slowly trickle down the line. But no energy will mysteriously disappear. If you wait long enough, all the energy will eventually make its way over. (In real life, there is energy loss during transfer through a phenomenon called joule heating; it makes conducting wires grow hot, and is the reason the light bulb exists and our computers need cooling fans. However, this effect is not modeled in blutricity.)

Now you might as yourself, why should you even care about power loss if you preserve all your energy? Or you might say, that's all fine and dandy that you don't lose any energy when you transfer a fixed amount of energy from A to B, but what about generators? After all, they produce energy all the time, at a certain rate. And indeed, therein lies the crux of it. Your solar panel farm wants to push a certain amount of energy into the network in any given time slice; in other words, it has a certain power output. If your connection is so long/has so much resistance that the voltage differential you can offer over the length of it will not support that amount of power, then you are choking the generator. If your connection allows for 2000 W to pass through at most, then you can hook up as many solar panels, windmills and thermopiles as you want, but only 2000 W at most will pass through the cable. The rest of the potential output will indeed be lost (or rather, it is never being generated in the first place - you can see a windmill on a choke spin down and idle for a while every so often).

Think of a clogged kitchen sink that drains only slowly; the only thing that you achieve from pouring more water into the sink is risking overflow. It won't make the water drain faster. The only thing you can do is make the ramp more steep... make the distance shorter with the same voltage differential, or increase the voltage differential over the same distance. Or, as a third option, you could "unclog the sink" - use a cable with less electrical resistance, if available. Using 10 kV wires, in this case, is option 2, increasing the voltage differential. They do have significantly more resistance too, but due to the way these cables work, the higher voltage differentials possible far outweigh the added resistance.

I hope that, by now, the answer to your final question is apparent. Try answering it yourself before you check inside the spoiler - is there any sense in raising the voltage of your generators by making the cable longer?
No, there is no point. The voltage increase in the generators is only caused, in the first place, by the fact that the larger distance needs a correspondingly larger voltage differential to sustain the same amount of power. At a lower voltage, not all the energy is able to travel along the cable, therefore it stays in the generator. And since charge status equals voltage, more charge in the generator means its voltage goes up, until it finds a new equilibrium voltage at which it can push just as much power into the cable as it generates.

Keeping your voltage up for more power generation is a good idea, but it cannot be done with distance; it needs to be done with buffer storage. A consumer will dip down to 60 V if it draws more power than a generator can offer, thereby forcing the voltage of the generator down as well and causing it to generate less power. A battery box between the consumer and the generator will be able to, for a limited time, expend its internal storage to keep the voltage at 80 V instead. It makes up for the missing power the generator cannot provide and therefore keeps the voltage from dropping, allowing the generator to work 33% more efficiently.
 

Nommy9

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Thanks for explaining, the buffer storage trick make sense, I'll try that.

I did that test again - here I was alternating between reading the wire next to the windmill then the wire next to the engine:

@Windmill ~5500W, @Engine ~4500W
The wire loops just out of view and is 13 blocks long. It's a storm in a mystcraft world and has been like this for the last few minutes so it's not the wires filling up I don't suppose.
If the transfer was lossless like the water example it would be 5500W at both points in the wire rather than a difference of 1000W wouldn't it?

I think maybe it's more like the wire is lossy, however the windmill sends extra energy at no cost to make up the amount lost in the wire, so the whole system ends up being lossless, like you said it was. This fits, because short or long wire I was getting the same amount arrive at the engine, it was just the amount generated which would change.

Kind of more like a blocked magical sink perhaps, where the more blocked it becomes the taller (and thinner) it grows to always drain at the same rate. And if you keep blocking the sink more and more (lengthening the wire) it'll eventually grow so tall that it hits the ceiling, and only then will the drainage slow down... or something. Yeah?

I think what confused me was how the wires could be lossy in a lossless system. This is how it is isn't it? I'm still not sure 100% TBH.

Edit: Put image in spoilers.
 

Omicron

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No, you're still confusing the terms. ;)

The windmill is not "sending extra energy". Watt is power, not energy, and the distinction makes all the difference. The windmill is sending the energy with "extra force", i.e. with higher voltage, and it is that force which is lost along the way. If the water analogy wasn't entirely helpful, try speed and distance. If you had a toy car, and you wanted it to roll a certain distance, it would need a certain initial speed, and thus you would have to push it with a certain force. If you wanted it to cover more distance (a longer cable), it would require more initial speed to do so (more wattage), and to give it that speed you would need to push it harder (higher voltage). The end result is still the same, though - it eventually arrives at its destination, just like the energy arrives.

Your magical sink analogy is a little strained, but it's going in the right direction. If there is more electrical resistance (due to a longer cable), then you need to push harder to force the same amount of energy through over time. That's why it is called resistance, because it resists the energy flow.

In your screenshot, note how the voltage is very different between the two measuring points, but the amperage is the same. What you are seeing here is the voltage differential between one end of the cable and the other; in your case, about 14.5 V. That is the differential you need to carry ~64 amperes through a cable of this length. The amperage is likely rising because your windmill is spinning up, generating more and more energy as it does. If your windmill was at constant speed, amperage would be constant at both ends of the cable (barring minor fluctuations as the blulectric engine gobbles up energy). Try measuring with solar panels, as they have a constant output.

Amperage is not energy either, mind you. It is the strength of electric current. It measures the amount of charge that passes through a conductor in any given time slice. If amperage is the charge traveling, and voltage is the force that pushes the charge to travel, then V * A = W, and the wattage is therefore the speed at which charge travels. This is what we call power. After the voltage has finished pushing the amperes along and they arrive after a certain amount of time has elapsed, the result is: power * time = energy/time * time = energy. And thus, with the "help" of both voltage and time, amperes are "turned into" joules, charge becoming energy.

Since the amperage is constant on both ends of your cable, you end up with the same amount of energy in the end. You just need more voltage to do it in the same amount of time. You could also do it at the same voltage with more time, but since the windmill is a constant producer you can't really transfer more slowly, because the created energy has to go somewhere. So the only choice is to push harder. You can say that the windmill is "building up pressure" in order to send all its energy output.
 

Nommy9

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Thanks again, I'm still waiting for an answer to this though:
If the transfer was lossless like the water example it would be 5500W at both points in the wire rather than a difference of 1000W wouldn't it?
(well I'm not really waiting actually, coz I know already I think, but you forgot or avoided it) ;)

I understand the distinction between energy and and power, how energy = J, watts = J/s or energy flow rate rather, and how energy = V*A. Thanks for explaining that too though. Your first post is what I use as a reference when I'm not sure exactly what something is actually, thanks for putting that together, it's a big help. Also, I realise sometimes I say energy when I should say power. I think it's because time is not a factor in what I'm talking about, in which case they are not so different, rather than a case of me not understanding the difference.

You might have misunderstood what I meant by 'sending extra energy' because surly if the amount of power a device is generating increases it is doing exactly this. e.g A windmill is generating 1000W of power(it's sending out 1000 joules of energy every second). If it's power output increases 500W (to 1500 J/s), it's sending 500 joules extra energy out each second compared to before. That is how I think of it anyway.

14.) There is no such thing as distance based energy loss in blutricity. However, there is distance based power loss, due to electrical resistance.
This is what I'm not sure about. Specifically that there is no distance based energy loss. I did a test to show what I meant by windmills and solar panels sending or generating extra energy to make up what is lost in the wire which also showed that there is distance based energy loss also, I think. I'm not sure if you will agree though.

For the test I set up 25 solar panels to power an engine which presumably used more power than they could produce constantly, and tested this using a both a 13 and a 3 block wire between them, measuring the wire next to the solar panels and the engine itself, waiting in both cases for the voltage to stop fluctuating (virtually) first. Here's what occurred:

The power reaching the engine was a constant 5982W (or J/s which is how I think of it) regardless wire length:
The extra wires junk in the background is not connected - the only change in the test setup was the wire length.
When the wire was 3 blocks long the solar panels output 6400 J/s.
When the wire was 13 blocks long the solar panels output 7799 J/s.
A few points:

- In this scenario there is both distance based power and energy loss.
The long wire is losing 1817W (6400 - 5982) power meaning that every second 1817 joules of energy go in and doesn't come out again, ever. Also 418 joules is vanishing within the short one each second. So Energy as well as power is being lost within the wires, and exactly how much energy is lost depends on how long the wire is.

- The solars adjust their power output (sending extra energy when required) to balance distance based losses.
We can see that each second is 5982 joules of energy arrives at the engine regardless of wire length. We also know energy is vanishing within each of the wires, more in the long one than in the short one. For the amount arriving to remain constant the solars must be sending more energy into the longer wire than the short one, in order to balance the increased loss. This is what I noticed with the windmills also.

- Due to the solars 'throttling' counteracting the power and energy lost to 'resistance', it appears that there is no loss of either when looking at the system as a whole.
By this I mean if you just looked at the engine you'd see that you got a constant 5982W (J/s) from the solars regardless of how long or short you made the wire, until you made it so long it reached some limit somewhere. But there is both power and energy loss occurring. Fortunately the device generating the power and sending the energy seems to adjust to ensure the same amount of both reaches the destination, so if you did't look closely you might not notice any ever went missing. I'm not sure if this is relevant.

I'm interested if you agree or disagree with those. Or if you just think I'm talking rubbish too :)

BTW, do you recall what led you to conclude that there was no distance based energy loss?
Edit: Put images in spoilers.
 

Omicron

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Thanks again, I'm still waiting for an answer to this though:
"If the transfer was lossless like the water example it would be 5500W at both points in the wire rather than a difference of 1000W wouldn't it?"
(well I'm not really waiting actually, coz I know already I think, but you forgot or avoided it) ;)

I didn't avoid it, I merely didn't directly address it because the point I was trying to make was better suited for a different part of the text. It's of little use to write the answer in two or three lines without explanation, when elsewhere in my post I am spending half a page of text on explaining it. The answer I am giving below applies just as much to the question above as it does to your questions below.

This is what I'm not sure about. Specifically that there is no distance based energy loss. I did a test to show what I meant by windmills and solar panels sending or generating extra energy to make up what is lost in the wire which also showed that there is distance based energy loss also, I think. I'm not sure if you will agree though.

(*snip*)

- Due to the solars 'throttling' counteracting the power and energy lost to 'resistance', it appears that there is no loss of either when looking at the system as a whole.
By this I mean if you just looked at the engine you'd see that you got a constant 5982W (J/s) from the solars regardless of how long or short you made the wire, until you made it so long it reached some limit somewhere. But there is both power and energy loss occurring. Fortunately the device generating the power and sending the energy seems to adjust to ensure the same amount of both reaches the destination, so if you did't look closely you might not notice any ever went missing. I'm not sure if this is relevant.

It's really really hard to put into words what I'm trying to say. Should I fail this time, I recommend you pick up a physics textbook (or at least hit wikipedia, though that's a lot less comprehensive) and see if the material presented there reinforces or counters your thesis. I certainly don't claim full authority over a subject I last dealt with while sleeping through highschool ;)

But let's go over a few points regarding your observations.

The first thing you really need to do is avoid thinking that the solar panels are somehow auto-adjusting their power output to fit certain situations.
It is the energy network as a whole that auto-adjusts, based on the laws of physics. The solar panels are extremely simple things, and they certainly don't have any controlling logic programmed into them. All they do is output 2 A. Constantly. As long as the sun is shining and the panel is active, this never changes. You may see different numbers sometimes when the circuit is swinging towards equilibrium, but once it is stable, 2 A it is. And the solar panel does absolutely nothing else.

The reason you see an increase in power is simply the fact that as you introduce additional resistance in the form of a longer cable, that current of 2 A is no longer supported. Keep in mind that ampere is a time-dependant unit much like power; current is charge traveling per time unit (ticks in this case). The long cable resists the attempts of the charge to pass through it, therefore it goes more slowly, and maybe only a current of 1.95 A can flow during that one tick. Then comes the next tick, and the solar panel is still stubbornly mandating a current of 2 A, because that is what it does. It is the only thing it ever does. But there is still too much resistance for that current...

And thus, every tick, a little bit of charge that was not able to travel remains behind, in the solar panel. And what does more charge inside an object mean? It means higher voltage, as I have written in the guide under 8.). So the voltage goes up automatically because not all charge can travel through the cable. And it will keep going up until there is so much extra voltage that all of the charge the solar panel attempts to send can overcome the cable's resistance in time, at which point no extra charge stays behind and thus the voltage is raised no further. And since amperage remained constant and voltage went up, then the product of amperage and voltage also went up, and thus you have more watts.

There is no active control logic here; it's all a completely passive result of the math. And it's not confined to the solar panel at all. In fact, since Minecraft works in discrete sections of cable, this process of the 2 A trying to get enoug voltage differential to travel on in time is happening at every single block border. First from the panel to the first cable section; then from the first to the second cable section, then from the second to the third and so on. Each time, there must be enough voltage differential to overcome the resistance of a single piece of cable, and that voltage differential will auto-create itself simply by virtue of little bits of charge failing to travel and staying behind.

The second thing, the experimental proof that there is no distance based energy loss, and also the answer to your thesis that it "only looks like" there is no loss because of only looking at the system as a whole:
Place down a fully charged battery box, and attach a solar panel to it. Then take an empty battery and let it charge inside the battery box. The solar panel will immediately begin recharging the battery box. Take a stopwatch and measure how long it takes for the entire circuit to return to 100 V, when the solar panel stops outputting power.

Next, separate the battery box and the solar panel by a length of no more than sixty blue alloy wire. You can't really go higher than that without risking to throttle the solar panel and falsifying the test results, but it also works with less. it's just more easily apparent when you use many cables, because you would expect there to be a large difference. Again charge an empty battery and measure the time it takes the entire circuit, including both ends of the 60 wire, to return to 100 V.

You will notice that the two times you measured will be just about identical, within a certain margin of error due to the imprecision of human timing and measurement. In both setups, the one solar panel recharged the battery box in the same time. But how can that happen, if the solar panel in the first test was sitting near 91V, generating 182 W, while the panel in the second test was close to 100 V due to all the resistance pushing the voltage up, and thereby generating almost 10% more power?



What happens is this - and read these two paragraphs carefully, because they are important.

The extra power - or rather, the voltage, which is the non-constant half of the two parts making up your power rating here - was consumed on the way. It was lost, spent to overcome the resistance. You introduced the resistance specifically to get more power, but that way of thinking is actually backwards. Every bit of "extra" power only exists in the first place because it must be spent to overcome the added resistance. If it was not there, the current could not flow. You were trying to create something that only existed because the very measure you took to create it required it to cease existing in order for the laws of nature to be fulfilled. In a way, it's a really cool mind trap, and I totally fell for it in the beginning as well, until I made my experiments and realized what was really going on. ;)

I understand that you want to state that there is energy loss in this system because you are losing something along the way that has the potential to become energy if it arrives. But again, that is the same mind trap as before. If you did not force that extra voltage, that extra power to create itself for no other purpose than to be lost, it would never have existed in the first place. And therefore you are not losing any energy, not even any that could hypothetically be. You cannot gain or lose something that does not exist.



There's actually a second test you can do, although you need to be even more careful not to accidentally throttle your solars here, because you will likely be using more than one.

Hook two blulectric engines up to two empty redstone energy cells. Connect the first engine to solar panels directly, clustering them as close around it as possible. The other blulectric engine you connect to solars with a really long cable, as long as you can safely manage without throttling your solars. Now, activate the two engines with a single lever, and let them run for a good long while (try doing it from sunrise to sundown).

When you switch the engines off again, both redstone cells will contain roughly the same amount of MJ. In fact, the one with the long cable will likely contain a scrap more, since the engine was able to consume additional energy buffered in the cables via self-capacitance, but if you left the assembling running long enough it should be a negligible difference.
 

Nommy9

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Thanks again Omicron, that all makes sense and confirms what I thought.

I'm afraid looking this up in a book or wikipedia would not be of any help though. After all, there are no volts and amps in minecraft, only numbers named after real world things. Perhaps there is some code in place which alters their values such that they conform to some of the laws of physics, but this does not mean all laws apply, or that those which seem to will always be obeyed. It can be hard to always remember this and avoid making false assumptions I think.

It's good to know how the solars were auto-adjusting their power output to match distance based power loss too. I only saw that they did, thanks for explaining.

About the experiment timing how long it takes a solar panel to replace a fixed amount of energy in a battery box, it just reinforces what I was saying really. Actually what we think is not much different except you don't believe in the distance based energy loss yet. It's a matter of perspective that has you a little confused I think.

Here's a couple of different ways you can look at or measure it:

1. Looking at what arrives at the destination bock only. (Timing how long it takes to charge a battery box)
You see distance traveled has no effect on power or energy input so it appears that there's no distance based losses.

2. Comparing what is sent from the source to what arrives at the destination. (voltmeter)
You see that the further the distance traveled the greater the source block power and energy output. The destination block power and energy input remain constant indicating the additional power and energy is expended traversing this distance.

You seem to use view #2 for power and view #1 for energy.

This explains why you think there is distance based loss for power but not energy. I think if you reread what I said and showed or redid your experiments keeping in mind the different perspectives you would agree on all points. But other wise I'm not really sure how I can convince you.

It is certainly a quirky system though. It seems rather than decreasing what arrives resistance increases what is sent so what you end up getting is the same. How odd. Tough to get your head around too, like you say.
 

Omicron

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I'm afraid looking this up in a book or wikipedia would not be of any help though. After all, there are no volts and amps in minecraft, only numbers named after real world things. Perhaps there is some code in place which alters their values such that they conform to some of the laws of physics, but this does not mean all laws apply, or that those which seem to will always be obeyed. It can be hard to always remember this and avoid making false assumptions I think.

Actually there are volts and amps in Minecraft, due to Redpower. Eloraam intentionally modeled her power system after real-world electricity. What you are seeing is a simulation of electricity physics, with a small number of simplifications (like no joule heating).

Calclavia's Universal Electricity API does the same thing, by the way. The Voltz pack in the FTB launcher is built on it.

This explains why you think there is distance based loss for power but not energy. I think if you reread what I said and showed or redid your experiments keeping in mind the different perspectives you would agree on all points. But other wise I'm not really sure how I can convince you.

They say that sometimes, the best ideas come to you in bed. It took me a good long while to understand what you were trying to tell me, but last night, just before falling asleep, I think it finally clicked.

I decided to run another test today:
- One battery box, directly attached to a blulectric furnace.
- One battery box, connected to a blulectric furnace by means of 64 blue alloy wire.
- Both systems were brought to ca. 82 V, and then the battery boxes had their internal storage filled up to maximum.
- I then determined how many pieces of cobblestone each blulectric furnace would be able to smelt before fully draining each battery box.
- Special caution must be taken to not consume the extra power available in the 64 wires; the test must be stopped while the system is still over 80 V.

The results: 60 cobblestone for direct attachment, 48 cobblestone for the long wire.

Umm, wow. It was so easy to confirm, and I simply couldn't see it. Thanks for bearing with me, Nommy9. It's people like you I need to doublecheck my work!

Guess I have a section or two to rewrite now... :oops:
 

Omicron

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Then you will be able to smelt 60 + 48 = 108 pieces of cobblestone, I would assume? Haven't tested it, but it would make sense...
 

Omicron

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Update: Completely rewrote the section on electrical resistance to fix a massive derp on my part. Sorry!
 

Nommy9

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They say that sometimes, the best ideas come to you in bed. It took me a good long while to understand what you were trying to tell me, but last night, just before falling asleep, I think it finally clicked.
Cool :)

It might be worth mentioning something like this too:
In practice, it's best to put battery boxes as close as possible to the machines which use the power whereas generators like solar panels and windmills will operate at full efficiency at any distance so long as they run at 100V or less. This is because generators will increase their power output when needing to send power over longer distances, resulting in the same amount of power reaching the consumer as when they are right next to it, whereas battery boxes don't - they discharge at 80V or less and any power lost to resistance is not compensated for and simply goes to waste.
 

Omicron

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I'd love to be more wordy, but I already had to cut out the entire introduction and another paragraph I wanted in to make the post fit.

I'm literally 3 words short of the 10,000 character limit right now :confused:

I thought about migrating the guide to a PDF file, but that would diminish the convenience of just pulling it up with a click on the forums... I also thought about asking a moderator if the the forum software allows for inserting a post after the first, o taking over someone else's post (I'm pretty sure ICountFrom0 wouldn't mind if I asked him), but then again, I doubt that kind of thing is possible.
 

TheLoneWolfling

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I'd love to be more wordy, but I already had to cut out the entire introduction and another paragraph I wanted in to make the post fit.

I'm literally 3 words short of the 10,000 character limit right now :confused:

I thought about migrating the guide to a PDF file, but that would diminish the convenience of just pulling it up with a click on the forums... I also thought about asking a moderator if the the forum software allows for inserting a post after the first, o taking over someone else's post (I'm pretty sure ICountFrom0 wouldn't mind if I asked him), but then again, I doubt that kind of thing is possible.
Just have a TOC in the first post that links to additional posts of yours in this thread, and/or a continue link at the bottom of each post linking to the next post in the guide.
 

Omicron

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I actually came up with a better idea... I did learn a little HTML back in highschool. And while plain HTML won't win you any bread in today's web design, it is perfectly sufficient for giving a page of plain text a little formatting with minimal effort. A 20 kB HTML file is probably going to be nicer to my Dropbox bandwidth than a 500 kB PDF with the same content. And it will open far more quickly, right in any browser with no additional software requirements.

I'm gonna put that on the back burner though, because I seriously need to stop procrastinating on the steam boiler analysis. The project's long done, I just need to find a way to compose a nicely flowing post for it.