Electricity is awesome. It used to be, back in olden days, that if you wanted to get mechanical power, you would build a giant windmill and then use that mechanical motion to do something like mill wheat. That’s where the “mill” part of windmill comes from. You either had to have your own windmill or share one with other farmers. The awesome thing about electricity is that you can transfer that energy over vast distances and then use it for whatever you want. In short, electricity is universal. What if we, as the human race, had never discovered electricity? Would we the industrial revolution never have happened? What else could act as a universal portable source of energy? The problem boils down to this:
1. How do you convert mechanical energy in one form, like wind or water turbines, into another useful form, like plowing a field or mixing cookie dough?
2. How do you move mechanical energy over vast distances?
My first thought would be to take a rotating disk and move it from one location to another. But even the fastest rotating things I’ve seen only rotate for at most 10 minutes, which doesn’t leave much time to move it a long distance. But then the answer, an answer, hit me.
Think about it, water in pipes could have replaced electricity. You could harness the energy in flowing water and pipe it from one location to another, satisfying both conditions above. Yes hydraulic power is analogous to electrical power.
It would probably be best to keep the system closed so that you don’t lose any water. The whole system needs less maintenance that way. But then you’re left with the problem of extracting energy from a closed system. You could do the same thing that we do for electricity today, use oscillating pressure/voltage. Imagine that instead of a power outlet you had a vibrating membrane that you could connect a hose to. That hose would power your device by converting that mechanical energy to whatever mechanical motion you needed.
It’s no surprise that this hydraulic power acts synonymous to electricity. Electricity is essentially electrons flowing through pipes, i.e. wires. Electrical inductors are like coils of pipe that store a large mass of moving water, that is inertia, and capacitors are like elastic membranes placed between two sections of pipe. The equations of motion are identical. A one way valve could act as a diode and pressure dependent valves could even act as logic gates, closing off a tube if the pressure is high, 0, and opening the tube when the pressure is low, 1. So we could even build a computer using hydraulics! That’s pretty freakin’ amazing.
There are some draw backs. If you wanted to power your house by storing a tank of water on top of your house, say 3 meters off of the ground, you would need a pipe of a diameter of 7 or 8 cm(about 3 inches) to produce 1000 Watts. That’s much bigger than an electrical wire but not unreasonable.
I wonder how thick the pipe would have to be to send hundreds of megawatts thousands of miles away without more than a few percent energy loss? I don’t know the answer but I have some thoughts about how to minimize energy loss. You would want to minimize motion as to reduce energy loss from friction and so you would naturally use very large pressures in transmitting energy long distances hydraulically. This is exactly what we already do with electricity. We step up the voltage to ridiculously high values, about 100,000 volts compared to the 120 volts that I use in my home power outlet (I live in the U.S.). Energy is force times distance and so if the pressure is high, the force is very high and the distance moved doesn’t have to be large to transmit a lot of power. Frictional force times distance the water moves is the frictional energy loss and frictional force doesn’t depend on pressure. So by maximizing pressure, we minimize the percentage of energy lost due to friction.
Imagine a world powered by hydraulic power? People into steam punk would love this world! I want to experiment with this. Maybe I should experiment with hydraulic systems? What do you think? I don’t know about you, but I’m getting excited about making some stuff using hydraulics.
I want to start this post by acknowledging that technology is exciting, making stuff is fun and sharing that stuff and how to build it makes all of our lives better. I recently started reading an autobiography by Olaudah Equiano with a long winded title about his experience with being abducted and thrown into slavery. While his account of the institution of slavery is well worth reading, what struck me is the description of his life before being forced into slavery. He was a young boy and he and his family were subsistence farmers. They made their own homes with local materials, made their own pottery and grew their own cotton which they turned into thread and then into fabric. There were no beggars and no one was idle. Everyone ate. It reminds me that life really isn’t very complicated. We need safety, food and those we love. That’s it. I feel like technology should enable us to firstly do those things more easily and secondly play.
Inspired by simplicity, I want to build something like this:
When I go for a walk I see leaves shaking in the wind and water flowing down streams. Sure, you could build a giant turbine to pick up this energy. But I imagine a world full of little simple generators like this shake generator. It’s hard to build a turbine but it’s easy to attach a shake generator to some fabric or hang it from a string while rushing current goes by. Its shear simplicity as a bit of power generation, would make it very easy to incorporate into the design for a larger generator. What’s more is that the design would be naturally fault-tolerant. If any one generator goes out, the rest can still generate power.
Sure you might need hundreds, even thousands of these things to power your home. I’m ok with that. A shake generator hanging from some vibrant cloth could be quite beautiful. Having several thousand would be dazzling.
I’m thinking about making a vibration charger for my phone and so I need magnet wire, i.e. thin copper wire to wrap around a magnet. So I discovered, to my disgust, that AWG is the unit of wire thickness. For some reasons, the powers that be decided that it would be smarter to use a logarithmic function of diameter to measure wire thickness, instead of just, hmmm, using the fucking wire diameter to measure the wire thickness!
I decided to make a table of conversions for those of us that still strive for sanity. In terms of the AWG number, you can get the wire thicknessm, in millimeters, using this formula:
I know someone is goint to respond to this post and say something like “they use that equation to make it a logarithmic scale”. The only reason you use a logarithmic scale is because the range of values are so vast that it becomes annoying to write out all of the digits. I question whether the range of values of wire thickness is vast enough to warrants the use of a logarithmic scale.
This is my maker blog devoted to sharing my projects and other peoples cool projects. I think stuff like this:
is pretty amazing.
Stirling engines are kind of awesome but at their best, they still under perform compared to combined gas-jet steam cycles. The benefit of Stirling engines though, is that you don’t need to build at an industrial level, as the person in the youtube video so clearly demonstrates.
I have so many questions, like is it cost effective to make a Stirling engine out of plastic rather than metal? The problem is that plastics tend to have thermal conductivity(i.e. how quickly they can give off heat) of between .19 to .5 whereas iron has a thermal conductivity of 80 . That’s about 400 times better than the best plastic, which is high density polyethylene. What this means is that to make a Stirling engine out of plastic with a similar power output as an iron engine, you would need 400 times the surface area between the working gas and the hot and cold reservoirs.
But what if 400 times the material was still cheaper if it was made out of plastic? Plastic typically comes form oil and oil is currently trading at about $93/barrel. Each barrel has about 159 liters in it so the raw materials for plastic cost at least $0.58/liter. By contrast, iron ore is trading at about $100/metric ton and a ton of iron has about 142 liters of volume. That’s about $0.70/liter for iron ore. I’m sort of shocked by the outcome. Oil and iron ore are trading for close to the same price per volume. If this translates into the cost of producing a Stirling engine, and this is a big if, then that would mean that a plastic stirling would cost several hundred times more than an iron stirling for the same energy output. Warning! These numbers are so rough that they should hardly be believed. They’re only meant to give some intuitive insight into the cost effectiveness.
There’s a lot that could be wrong with this picture. Plastics are easier to work with and you might require less plastic than metal, especially for low temperature stirling engines. There are so many questions and so little time!!!……..