Author Topic: Solar Power Tower  (Read 1316 times)

zimirken

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Solar Power Tower
« on: February 20, 2015, 11:21:26 AM »
Hello everyone, I'm an engineer in Michigan. I had a crazy idea to build a solar power plant to make money. I think I've finally settled on building a solar power tower. PV cells, while definitely cheap and easy, really aren't something I can build myself. Build a PV solar farm requires a large capital investment, and since all you can do is send money to china and get solar panels, there is no real way to build things yourself to offset the monetary investment. Since I have experience with steam engines, I thought about building a solar thermal farm. I don't like parabolic troughs because you have a huge distributed high pressure boiler network, which is both expensive and risky. I like the idea of a solar power tower because the boiler is in one little spot, and heliostats are very modular. I figure something like this is about the most reliable way to own your own business you can get. In order to make a decent salary I'll probably need at least 200KW of generating capacity, which comes out to something like 5ish acres of heliostats. This is obviously not something that I can do in a year, I was thinking of slowly building it in my free time over a long period, as sort of my life's work. I figure I can just build heliostats here and there as I get the time and money, and once I settle on an efficient steam engine design I would only have to upgrade the tower and engine every once in a while.

What do you guys think of this idea? None of this seems terribly difficult, and would be like eating an elephant. The hardest part for me would be all of the legal things like permits and property taxes.


Gabriel

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Re: Solar Power Tower
« Reply #1 on: February 23, 2015, 07:01:27 AM »
It's probably doable, although I would check to see how much solar radiation your site receives first. I have a program that you can use to do this. http://www.cerebralmeltdown.com/2014/03/25/pc-based-arduino-sun-harvester-program-interface-solar-radiation-data-analysis-program-update/#more-3972

If you are basing it around the Arduino Sun Harvester Program (which would be awesome by the way) there would have to be some changes to the program to deal with such a large number of machines.

There are quite a few research papers out there on power towers. One of the difficulties they mention is getting a large number of heliostats located far away from the target to truly focus their reflections onto one spot. No matter how rigid the heliostat, there is always going to be some flex, which may or may not be easily compensated for in software. I wonder if it may be easier to just have several smaller steam engines set up to produce the same amount of power. They might not even necessarily be on the same site. That way you could take the small power plants to where they are needed to avoid transmission losses.

I also think that it would be cool to try and store the heat overnight in liquid salt (I think it's salt) like they do in some of the larger installations to generate power even when the sun is down.

It would definitely be a lot of work, but I think that it would totally be worth it to try at least on a small scale.


zimirken

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Re: Solar Power Tower
« Reply #2 on: March 18, 2015, 06:05:45 AM »
Oh yeah, I definitely plan on starting small, starting on say a 1kw solar "garden" to work on things like software and hardware. I'm going to have to start delving into the heliostat program to figure out how to separate the various components. I'm thinking of having a main control center that does all the hard work, and then just sends the movement data to the individual heliostats. Considering you can buy a arduino wifi adapter for $4, I'm thinking that wireless ethernet would be the best way to do it. All the heliostats would need to do is take simple position commands like like home and move to angle. It might be easier to even dumb it down more to the host controller telling the heliostat controllers how many steps to move.

Also, I've been doing some thinking, and regardless of any energy storage plans I think I will use oil as an intermediary heat transfer fluid. I would much rather have oil pipes up in the air than a pressurized boiler. Molten salt tech is far too expensive, complicated, and dangerous for any one person installation.

Gabriel

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Re: Solar Power Tower
« Reply #3 on: March 20, 2015, 07:33:56 PM »
I was wondering where the heck you were going to find a way to get onto wifi for $4 and just so happened to come across this article on Hackaday earlier today. http://hackaday.com/2015/03/18/how-to-directly-program-an-inexpensive-esp8266-wifi-module/
That's pretty awesome that this wifi stuff is getting so cheap. I need to get a few of those chips to play around with. I think that having a wireless heliostat array would be awesome, but until now it seemed to be too expensive. It also has a built in chip that you can program too, so presumably you might be able to just send simple position commands to each one like you said. All you would have to do is add a small solar panel and battery and you could make these things completely wireless. I would be a little paranoid about the wifi being buggy from time to time, but in the hands of a capable individual it wouldn't be a big deal.

There was actually a heliostat based power plant with molten salt that actually had an explosion from it, so yeah it probably isn't safe. :)

zimirken

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Re: Solar Power Tower
« Reply #4 on: March 27, 2015, 12:47:19 PM »
I've been starting to prototype some little mini pan tilt mechanisms with the $3 stepper motors this week thanks to a slow week at work. I'll be sure to post all my designs on thingiverse once I come up with a design that works well. I've also been looking at the heliostat code and it looks to be incredibly well written, straightforward, and most importantly compartmentalized. It will hopefully be fairly easy to modify for my purposes.

 I've done some reading up on concentrating photovoltaics and it might make this project far more economical and more likely to actually happen. It would also make it way easier to get through the various regulatory requirements. I figure, if I can build a heliostat way cheaper than I can buy the same sized solar panel, then I come out ahead. It's way easier to go to my local friendly power company and say I've got a solar panel setup with pre-approved inverters than it would be to say I want to put a gigantic asynchronous generator on their grid. Coming up with a cooling system for some pv panels is also an order of magnitude easier than a steam power setup, despite my infatuation with steam engines.