Battery vs. Water Tank
How much water does it take to replace a battery?
I was discussing solar panels and renewable energy a few weeks ago. One of the new alternatives that came up was the super-heating of water using mirrors.
There is some REALLY cool stuff being built. Crazy stuff. I wish I had a $40M grant to go tinker...
Solar Tower System by Abengoa Solar located in Spanish province of Sevilla
So freakin cool. Basically you turn all the mirrors toward the tower to heat up water to 250C at 40bar (580 psi)!
After using a solar panel and a deep cycle marine 12V battery system at
Burning Man, I wondered what it would take to replace my sealed lead
acid battery with a tank of water. If I could heat the water and use it
as my energy storage device, could I get rid of the need for a car battery? Let's
assume I've got some solar apparatus that can heat the water - the thing I want to know is the size of the vessel of water it would take to replace the battery. If the required size of the vessel is equal to an Olympic-sized swimming pool, then the system is not feasible.
Tanks holding pressurized super heated water
Super heating water is a complex thing that requires pressurized vessels. Because I'm trying to replace a system used at Burning Man (think simple and portable), I don't want to heat the water past ~120F. At 120F, if water spills, it'll only discomfort a human and not physically burn or harm them.
Get the calculation excel file here. It would take roughly 9 US gallons of water, heated from room temp (25C) to 50C to equal the power behind a very heavy, filled with lead (Pb) and sulfuric acid, expensive, car battery. If my calculation is correct, 9 gallons is not so bad! That's like two water coolers (5 gallon carboys). Neat. So now I just need a way to heat the water - maybe with some mirrors and a control system, some motors, probably some batteries...
Wait - once I have 50C water, what do I do with it? Here's the problem - how does one convert thermal energy efficiently to mechanical energy, and then to electrical energy? The great thing about a 12V battery is that you can immediately 'hook-up' devices that do work for you. With hot water, I don't how to do anything but take a nice shower. How would you convert hot water to usable work?
Wait - once I have 50C water, what do I do with it? Here's the problem - how does one convert thermal energy efficiently to mechanical energy, and then to electrical energy? The great thing about a 12V battery is that you can immediately 'hook-up' devices that do work for you. With hot water, I don't how to do anything but take a nice shower. How would you convert hot water to usable work?
