Usable Amps? How does one optimize Earth battery current?

[Romanader]

Hey folks!
I have an earth battery that makes a fabulous 1.7 volts! It only puts out 60 Microamps (uA). I can't get a simple Joule thief to work! Just how much current does one require to do any useful work?

(Back story: can be skipped if you like)
I've been working on optimizing a bank of Earth Batteries to rig them together using an oscillator (Wayne.ct suggested the Joule Thief) and then l aim to connect them via isolation transformers to get some seriously scary power out of them! Sounds great so far, but they won't even get a Joule thief to operate. The JT works, confirmed it with an AA battery (runs my uber LEDs great) so with that, I can only surmise the current is inadequate.

Does anyone know of a trick to beefing up the current from earth batteries? I'm happy as can be with 1.7 volts, but that 60 microamps is just killing me! Any suggestions?

[NickZ]

@ Romanader:
I connect two or three cement batteries in PARALLEL to be able to run a joule thief. If you remove the resistor it might help to get it going.
The stronger the coil is on the Jtc or Hartley Oscillator circuit (which can run on MUCH lower mAs), the brighter will be the led(s) that can be lit.
Making the cement type batteries with a spiral shaped coil that inverts through itself and up to the top makes a big difference in getting much higher mAs, and slightly higher voltage as well. The current will still drop down quickly once a load is connected, so I think that the Hartley type circuit or Inverse Joule Thief circuit may work the best combined with these types of batteries. That way the mAs will stay up higher and the led light intensity not drop as much.
I am going to make the same battery as before (soda can and beach sand-cement) but using the 33% taller cans, which should increase the batteries voltage to at least a solid 1.5 volts per can. The longer you make the copper spiral coil in the batteries, and the more turns or winds, to higher the mAs will be. Voltage does not increase much, but several cans can be connected together to make up the needed voltage. The weakest battery will restrict the flow through all the rest of the batteries, just like a pinched water hose.
I'm also going to make the same type soda can battery with the same copper spiral coil set up, but using agar or gelatin instead of cement, just to see what happens. Can't find Alum here, any ideas...