The Last Wire refers to the power cord. After you’ve got your wireless networking/communication solution, the final concern is “how long will the batteries last till I need to recharge ?” for any portable / mobile device. The two sources suggested here would mostly likely only suit devices that use low – or very, very low low – amount of power.
I had 2 brain-farts concerning possible recharging alternations :
1) Self Winding for the 21 century : A major innovation in watches prior to the very small batteries – space spin off? – was the so-called self winding watch. The day to day motion of the user keep the watches spring coil fully wound.
I wonder if this could be scaled up to provide power for today’s (or more likely, tomorrows) mobile devices, especially ones you carry in your pocket or purse. It would require that the spring coils be made of some kind a nano-tube material (could be carbon, could be something else) : super strong and flexible to store the mechanical energy used by even the most miserly electrical device, but it spring Coils do hold real potential as a storage device.
Note that even though the materials are nano derived, the final “battery” could be much larger : as big as a finger nail or a house.
The self winding aspect is a optional bonus give a object that spends it life being dropped and bounced around ( based on my usage).
2) Passive Absorptive Power : A Device which converts a (wide) range of the electromagnetic spectrum – say radio – into electricity. Main use would be for lower power devices which are not mobile (smart dust?).
This blue sky things started with 2 common device (one every day, one more experimental) Solar Cells, and Beamed Microwave power. Solar Cells convert free falling sunlight into electrics. Beamed Microwave power was the idea of sending a microwave signal at a moving target (say a unmanned plane) to provide the electrical energy for the electric (propeller) engine. Beaming energy from space to a fixed point on earth is another variation on this (combining solar and beamed energy).
Rather than use light (which is “just” part of the electromagnetic spectrum ) use the background radio noise. Another alternative would be to use background radiation, of the sort picked up by a Geiger counter – to generate power, rather than running it though a speaker.
Another Energy storage device, in addition to the nano spring coil, is the fly wheel which appears to a faded from the view screen after some promising work in the last 90′s looked close to commercialization What happened? Fly wheels on the micro and macro scale are going to be important. Batteries, whether for chemical or mechanical energy are critical for a whole host of devices and solutions, but they not improving on any sort of Morse Law for them – or if we are then it on the flat early stage.
update questions : what would be most energic part of the em spectrum to absorb? What part do plants absorb. Might there be ocasional energic events which might be aborbed ? (like cosmic rays or neutrinos? althogut detectors for these events are so large it would likely rule out them, but how energic are they?)