The iPhone 4 has a battery with 3.7 V at 1420 mAh. This is 5.25 watt hours
* Amp-hours multiplied by battery voltage will give you watt-hours. Divide by 1000 for kWh.
* The energy density of lithium-ion batteries varies from chemistry to chemistry. The specific energy density can range from 100 wh/kg to 125 wh/kg, and volumetric energy density from 240 wh/L to 300 wh/L (double of the Ni/Cd, 1.5 times of Ni/MH) , which has not reached the maximum energy density in theory of 150 wh/kg or 400 wh/L.
* A 1-farad capacitor can hold 1 amp-second of electrons at 1 volt.
* A standard alkaline AA battery holds about 2.8 amp-hours All battery sizes with standard storage statistics is at wikipedia
* To store one AA battery’s energy in a capacitor, you would need 3,600 * 2.8 = 10,080 farads to hold it
* There are various claims of batteries being able to achieve ten or even twenty times the energy storage of current batteries. Prieto Battery is working on nanowire batteries that could get 20 times better storage. silicon and seaweed anodes could get eight times better storage.
Back in March, 2011 Elon Musk indicates that would bet on ultracapacitors instead of batteries as power storage for electric cars. The original reason Musk came out to California years ago was to do research on advanced, high energy density capacitors at Stanford, and to try to leverage what Musk said was tens of billions of dollars of R&D that’s been applied to capacitors for advanced ship making. But then, that whole Internet thing and PayPal happened. And then Tesla (and SolarCity and SpaceX).
Adapteva has delivered a multicore processor that can get 70 gigaflops per watt. Currently smartphones need to try to use about one watt for the processor and then put the processor to sleep when not in use.
A smartphone in 2016 or 2020 should have the better batteries or ultracapacitors and have new energy efficient processors.
A minimal amount of energy harvesting or wearable/flexible solar cells on clothing would also be able to charge smartphones and other wearable or portable electronics.
Cyborgs and Cyborg-lite
Experimental studies show that up to 20 W of power per foot is simply lost as heat during normal walking. This might sound like a lot, but in fact this is still a small fraction of about 300 W of total metabolic power that the person typically generates during walking
The power generated by the footwear-embedded harvester can be used in one of two ways. It can be used directly to power a broad range of devices, from smartphones and laptops to radios, GPS units, night-vision goggles and flashlights. In this case the power can be delivered to the device using a number of methods, ranging from simple wiring to conductive textiles to wireless inductive coupling.
The Walk Again Project wants to make a brain controlled exoskeleon for a quadriplegic to walk out on the opening day of the 2014 World Cup soccer tournament in Brazil. They have demonstrated brain-machine connections with monkeys using electrical currents delivered straight to each monkey’s sensory cortex by four filaments the breadth of a hair.
2015-2020 Energy harvesting of 10 watts to power smartphones, tablets or laptops with processors that are one hundred times more powerful. There would also be power for other gadgets and devices. Non-invasive brain computer interfaces could also be used as an interface to the devices.