My vote goes to the "Personal Hydroelectric generator". It will be great help for those campers and trekers exploring wildlife, those surfers and water rafters. They can keep their mobiles charged while away in the wilderness.
Charging from a stream seems great, if one's available. If you have a stream of rainwater coming off a roof, it looks like it could work OK as long as the rain lasted.
I'm not happy with the idea of attaching it to a faucet. They say "only one gallon per minute" but a 2..3 hour charging time seems like it would often mean running 120..180 gallons of clean drinking water down the drain. Power generation runs a pump, which pushes water through a network of pipes, which turns the HydroBee generator, which charges some batteries. Then there's whatever energy is spent on water treatment and running the local sewage plant. The faucet attachment seems like a really low efficency approach to charging batteries.
The Faucet attachment also can work without wasting water, if the faucet water is routed through this generator and at the outlet also a faucet is attached.
So whenever the faucet is used the generator will run on the flowing water and can generate electricity. Off course the time taken for a such a charging process will depend upon the the usage of the faucet.
prabhakar, my vote also goes to the water-charging battery. Cell phone battery life is a real concern for backpackers on overnight or multi-day trips. Solar chargers help, but how much cooler would it be to charge your phone from a nearby stream?!
One "catch" with silicon anodes has been the limited number of charging cycles. The fact that these researchers were able to get 100 charging cycles out of this battery is a huge improvement. Considering the higher capacity compared to carbon anode lithium ion batteries, 100 cycles should last the average user a couple years, which I think should be enough to make these batteries acceptable in the marketplace.
Junko, my guess is both the cost to manufacture this new cell and while 100 charge cycles is a great improvement it is not enough given the cost of the battery. It does look like this could be a promising avenue to pursue for further battery improvements! It would be great to have this capacity in a battery both for portable use (electric cars as well) and backup storage (think off peak power storage / solar energy storage).