Surely you’ve heard by now that researchers at the University of Alberta figured out how to turn water into electricity? No?
Lucky you — you haven’t been subjected to the barrage of science illiteracy flooding the news.
Here’s an article which actually explains the technology. It’s a new method of generating electric current from a pressure difference; or if you prefer, converting mechanical energy to electrical energy.
Obviously energy is not created nor destroyed. Just as obviously, you need to have more energy available from the pressure than you get in the generated current. This is a direct consequence of the laws of thermodynamics: energy is conserved, entropy is increasing.
As it turns out, the process is only 1% efficient, which is to say that 99% of the energy available is lost. Compare this with the traditional method of converting pressure to current — i.e., magnetic generators like those in dams — which are over 90% efficient. Clearly some effort needs to be made here: microfluidics-powered cell phone batteries are not coming soon to your pocket.
It’s still a cool technology, and it’s still exciting. The University’s press release actually has a pretty good perspective on it. It’s a new way of generating current that hasn’t been described in the literature before. But if you’re only getting 1-2 microamps from 3/100 of an atmosphere, even if it scales linearly, you’d need 10 atmospheres to get 6 milliamps. And if the efficiency went up from 1% to 90%, you’d be getting .5 amps — you could almost power my cell phone charger for that. Of course, you’ll have to keep that head pressure sustained while you’re drawing charge, so expect to take a pressure tank with you wherever you’re going… oh, did you want to fly on a plane?