If you really need electrical power, it may ill suit you to be fussy about where it comes from. British researchers, for instance, have developed a fuel cell that can use urine and steps to generate electricity.
The urine comes from the expected source. The breakthrough here is using human power generated by walking to circulate the pee through microbial fuel cells, which generate electricity. Previous work with urine-powered fuel cells required external power to circulate the liquid.
How much power can you get out of this system? Enough, apparently, to power a mobile phone.
Engineering and Technology Magazine names the lead researcher as Professor Ioannis Ieropoulos from the Bristol BioEnergy Centre at the University of the West of England (UWE Bristol); it describes him as “one of the world leaders in the research of pee-power,” which is apparently a thing. A joint project with Oxfam, for instance, has developed urine-powered bathroom lights for use in refugee camps.