The voltage delivering 1 watt depends on how many amps are present. We use watts to measure power (P), and amps (I) times volts (E) equals watts.
The urea and water that make up urine are removed from the blood in  the kidney. This is then passed on to the bladder which will be  excreted as urine.
Urea waste. Urea is excreted by the kidneys, and is less toxic than ammonia and can be transported in the blood from the liver where it is formed from ammonia. This molecule is very small, diffuses easily across cell membranes and requires no specialized transport system.