DD, I am sure your intentions are honorable, but if Hashem gave us two kidneys, that is what He intended us to use. The fact that we CAN live with only one kidney (and the life is NOT 100% the same as if there were two functioning kidneys, no matter what you may have heard from eager “do a mitzvah” kidney solicitors), does not mean that we SHOULD deliberately put ourselves in that position without extremely mitigating circumstances. You can live without one earlobe, you can see with one eye,and you can
even live with only one good arm. Would you want to lose any of those? Chalilah v’chas.
Even to save the life of another person, we cannot just make an arbitrary decision to risk our own, because our lives are as choshuv as theirs. Maybe the reason G-d put two kidneys in us was because the kidneys perform such a vital function to our well-being and survival, that He wanted to make sure we were protected in case one of them malfunctioned.