Does Celibacy help to conserve physical and mental energy?

Yes but the peace comes after a great struggle against temptation to break it; if you succeed to keep celibacy over a period of time longer than a month, then you'll start feeling the peace. My idea is close to the Buddha, that once the mind has given up on craving through the body, it will recoil inwards and find it's strength in solitude. But mind you, celibacy has to be sustained moment after moment, avoiding not only actions, but most important fending off sex thoughts... find your way.