Be aware that they don't put out a lot of light. You need 3 or 4 to equal a "normal" cheap kitchen candle for light, and probably for heat. I bought 100, then a year later another 100, then I had a powercut and was most disappointed. Nowadays I reckon they are OK for incense burners and decoration and not much else.

Candles generally are a fire risk. They melt if it gets too hot. Tea lights only burn for 4 hours. And they are not that small either, compared to, eg, a coin-cell keyring light. For emergency lighting you are better off with LEDs and a stockpile of batteries.