Any mining that you are going to do that requires only a little bit of power is not going to earn you much. Most mining setups require many watts of power to run in order to make any kind of interesting payout.

You are basically advocating misappropriation of energy from other people who are kind enough to offer some for your convenience

If you are going to mine cryptocurrency you should not be mining Bitcoin in the first place as there are much more profitable altcoins to be mined which can be sold to acquire more Bitcoin that you could have mined by just mining Bitcoin.