Unless you want to do it on a huge scale (see <a href="http://theverge.com/2013/12/2/5165428/bitcoin-mine-in-hong-kong-uses-jelly-to-keep-cool" rel="nofollow">http://theverge.com/2013/12/2/5165428/bitcoin-mine-in-hong-k...</a>), it's not.<p>You might want to look into mining litecoin (LTC), which might still be profitable and whose mining is CPU-based.
My understanding is that you need essentially free electricity to make it worthwhile.<p>Also, Bitcoin is wasteful. People are using an incredible amount of energy unnecessarily. It's a pretty selfish thing to do. This is a flaw in the system's design. I'm not sure other coins are much better in this regard.