Generating electricity from temperature changes

I am monitoring the temperature of a cup of water with a temperature sensor and I was wondering if it would be possible to generate electricity (to recharge batteries for example) with response to a temperature change?

Thanks for the help!

Google "peltier effect"

Although it would be possible to generate a small current this way, it wouldn't be a practical way to charge a battery. (unless you live near the top of an active volcano).

(unless you live near the top of an active volcano).

Or a radioactive isotope.

My world book Encyclopedia had a candle powered radio that used a thermocouple pile. Probably not enough to charge a battery, though.

Google "peltier effect"

Or "Seebeck effect". They are the reverse of each other.
A Peltier device produces heat and cold at two dissimilar junctions when a current flows.
A Seebeck device produces a current when one junction is hotter than the other.
Both devices are physically identical and both are highly inefficient.
In the middle 60s, I knew someone who was doing research into making a Peltier fridge. They were using Tellurium as one of the metals in the junctions. I understand that the company went broke!