I would recommend if you already updated the system with the latest packages (And also installed the proprietary drivers for your video card if it applies) installing powertop:
sudo apt-get install powertop
Then run it from a terminal like so:
It will show you what is using so much power. If you press the right arrow key and go to the last option called "Tunables" it should show you what optimizations you can do to lower the temperature.
Aside from powertop, there are also a couple of others like Jupiter and TLP. But those are better explained in this post: Is system cleanup/optimization needed