Comment 43 for bug 1765363

Ok, here's more complete detail, for 18.04. Do same as before with
kernel param nouveau.modeset=0 (I think this is probably dumb of me, but not sure)

sudo apt install nvidia-prime
sudo prime-select intel
sudo apt install bbswitch-dkms

then, the last part is a little different:

sudo gedit /etc/modules

and add

bbswitch

(no load_state=0)

sudo gedit /etc/modprobe.d/bbswitch.conf

write

options bbswitch load_state=0

and save and quit.

Now it runs intel, with nvidia off, every time from startup.