can you buy and place a hybrid engine in a H2?

It's possible but very expensive.

http://www.hlineconversions.com/goodwin-assist

it would be done more as a technology demonstrator than for actual use.

No. Hybrid engines are usually very small in displacement. The larger ones don't really get much better fuel mileage than their non-hybrid counterparts, so it's (IMO) pointless to bother with it.

Then, there's the electric motor, large battery and all the electronics that make it all work. FORGET IT

Anything is possible with money

But i think it's a stupid idea.

Not for any reasonable amount of money. If you had a couple hundred grand, yes.