Nah. I laid out some drawings once. Big hole, observation facilities built into the walls using slot windows comfortably smaller than a T-Rex head. Electricity goes off, so what. Similar designs work well for other animals. Very large animals, regardless of the acrobatics you see a T-Rex perform in the movies, can't really jump without busting their bones. Elephants can't jump at all.

The raptors need a bit more care, since they CAN jump, but they can't fly either.

It's pretty much the standard design for large animal facilities, particularly ones who like the animals in a more natural environment. When I was a kid in Minnesota, the Como Park Zoo had many animals in standard iron-bar cages, pacing back and forth. Only the bears had large open pit facilities. This has, thankfully, changed since then. The Oakland Zoo put a huge new lion facility in, with overhead walkways integrated into it. The disadvantage is that in such large facilities, sometimes the animals choose to move way off and are hard to see. The zookeepers say it's their choice.

The new Minnesota Zoo is also a hallmark of natural enclosure design. The kicker is that all the large animals outside are native to cold environments.

Better zoos are an example of naturalists and rational environmentalists doing some good. Of course the radical environmentalists don't think animals should be in a zoo at all.