Curved Space Time

In flat space time, we can only get a triangle with a total angle of 180 degree. We can never have 3 90 degree angle corners for triangle. In curved space time, however, this is very different. Imagine you make a 90 degree angle corner at the north pole, and make two north to south lines from the corner down to equator. At the equator, one line make a 90 degree left turn and the other make another 90 degree right turn. and make a line length of a quarter of equator circumference. Here you have a triangle of three 90 degree angle corners in curved space time.

How do we get more energy out from curved space time then?