Final answer:
OPEC's power has been limited by global energy independence and the presence of consistent oil reserves outside of its control.
Step-by-step explanation:
The two realities that have limited the power of OPEC are global energy independence and consistent oil reserves. With the advent of alternative energy sources and technological advancements, many countries have been able to reduce their dependence on OPEC oil, thereby weakening OPEC's influence over global oil prices. Additionally, the consistent availability of oil reserves outside of OPEC has provided a competitive alternative to OPEC's supply, further limiting their control.