Final answer:
Nuclear energy is the renewable energy source that poses problems most similar to those of fossil fuels due to environmental concerns and limited reserves.
Step-by-step explanation:
The renewable energy source that poses problems most similar to those of fossil fuels is nuclear energy. Like fossil fuels, nuclear energy has environmental concerns, including the safety and disposal of nuclear waste. Furthermore, non-renewable sources of energy, including nuclear energy, are limited and may not last for more than a few hundred years.