Complex sentence: One of the main technological barriers is the fluctuating nature of renewable energy (e.g. the sun, wind or waves) while constant and continuous reverse osmosis operation is preferred from a operations, maintenance and water quality perspective.
Split into simpler sentences: One of the main technological barriers is the fluctuating nature of renewable energy, such as the sun, wind or waves. Constant and continuous reverse osmosis operation is preferred from a operations, maintenance and water quality perspective.