Tidal energy is clean, renewable energy that occurs in kinetic and potential form in oceanic tides, and which can be harnessed for any of various purposes.
Thermal energy is energy that is transferred by conduction, convection and radiation; and measured in terms of temperature change. Thermal energy definition
Offshore wind vs onshore wind comparison is based on energy source, relative magnitude, energy systems, locations, complexity, technological maturity, and acceptance.
The concept of offshore wind turbine relates to the development and deployment of wind turbines to offshore locations where they can access large amounts of wind energy.