Tidal power is still far from being widely used despite having good potential in many areas of the world. Tidal power plants generate electrical power through the harnessing of the ebb and flow of the tides.
Tidal power pros:
Tidal power is a renewable source of energy. Tidal forces are the result of gravitational interaction with the Moon and Sun and tidal power will therefore be available as long as Moon and Sun continue to exist.
Tidal power is very efficient source of energy, with efficiency of around 80%. That is much, much better compared to efficiency of solar and wind energy, and even better than the efficiency of coal and oil.
Predictability of tides. We can know for certainty when the tides will be in and out as rise and fall of tides are much more cyclic than random weather patterns.
It produces no greenhouse gas emissions like this is the case with fossil fuels, meaning it doesn't contribute to climate change and air pollution.
Barrages and small dams needed to harness tidal power could be very helpful in protecting the coastal areas or ship ports from dangerous tides during a stormy weather.
Tidal power cons:
High construction costs and therefore a lack of cost-effectiveness.
Tidal power can only produce electricity during tidal surges which is in average around 10 hours each day, meaning that it cannot ensure reliable delivery without some effective energy storage solution.
The possibility of negative environmental impact. Some environmentalists fear that the frames of the turbines could disrupt the movement of large marine animals while construction of tidal power plant can disrupt fish migration in the oceans.
Needs big funds and plenty of scientific research to become commercially viable energy option.