Tidal Wave Energy which utilizes the energy of tides to generate electricity holds big potential though it is still a decade away from reaching large commercial scale .Tidal Wave Energy is a niche renewable source of energy and there are only a handful of commercial tidal power plants in operation worldwide.There are a number of small companies like Pelamis,SeaGen which are developing unique technology to harness the power of tides and waves.However it will take a long time for these technologies to attain a mature stage.Most of the new technologies are still in the pilot stage while the developed Tidal Energy Technology of Tidal Barrages suffers from a lack of investment.The main disadvantages of Tidal Energy are

1. High Initial Capital Investment – Tidal Barrages require massive investment to construct a Barrage or Dam across a river estuary.This is comparable to construction of a massive dam for Hydro Power.This is perhaps the biggest disadvantage of this technology
2. Limited Locations – The US DOE estimates that there are only about 40 locations in the world capable of supporting Tidal Barrages.This is because this Tidal Energy Technology requires sizable Tides for the Power Plant to be built.The limited number of locations is a big hurdle.
3. Effect on Marine Life – The operation of commercial Tidal Power Stations has known to moderately affect the marine life around the Power Plant.It leads to disruption in movement and growth of fishes and other marine life.Can also lead to increase in silt.Turbines can also kill fish passing through it.
4. Immature Technology – Except for Tidal Barrage,the other forms of Technology generating Tidal or Wave Power are quite immature,costly and unproven
5. Long Gestation Time – The cost and time overruns can be huge for Tidal Power Plants leading to their cancellation just like that of the Severn Barrage in the UK.Many of the Tidal Power Stations like the gigantic Plant being planned in Russia will never come to fruition because of the very long gestation time.
6. Difficulty in Transmission of Tidal Electricity – Some forms of Tidal Power generate power quite far away from the consumption of electricity.Transportation of Tidal Energy can be quite combersome and expensive.
7. Weather Effects – Severe Weather like Storms and Typhoons can be quite devastating on the Tidal Power Equipment especially those place on the Sea Floor.

Summary

Tidal Energy has many disadvantages because it is still in the baby phase of development and lacks a strong industrial and technological base.With time and maturity,Tidal Energy may remove many of the disadvantages that are listed above.There are numerous very smart companies that are developing cutting edge innovative technology to harness the free energy of wave and tides.It is not improbable that one or two of these approaches leads to the realization of the large potential of Tidal Energy.