3. Tidal Stream

3.5. Economical Factors

Tidal stream power schemes have a high capital cost and a very low running cost. As a result, such a scheme may not produce returns for years, and investors are thus reluctant to participate in such projects. Governments may be able to finance tidal power, but many are unwilling to do so also due to the lag time before investment return and the high irreversible commitment. For example, the energy policy of the UK (key principles 4 and 6 within Planning Policy Statement 22) recognizes the role of tidal energy and expresses the need for local councils to understand the broader national goals of renewable energy in approving tidal projects. The UK government itself appreciates the technical viability and siting options available, and has provided a grant scheme called the 'Marine Renewables Deployment Fund', while is also currently looking at increasing revenue support for tidal energy through the 'Renewables Obligation'.

There are three elements to the cost equation that determine cost effectiveness:

  • The 'effectiveness' of the technology at capturing energy (for example, the fact that all commercial wind turbines today use a horizontal rotor axis in preference to other configurations indicates the fundamental effectiveness of this approach)
  • The capital cost of the installed devices
  • The operating cost of the devices


The capital installed cost of tidal stream devices can be broken down into:

  • The cost of the device itself
  • The cost of everything else required making it operational - foundations, cabling, installation, and grid connection