An introduction to tidal stream power was given on Monday in this post: “The MeyGen Tidal Stream Power Station: Pentland Firth, Scotland”. The simplest way to imagine tidal stream power of the MeyGen variety is an underwater wind turbine deployed in an area of high tidal flow. Two ebb and two flood tides daily produce four daily spikes in generation with nothing in between.
One aspect not covered in the above post was longevity and maintenance. This press release says this:
Sitting in 30-50 m of exposed fast flowing turbulent waters where the Atlantic meets the North Sea, the steel tripod gravity foundations have been designed from first principles to enable year-round turbine operation over a 25-year life with no maintenance, the awards website states.
It’s a bit ambiguous, but I believe refers only to the steel tripod base and not the turbine itself. But it does imply that the system is designed to last 25 years. It raises the question about repair and maintenance of the nacelle. Recovering the nacelle for repair and maintenance requires the services of a jackup rig and ship. Purpose built light-weight jack-ups are estimated to cost ~ €70,000 / day that could lead to hefty repair bills. If turbines break down and are left idle for lengthy periods this also negatively impacts electricity production and EroEI.
Previous entries in this series:
The Externalities of Energy Production Systems (Day 1 Coal)
Energy Externalities Day 2: Gas-fired-CCGT
Energy Externalities Day 3: Biomass-Fired-Electricity
Energy Externalities Day 4: Nuclear Power
Energy Externalities Day 5: Wind Power
Energy Externalities Day 6: Hydroelectric Power
Energy Externalities Day 7: Solar Photo Voltaics
Energy Externalities Day 8: Diesel
Energy Externalities Day 9: Solar Thermal or Concentrated Solar Power (CSP)
Energy Externalities Day 10: Tidal Lagoon Power
Energy Externalities Day 11: Geothermal Electricity
Energy Externalities Day 12: Wave Power
…click on the above link to read the rest of the article…