For tidal, obviously, as Mr. Marshall said, we have these daily cycles of the tide flowing in and flowing out, and between the tides there is a slack period. But it is very predictable. It is possible for us to think about a number of tidal installations throughout a geographic area that would have different slack water times, so they may actually cancel out the variability in the tidal system within a region.
With wave, it's very clear that when you have a windstorm, it can blow through in 12 hours or 24 hours. A windstorm at sea may generate a wave train that will actually endure for many days, even if the wind only lasts for 12 hours. So it would be more forecastable.
The reality we are looking forward to by the middle of this century is that our electrical system will be harvesting energy from a whole number of different resource areas. And brilliant people like Mr. Marshall are the ones who are challenged to balance how we take that power and bring it together to provide a firm, reliable mix of electricity from a number of different resources.
My vision is that we in fact have all these resource opportunities available to us so that we have a significant renewable energy supply.