On Tue, 26 Feb 2013 08:31:40 -0800 (PST), Graham Easterling wrote:

Tidal is not available all the time but at least it's predictable.

Once we have enough tidal generators spread around the coast, it will
be available all the time.

Indeed, for a relatively small island we are lucky with the range of
tide times.

But where do you *build* all these tidal systems?

The have a 250kw SolarPV system which generates about 250,000kwh per
annum.

250kW is a miniscule drop in an ocean at 0.00025 GW. But even that drop, when
added with the other dropsn needs some other form of dispatchable generation
capacity to back it up when the sun goes behind a cloud or simply because
it's dark. The costs of this back up capacity is not bourn by the wind mills
or solar PV that makes the grid need it.

--
Cheers Dave.
Nr Garrigill, Cumbria. 421m ASL.