Many types of poweful aluminum batteries have been built in the last 50 years, and it's true that formation of bauxite sludge/gel is a major bottleneck to releasing the potential of this metal's capacity to store energy.
I read a follow up report that a new battery is being claimed, by Europositron in Finland. This is an Aluminum battery with a claimed density of 1330Wh/kg, 3000+ cycles, life 10-30 years and -40F to + 159F working temperature and which claims to sidestep the hydroxide sludge barrier.
This is BTW only about twice the capacity of Glen Amatucci's Telcordia Technologies [Morristown NJ] 2002 patent No 6,482,548 claim for an Al-Li cell, so not outside the realms of reality.
If giant batteries can be made economically to transport electricity by ship from hydro plants, there is no sludge to carry back, just enough charge for the electric propulsion units to return the ship to the hydro power station's distributors.
http://www.europositron.com Alan
[This message has been edited by Alan Belson (edited 08-22-2006).]
