Simon - Actually I'm surprised that this aspect hasn't gotten as much attention. In years to come will people look back at the wated energy to 'discover' some numbers and shake their heads?
Good point. Data centers use huge amounts of energy for the servers, and then for air conditioners. There must be more efficient energy recovery systems to harvest energy from server heat to cool the room, similar to how hybrid cars can harvest heat to charge their batteries.
Besti - the underlying technology could be used for many things where validating identity without a 3rd party middleman would be useful. Examples include the exchange of contracts and voting systems.
Can you explain how that would work. I'm showing my ignorance here, but what does bitcoin technology have to do with identity validation?