I've just done a count, and I reckon there are eleven hard drives in my house at the moment, if you include the two iPods. They provide over two terabytes worth of storage, which may seem rather a lot but actually feels quite modest.

Three of them are external drives,  the others in laptop and desktop PCs, and they use a lot of power, especially the ones in the main server computer as it is on most of the time.

Of course their energy consumption is nothing compared to a large corporate data centre, but there are a lot of houses in Cambridge, and most of the will have at least one PC - many in this high-tech town will have more.  Now it seems that drive manufacturers have realised that there could be benefits from reducing the power consumption, especially when drives are idle.

Hitachi's new  drive, the Deskstar 7500, promises to use 40 per cent less power than comparable drives of the same capacity - although since we haven't seen the detailed figures we can't be sure that the claim will stand up to scrutiny. It will be fitted in ENERGY STAR PCs, helping keep their power consumption down, and presumably will be available to buy as a replacement or perhaps even an external drive.

 The announcement has generated some debate on Slashdot, the technology community including an interesting point from 'soldack' that

My bet is that solid state drives do much better. Moving parts consume a lot of power.
http://news.digitaltrends.com/news/story/12556/samsung_announces_64_gb_solid_state_drive "...consumes just half a Watt when operating (one tenth of a Watt when idle)" vs. from the article:"Through a 40-percent power reduction, Hitachi GST has delivered unmatched idle power utilization of 3.6 watts on the 250GB capacity model and 4.8 watts on models with capacities of 320GB or greater. Similarly, the P7K500 has reduced its active power requirements to 6.4 watts and 8.2 watts for its one- and two-disk models, respectively. By utilizing roughly half the 7 watts of idle power typically allocated for hard drives..." 

This seems to indicate that the energy savings, though significant, are not as good as we can get from an alternative technology.  This in turn raises the question of how hard we should be working to fix old ways of doing things and how much effort should go into more radical and perhaps far more effective solutions.