What was supposed to be one or two posts on DC became four, and what was supposed to be a single post on AC became three. It’s time to pause and consider.

The main idea so far is on the DC side of things. Supply computers with the DC they need rather than the AC which is convenient for us to provide, and three big impacts arise:

1. The need for invertors (DC-AC convertors) and PSUs (AC-DC convertors) is eliminated. Manufacturing, shipping and destroying these components has a big carbon impact.
2. A major source of 0ver-capacity is removed, thus allowing for leaner designs. A leaner design will be less wasteful, and less waste is always a good thing and nearly always green.
3. Those data centres that use batteries need far fewer batteries, again with a big carbon impact.

On the AC side of things, the main load is cooling. All resources expended on cooling basically go up in smoke, so the more efficient cooling is, the better. Cooling is well-understood, but there is much more that data centres could do in terms of little things. Add all of these little things up and, although it may only be one percent here and a couple there, the cumulative effect would be to consume far less electricity.

The flip side is that, if we are to consolidate huge DC power supplies as the primary power source for IT, but stick with AC supplies for cooling, we may end up with a more complex design.

(I’ve included A and B cooling systems to show how a Tier-4 or some Tier-3 configurations may, though need not necessarily look. For Tier-2, remove either cooling system and locate the redundancy within the system.)

Or, if we simply get rid of batteries and use flywheel or DRUPS:

This may not look very different from a conventional topology, but with 70% of the power now in the DC side, it is very different. It also brings to mind a separate, though related point: how clean is the power that comes in at the top? The next few posts will look therefore look at clean power in general. After those, I’ll try and put all the pieces together.

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