PUE and Demand Reduction Using Solar and Ice at AFCOM Data Center World

At the AFCOM Data Center World conference in Nashville, TN.  I’m actually presenting tomorrow on utility incentives for data centers, and am looking forward to that.

There’s been a good facilities greening track that covers a lot of issues related to data center efficiency.  The most popular topic I’ve seen is about Power usage effectiveness (PUE). If you haven’t heard about PUE it’s time to study up because I think it’s here to stay.  Popularized by the Green Grid, PUE is a measure of the overhead of the infrastructure of a data center (technically it’s the power of the whole facility divided by the utility IT power).  So a high PUE means you spend more power than you need providing power and cooling to your IT equipment, or that your infrastructure is less efficient.  The average PUE according to the EPA’s latest data collection is about 1.9, meaning facilities are spending almost as much energy powering and cooling the IT equipment than the IT equipment uses itself.

As an aside PUE’s prime competitor was DCIE, which was the inverse, and so measured as a percentage that reads more like an efficiency metric.  However, PUE won the day because it was believed a metric expressing overhead would be more digestible by the C-suite.

Here’s a great slide describing what PUE is from a presentation from Steven Carlini of APC on PUE “hype”.

It seems that PUE is everywhere and people are giving advice about where and how to measure it, what it means, and how different decisions in the data center affect the PUE.  It’s great that PUE is taking hold because it will lead to greater instrumentation in the data center and is a starting point to talk about the facility infrastructure efficiency. The EPA’s uptake of PUE for their data center building rating (taking effect in June) will also help standardize the way people measure and report this metric. That said, PUE is not without its problems. The APC presentation did a great job of explaining a lot of the drawbacks of PUE, including how not all measurements of PUE are created equal so you need to make sure you’re comparing apples to apples (the Green Grid is working on making the metric more comparable across facilities).  In addition, certain improvements to your IT load can actually increase your PUE and make the infrastructure look less efficient if you don’t appropriately scale your power and cooling subsystems.

All in all, PUE is great for the industry and it will get even more useful when it becomes more standardized in how its measured and reported.  For now – it’s a useful tool for incremental improvements to a facility, but make sure you know what’s behind the numbers.  PUE is a useful metric, but the most important is overall energy saved (or demand reduced) by the facility.

I also saw a great presentation from i/o Data Centers, which I mentioned before in a post about demand reduction due to their peak shaving system of creating ice at night to cool the data center during the day.  The speaker kept saying “it’s all about power” and that space isn’t the prime issue anymore.  They’re also now planning an 11-acre solar array on top of the same data center, partially to lower their utility feed usage during peak times.  Here’s an article on that from Data Center Knowledge on how the ice system and solar work hand in hand.  Pretty cool and innovative stuff.

Remote Data Centers as a Consistent Load for Renewable Energy

Interesting snippet from a datacenterknowledge article on a data center powered by 100% wind power from an onsite turbine:

Microsoft has tapped into a major advantage of containers: they can easily be placed near renewable energy sources, allowing companies to chase green power to meet carbon reduction goals.

This made me think about recent projects trying to get approval for large transmission lines to bring renewable energy from less populated areas where renewable energy can be generated cost effectively (Good Article here from colorado).  Some of these transmission lines are being planned through parks or other natural spaces and are creating controversy in that respect.  It’s an interesting idea to locate data centers (whether containerized or otherwise) in areas to take advantage of these renewable power sources and to potentially limit the environmental damage required to build large transmission lines to pipe alternative energy around the country.  These remote data centers still need access to fiber to pipe in and out the information they’re processing and storing, but perhaps that’s more efficient then redirecting renewable elsewhere.  My gut reaction is that it would be.

Many developers have utilized the cheap electricity from plentiful hydro power in Eastern Washington State.  They’ve moved large data centers to the area and have taken up a lot of that excess capacity, limiting the need to use transmission lines to pump that cheap hydro power to other parts of the country.

However, unlike hydro, the challenge with wind and solar is the variable output depending on conditions.  Data centers provide a very consistent 24×7 load, so until more cost effective energy storage is developed this may be difficult to implement.  But once it is, having a consistent load from data centers could be ideal for renewable energy with a storage buffer, rather than trying to service a highly variable (and less predictable) load.