A week ago I was able to interview Google’s Joe Kava, VP of Data Centers regarding Better Data Centers through Machine Learning. The media coverage is good and almost everyone focuses on the potential for lower power consumption.
Google has put its neural network technology to work on the dull but worthy problem of minimizing the power consumption of its gargantuan data centers.
One of the topics I was able to discuss with Joe is the idea that accurately prediction of PUE and a mathematical model of the mechanical systems enables Google to focus on the Peak Demand during the billing period to reduce overall charges. The above quote says power consumption is dull. What is focusing on peak power demand? Crazy. Or you understand a variable cost of running your data center. :-)
How you get billed is complicated and varies widely depending
on your specific contract, but it’s important for you to understand your tariff. Without knowing exactly how you're billed for energy, it's difficult to prioritize which energy savings measures will have the biggest impact.
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In many cases, electricity use is metered (and you are charged) in two ways by your utility: first, based on your total consumption in a given month, and second, your demand, based on the highest capacity you required during the given billing period, typically a 15-minute interval during that billing cycle.
To use an analogy, think about consumption as the number that registers on your car’s odometer – to tell you how far you’ve driven – and demand as what is captured on your speedometer at the moment when you hit your max speed. Consumption is your overall electricity use, and demand is your peak intensity, or maximum “speed.”
National Grid does a great job explaining this: "The price we pay for anything we buy contains the cost of the product plus profit, plus the cost of making the product available for sale, or overhead.” They suggest that demand is akin to an overhead expense and note that “this is in contrast to charges…customers pay for the electricity itself, or the ‘cost of product,’ largely made up of fuel costs incurred in the actual generation of energy. Both consumption and demand charges are part of every electricity consumer’s service bill.”
When you think about the ROI of reducing your energy consumption the business people should understand the overall consumption and the peak demand of its operations. Unfortunately it is all too common for people to focus only on the $/kWhr.
Google can look at the peak power consumption and see if there are ways the PUE could be improved to reduce the peak power for the billing period.
Here are tips that can help you shave peak demand.
Depending on your rate structure, peak demand charges can represent up to 30% of your utility bill. Certain industries, like manufacturing and heavy industrials, typically experience much higher peaks in demand due largely to the start-up of energy-intensive equipment, making it even more imperative to find ways to reduce this charge – but regardless of your industry, taking steps to reduce demand charges will save money.
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Consider no or low-cost energy efficiency adjustments you can make immediately. When you start up your operations in the morning, don't just flip the switch on all of your high intensity equipment. Consider a staged start-up: turn on one piece of equipment at a time, create a schedule where the heaviest intensity equipment doesn’t all operate at full tilt simultaneously, and think about what equipment can be run at a lower intensity without adverse effect. You may use more kWh – resulting in greater energy consumption or a higher “energy odometer” reading as discussed above – but you'll ultimately save on demand charges and your energy bill overall will be lower.