FEATURE DATA CENTRE MANAGEMENT HOW GREEN IS YOUR DATA CENTRE?
Rising energy price trends, more stringent carbon taxation, and a need to present green credentials, are all motivating data centre operators to cut energy consumption wherever possible. In this article, Alan Luscombe, director at Uninterruptible Power Supplies, a Kohler company, shows how choosing the right UPS topologies, and operating them efficiently, contributes to meeting these objectives
Figure 1. A
ccording to a Guardian article, our growing appetite for digital services
means the data centres that power them are responsible for about 2 per cent of greenhouse gas emissions; a similar share to aviation. While an individual’s everyday browsing has a minimal impact, it is a different story with technology giants like Facebook and Google, and their billions of users worldwide. Google’s carbon footprint for 2013 was 1,766,014 tonnes CO2 equivalent, mostly generated by their data centres. While most organisations are far
smaller than these giants, the percentage of their energy bill attributed to their data centre has nevertheless grown with their increasing dependency on IT. This has major cost implications, both through direct energy costs and the impact of the Government’s Climate Change Levy – an energy tax payable by non-domestic users, intended to provide
an incentive to increase energy efficiency and reduce carbon emissions. On top of this, shareholders, customers, employees and the media increasingly seek evidence of green credentials as part of their evaluation of any company they associate with. As UPSs usually handle all of a data
centre’s ICT power, any improvement in UPS efficiency will contribute significantly to reducing its energy demand. Fortunately, UPS efficiencies have been improving; 10 years ago, UPS efficiency levels were typically around 94 per cent, but, today, 96 per cent is possible, with 97 per cent expected soon. So, let’s look at the factors that contribute to UPS efficiency and how they can be invoked to maximum effect.
TRANSFORMERLESS TOPOLOGY AND MODULAR UPSS The most important game changer of recent years was the appearance of
transformerless topology, as this has brought both direct and indirect benefits. Firstly, going transformerless immediately improves efficiency by up to 5 per cent across most of the load spectrum, as shown in Figure 1. This not only yields a direct reduction in energy use, but also saves on energy needed for cooling. Additionally, the conversion electronics used by transformerless UPSs present an input power factor that is much closer to unity and more load-independent than previously. This improvement reduces the magnitude of the input currents, minimises associated cabling and switchgear sizing, and in some circumstances reduces electricity running costs. Also, input current total harmonic distortion (THDi) of less than 3.5 per cent virtually eliminates harmonic pollution of the mains supply. This saves unnecessary oversizing of gen-sets, cabling and circuit breakers, avoids extra input transformer heating and extends the overall lifetime of all input components. Yet transformerless topology also brings indirect energy- saving benefits; the associated space and weight savings are so significant that implementing a UPS as a rack-mounting module rather than a large, floor- standing system becomes viable. This means that UPSs can be built as modular solutions that can be incrementally sized to closely match their critical load. Unnecessary UPS capacity, and its power and cooling demand, is eliminated. This remains true even as the load grows, as the UPS can be scaled to match changing load requirements.
8 JUNE 2018 | ELECTRICAL ENGINEERING
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64
