Against the backdrop of ever increasing power consumption of computers and communications equipment, David Bond, managing director of Uninterruptible Power Supplies Limited, explains how the recent technological developments of modular on-line double-conversion UPS systems are helping UK corporations become more energy efficient and fall in line with the UK government’s initiatives to promote energy efficiency.
In this ‘information age’ we are experiencing exponential growth in voice and data communications and on-line processing for both business and pleasure. Internet surfing and transactions, VoIP, e-mail, social networking and a/v downloads, plus e-commerce and financial services on-line 24/7, present high demand for bandwidth and for power around the clock.
Power consumption is rising rapidly for several reasons. One is that UK organizations are fulfilling expectations to provide an ever increasing number of IT services with consistent, reliable power, 24 hours per day, with little or no down-time. Another reason is that they are obliged to comply with legislation enacted to promote improvements of corporate accountability, which in turn requires additional, and secure, IT resources and power consumption.
UPS systems have become commonplace in computer rooms, data centres and server farms, and play a vital part in maximising the availability of the systems that they support. However, their running costs can be high, and there’s the additional cost of providing redundancy to ensure the highest levels of power availability. Factors like the Climate Change debate, the emergence of the low-carbon economy and tax breaks – like the Enhanced Capital Allowance or ECA – and the rising cost of mains electricity, collectively make energy efficiency in data centres a very important commercial consideration. A survey by Gartner, published in the summer of 2006, identified that typically sixty per cent of data centre budgets are concerned with delivering power and expelling extraneous heat. It goes without saying that any improvements in the energy efficiency of the uninterruptible infrastructure are very welcome.
Occurring during the same period, several fiscal events have influenced the direction of developments of UPS systems. One of them is the Climate Change Levy (CCL), a tax on energy delivered to users in the United Kingdom.
Introduced on 1st April 2001 under the Finance Act 2000, it was forecast to cut annual emissions by 2.5 million tonnes by 2010, and forms part of the UK's Climate Change Programme. It applies to energy used in the non-domestic sector (industry, commerce, and the public sector). The aim of the levy is to encourage these sectors to improve energy efficiency and reduce emissions of greenhouse gases. From when it was introduced, the levy was frozen at 0.43p/kWh on electricity, 0.15p/kWh on coal and 0.15p/kWh on gas.
The rising price of electricity and the levy on it have pushed energy efficiency to number one in the list of considerations in the procurement of a new UPS system.
Types of UPS technology
Of the three types of UPS technology, off-line, line-interactive and on-line, implementations of on-line double-conversion (AC-to-DC and DC-to-AC) UPS systems are the most popular in computer rooms and data centres because they protect their critical loads from the full range of mains electrical supply problems – transients, interruption, sag/under-voltage, swell/over-voltage, waveform distortion, voltage fluctuation and frequency deviation - and consequently deliver the highest levels of system availability.
Two technological developments, in particular, have been instrumental in improving the efficiency of on-line UPS systems; they are transformerless double-conversion technology and parallel-redundant modular architecture.
Furthermore, when supplying critical loads that have leading power-factors, as is the case with increasingly prevalent blade servers, state-of-the-art UPS system modules operate more efficiently than their traditional counterparts.
Benefits of UPS systems with parallel architecture
All parallel UPS systems comprise two or more UPS modules operating in parallel to feed a common critical load bus. UPS modules are paralleled for three reasons:
To increase the power rating of a UPS system because of an increase in the size of the critical load. Such parallel systems are known as capacity systems.To increase the availability of a UPS system because of the importance of the critical load. Such parallel systems are known as redundancy systems. To allow simple and cost effective system upgrade by adding UPS modules in parallel when required, known as system scalability. Transformerless UPS systems save energy
Transformerless UPS systems are more energy efficient than their transformer-based counterparts for two reasons. First, there is no iron-loss and greatly reduced copper-loss, and consequently less extraneous heat to be removed from the data centre by the air-conditioning infrastructure, which can be down-sized. Iron loss occurs in the cores of electrical transformers and inductors when a fluctuating magnetic field is present due to eddy currents and hysterysis. Copper loss is due to the resistance of the windings of transformers.
Transformerless UPS modules are considerably lighter than their transformer-based counterparts. The combination of lightness and ‘hot swap’ capability (adding modules to, or removing them from a UPS system without disruption to the critical load) to match its capacity to that of the critical load it is supporting, greatly simplifies ‘right-sizing’.
In a traditional example, it is common practice to initially install a UPS system with sufficient capacity to support the expected maximum future loading. However, it is invariably found that the actual load falls a long way short of the anticipated load, resulting in the UPS system operating well below its rated capacity and therefore running very inefficiently and wasting energy.
By comparison a modern (modular hot-swappable) UPS system in the identical scenario would fare much better. As the load grows, the UPS can be upgraded in incremental steps by adding modules (without increasing the footprint) and the system utilization is greatly improved.
Transformerless UPS modules represent a much lower input power factor (than their transformer–based counterparts) to the mains electricity supply. That means that they draw much less current (Amps), economizing on electricity running costs and minimizing upstream cable and switchgear sizes. Transformerless UPS modules feature flat efficiency from quarter-load to full-load. Because the modules of parallel-redundant UPS systems by necessity operate at partial-load, high operating efficiency at partial load is a highly desirable feature.
Improved operating efficiency of UPS systems reduces the burden on air-conditioning plant in computer centres, thus making a further contribution to energy efficiency.
Incentives and technologies paving the way to more efficient UPS systems
More system managers and end-users expect ever higher levels of availability of business critical systems, and consequently, higher levels of availability of the UPS systems that support them.
First among EU member states to do so, the UK Government is publishing a draft Climate Change Bill for pre-legislative scrutiny and public consultation. It is also publishing a strategy document that sets out how the draft Bill fits with the Government’s broader strategy for tackling climate change. It highlights some key announcements coming up, which will be central to the Government’s strategy – in particular the Energy White Paper, the Waste Strategy and the Planning White Paper.
The debate on climate change has shifted from whether UK citizens and corporations need to act, to when, and to what extent they need to act. The Government has expressed its commitment to moving to a low-carbon economy and has instigated several energy-saving measures that work. One of them is the Enhanced Capital Allowance (ECA) scheme. Before it makes a claim for relief under the scheme, a business must obtain a certificate to confirm that its chosen system is on the Energy Technology List (ETL) and therefore meets the relevant qualifying criteria. The Carbon Trust maintains and publishes the ETL and manages ECA claims on behalf of the Department for Environment, Food and Rural Affairs (DEFRA) and HM Revenue & Customs. Uninterruptible Power Supplies Limited is, like other UPS suppliers, lobbying the Carbon Trust for static UPSs to be included in the scheme.
Five ways to improve energy efficiency
1. Use more efficient power protection equipment. Invite UPS specialist firms to survey your current UPS installation and advise on possible savings to be made by using state-of-the-art equipment. Today’s best-in-class UPS systems are considerably more efficient at operating at partial loads (e.g. when UPS modules operate in parallel-redundant configurations). 2. Right-size your power protection infrastructure. Considerable gains in energy efficiency can be made by using a modular, scalable power protection system, enabling UPS to be right-sized to match the critical load. 3. Review your server requirement/ Review server usage Significant energy savings can be made by rationalising lightly loaded servers and switching off the vacated ones. 4. Optimise the design and operation of the air-conditioning system used in the data centre. Invite specialist firms to survey your current HVAC installations and propose improvements. The survey might uncover energy wasting scenarios such as restricted air paths, poor circulation around racks, inappropriate alignment of CRAC units, incorrect location of vented floor tiles, etc. 5. Optimise the design and operation of the lighting system used in the data centre. Use more energy efficient lighting, or try installing motion sensors or lighting timers.