How uninterruptible power supplies can cut tax as well as energy costs

Green strategies are increasingly essential to meet organisations’ environmental and legal obligations. However these strategies can reduce costs due to reduced energy consumption. They can also save tax under the Government’s Enhanced Capital Allowance (ECA) scheme if they involve investment in approved low carbon equipment. Such equipment now includes uninterruptible power supplies (UPSs); Here, Matt Henley, Technical Support Manager for Kohler Uninterruptible Power Limited, a Kohler company, explains the ECA scheme, how UPSs have been optimised for energy efficiency, and how users can use the ECA to optimise both energy and tax efficiency within their organisation..

All businesses need ‘Green’ strategies to comply with social if not legal obligations. However, the good news is that such strategies can also offer cost-saving opportunities. These arise not only through the reduced energy bills of a greener strategy, but also from tax-saving possibilities available through the Government’s Enhanced Capital Allowance (ECA) scheme. This scheme, launched in 2001, encourages businesses to contribute to the UK’s Kyoto target of reducing carbon emissions by 20%, by investing in low carbon, energy-saving equipment.

Managed by the Carbon Trust, the scheme provides 100% first-year capital allowance on investments in qualifying energy-saving equipment against taxable profits for the period of investment. A company paying 26% Corporation Tax would therefore reduce its tax bill by £260 for every £1000 invested. It’s worth noting that relevant delivery, installation, project management and professional fees can also count as part of the investment, providing even greater savings.

Energy-saving equipment qualifies for the ECA allowance by being included in the Energy Technology Product List (ETPL). To achieve this listing, the equipment must satisfy criteria for its relevant technology published in the Energy Technology Criteria List (ETCL). The Government wishes to ensure that the ETCL accurately reflects the latest and best of energy saving technology, so the list is reviewed and updated annually. A good example of this was the introduction of uninterruptible power supplies (UPSs) in 2009.

Today almost all enterprises critically depend on electronics hardware for computing and communications, while the hardware in turn depends on clean, continuous mains power. UPSs provide the best way of supplying this, but they must do so efficiently. They handle significant loads, and any losses they sustain can be amplified by extra demand on air-conditioning for cooling. The ETCL is helpful to both suppliers and users in ensuring migration to the most efficient ups solutions. Within its coverage of UPS technology, the list specifies the minimum qualifying power efficiencies for different capacity products over various load conditions ranging from 25% to full load. The list also includes other essential or minimum criteria and advises on relevant BS EN Standards carrying more detailed information.

The list specifies minimum efficiencies of 93.5% at full load for UPSs of all sizes from 10 kVA to larger systems up to 200 kVA and beyond. The efficiency values reduce slightly as loading reduces, to 90.4% at 25% load for larger systems, and 92.5% for those below 200 kVA. However UPSs ranging up to about 300 kVA can meet or exceed these specifications using a modern approach known as transformerless design.

When static on-line UPSs were first introduced in the Seventies, they used an internal transformer to step up the inverter output voltage to a level compatible with the utility or generator mains supply. More recently advances in power semiconductor technology and the introduction of the Insulated Gate Bipolar Transistor (IGBT) device have allowed the use of a DC boost converter after the UPS’s internal rectifier instead of a step-up transformer after its inverter. The resulting transformerless design brings several significant advantages to UPS users compared with the earlier transformer-based approach.

Elimination of the transformer itself directly yields efficiency improvements of about 5% across the UPS’s entire load range. This cuts energy losses within the UPS as well as reducing associated air conditioning requirements. However, the transformerless design also leads indirectly to further energy savings by facilitating modular technology. This arises because the savings in space and weight are so significant, transformerless UPSs can be implemented as a set of rackmounting modules instead of as large standalone systems. UPS capacity can be incremented – or decremented – module by module to closely match the critical load. In this way, each module can be run at nearly full capacity, so its operating efficiency is maximised.

Modular technology benefits extend further than energy saving though. N+ 1 redundant systems with high resilience to failure are easy to configure with suitably chosen modules, and repair time is reduced to swapping a faulty module instead of extended on site component-level diagnostic effort. Future site load growth can be accommodated by adding modules, and if necessary, racks.

Potential purchasers wishing to check their prospective UPS’s energy-saving credentials can refer to the ETCL’s UPS specification to see definitive and up to date information on the efficiency standards they should expect. They can also quote the criteria within project briefs or installation specifications, constraining contractors, designers and consultants to use the most efficient available designs. Alternatively, users can simply refer to the ETPL and select the supplier and product that best meets their particular requirements. This gives two ultimately money-saving benefits: Firstly, they can be assured that they have accessed the most energy-efficient available UPS technology, and secondly, the ETPL listing guarantees eligibility for ECA tax relief.

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