Combined heat & power
Small-scale CHP is here to stay
With year-on-year growth of an average 20 per cent in the UK market, combined heat and power technology is one of the more popular energy efficiency measures of our time. Damian Shevloff argues the case of commercial small-scale CHP as one of the most efficient technologies for energy-intensive buildings from hotels to retail outlets
to say that CHP tech- nology is a modern success story but that does not mean that cogen- eration is all new. In fact, modern packaged CHP schemes have been around for some 30 years. It is only in the face of rising demands for cleaner energy and reduced energy waste that CHP installations have really taken off as an energy- efficiency measure, and rightly so. Large-scale application or small- scale packaged CHP, the dual gen- eration of power and heat in one simultaneous process reduces car- bon emissions by up to 30 per cent, helping organisations to meet their carbon commitments. While those responsible for
large energy-consuming facilities like industrial and manufacturing plants have long recognised the benefits of onsite cogeneration, it is the smaller sites with a ready demand for heat as well as power that have been seeking its carbon- reducing benefits in the more recent past. Currently, some 40MWe worth of CHP capacity are installed annually, and new mar- ket research supports the notion that small-scale CHP under 1MWe will continue to grow strongly in the next five years, taking the capacity to 60 – 80MWe per year by 2020.
Onsite CHPs are an attractive option for many as they can achieve energy efficiencies of around 90 per cent, which makes them twice as efficient as a site using grid supply electricity and onsite boilers. This efficiency is down to the improved fuel use of the CHP during the simultaneous production of power and hot water, and the immediate distribu- tion of electrical and thermal energy to their points of use that avoids transmission and distribu- tion losses commonly associated with the grid. Such dual exploita- tion of the primary fuel source will lower both cost and the quantity of CO2 emitted during what would be traditionally two separate fuel- consuming processes. Typically, a
26 | July 2014 | HVR Dalkia CHP in assembly area at Cogenco
payback of two to five years can be made on a site operating a 200kWe CHP plant, ultimately resulting in a carbon saving of 325 tonnes, provided that the heat load available to the CHP exceeds 3,500 hours annually to make the appli- cation viable, as efficiencies are maximised along with increased operating hours.
Commercial buildings such as retail sites and hotels lend them- selves to a combined approach due to their continuously high demand for both heat and power throughout the day. UK retail chain Tesco, for exam- ple, adopted CHP technology in 2009 after a number of pilot proj- ects, with the installation of 20 units across its main outlets. Since then Tesco has added another 120 cogeneration units to its portfolio – now boasting a combined capacity of over 16MWe – which have contributed to substantial CO2 reductions each year. Every 20 units of 121kWe CHP save the retailer 68,000 tonnes of carbon, given that each unit operates 4,000 hours annually.
More units are being installed, however, in a sustained effort to halve carbon emissions from
Tesco’s buildings by 2020, and eliminate emissions by 2050. Crucially, each upgraded site makes the retail chain less dependent on off-grid energy procurement and mitigates elec- tricity and fuel price fluctuations. Besides these benefits, small- scale packaged CHP is further helped into the market by the difference in gas and electricity prices (spark spread), attractive finance deals and supportive policies that incentivise the employment of energy efficiency measures through the Renewable Heat Incentive, the RO, FiTs and related drivers like Climate Change Levy exemption depending on input fuel type.
Companies like Marriott Hotels, by contrast, are already having the second generation of CHP units fit- ted in their properties after leading the way to more efficient heat and power generation in the 1990s. With its existing fleet nearing the end of its operational life, the hotel group has recently replaced 14 CHP units across its 58 UK proper- ties with individually sized state-of- the-art CHP engines, ranging from 121kWe to 400kWe each. Upfront capital investment for
Dalkia packaged CHP
such installations is often unneces- sary, turning small-scale packaged CHP into a cost-effective option for commercial organisations. Where the energy management provider retains ownership of the equipment, operation and mainte- nance services are simply covered by a periodical service charge. The advantage of a small-scale packaged energy solution is clear. As a fuel-efficient process, onsite CHP provides those striving for decarbonisation with operating cost and carbon savings based on power outputs that are scaled to meet the needs of small to medi- um commercial sites, be it 30kWe or up to around 2MWe or multi- ples of these, without the need for a cost-intensive bespoke design- install approach.
By seeking the right advice,
energy or building services managers can determine whether there is a benefit to be found in applying CHP at their estate and whether there is feasibly enough room to accommodate the logistical considerations of its installation.
// The author is the sales director for Cogenco, Dalkia’s packaged CHP subsidiary //
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