Tri-Generation (or sometimes written as Trigeneration) is an extension of the Combined Heat and Power (CHP) concept. With CHP the waste heat from the generation of electricity is used to provide heat, most usually as central heating to homes via a District Heating scheme.
Tri-Generation takes this a step further by providing cooling via an absorption chiller, using waste heat from the generator as its energy source.CHP is not new, Scandinavia has installations dating back to the 1960’s and in the UK Sheffield’s CHP system went live in 1987 and Nottingham’s in 1989. The recent renewal in interest is because CHP solves two of the country’s problems: 1) it reduces energy use and along with it carbon emissions and 2) it reduces demand on the existing power supply grid.
It is when CHP is extended to Tri-Generation that it becomes of interest to the data centre community because data centres have a steady demand for power and a continuous need for cooling. Thus, by generating power on site, the waste heat can cool the data centre. If there is also a need for heating in the locality, for example for offices, shops or homes nearby, the scheme really starts to gel, using up to 80% of total energy from the fuel as compared to around 30% in conventional power stations. A further benefit is that not only is the power generation more efficient but the power demand is reduced because no electrical power is required for the chillers, these being power by the waste heat. It is somewhat counter-intuitive to understand how heat can be used to cool but the technology of absorption refrigeration goes back to the earliest refrigeration systems and will be familiar to many owners of boats or caravans where gas fired fridges are still commonplace.
CHP and tri-generators are generally powered by natural gas but could easily use bio-gas making the facility even more environmentally friendly and sustainable.Another reason for looking at tri-generation is if you have a site for a new data centre, or an existing data centre requiring expansion, and have insufficient power available. By generating your own power on site you avoid the necessity of bringing in additional power from the grid. The cost saving will help off-set the cost of the tri-generation system further improving the ROI.
For data centre applications careful consideration does need to be given to the resilience of the system, naturally the generators and chillers will have redundancy but what provides the back-up if there is a failure in the gas supply? Options will include connection to mains power and/or diesel powered standby generators.
In spite of the clear benefits in energy savings and reduced carbon emissions this technology has yet to find many in the data centre world ready to take the plunge. This is beginning to change, with the National Australia Bank investing $6.5 million in a scheme at its Melbourne data centre which is expected to save $1 million p.a. in fuel costs.
Many CHP and tri-generation schemes are large with capacities of several megawatts but smaller generators are available and data centres with loads as small as 60kW can be accommodated.
If you have a data centre, whatever the size, and would like to discuss the benefits of tri-generation or any other aspect of data centre infrastructure, please contact James Wilman on 0845 9000 127 or contact us.