Trigeneration at the new Royal Children’s Hospital

Carbon savings and energy efficiency

Rapid developments in medical technology, the paradigm shift to patient and family-centred care, and the inability of aging hospitals to accommodate the latest models of care, have all contributed to the current worldwide boom in hospital redevelopment.

Melbourne’s new Royal Children’s Hospital (RCH) is not only regarded as a world-class facility by virtue of its design and cutting-edge medical technology, but it also incorporates the very latest building services technology and sustainability initiatives.

The trigeneration plant and technology engineered by Norman Disney & Young (NDY) is one of the cornerstone ESD initiatives implemented for the hospital. Apart from the carbon reduction benefits provided, it will also produce electricity and heat energy with a system efficiency of around 78%. This higher efficiency level is far in excess of the 35-40% system efficiency associated with grid power. The poor efficiency of grid power is largely due to the traditional coal-fired generation plant currently employed as well as transmission and distribution losses which account for aroun

RCH has a heat-led trigeneration system comprising two 1160 kW gas reciprocating engines and two 1267 kW two-stage absorption chillers. The system generates 25% of the RCH base building electrical demand, plus a contribution to chilled water and heating hot water for air conditioning, and a heating contribution to domestic hot water. Carbon reduction from the trigeneration system is said to be around 37%, with a further 10% reduction in carbon emissions from the use of a renewable technology biomass boiler (burning compressed timber pellets from forestry waste) and solar preheating of domestic hot water serving the inpatient unit. The two trigeneration engines also contribute to the 100% overall standby capacity which operates in the event of a grid power failure.

There are significant environmental gains from the on-site generated electrical contribution which offsets the need for the equivalent capacity in much less-efficient grid power and effectively reduces the electrical demand by 25%. Further benefits accrue from the recovery of otherwise wasted heat for use in space heating and cooling, which means that the equivalent capacity of heating and cooling is saved from needing to be generated via gas-fired boilers and electrically powered chillers. While trigeneration is not ‘a replace all’ solution, it does mean that the overall capacity of the conventional electric chillers and gas boiler plant can be somewhat reduced in capacity.