The Prince Charles Hospital
The Prince Charles Hospital is a major tertiary-level cardiothoracic referral hospital for Queensland, the largest such unit in Australia and one of the largest services of its type in the world. The hospital is also the district hub for specialist needs in psychiatry, geriatric medicine, orthopaedics and aged care.
Following redevelopments in 2007, services now include general medicine and general surgery. The hospital consists of a total of 23 significant buildings over an approximately 30 hectare area.
The technology
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Cogeneration technology was selected because it generates substantial energy savings and provides a large reduction in greenhouse gas emissions. It uses proven and reliable technology, at a significantly cheaper cost to client.
The 1.6 megawatt (MW) cogeneration plant at the Prince Charles Hospital combines hot water, steam and electricity generation utilising a natural gas-fired reciprocating engine, designed and installed by Total Energy Solutions (TES) in 2010.
The plant operates 24 hours a day, 7 days a week. When maintenance time is taken into account, the plant operates for 8,660 hours per year, and has a daily output of 34,800 kilowatt (kW) hours per day.
70 per cent of the building’s energy demand is satisfied through the cogeneration facilities, which have an expected lifespan of 15 years.
The technology is monitored both locally and remotely, and preventative maintenance is performed by hospital staff and the engine manufacturer. The estimated maintenance costs ranges from $86,000 per year over 15 years.
Other generation and energy efficiency initiatives on-site include variable speed drives on pumps, heat pump for domestic hot water generation, energy efficient lighting for over 3,000 fittings, and building management system optimisation for energy reduction.
Project challenges
Challenges encountered during project implementation included the design of electricity generation to the hospital high voltage ring main and replacement of the existing transformer and high voltage switchgear.
In addition, issues relating to the real-time kW feed signal from the revenue meter operated by Queensland energy company Energex had to be resolved to ensure the safety margin was met.
There was also limited space for plant and equipment, due to many tight bends in the exhaust system, which produced higher than expected exhaust back pressures during commissioning.
Grid connection
Energex requires a minimum of 20 kW to be drawn from the grid as a buffer, however a safety margin of 200 kW is maintained. The connection agreement is a deed of parallel agreement with no export.
Air quality and noise impacts
Nitrogen oxide emissions are managed using a selective catalytic reduction system. This reduces the emissions from 200 parts per million (ppm) to 18 ppm. The choice of natural gas as a fuel source also reduces particulate and sulphur emissions.
A sound-proof enclosure and specially-designed heat dump radiators reduce noise levels to below that of the existing gas steam boilers, to 80 decibels adjusted. Plume dispersion modelling and sound level measurement are undertaken in surrounding residential areas for background creek and council approval.
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