Trigeneration precinct for commercial buildings

Reducing carbon footprint in Sydney

In April 2011, Investa Property Group and Cogent, a subsidiary of Origin, established a trigeneration facility that reduces the carbon footprints of two commercial buildings in Sydney.

The trigeneration plant at Coca-Cola Place in North Sydney supplies lower-carbon electricity, hot water and chilled water to the base building and now exports surplus electricity via Ausgrid’s electricity distribution network, so the benefits can be shared with another Investa building (Deutsche Bank Place, 126 Phillip Street, Sydney).

This is a first for a commercial building in Australia; paving the way for precinct-based trigeneration systems that can serve multiple buildings.

This new precinct is formed via an arrangement between Cogent and Investa which overcomes operational challenges and will enable other organisations to share surplus lower-carbon benefits between buildings.

Origin’s cogentpower addresses the challenges that have been limiting the use of other cogeneration plants at large commercial sites. cogentpower creates a ‘virtual private energy network’ overlaid with the Ausgrid network to balance the energy demand between the two buildings. This solution allows Coca-Cola Place’s trigeneration plant to operate at maximum capacity and efficiency all year round.

Under the cogentpower model, the plant at Coca-Cola Place in North Sydney runs at maximum capacity and sends surplus power to the grid, sharing the benefits with Investa’s Deutsche Bank Place Building at 126 Philip Street in the Sydney CBD. The North Sydney building can achieve its sustainability targets and also share the lower carbon benefits with the Phillip Street building. This is the first step in the creation of a precinct-based trigeneration system where buildings are connected within the same distribution network and surplus, lower-carbon electricity can be exported to the electricity grid.

The trigeneration plant at Coca-Cola Place consists of: a 774 kW MWM, low NO_x, gas-fired reciprocating engine coupled to a 415 V generator located on level B2 which provides power to the base building; a 650 kW single-double effect broad absorption chiller located on B1 mezzanine level. The absorption chiller uses both engine jacket and exhaust heat and can supply either chilled or hot water to the building; and control, metering and switch gear that will manage the plant and interface to the site’s main switchboards and the grid for safe operation.

Other benefits include: increases the NABERS energy rating of both buildings; ‘waste heat’ captured from the plant is used on site for heating and cooling, significantly reducing the operation of boilers and electric chillers, thereby increasing efficiency and reducing energy use and CO₂ emissions; in the event of a blackout, the trigeneration plant at Coca-Cola Place would still provide power, heating and cooling to the tenants; surplus energy is exported to the grid, maximising efficiency and allowing the benefits to be shared between buildings; as waste heat is harnessed, trigeneration provides up to 80% efficiency, a significant increase on conventional coal-fired power stations which convert only 30-40% of their fuel energy into electricity; and when electricity is generated inside the CBD and shared into the grid locally, energy is not lost via the high-voltage transmission network.