Sydney's trigen power play  

The Climate Spectator has an article on interest in trigeneration in large Sydney office buildings- Sydney's trigen power play.

The path towards distributed generation in Australia made another important step forward today with the switching on of the country’s first trigeneration precinct.

Distributed generation has become an important part of energy systems in Europe and elsewhere in recent years, but it has barely taken a toehold in Australia. However, the deal struck between the Origin Energy subsidiary Cogent and Investa Property Group, for the supply of energy to two buildings owned by Investa, may signal a change in the way energy use and network demand is managed in our CBDs.

The system switched on today is a trigeneration facility installed by Cogent in the Coca Cola Place building in North Sydney. Trigen uses gas to generate electricity on site, but then captures the excess heat for use as heating, and for cooling via an absorption chiller. Its promoters say it increases energy efficiency to around 80 per cent, compared to just 30-40 per cent in coal-fired power stations, where excess heat is usually vented.

It is not the first trigen system to be installed in Australia, but the groundbreaking nature of this facility is the “precinct” concept, meaning that Investa will be able to use the excess energy generated in one building to supply power to its Deutsche Bank building located on the other side of the harbour.

It’s a development that considerably enhances the economics of tri-gen, as some tri-gen facilities have been installed and then left idle because the buildings in which they were located could not generate the demand needed to make them efficient and to properly balance the demand on electricity and thermal energy. The precinct concept solves this by providing another electricity outlet, and could also allow the installation of larger and more efficient facilities. It is expected to be the fore-runner of numerous other such precincts in coming years.

“It is a great example of how we are paving the way for more intelligent energy systems of the future,” said Frank Calabria, the head of energy markets at Origin Energy.

The City of Sydney has bold plans to make its CBD virtually self sufficient in energy within two decades by having 360MW of such generation installed in its city building, helping avoid the costs of new generation capacity and transmission upgrades. It is negotiating on a contract with Cogent to begin installing trigen systems at various council buildings that it hopes will be able to supply energy to other council buildings, and also neighbouring offices.

Craig Roussac, the general manager of sustainability, safety and environment at Investa, said the precinct concept meant that trigen systems were now an attractive proposition, and that the company, Australia’s biggest office building owner, would be looking to retro-fit them in other buildings with the aim to create more energy precincts.

Roussac says he was not in favour of trigen systems before the precinct concept, because buildings were either forced to create artificial energy demand, switch the trigen systems off, or run them inefficiently. For him, many of these plants were only there for show.

“Responsible building operators strive to use as little energy as possible,” he said. “This agreement proves we can have our cake and eat it too. We can power a super-efficient building with lower emissions electricity, while at the same time heating and cooling it with the waste heat that would normally go up a coal-fired power station’s smoke stack. In addition, further benefits flow from the ability to export excess electricity to the grid.”

Roussac said such systems would be essential for any building aiming for a 6-star green rating. The installation costs were around “a couple of million per megawatt”, but in the case of the Coca Cola building, the return on investment was enhanced because it was leasing the plant back to Origin/Cogent and gaining a fixed income from that. “It’s like having an extra tenant. when you capitalise that income, the return on investment is quite good – it increases the value of the asset by considerably more than the cost of the plant.”

Origin's Calabria says the tri-gen plan provides 774 kWe of power to the base building and 650kWe of cooling to the air conditioning system when running at full capacity. About 50 per cent of the energy will be consumed by the base building and about half will be to the grid, for the benefit of the other building.