Cogeneration, trigeneration, my generation

In a panel discussion at the Air Conditioning, Refrigeration and Building Services exhibition (ARBS 2010) chaired by Steve Hennessy Director at Steensen Varming (Aust) Pty Ltd, panellists Chris Derksema of City of Sydney, Blair Healy - founder and Manager of Cogent Energy, and Bruce Precious - Sustainability Manager at The GPT Group will discuss the opportunities and barriers to cogeneration as a practical and viable tool for reducing a building’s carbon footprint.

At ARBS 2010, the panellists will debate the future of cogeneration and trigeneration technology. The exhibition is being held from 12-14 April at the Sydney Convention & Exhibition Centre.

While the principles of cogeneration are not new, the technology is enjoying a resurgence in Australia based significantly on the need for buildings to achieve good NABERS ratings.

The discussion will prove interesting, with a good mix of theoretical and practical information. While all the panellists believe that cogeneration is an important technology to pursue, there is not universal agreement that it necessarily provides all of the outcomes the hype suggests.

There’s widespread agreement that changing the fuel mix in a building to use more gas and less electricity automatically gives a significantly lower volume of greenhouse gas emissions, and using waste heat from the fuel-generation process to provide heating or cooling results in less overall building energy use as well. Beyond that, opinions begin to diverge.

Hennessy notes that natural gas is still a fossil fuel with its attendant carbon costs, and Precious suggests that cogeneration is often presented as a transitional technology - not a long-term solution for greener buildings.

“Despite having been implementing cogeneration systems across the last 10-15 years, as an industry, we do not yet have our heads around it,” says Precious.

Still, there are many who are prepared to back its success. As part of its 2030 strategy, the City of Sydney has committed to the technology, planning for district heating and cooling. Its thought is that there is only so much a building owner can do, but even after the best green initiatives are in place in a building, that building will still use a significant amount of energy, so that energy should be green.

Precious suggests that most cogeneration system designs are guided by Green Star requirements, but if those requirements are applied naively, it’s possible that you won’t achieve the desired outcomes. There is a need, he suggests, to apply really detailed analysis in order to make decisions on system size.

Other factors being discussed will be: how beneficial cogeneration systems are in terms of cost and greenhouse gas savings, and the issue of dealing with electricity providers. To commission cogeneration systems, electricity providers need to provide easy access to the grid, but they are naturally concerned to protect network reliability, and their approvals processes can sometimes be arduous. While not an insurmountable problem, it can impede the willingness of building developers to implement cogeneration systems.

Another factor to consider before implementing cogeneration systems is the potential for pollutants including nitrous oxides. These are more likely in areas of high sunlight and higher temperatures - so more of an issue in Sydney and Brisbane than in Melbourne, for example. Adding devices to monitor or filter the exhaust stream to deal with these pollutants should be factored in to the budget.

The discussion at ARBS will explore the general principles of cogeneration technology, the products as applied to specific climatic and local conditions, the barriers to optimal efficiency and where this technology might ultimately take us.

To find out more, or to register for this panel discussion, visit www.arbs.com.au or call 03 8623 3014.