District energy plant at Calgary

13 December 2012 – The message from Rob Thornton was clear: district energy is profitable for providers, and beneficial to property owners, as well as being great for the environment.

Rob is chief executive officer and president of the International District Energy Association, based in the US and he was presenting at Day 2 of the Energy Efficiency Council’s 2012 National Conference in Sydney last week.

  • Photo: inside a district energy system in Canada

The EEC has really stepped up to the challenge of broadening the conference to include a day dedicated to cogeneration, precinct trigeneration and district energy. Attendees took in a wide range of presentations covering international perspectives, energy security, energy prices and local success stories. Rob Thornton’s presentation showing 30 years of industry experience and project case studies was certainly a highlight for many in the crowd.

Firstly it is important to point out, district energy is not a technology, and does not rely on a particular technology. It is technology agnostic. Quoting the IEA, “District heating and cooling is an integrative technology that can make significant contributions to reducing emissions of carbon dioxide and air pollution and to increasing energy security.”

District energy sees underground thermal networks combine the heating and cooling loads of several to many buildings. Aggregation of thermal loads creates a scale where technologies can be applied that are not normally feasible on a single building basis. This can include gas fired trigeneration, which can capture and utilise  the waste heat from electricity production. Many district energy schemes move to recovery of waste heat from other sources, such as waste to energy and renewable energy sources.

A district energy company providing heating and/or cooling is providing more than a commodity. It are providing a service that has more value than just cents per kilowatt-hour. Rob Thornton used the analogy of running a car. The cost of running a car is more than just the fuel cost. It also includes the capital cost of the car, registration, maintenance and other costs.

The same applies for a district energy company providing cooling services to a building (or a city). The building receives the cooling when it needs it, including the cost of chilling capacity ready for peak demands. But the building connected to a district cooling system also no longer has to worry about operational maintenance of the chillers and cooling towers and, over time, the replacement of plant.

And for buildings in dense urban environments, the space savings are crucial. Receiving a heating or cooling service from offsite frees up space in buildings that would have been used to house boilers and chillers.  Buildings connected to district energy systems only need small energy transfer stations providing heat exchangers and meters to connect.

Rob showed this benefit by comparing the roofs of two buildings side by side. One full of cooling towers, and one, connected to a district cooling system, with a tennis court and swimming pool. Which property owner is happier with that use of space?

With the wide range of projects Rob presented, he showed that district energy is not just prominent in Scandinavia, but is widespread throughout North America, Asia and the Middle East. But we are taking our time in Australia.

The New York steam district heating system was devised 100 years ago. Washington, Phoenix, Cleveland and many others are all cities with district energy systems that you wouldn’t know about unless told.

Rob describes the electricity demand load of electric chillers as the cholesterol of the grid. All are placing peak demands on the grid at the same time. Even worse, as the temperature and humidity outside rises, the efficiency of electric chillers drops, increasing peak demand.

The Chicago District Cooling system includes ice storage to smooth out this electricity load. It includes four cooling hubs producing cooling services for over 100 connected buildings. Rob remarked that even a sports stadium or event centre with intermittent load can be connected to a system and be a profitable customer for the district energy company. This is much better than a centre operator having to worry about thermal plant maintenance. rather than delivering its core business, events.

When Hurricane Sandy hit the New York district, Princeton University’s campus district energy system continued to run. With many homes and businesses losing power, the university became a hub for the community in a time of crisis.

One challenge that Rob noted is the negotiations needed to convince property owners connecting to a scheme that they do not need as much contracted capacity as they might think.  Engineering typically applies safety margins to predicted energy demands to ensure selected chiller sizes meet peak demands.

Most of North America’s systems have grown significantly in the past two to three decades. Each with different technologies and different objectives and drivers.

As long as people move towards cities around the world, district energy will continue to grow and its benefits continue to spread.

When asked by EEC CEO, Rob Murray-Leach, what he would like to see in the next few years that is ‘cool’,  Rob Thornton remarked that district energy is cool, but not many people see this. It is all hidden, deliberately, behind facades or underground. He’d love to see a wider appreciation of the benefits of district energy and the role it is already playing in our communities.

Jonathan Prendergast is director of Prendergast Projects, which provides energy technical and commercial advisory services for existing built form and new development projects.