The Integrated Rankine Cycle project
The Integrated Rankine Cycle project examines how to utilise waste heat and consequently provides a number of pathways toward greenhouse gas reduction.
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6 June 2005 | Updated 14 October 2011
Summary
Power can be produced by small, modular, generators positioned throughout an electricity distribution network. These small stationary generators have mechanical efficiencies of around 25 to 35 per cent, similar to that of a car engine. A car engine uses approximately a third of its energy output to drive the car while a third is lost through the exhaust and the remaining third is lost through the water jacket or radiator. Wouldn’t it be good to utilise this waste heat somehow?
The Integrated Rankine Cycle project is primarily about the utilisation of waste heat
This is what the Integrated Rankine Cycle project is primarily about: the utilisation of waste heat to increase the overall efficiency of small stationary generators.
Specifically, the Integrated Rankine Cycle project aims to develop cost-effective heat utilisation for distributed generation, by converting heat to useable shaft power in relatively small-scale distributed and renewable energy applications.
This project is one of three projects that make up the Low Emission Distributed Energy Theme of the Energy Transformed Flagship. By utilising waste heat within the Rankine cycle and therefore increasing its efficiency there is also a reduction of greenhouse gases – one of the primary aims of the Flagship.
Current activities
The Rankine Cycle is a method for converting heat into electricity. The basic process is illustrated below:
The Rankine Cycle is a method for converting heat into electricity.
The process involves circulation of working fluid around the cycle in such a way as to create high pressure working fluid which drives an expander to generate power. When an alternator is connected to the expander’s shaft, electricity can be generated.
Low pressure liquid working fluid is pumped up to pressure, where it is boiled to create high pressure vapour. The heat for boiling comes from the available heat source e.g. solar thermal heat, industrial waste heat etc. The high pressure vapour is used to drive an expander to produce shaft power. The low pressure exhaust vapour exiting the expander is then condensed in a heat exchanger to form the low pressure liquid working fluid, which completes the cycle.
Ms Sarah Miller of CSIRO Energy Technology, who leads this project, explains that there are three main areas for research in this technology, 'We have been looking at process cycles, working fluids and component parts. With working fluids for example, the performance, cost and safety of the Rankine Cycle will depend on the fluid being circulated inside the system. Also, as a point of interest, if organic fluids are used, such as refrigerants or iso-butane, the cycle is called the Organic Rankine Cycle (ORC).'
Ms Miller adds 'We are also researching how solar energy, which is an important and attractive option as a renewable heat source, can be integrated into the cycle. We already have a solar thermal Organic Rankine Cycle prototype under construction.'
Outcomes
The Integrated Rankine Cycle project provides a method for producing solar thermal renewable electricity and for enhancing the efficiency of current and future fossil fuel distributed generation. Consequently it provides a number of pathways toward greenhouse gas reduction.
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