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Heat recovery to electricity can be applied in almost any industrial setting where fuel is combusted as part of the industrial process, or a chemical reaction takes place that produces heat. This technology can be implemented wherever there is a waste heat stream (either liquid or gas) of adequate temperature and flow. The electricity generated can be returned as a source of power for running the process or used in a separate application.

To generate the electricity, the hot gas or liquid from the process is passed through a waste heat boiler to produce high-pressure steam. This steam is then passed through a turbine. For lower temperature heat sources where steam of sufficient pressure cannot be created, low temperature electricity generation cycles can be used, such as an organic rankine cycle (ORC).

Sectors and common applications

  • Mining, oil and gas – generators and cooling applications
  • Manufacturing – chemical reactions, cooling applications, boilers, ovens and kilns

Score

  • 70/100
  • Energy saving across sectors is 81 PJ (2014 estimate).

Weighting

Indicator Score
1. Energy saving potential  
1.1 Level of energy efficiency 15/15
1.2 Market prospect 4/10
1.3 Energy saving potential 10/10
2. Technical practicality  
2.1 Innovative or advanced nature 15/25
2.2 Reliability 6/10
3. Economic characteristics  
3.1 Investment per unit energy 6/10
3.2 Payback period 6/10
3.3 % of Industry $ gross added value 5/5
4. Social characteristics 3/5
70/100

 Example

Nyrstar Australia Pty Ltd undertook a transformation project where they adopted new sintering technology which would allow for a potential increase in energy recovery. A waste heat boiler and cogeneration facility to produce electricity was also assessed. The project has completed the concept phase +/- 30% and has since secured funding to proceed to the next feasibility phase. The transformation project capital, operating costs and the amount of electricity generation is being determined to a +/-12% accuracy level as part of the next phase (Bankable Feasibility Study).

Other companies that have identified heat recovery to electricity as a source of energy savings:

For more information, see:

Waste heat minimisation and recovery

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