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Opportunities to decarbonise process heating using heat pumps in New Zealand.

Number: 1124

Author(s) : CLELAND D. J., LOVE R. J., ATKINS M. J.

Summary

Process heating accounts for 34% of New Zealand’s energy consumption and 27% of all energy-related GHG emissions. Of the process heating total of 200 PJ, 56% is supplied by burning fossil fuels, mainly in boiler systems and about 25% is for the food processing industry mostly at temperatures less than 200oC. NZ’s electricity supply is already 85% renewable and the target for 2035 is 100% renewables. Further, the typical electricity to fuel price ratio is currently about 3 and is likely to lower as carbon charges through the Emissions Trading Scheme (ETS) increase. Therefore heat pumps (HPs) represent a significant opportunity to decarbonise process heating, particularly in the food processing sector. However, for most food processing sites once low cost process heat recovery by heat exchange is optimised, waste heat sources are seldom available above 60oC. In this paper, HP opportunities are examined from both technical and economic perspectives via 4 case studies. Below 120oC, existing technologies such as water MVR systems, ammonia high temperature HPs and trans-critical CO2 HPs are suitable and available, and will become more economically attractive as carbon prices rise. Cost and complexity of both the enhanced electricity supply and HP technology remain significant barriers plus there is a paucity of experience with design and operation of such higher temperature HP systems in NZ. Above 120oC, suitable HP technologies are emerging and multi-stage cascaded HPs or hybrid compression/absorption systems look to be promising fits to the NZ heating needs. However, the negative effect of lower COP due to the larger temperature lifts on the economic case and the immaturity of the HP technology for such a temperature range remain significant barriers. To be successful, HPs will need to be closely integrated with other heat recovery and thermal storage systems.

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Pages: 7

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Details

  • Original title: Opportunities to decarbonise process heating using heat pumps in New Zealand.
  • Record ID : 30027651
  • Languages: English
  • Source: IIR Rankine Conference 2020.
  • Publication date: 2020/07/31
  • DOI: http://dx.doi.org/10.18462/iir.rankine.2020.1124

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