A comparison of two low grade heat recovery options


Low grade heat (LGH) recovery is one way of increasing industrial energy efficiency and reducing associated greenhouse gas emissions. The organic Rankine cycle (ORC) and condensing boiler are two options that can be used to recover low grade heat (<250 °C). This paper assesses the lifecycle greenhouse gas reduction impacts and discounted payback periods associated with both technologies. Generation of electricity through the operation of the ORC saves approximately 11 kt of CO2 annually, but the high carbon intensity of the coking process means this has a negligible influence (<1%) on the overall process lifecycle impacts. However, if the electricity generated offsets the external purchasing of electricity this results in favourable economic payback periods of between 3 and 6 years. The operation of a condensing boiler within a woodchip boiler reduces the fuel required to achieve an increased thermal output. The thermal efficiency gains reduce the lifecycle impacts by between 11 and 21%, and reflect payback periods as low as 1.5–2 years, depending on the condenser type and wood supply chain. The two case studies are used to highlight the difficulty in identifying LGH recovery solutions that satisfy multiple environmental, economic and wider objectives.

Publication DOI: https://doi.org/10.1016/j.applthermaleng.2012.04.035
Divisions: College of Engineering & Physical Sciences
College of Engineering & Physical Sciences > Energy and Bioproducts Research Institute (EBRI)
Additional Information: © 2013, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Publication ISSN: 1873-5606
Full Text Link: http://www.scop ... tnerID=MN8TOARS
Related URLs: https://www.sci ... 2785?via%3Dihub (Publisher URL)
PURE Output Type: Article
Published Date: 2013-05-02
Authors: Walsh, C.
Thornley, P. (ORCID Profile 0000-0003-0783-2179)

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