Improving gaseous biofuel production from seaweed Saccharina latissima: The effect of hydrothermal pretreatment on energy efficiency

Richen Lin, Chen Deng, Lingkan Ding, Archishman Bose, Jerry D. Murphy

Research output: Contribution to journalArticlepeer-review

78 Scopus citations

Abstract

Marine macroalgae (seaweed) is a promising feedstock for producing biohydrogen and biomethane via dark fermentation and anaerobic digestion, respectively. However, one of the limiting steps in the biological process is the conversion of polymeric carbohydrates into monomeric sugars. Here hydrothermal pretreatments were assessed for hydrolysis and subsequent production of biohydrogen and biomethane from the brown seaweed Saccharina latissima. The solubilization of S. latissima improved with increasing temperatures from 100 to 180 °C, resulting in a maximum yield of 0.70 g soluble chemical oxygen demand/gram volatile solid (sCOD/g VS); equivalent to an increase of 207.5% compared with untreated seaweed. However, the yield of the derived monomeric sugar mannitol peaked at 140 °C and decreased with increasing temperatures, likely due to production of fermentative inhibitors. Microstructural characterization revealed that the algal structure was significantly damaged, and the major chemical groups of carbohydrates and proteins were weakened after pretreatment. Regardless of hydrothermal temperatures, biohydrogen yield only slightly increased in dark fermentation, while biomethane yield significantly increased from 281.4 (untreated S. latissima) to 345.1 mL/g VS (treated at 140 °C), leading to the sCOD removal efficiency of 86.1%. The maximum energy conversion efficiency of 72.8% was achieved after two-stage biohydrogen and biomethane co-production. In comparison, considering the energy input for pretreatment/fermentation/digestion, the highest process energy efficiency dropped to 37.8%. Further calculations suggest that a significant improvement of efficiency up to 56.9% can be achieved if the heat from pretreatment can be recovered.

Original languageEnglish (US)
Pages (from-to)1385-1394
Number of pages10
JournalEnergy Conversion and Management
Volume196
DOIs
StatePublished - Sep 15 2019

Bibliographical note

Funding Information:
This work is supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant (No. 797259 ) and the Environmental Protection Agency – Ireland ( 2018-RE-MS-13 ). This study is also co-funded by Science Foundation Ireland (SFI) through the Centre for Marine and Renewable Energy ( MaREI ) under Grant No. 12/RC/2302 and 16/SP/3829 . Industrial co-funding from ERVIA and Gas Networks Ireland ( GNI ) through the Gas Innovation Group is gratefully appreciated.

Funding Information:
This work is supported by the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant (No. 797259) and the Environmental Protection Agency – Ireland (2018-RE-MS-13). This study is also co-funded by Science Foundation Ireland (SFI) through the Centre for Marine and Renewable Energy (MaREI) under Grant No. 12/RC/2302 and 16/SP/3829. Industrial co-funding from ERVIA and Gas Networks Ireland (GNI) through the Gas Innovation Group is gratefully appreciated.

Publisher Copyright:
© 2019 Elsevier Ltd

Keywords

  • Biohydrogen
  • Biomethane
  • Energy efficiency
  • Hydrothermal pretreatment
  • Macroalgae

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