Combustion characteristics and NOX emissions of biogas fuels with various CO2 contents in a micro co-generation spark-ignition engine

Yungjin Kim, Nobuyuki Kawahara, Kazuya Tsuboi, Eiji Tomita

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Biogas is a renewable alternative fuel for internal combustion engines that has several advantages over conventional fuels, including lower costs and reduced levels of harmful emissions. In particular, it exhibits a neutral recirculation loop for carbon dioxide (CO2), which is one of the main causes of global warming. In this study, we investigated biogas fuels with various compositions using a micro co-generation engine system. The ratio of methane to CO2 and engine load were varied, and the intake air and fuel flow rates were controlled to change the equivalence ratio. The results show that for a given engine load, the ignition delay and combustion period increased with CO2 content, and the combustion speed decreased. The fuel consumption increased slightly with CO2 content; however, the thermal efficiency improved using a lean burn strategy, resulting in lower nitrogen oxide (NOX) emission, and moreover, the use of biogas with the stoichiometric air–fuel ratio appears effective in reducing NOX emissions and can improve the fuel economy at higher loads.

Original languageEnglish
Pages (from-to)539-547
Number of pages9
JournalApplied Energy
Publication statusPublished - Nov 15 2016


  • Biogas
  • Carbon dioxide
  • Lean burn
  • NOx reduction
  • SI combustion

ASJC Scopus subject areas

  • Building and Construction
  • Energy(all)
  • Mechanical Engineering
  • Management, Monitoring, Policy and Law


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