The conversion efficiency of wastewater biomass (sludge) to bio-methane (biogas) varies depending on the composition of the sludge and the design of the biodigester. This efficiency ranges from 65% to 85%.

Now you need to multiply this efficiency by the conversion efficiency from bio-methane to electricity which say about 38%.  Hence the overall conversion efficiency would range from 25% to 32%

Hope this helps answer your question.

Professor Yehia Khalil, Yale University, USA

Fellow of the University of Oxford, UK

Thank you very much Prof. Yehia Khalil. Biomethane is a fuel therefore its direct utilization as fuel will have a better impact on economy rather than its conversion to electricity. Sir, what is your opinion in this regards.

DR. A. M. KHAN

Dr. Khan,

In countries where natural gas for heating is scarce, then using bio-methane for heating purposes would be a viable option. In other countries with limited resources for electricity generation, then biogas-to-electricity conversion would be an option although in this case the efficiency will drop as I should in my previous reply to you. Remember that whenever you add a new system in the loop, the efficiency of the integrated system will drop.

Best,

Prof. Khalil