I want to make a report about the study of the production of landfill gas from municipal waste (MSW). Any experience on field.
Good to hear from you, and thanks for forwarding the thread. Unfortunately, I am not an AIChE member, so I cannot access the discussion directly. However, I do think it would be useful to respond to Dr. Smith's comments. In particular, since he references the efficiency of WTE via combustion versus landfill gas to energy, you may want to direct him to a paper co-authored by NC State University and U.S. EPA scientists, titled Is It Better to Burn or Bury? and published in ES&T, available here: https://pubs.acs.org/doi/abs/10.1021/es802395e
The following excerpt from the paper is relevant:
One notable difference between LFGTE and WTE is that the latter is capable of producing an order of magnitude more electricity from the same mass of waste. In addition, as demonstrated in this paper, there are significant differences in emissions on a mass per unit energy basis from LFGTE and WTE. On the basis of the assumptions in this paper, WTE appears to be a better option than LFGTE. If the goal is greenhouse gas reduction, then WTE should be considered as an option under U.S. renewable energy policies. In addition, all LFTGE scenarios tested had on the average higher NOx, SOx, and PM emissions than WTE. However, HCl emissions from WTE are significantly higher than the LFGTE scenarios.
With regard to efficiency, Dr. Smith may be thinking of the efficiency of the energy recovery process itself. It is true that the combustion of landfill gas for electricity generation is more efficient than combusting solid fuel; however, this leaves out several crucial inefficiencies inherent to landfills: efficiency of gas collection (typically 50-60% on a lifetime basis), partition of carbon into CO2 and methane, incomplete conversion of biogenic feedstock to gas, and the stability of fossil-based components in the landfill.
To Dr. Smith's second point, feedstock preparation is less critical than one might think. While it is true that Europe does have higher recycling rates, it has a relatively minor impact on boiler efficiency. Boiler efficiency is driven more by basic boiler design, and, more widely done in Europe, the incorporation of combined heat and power systems.
I would be happy to speak with Dr. Smith and anyone else on the thread in more depth, if they are interested.