Question

I have seen laboratory documentation from a reputable lab in southeast Asia that a company has achieved a solid fuel product made from landfill material with a high heating calorific value (CV

) of approximately 10,000 kcal/kg (42 MJ/kg). The technology is referred to as Refuse Derived Fuel (RDF). From what I understand, such calorific values are only even possible with fluid fuels such as liquefied natural gas (etc.) which can get up to 12,000 kcal/kg.

Doing some calculations around the fixed carbon composition of landfill as similar to a question I've asked previously, I found that the fixed carbon (FC
) content of the feedstock composition must equal approximately 130% to have the CV mentioned above. This number is obviously impossible but I'm very surprised that it was reported by this lab. Similar products usually get a CV of around 2500 - 5000 kcal/kg if they're lucky. There are several formulas to calculate CVs, the one I've used is below and notably only a function of the fixed carbon content to calculate the calorific value [kcal/kg], so perhaps my equation is too simplified?

CV=0.196FC+14.119

The company of course masks the idea saying it's their intellectual property (etc.) but I'm just curious of if this is even possible or should the laboratory's reputation be called into question?

Answer 1

The question addresses the possibility of achieving a calorific value of approximately 10,000 kcal/kg for Refuse Derived Fuel, which seems unlikely considering typical energy densities of biomass.

Step-by-step explanation:

The question is concerned with the calorific value (CV) of Refuse Derived Fuel (RDF) and the plausibility of the claimed high CV for a solid fuel product made from landfill material.

It's asked if such a high value of approximately 10,000 kcal/kg (42 MJ/kg) is possible, since it seems to require an impossibly high fixed carbon (FC) content in the feedstock composition based on the used calculation formula (CV = 0.196FC + 14.119).

Biomass sources, like wood, typically have a calorific value of about 16 MJ/kg, much lower than the value reported for RDF. It's important to consider that the calorific values of different fuels can vary widely, with natural gas having a high CV of around 13 kcal/g.

While coal has lesser energy density and produces more CO2 per unit of energy compared to natural gas or oil. Moreover, factors like moisture content, material composition, and the efficiency of the conversion technology can influence the CV of RDF.