answer:Welcome to Fluther. I’m not a chemist or a petroleum / fuels engineer, but it seems to me that the source of the fuel is immaterial. That is, if you have “a diesel-like fuel”, which you should be able to determine by comparing the otherwise known properties of what you have to standard diesel fuel, then you can predict the BTU value of the fuel, verify that experimentally, and establish the value/s you seek on your own. Or am I missing something in your question?