Biomass Conversion$/$Renewable Diesel

a$.$ Describe the main differences between HVO and FAME in terms of

composition and production pathways. Which one is a drop$-$in fuel and why?

b$.$ Describe an example of biofuel that is not considered sustainable.

c$.$ The pre$-$industrial atmospheric CO $2$ concentration was around $280$ ppm $,$

whereas currently it is around $420$ ppm $.$ What are the implications on claimed

emissions reductions compared to fossil fuels? Make an argument for or

against the sustainability of advanced biofuels and RFNBOs. Please explain

your reasoning clearly and rely on sources where appropriate.