The following link is useful

www.diva-portal.org/smash/get/diva2:8949/FULLTEXT01.pdf

The densities of of the pyrolysis gas (pyrogas) and tar vary depending on many parameters including:

1) Feedstock.

2) Inert gas (N2 or CO2)

3) Temperature of the pyrolysis.

In any case, the pyrogas density is about 1E-3 g/cc and the tar density is about 1.2 g/cc.

Hope this helps answer your question.

Professor Yehia Khalil, Yale University, USA

Fellow of the University of Oxford, UK