Glossary of technical terms

Although I cover some technical subjects, I try to keep this blog as accessible as possible to everyone. Where it’s not really practical to avoid using terms that not everyone will know, I’ll include a short introduction to the term here, and link to it from relevant posts.


Biogas is gas produced from the rotting of biomass in the absence of oxygen. It consists of typically around 60-65% methane, with the rest of the gas being CO2 plus a few impurities. The largest source of biogas in the UK presently is capped landfill sites, followed by sewage plants. Biomethane is biogas that has been upgraded to a methane (CH4) content of >95%, at which point it can be used as a vehicle fuel and/or injected into the gas grid.

CAV – Connected Autonomous Vehicle

GHG – GreenHouse Gas

The most common GHG is the one we all know about, carbon dioxide. However, I more often talk about ‘GHG’ rather than ‘CO2’ because there are several other GHGs that play a smaller but still significant role in climate change – most notably methane (CH4) and nitrous oxide (N2O). When figures for GHG are quoted, they are often given in units of CO2e – this is CO2equivalent, and it means that the climate change effect of CH4 and N2O has been calculated and added to the figure as an equivalent amount of CO2.