The Poo Bus

Apologies, but I can't resist the prospect of using this story about a new solution to the market failure of pollution: an eco-friendly bus which has just gone into service to transport people between Bath and Bristol Airport.

Students are well-used to analysing the negative externalities associated with over-crowded roads and carbon fuels, and to proposing solutions in the form of interventions to correct the market failure. So, here is another option they can use for that purpose. The bus, nicknamed 'the number two', runs on biomethane, which is produced from 'human waste fuel' - in other words, sewage.

What a brilliant idea - as the reporter points out, there is no shortage of the raw materials for the fuel. The annual waste of five people can power the bus to travel around 300km, which must be a good way of making use of what is otherwise a waste product. They are clearly proud of the concept, and not at all shy of using the bus livery to make sure that everyone knows about it too.