"Your reference to ammonia nitrate reminded me of a website that is promoting ammonia as a fuel. Matt Simmons - he of Twilight in the Desert fame- is a great enthusiast for the technology as it produces no greenhouse gases and is clean. In 1943 buses in Belgium were run on this stuff. Perhaps we are not doomed to be driving horses and carts in the long run after all!"

Eoin Treacy's view Thank you for this informative email, although if your were at the St. Patrick's Day parade here in Killarney today you might have been forgiven for thinking that the age of the horse and trap has already returned.

If I am reading the table on the Ammonia Fuel Network's site correctly, ammonia has only about half the energy content per kilo of gasoline which could suggest cars would need bigger fuel tanks if they were to get the same mileage.

Since the nitrogen for ammonia production is mostly produced from natural gas or coal, potentially lower natural gas prices resulting from shale gas production could make the compound cheaper than its competitors over the medium to longer term.