I saw my first and only hydrogen car in Brisbane City Square in the 1960's. No one saw it work, but now, fifty years later, the "hydrogen economy" has become green gospel.

Hydrogen combines readily with oxygen to produce energy via combustion engines, gas welders or fuel cells - there is nothing new about this process. And the sole exhaust product is pure water, another greenhouse gas.

Hydrogen is an abundant element. However, pure hydrogen gas is very rare on earth - it is almost always combined with other elements, commonly oxygen or carbon.

Hydrogen is not a primary source of energy. To produce hydrogen fuel, the gas has to be extracted from water or hydrocarbons using electrical or chemical energy. And the energy needed to make hydrogen exceeds the usable energy that can be generated from it. To make hydrogen from water needs huge volumes of cheap electricity from sources such as nuclear, coal, gas or hydro power.

Rich yuppies will want to be the first in their suburb with a taxpayer-subsidised hydrogen-powered electric car. But in the Australian energy equation, hydrogen is just an expensive way of transferring hydro-carbon energy from a power station in the country-side to a car in the city.

And it destroys energy in the process.