According to a report on this week's Tomorrow's World from the BBC, recycled cooking oil is now available at petrol pumps in Tokyo.

Cooking oil is normally used in Japan for the likes of tempura - a dish of fish, vegetables and shrimps dipped in batter and deep fried.

Cooking tempura requires fresh oil each day

The secret of tasty tempura is to use fresh oil each day which leads to a lot of waste.

But the left-overs are now being taken to a facility in a Tokyo suburb to be recycled.

After being filtered to remove food particles, it's pumped through machinery at a rate of a 1000 litres a day.

Because vegetable oil is too thick and sticky to be used in car engines, a catalyst is added to break down the oil molecules, then alcohol is added which binds to the smaller molecules to make fuel.

The fuel is then sold at their own filling stations to more than a hundred customers and several major companies.

It costs the same as normal diesel and is certainly green because it is not only recycled but produces less soot and sulphur dioxide than ordinary diesel.

Fish and chip test

A possible source of alternative fuel?

So could it be done with fish and chip oil?

A small scale test was done at the Pig & Whistle - a Japanese attempt at a traditional British pub.

Once the oil separated, the bio-diesel was added to a car already containing diesel with no adverse effects.