A US company has worked out how to convert household rubbish into bioethanol.

Bioethanol has become one of several so-called green alternatives to fossil fuels.

But critics argue that crops grown for biofuels like ethanol take land away from food production.

INEOS, the world's third largest chemical company, has come up with a solution that it said takes the production of ethanol away from the food versus fuel debate.

The process works by superheating waste to produce gases that are then fed to naturally occurring bacteria which produce ethanol.

The ethanol is then purified to make a fuel that is ready to be blended for use in cars.

INEOS Bio chief Peter Williams says just about any kind of waste can be used to make ethanol: "We want any waste that contains what we'd call bio-degradable carbon, so you could take waste from paper process, you could take agricultural waste, you can take forestry waste and you can take household waste once collected and use that in the process."

INEOS Bio says that although it's technically feasible it will focus initially on waste destined for landfill now, as well as agro and forestry waste, rather than from existing landfill.

But Professor Pat Harvey of Greenwich University says whatever waste you use to create ethanol the same questions arise: "To what extent are there other materials other than carbon, oxygen and hydrogen. If there are chlorine contaminants present all of them have the potential to poison the fermentation process and cause the whole technology to collapse - and those kinds of issues we haven't yet sorted."

INEOS expects to go into commercial production with what it calls its breakthrough technology by end of 2010 beginning of 2011.

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