At the end of the film Back to the Future something amazing happens. Doc Brown appears in his time-travelling DeLorean car and, as he talks excitedly to Marty McFly, he starts pulling things out of a bin.

“I need fuel,” he says, before dropping a banana skin and other bits into a hopper on the back of the car. 

There is no time machine, but in Bangalore, India, Shell is building a pilot plant that will turn waste – even discarded household junk – into petrol or diesel that can power cars.

“The quest to turn rubbish into energy is this century’s alchemy,” says Dr Alan Del Paggio, vice president of CRI Catalyst Company, the Shell business which licenses the technology worldwide. “Only, it’s not magic; it’s simple chemistry.”

There is certainly no shortage of waste – whether from households, agriculture or forestry.

A recent report for the World Bank warned that by 2100 the world’s growing urban population will be producing three times as much domestic waste as it does today. The study predicted the amount of domestic waste will rise from around 3.5 million tonnes every day in 2010 to more than 6 million tonnes by 2025 – about the weight of the Great Pyramid in Giza, Egypt – and to 11 million tonnes by the turn of the century.

In Bangalore, efforts to turn this waste directly into fuel will use a two-stage catalytic reaction in a process developed by a USA-based research centre, the Gas Technology Institute, and called IH2 *.

The IH2 process uses heat, hydrogen and catalysts to convert large molecules of the sort found in waste into smaller fragments. Oxygen and other contaminants are removed to create two pure elements: hydrogen and carbon. The two are then combined to create hydrocarbon molecules: petrol, diesel and jet fuel.

The process works with forestry and agricultural waste, but is also robust enough to handle sorted municipal debris. Glass, metal and rubber have to be removed, although IH2 is able to handle a small amount of plastics despite their chemical complexity.

“This technology can cope with a lot of what gets thrown away,” adds Del Paggio. “Cardboard and paper are cellulose, so it can deal with them. Natural fabrics are fine. Food waste like banana peels is no problem. We can process the lot. It can even take up to 15% plastics, including fabrics like polyester and nylon.”

As exciting as the technology sounds, challenges remain. For example, facilities need to be close to a substantial and reliable source of waste – otherwise the costs of transporting the refuse to the facility could become too costly.

“After successful laboratory trials, we know the IH2 process works. The real challenge is doing it economically and sustainably on a large scale,” says Del Paggio. The demonstration site will handle five-tonnes of waste every day – about the weight of two adult elephants.

The technology also produces enough of its own hydrogen to be self-sufficient. Hydrogen produced during the first stage of the process is simply kept and then, during the final stage, recombined with the carbon to make hydrocarbons. 

If the pilot plant is a success, the next step, according to Del Paggio, is a first commercial-scale facility.

If he returns in a few years, Doc Brown would be thrilled.

His DeLorean really could run on rubbish.


*IH2 is a registered trademark of Gas Technology Institute


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