Japan is turning to a bizarre new fuel source - waste from adult nappies. 

Japan’s ageing population produces tens of thousands of tonnes of waste a year, and one town is now looking to recycle the material into fuel pellets.

In Japan, social demographics mean that more nappies are now being used by older, incontinent people than by babies. 

In the town of Houki, the nappies represent about one-tenth of local refuse totals. In a new scheme, it is being diverted from the rest of the garbage that would otherwise be dumped in incinerators. 

One of the town’s two incinerators has now been turned into an exclusive nappy-recycling plant to produce fuel to help reduce natural gas heating costs at the nearby public bathhouse.

It takes about a tonne of nappies each day. They are sterilised and fermented for 24 hours in 180-degree heat, which reduces them to about a third of their soiled weight. They are converted into a fluff that can be processed and turned into strings of grey pellets, each about 5cm long.

Now, unbeknownst to most bathers, the boiler heating the water for their idyllic baths is run on pellets recycled from soiled adult incontinence pads.

The technique may be expanded to other sites around the world that wrestle with significant volumes of human waste. 

“When you think about it, it is a difficult and big problem,” says Kosuke Kawai, a senior researcher at the National Institute for Environmental Studies. 

“Japan and other developed countries will face similar problems in the future.”

Japan’s environment department says the amount of adult incontinence pads entering the waste stream in Japan has increased by nearly 13 per cent in the past five years, now up to almost 1.5 million tonnes per year. 

Over 80 per cent of the country’s waste goes to incinerators. Incontinence pads contain large amounts of cotton pulp and plastic, swelling to several times their original weight after soiling. This means that much more fuel is needed to burn them than other sources of waste. 

However, unlike other single-use plastics like straws and cocktail umbrellas, the use of nappies cannot be restricted without compromising sanitation and health care.

So, Japan set up a working group last year to come up with alternatives to incineration for incontinence pads. The town of Houki has become the first to start turning the nappies into fuel pellets, but several are looking to mimic the approach. Other towns are experimenting with converting the nappies into material that can be mixed with cement for construction or road paving.