For people living in some remote villages in Indonesia, heating houses and fuelling stoves can be a real challenge. The resources required, like gas and wood, have to get shipped in and distributed to individual households, and not only does this process take a whole lot of time - some families wait weeks for new gas to arrive - it also produces a tonne of emissions that contribute to global warming.
The good news is that this antiquated system is now on its way out, thanks to an unlikely source: tofu.
You're probably familiar with tofu as a delicious, fluffy treat that's made from bean curd, but in Indonesia, tofu isn't just a snack - it's a livelihood, with hundreds of small, family-run shops producing tofu in massive quantities every day.
Now, thanks to a government-run program, the waste water from all that tofu production is getting transformed into biogas that can be pumped directly to houses.
But how does it work?
First, let's talk about tofu. Tofu has been made the same way for generations, and it's a rather simple, yet time-consuming process.
Basically, producers start by soaking and grinding soybeans to separate the soy milk from the soy pulp. This step takes the longest because the beans have to soak for hours before they are ready for separation.
After the separated parts go through a filtration system, the protein and oil are separated from the soy milk. A chemical coagulant is added to firm everything up. Once formed, you have tofu ready for cutting. So, in essence, tofu is coagulated soy milk that you can pick up and eat.
Though simple in practice, an enormous amount of water is required to make tofu - roughly 33 litres for every kilogram of spongy bean curd.
Researchers found that this waste water could be turned into biogas if a certain type of bacteria is added to it.
Every day, the waste water is collected from various shops and treated with bacteria. Once transformed, the gas is pumped directly to local homes.
Besides creating a green energy source for locals, using all that waste water has significantly helped the local environment. Thousands of litres of waste water drained from raw tofu was once pumped daily from factories around the village into nearby rivers, befouling waterways and contaminating rice fields downstream.
Without all that wastewater lying around, farmers have seen an increased rice yield and the foul smell that comes with tofu production has left the area.
The hope for Kalisari is to become the first full-blown green village in Indonesia. If they're successful, there's no reason why similar programs couldn’t sweep across the region, dramatically changing the way people get the energy they need to live out their lives.