As restaurants and bars in Australia were forced to close due to the pandemic, millions of liters of unsold beer went stale. But instead of going to waste, some inventories of expired beer are being turned into renewable energy to power a water treatment plant in the state of South Australia.

In an effort to prevent waste, over the last couple of months, the Glenelg Wastewater Treatment Plant has been collecting millions of liters of expired beer from local breweries to turn it into renewable energy to power its water treatment process.

The plant mixes organic industrial waste with sewage sludge to produce biogas, which is then turned into electricity to power the whole facility. It usually generates enough biogas to provide about 80 percent of its energy needs.

But the recent influx of beer has boosted its energy generation to new levels, reaching 654 megawatt-hours in a single month.

“By adding around 150,000 liters of expired beer per week, we generated a record 355,200 cubic meters of biogas in May and another 320,000 cubic meters in June, which is enough to power 1,200 houses,” said Lisa Hannant, senior manager of production and treatment at SA Water.

The process entails biodegrading the beer under high temperatures in oxygen-free “digester” tanks, which produces methane-rich biogas. According to Hannant, the booze’s high calorific value – the amount of heat released during combustion – makes it “perfect” for the anaerobic digestion process.

“Honorably, our thirsty digesters have been doing their bit for the environment by drinking themselves silly and with such a horrific diet it’s no wonder they produce so much gas!” she said.