Energy and waste go together like clean and tech

Ever contacted the sanitation department to retrieve something you lost down the drain? Jewelry? Keys? A turtle? Dentures, even?

Or maybe you’ve never felt strongly enough about a nick-nack or a pet to go through such indignity. Now what if you lost 350 billion kWh of energy down the drain? What then?

According to New Scientist magazine, the US pulls the plug on that much energy every year. After paying good money to heat baths, dishwashers, sinks and washing machines, we flush all that hot water away. Affluence, meet effluent.

On average, that wasted heat warms the sewer to a useless 60°F. Around the world, cities are now going back to get that precious energy. In Oslo, Norway, for example, engineers are reversing the principles of refrigeration to drag heat up from under the city.

Large coils containing refrigerant fluid extract heat from the sewer and carry it above ground. It’s then concentrated to 194°F using compressors and piped to 13,000 apartments. In Vancouver, a similar system was used to provide 70% of the heating for the 2010 Winter Olympics village.

With progressive farmers already proving there’s good methane energy in effluent—generating up to 4 kWh per cow, per day—this is just another way to rethink the relationship between energy and waste.

Produced by Eammon Conaghan