Every spring, the city of Seville, Spain is littered with 11.4 million pounds of oranges that fall from its 50,000 bitter orange trees. Many of the fruits end up flattened and rotting on the city's streets, much to the dismay of the Seville Sanitation Department.
Emasesa, the company that controls a large portion of Seville's water and sewage treatment needs, may have a solution.
"Emasesa is promoting a pilot project at the Copero waste water treatment plant for the second consecutive year to generate clean energy thanks to the juice of bitter oranges from the streets of the city," reads a press release from Emasesa's website.
The juice of bitter oranges is rich in fructose, which consists of very short carbon chains. The fermentation process runs hot enough to power five homes for one day on only 2,000 pounds of oranges. The leftover parts of the orange are turned into compost to regenerate the soil in local fields.
The team behind the project believe that if Seville's oranges were not exported to Britain, where the citrus fruits are used to make marmalade, and were instead utilized by the city's methane electric plants, over 73,000 Seville homes would be able to receive sustainable power for the duration of the harvest season.