This is the time of year when the Spanish city of Seville turns orange and becomes one of Europe's largest orange groves. But few locals eat them. In fact, the fruit from this city's 50,000 trees usually just gets in the way.
"It is one of the trees that most represents the image of the city and one of its tourist attractions," says David Guevara from Seville City Council.
"Above all, it is the smell of orange blossom in spring that makes many people come to the city. But also, when the fruit falls to the ground, it generates difficulties and many problems for citizens."
The main export destination for the fruit is Britain, where they become marmalade, but the rest are left to fall on the streets. But now Seville's water utility company Emasesa is piloting a pilot scheme that uses the fruit to generate clean energy that runs one of its purification plants.
"Look, it's a very simple process: 50% of that orange is juice," says Benigno Lopez, the head of the company’s environmental department. "Through this juice, we generate a gas rich in methane that we use to produce energy. It is a very simple process. It does not require any type of additives, it is environmentally controlled and it closes the circular economy of urban waste, which also means that this facility contributes to mitigating climate change by self-sufficient energy."
The results of the pilot suggest one ton of oranges can produce up to 50 kilowatt-hours of electricity. That's enough to power five homes for a day. The water company says if all Seville's oranges were harvested, they could create enough electricity to power 73,000 homes.
That's what the juice does. And what about the pips and skin? They become organic fertiliser.