Emasesa, the municipal water company in the southern city of Seville, has launched a pilot project to generate electricity from methane produced from abandoned oranges.
Seville is essentially the world capital of oranges – more than 50,000 trees grow there and every year 5.7 million kg of oranges are harvested.
But the oranges growing in Seville are bitter and not suitable for eating. Previously, they were used as livestock feed, perfume production and for cooking.
Thirty-five tonnes are now being used to produce electricity. Juice is squeezed from the oranges and then allowed to ferment – the sugar it contains is used to produce biogas, the basis for producing electricity. Leftover peel is used for fertiliser.
For now, the energy is used to power Emasesa’s water purification plant, but within two years the company intends to send surplus power to the city’s grid. The project is expected to produce about 1,500 kWh of power – enough to meet the needs of 150 households.
A company experiment showed that 1,000 kg of oranges can produce 50 kWh of electricity – enough to power five homes for an entire day. And if all the oranges in Seville were used, the power produced could meet the needs of 73,000 households.
Spain has drafted a plan for transition of its electricity system to renewable sources by 2050, to achieve a carbon-neutral economy and to reduce greenhouse gas emissions by 90 % compared to 1990 levels.