One popular use for nopal, or prickly-pear cactus, is to boil it up and make a salad. Alternatively, you can ferment it and make some electricity.
That’s what an enterprising Mexico City firm is doing with some help from the city’s Secretariat of Science and Technology Innovation. They’re building a biodigester in the borough of Milpa Alta, using the waste from the nopal harvest.
Suema, short for Sustentabilidad en Energía y Medio Ambiente, develops projects to manage environmentally-friendly and sustainable solid-waste treatment systems.
One of those projects is a biogas plant that will produce electricity from organic waste through anaerobic digestion.
The treatment plant, which is mobile, has been set up at the nopal collection center in Milpa Alta, the most rural of Mexico City’s boroughs, whose economy is based on agriculture and food processing.
There doesn’t appear to be a shortage of solid waste from the processing of nopal. The collection center produces some 10 tonnes of the stuff every day. Not only will the nopal produce electricity, but what’s left over after the digester has done its work can be returned to the soil as fertilizer, plus the whole process will utilize a waste product that currently goes to, well, waste.
Furthermore, residual water will be used for irrigation.
The Milpa Alta plant is a pilot project the company hopes to replicate in markets such as La Merced and Jamaica where large quantities of organic waste are generated. The city seems to think it’s a good idea: it put up 10 million pesos (US $670,000) to help get it going.
The system is expected to be operating by September or October, when it will connect to the electrical grid as well as supply power for its own use.
Some 5,350 nopal producers will benefit, and 30 direct jobs will be created.
A Chilean engineer, Rodrigo Morales of Elqui Global Energy, estimates that an acre of cactus can produce, in biogas, the equivalent energy of 25,000 liters of diesel.