A staple of Mexican landscapes and countless dishes, nopal — also known as prickly pear cactus — is now powering a tortilla plant and two vehicles in Michoacán.
It was 10 years ago that Rogelio Sosa López, a farmer and tortilla producer in Zitácuaro, Michoacán, and an associate, Antonio Rodríguez, began investigating cheaper sources of fuel and power generation, which represented Sosa’s biggest costs.
Using old equipment and a trial-and-error approach they began producing methane with nopal, reducing energy costs by between 40% and 50%, said Rodríguez, a former Pemex employee.
Now they have a two-hectare nopal plantation and a processing plant where a special machine liquefies the nopal. The resulting pulp is mixed in large tanks with water at 38 degrees C, “the right temperature for nopal to break down and release methane.”
Further treatment with sulphuric acid extracts carbon dioxide, giving the plant a 96% concentration of methane at a production rate of eight tonnes a day.
The complete process is sustainable, said Rodríguez, because it produces only water and nopal waste that is used to irrigate the plantation, and a fiber that can be used directly as fertilizer or added to compost.
Sosa’s and Rodríguez’ project, now a firm called Nopalimex, is the first in the world to produce biogas from the cactus.
Another inadvertent result of their investigation was that the methane could also be used to power motor vehicles.
Two have been running on nopal methane for two years at a cost of 10 pesos per liter. Come next year, the farmers turned fuel innovators plan to be ready to supply the fuel needs of vehicles owned by the Zitácuaro municipality, such as police patrol cars and ambulances.
In order to run on methane, the vehicles have to be modified with a small container tank, a vaporizer and a nitrogen container. In all, the ZItácuaro municipality will save 30% of its fuel costs during the first two years, said the mayor.
Sosa said the state government has also shown interest in further developing their project and investing in it, as has a Spanish firm that has even suggested international clients for the nopal methane.