Monterrey subway, operating on bioenergy
Monterrey subway, operating on bioenergy
David Cornejo, Tamara Muñoz and Laura Villahermosa

MEXICO CITY — Dr. Emmett Brown takes banana peels, leftover beer, and some other pieces of garbage from the trash to charge his car — a DeLorean equipped with the Mr. Fusion Home Energy Reactor. Although in this scene from the movie Back To The Future (1985), the technology was invented in 2015, energy generated from garbage can now be seen in real life, and right here in Latin America.

The system, called biodigestion or anaerobic digestion, generates electricity from gases produced by different organic materials. While Chile and Argentina have just discovered this type of energy source, Peru and Mexico have been using it for the past for 30 years. In fact, the Monterrey subway in northern Mexico operates with electricity from garbage.

In Andean countries such as Bolivia and Peru, close to 20% of the population does not have access to electricity, according to the Latin American Organization of Energy. Biodigesters could be a viable solution there. “They contribute to the economy and environment by reducing the environmental impacts of livestock and poultry,” says Sergio Luiz Pereira, Professor at the Business School of São Paulo.

Good as Gold?

There is a long tradition of biodigesters in Asia and Africa. There are currently 500,000 such generators installed worldwide. These biodigesters seem to be good business, given that they produce energy, reduce environmental damage, and create fertilizer rich in potassium, nitrogen, and phosphorus. “Besides, they eliminate methane, which is a partial cause of global warming,” adds Juan Jorge Hermosillo Villalobos, a specialist in renewable energies at ITESO in Mexico.

Considering the increasing waste in Latin America, both in legal and illegal landfills, using garbage as an energy source could help manage the related public health and urban planning problems. This would be a kind of “energy alchemy” in which organic waste feeds the productive cycles. “At the same time, it doesn't spark controversy like wind farms and are it's cheaper than other energy sources,” adds Beatriz Olivera, coordinator of energy efficiency at Greenpeace in Mexico. According to the international consulting company BiogasMaxx, the return on investment for biodigestors is approximately seven years.

But not all fertilizer is good as gold. There have been constant roadblocks in Latin America: The population isn't in the habit of using the biodigesters, there is scarce follow-up on projects, and national or regional planning are completely lacking. The first biodigesters were installed in the 1980s in the areas of Cajamarca and Arequipa in Peru to help small, agricultural communities. After a promising start, the project failed. “Many people were not interested. They even gave the biodigesters away,” says Fernando Acosta, a specialist in bioenergy at SNV World in Peru.

The key is to train people to use the biodigesters’ by-products and to continue to monitor the process. “It is a very simple technology, but at the first sign of trouble, they won’t know how to fix it. They must be taught how to use the gas and the fertilizer,” says Acosta. This is especially important because the products need to be handled with care. It takes minimal guidance to safely handle the biogas, which is mainly a mixture of CO2 and methane gas. “It also contains gases such as hydrogen sulfide, which can cause problems in the community if not handled properly,” explains María Teresa Varnero, Professor at the University of Chile.

There is also the cost issue. In Peru and Bolivia, where they are more wide-spread, there is a state subsidy for biodigestors. “A family biodigester is around $800 or $900 if it is made out of membrane. If it is made out of concrete, it can be around $100,000 dollars,” sayss Fernando Acosta. Without the subsidy, the costs are too high for a small farming community.

Climate variations in Latin America are another limitation to the widespread use of biodigesters in the region. Biogas production requires temperatures over 18 °C (64 °F). But this is a solvable problem. “Possible alternatives include using solar panels or biogas to mitigate temperature changes,” says Varnero.

These energy sources have more pros than cons, and are a viable alternative for Latin America. “Today, the possibility of opening up towards non-traditional, renewable energies like biodigesters is almost an obligation in the region,” emphasizes José Alejandro Martínez, Professor at the EAN University in Colombia. But what is the current state of biodigestors on the ground?

The Sound of Engines Running

Last May the Bethia Group, one of Chile's largest holding companies, inaugurated its first biodigester in San Carlos of Purén in southern Chile. The project cost $11 million and was heralded as a great innovation. But biodigesters are still absent from rural areas, where the government has primarily promoted solar ovens.

People in Latin America have seen energy made from garbage for the past three decades. It has been a way to conserve resources and protect the environment. Today, the best example of biodigesters in action is in Mexico. Since 2006, 80% of the Monterrey metro's electricity comes from biogas from the municipal landfill. The landfill's biodigester is 300 meters by 100 meters and is 10 meters deep, and generates most of the energy required to transport 470,000 people on a daily basis.

Latin America still has a long way to go to fire up bioenergy in the region. Then again, even if a car like the DeLorean doesn't exist just yet, the Monterrey subway comes pretty close.

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