Exploiting Methane from Landfills for GenerationWed, 02/19/2014 - 09:12
Methane is 21 times more effective at preventing infrared radiation from escaping the planet than CO2, making it a far more dangerous greenhouse gas. However, it is far less prevalent than CO2 and has an atmospheric lifetime of just 12 years, versus between 50 and 200 years for carbon dioxide. Jorge Armando Gutiérrez Vera, President of Cogenera México, stresses that one of the main environmental challenges Mexico is facing is in avoiding the emission of biogas into the atmosphere as it is mainly made up of methane. The association has strongly recommended that SENER force landfill management teams to pump out the biogas and burn it to turn methane into CO2. “CO2 can be mitigated with trees. The best approach is to use biogas as a fuel for internal combustion engines and to produce electricity, but if that is not an option, the second best thing is to burn it,” says Gutiérrez Vera.
An example of generating electricity from a landfill can be found in Monterrey, where 16MW are being produced using the biogas that is pumped out from a landfill. Gutiérrez Vera explains how a similar concession exists to develop the same scheme in Bordo Poniente, the huge landfill near Mexico City Airport, which before it was closed in 2010, was the biggest landfill in Latin America. In Mexico most landfills are developed, built, financed, and operated by states or municipalities. In the case of the state of Nuevo Leon, the landfill is owned by a state government company from which in 2000 it launched an international bidding process and a successful partnership between the private and public sector was born.
Guascor began manufacturing diesel engines in 1966 and soon after created a complete range of gas engines. It was only logical that after 30 years, its first biogas engine came into operation. The company began working in Mexico in 2001 with a focus on cogeneration, but it also develops turnkey projects in biogas. Its signature project was done in the city of Saltillo for Lorean Energy. “When the project is complete, it will generate 3MW of electric power after having started with 1MW in the first phase. The consumption of the municipality of Saltillo for public lighting is around 4MW, so we will be providing 75% of the power needed for municipal lighting just by taking advantage of the residual biogas generated from waste,” explains Gerardo Pandal, Project Development & Renewable Energy Director of Guascor de Mexico. The municipality of Saltillo, which has a population of 800,000, saves over US$30,000 a month on its electricity bill with this project, which began operating in late 2013. Another representative project is a cogeneration project using biogas from the municipal water treatment facility of Leon, Guanajuato. Pandal explains it is an anaerobic plant that separates water from the residues, which then go to a large scale bio-digester. Prior to the project, the bio-digesters needed boilers that kept water temperature at 37°C, requiring a lot of energy. The plant used to burn LP gas, while additional energy was taken from the grid. Pandal stresses that using electricity to treat water is expensive in Mexico. Guascor reengineered the process so the water treatment plant could produce electricity with the biogas that resulted from the treatment in the bio-digesters. Currently, the project generates 21,000m3 of biogas daily, of which 66% is methane, which project produces 1.5MW representing 66% of the electricity consumed by the plant. The project was inaugurated in 2011 and represents a turning point for sustainability projects in Mexico for Pandal. “If we could implement these types of projects nationwide, the electricity needed for water treatment would be free and clean. We might not be able to generate all of Mexico’s required power but two thirds of the power could be supplied by the country’s own biogas potential. The operators would pay only for a third of the electricity,” says Pandal.
For Cogenera México, convincing SENER of the benefits of biogas is a priority. “The Energy Minister, Pedro Joaquín Coldwell, has to get in touch with the governors, while making an effort to convince landfill management to develop cogeneration schemes to extract the biogas and use it as a fuel for internal combustion engines. This will mean that less methane will be released into the atmosphere,” Gutiérrez Vera says. “In Monterrey, this was a real success as this energy was provided to the seven municipalities in the metropolitan area, resulting in important cost savings for public lighting, the subway system and the water system.” Pandal is very positive about the future of renewable energies in Mexico. “We could generate 40% Mexico’s electricity from renewable sources, while cogeneration could add 13% more. If we really pressed on with developing renewable energies and diversifying our energy sources, we could reach that scenario by 2020. However, the government has to simplify paperwork and let the private sector participate. We do not want to privatize the energy sector; we want to participate so we can reach 40% renewables and 13% CHP in the energy mix. This would bring stable prices and significant economic benefits for the country,” he adds.