Brazil has been actively taking advantage of the Clean Development Mechanism program. The country, which is responsible for developing the concept of CDMs, undertakes more CDM projects than any other Latin American country; globally only China and India have more. Their projects run the gambit, ranging from fueling garbage trucks with used vegetable oil in Rio to decentralized hydropower projects, the majority being in energy production from biomass. In 2008, 22 percent of their projects have specifically focused on capture of methane from waste.
In a country that is home to over 16 percent of the world’s cattle, and where agribusiness makes up 36 percent of GDP, it may be tempting to conclude that much of the methane capture projects are focused around livestock; however, the majority of these projects are actually capturing methane from landfills. In 2008, only 6 percent of all CDM projects were methane capture from non-landfill sources, despite the fact that landfills are responsible for only 3 percent of Brazil’s methane emissions.
Likely contributing to the low number of projects is the fact that Brazil has tried biogas in the past. Throughout the 1970s and 1980s, the federal government offered incentives for the installation of biodigesters, leading to hundreds of them being installed. Poorly chosen materials, upkeep issues, and lack of adequate technical instruction led to the majority of the digesters being left unused.
Strangely, the majority of biogas projects currently in Brazil focus on production from pig waste rather than cattle. Studies have found that, as part of CDM projects, biogas produced from large hog operations is an economically viable option, especially if the biogas is used to produce electricity that is then sold, or used to reduce costs.
Turning pig manure into biogas may not be as effective for mitigating methane as developing similar techniques with cattle, however, the production of biogas from pig manure has very positive effects on the environment. High concentrations of manure in runoff from pig farms causes eutrophication in waterbodies, which allows for the proliferation of algae; it is for that reason that many hydroelectric damns have recently recently embraced biogas.
One of the longest running biogas projects from pig manure is run by Carroll’s Foods do Brasil in the state of Mato Grosso. The project uses the manure produced by 12,500 sows, at two different confined animal feed operation sites–one of the sites, Diamantino I, accounts for 11,000 sows and is the largest pig farm in Brazil. Both sites run off electricity generated from the biogas they produce, and both sell excess electricity to the grid. The project has proven to be economically viable, producing an annual net gain of 500,000 USD, accounting for maintenance, electricity savings, and electricity sales. The project is estimated to reduce 75,000 MTCO2 emissions per year.
While biogas is an economically viable approach for lowering emissions and reducing pollution from manure run-off, electricity from biogas should be put into perspective. If all the pig manure in the state of Rio Grande do Sul was used to produce biogas, the electricity generated would amount to 250 GWh annually, only 1 percent of Rio Grande do Sul’s annual electricity needs.