Improving the production of biochar from green waste in Lima (January 2017)
The principal research site for the Peruvian component of the B4SS project is in Lurin on the southern fringe of Lima, which is the second largest mega-city in a hyper arid environment after Cairo in Egypt. Although the environment is extremely arid, much of Lima is built in the rich valleys that receive alluvial runoff from the Andes. It is estimated that Lima has 3m2 of green space per capita. Multiplying this by 9 million (a low estimate of Lima’s population), there should be at least 27 million m2 of green space in Lima. At present, only 3% of the biomass residues collected from this green space (grass clippings, branch prunings, etc.) is recycled; the rest is burnt or sent to landfill. Therefore, the B4SS in Peru has focused on the development of an approach for the efficient processing of this waste stream. Our local partners have been trialing a simple classification of green waste in which large trunks and branches are converted into BBQ charcoal, whereas grass clippings and small branches are converted into biochar.
The technique for efficiently converting trunks and large branches into BBQ charcoal (Figure 1) was developed by Eusebio Ocana (el gordo) who has been working for the B4SS in Peru producing biochar, establishing experimental trials and securing the biomass feedstocks. The B4SS in Peru has found the portable Kon-tiki reactors (Figure 2) to be extremely efficient for converting municipal green waste into biochar because little or no processing of the municipal green waste is required before feeding the feedstock into the Kon-tiki reactors. A life cycle assessment, however, is needed to quantify the potential economic and environmental benefits of the green waste strategy that the B4SS is developing for Peru.