## 3 Results and Discussion
### Policies and Standards Linked with the Energetic Use of Agricultural Waste in Ecuador
These high costs would increase biochar prices to the range of 600-900 USD/t, which is out of reach for farmers in low- and middle-income countries [67]. Patents and the payment of licenses linked with the use of complex pyrolysis equipment are mechanisms that give preferential access to state-of-the-art technology to countries in the Global North to the detriment of low- and middle-income countries in the Global South [68]. In this regard, open-source technology can play a key role in democratizing knowledge on carbonization processes and facilitating access in low- and middle-income countries to efficient, safe, and affordable designs of pyrolysis facilities. On an increasing scale of complexity, the Kontiki Kiln (a type of flame-curtain kiln [69]), the Cornell University Pyrolysis Retort [70], and the Pulpa-pyro Reactor [71] are open-source designs that can be fabricated locally and adapted for use in rural areas of middle-income countries. The Cornell University Pyrolysis Retort [70] and the Pulpa-pyro Reactor [71] satisfy the  
Figure 4: Tentative design of a pyrolysis process integrated into local processing centers. The heat generated by the combustion of pyrolysis gases is used to drive the carbonization process and to replace the fossil fuels that are currently used in mechanical drying. This complies with the selection criteria (Table 1). selection criteria (Table 1). Nonetheless, these open-source technologies can require significant engineering input to adapt the original designs that are optimized for the use of forest biomass as feedstock to the use of agricultural waste. Major modifications must be expected to be implemented considering the significant differences in the physicochemical properties of residual forest biomass and agricultural waste. Unlike wood chips or wood pellets, the low density of agricultural waste (e.g., coffee husks) may present the following problems: irregular feeding to the reactor, bridging in the storage facilities and hoppers, blockage of feeding valves or transporting systems, and unwanted secondary reactions in the feed line [72]. In this context, the consolidation of knowledge of carbonizations processes and skills in the handling and processing of agricultural waste among local practitioners and engineers can be a crucial factor for the successful and efficient integration of open-source designs of pyrolysis equipment in the rural sector of low- and middle-income countries. A pilot-scale pyrolysis experiment in Ecuador with a continuous reactor demonstrated the integrated use of pyrolysis gases as an energy source for the carbonization process [73]. This modular system integrates an auger-type reactor and has a starting biomass burner that uses agricultural waste as feedstock to initiate the carbonization process. Thereafter, the pyrolysis gas generated is burned to produce thermal energy and support the pyrolysis process, in agreement with the selection criteria (Table 1). This modular system has proven to be effective for the production of biochar from agricultural waste with both high density (i.e., palm oil kernel shell) and low density (i.e., coffee husk, quinoa husk, and quinoa stems) [29]. A complementary pilot-scale experience in Ecuador demonstrated the carbonization of residual biomass generated during the extraction of _latropha curcas_ (Barbados nut) oil using an electrically heated auger-type reactor [74]. In this case, the use of high-quality energy vector (i.e., electricity) to produce a low-quality energy vectors (i.e., heat to drive the carbonization processes) is detrimental to the energetic efficiency of the process. Furthermore, the high voltage required to supply the facility can restrict the implementation of this type of reactor in isolated rural communities with limitations in the supply of electricity and does not comply with Criteria 1, 3, and 4 (Table 1).