Sugarcane Renewable Electricity (SUCRE) Project Brazilian Biorenewable National Laboratory (LNBR) Brazilian Center for Research in Energy and Materials (CNPEM). The project was funded by the Global Environment Facility – GEF and implemented by the United Nations Development Program – UNDP in coordination with the Brazilian Ministry of Science and Technology Innovations and Communication – MCTIC.
PREFACE
The main goal of the SUCRE is to reduce greenhouse gas emissions through the increase of renewable electricity in the Brazilian national grid. Another important impact of the straw mulch is the water balance (infiltration, evaporation and runoff).
GOVERNANCE
UNDP represented the ownership of the project, chairing the BP and organizing its meetings at least once a year or at the request of one of the Parties. The Project Advisory Committee (PAC) provided political and technical advice and guidance through periodic meetings.
SUCRE RESULTS
Agricultural Systems
- Agronomic and Environmental Implications of Straw Removal
- Impacts on Soil Physical Quality
- Impacts on Soil Chemical Attributes
- Impacts on Soil Biological Attributes
- Impacts on Soil and Nutrient Losses by Erosion
- Soil Carbon Stocks and Greenhouse Gases Emissions
- Impacts on Sugarcane Yields
- Final Considerations on Impacts of Straw Removal
Removing straw did not affect soil acidity (pH and H+Al), while macronutrients were affected (Figure 2). Straw removal rates: total removal (TR), high removal (HR), low removal (LR) and no removal (NR).
Agronomic Routes for Straw Recovery
- Hay Harvesting (Route 1)
- Baling (Route 2)
- Integral Harvesting (Route 3)
- Integral Harvesting with Shredded Straw (Route 4)
- Costs, Energy and GHG Emissions in Recovery Routes
- Final Comments on Recovery Routes
For the configuration that recovers 50% of the available straw in the sugarcane field (Figure 26) there was an increase in cleaning efficiency of 67% (from 9% to 15%) using the chopped straw. Straw recovery can reduce nitrogen oxide (N2O) emissions, due to the degradation of straw remaining in the soil.
Industrial Processing
- Straw Handling and Storage
- Straw Processing
- Sugarcane Dry Cleaning Systems (DCS)
- Alternative Straw Processing Systems
- SUCRE’s Proposals for Straw Processing
- Evaluation of Sugarcane Straw and Bagasse Burning in Biomass Boilers
The bottleneck in the system is the low stability of the knives and the constant choking of the system. In the second method, the straw is chopped in an independent mill and then added to the bag on the conveyor belts (C2: Alternative 2). In the third, the straw is ground and mixed with a part of the bagasse produced using a stand-alone mill (C3: Alternative 3).
The use of a conventional milling system has been shown to be more effective than conventional shredders in reducing straw particle size. During the off-season tests, dirt/slag and corrosion samples were collected from different areas of the boiler. The results show considerable differences in the amount of straw used in the evaluated mills.
Elemental analysis of the fuels showed little variation in the concentrations of carbon, nitrogen and hydrogen between bagasse and straw. The total ash content of the straw was much higher than that found in bagasse.
Guidelines for Sugarcane Straw Removal
- Methodology
- Results
- Case Study: Applying the Step-by-Step Process for Sugarcane Straw Removal
- Conclusions and Comments
In parallel, a major literature review was conducted on the effects of straw removal on soil quality, greenhouse gas emissions and sugarcane biomass production. In addition, agroclimatic zoning of straw removal was performed to define relationships between climate conditions and straw management effects on sugarcane yield. Another important step in the development of the guidelines was the agroclimatic zoning of straw removal.
Climatic suitability is defined by considering the agro-climatic zoning of straw removal to classify areas according to their (iii) suitability for straw removal and (iv) solar radiation incidence. This decision tool is the "backbone" of the stepwise strategies for sugarcane straw removal. With the definition of thatch removal sensitivity, a potential map (IV) can be obtained, which consists of using a digital tool adapted to geotechnologies (GIS) to produce visual maps of the cultivated area.
Assessments and Tests from Case Studies
- Results and Discussion – Industrial Simulations for Straw Recovery
- Techno-economic Assessment – Assumptions and Results
- Environmental Assessment – Assumptions and Results
- Final Comments
In this case, the increased investment in the industry (mainly the dry cleaning system) is estimated and presented in Table 31. In the industry, the most important part of GHG emissions is related to the combustion of biomass in the boiler, about 70% of the emissions . Then, the scenario with straw recovery presents an increase in emissions in the industrial part due to the larger amount of biomass burning in the boiler.
Considering the integrated assessment (agricultural and industrial phase), the scenario with straw recovery shows lower emissions (Table 33), under the conditions of the assessed scenarios. Such avoided emissions take into account the difference between the carbon intensity (CI) of electricity produced from sugarcane in the two scenarios evaluated compared to electricity from natural gas, shown in Table 36. Furthermore, straw recovery can reduce GHG emissions mainly due to lower field N2O emissions and increased electricity production.
Customized Assessments
- A Custom Evaluation Using the Virtual Sugarcane Biorefinery (VSB)
- Main Lessons Learned from SUCRE Project
- Techno-economic and Environmental Assessment of Mill A
- Techno-economic and Environmental Assessment of Mill B
In this case, the incremental investment in the industry (mainly the dry cleaning system) was estimated at $3.59 million, according to the amount of straw recovered and delivered to the industry. The costs for sugarcane stalk and straw recovery in the evaluated scenarios are presented in Table 54. The cost of sugarcane stalk increases in scenario 1 due to the change in both harvested area and harvesting efficiency.
As can be seen, there is a region of stability that prevails in the selected ranges for sensitivity. This possibility has been explored due to the availability of such biomass in the context of sugarcane milling. Taking into account the possibilities of changes in the cost of eucalyptus chips and the price of electricity, a sensitivity analysis was carried out.
Country Level Environmental and Social Impacts
- Sugarcane Electricity: Potential Mitigation of GHG Emissions
- Social Effects of Sugarcane Electricity: Potential for Straw Recovery and Use
- Environmental Assessment: Beyond GHG Mitigation
However, it is also important to assess the potential social impacts of the additional technologies and processes required for straw processing and electricity generation. In addition, a significant proportion of the jobs created in sugarcane electricity generation are in the sugarcane farming sector, which is beneficial as it increases employment opportunities in rural areas. The main goal of the SUCRE project was to increase the supply of clean and affordable energy (SDG #7: Affordable and clean energy) while simultaneously reducing greenhouse gas emissions and thus contribute to mitigating climate change (SDG #13: Climate Action).
The data showed that 96% of the new sugarcane areas in the evaluated period did not cause direct deforestation. Another study that considered one of these two former basins showed that the total removal of straw left on the ground after sugar cane harvest had a slight negative impact on the flow of the basins occupied by large areas of sugar cane (Henzler et al., 2019). However, the simulations showed that the partial removal of straw does not change the flow pattern of the basin; part of the biomass can be removed from the ground for energy purposes without harming the availability of water in the basin.
Electric Sector Legal and Regulatory Framework
Generating plant location is not effectively compared from an economic point of view, nor are differences in price risks between submarkets. Underpricing the benefit of generation concentrated in the dry season | In 2019, 91% of the total sugarcane bioelectricity on the grid was supplied in the dry season, between April and November, with bioelectricity saving the equivalent of 15% of the total energy stored in Southeast/Central hydropower reservoirs. -Western submarket (UNICA, 2020). Furthermore, 75% of bioelectricity for the Brazilian Electricity Sector in 2019 was concentrated in months when the Tariff Flag System was in yellow or red (UNICA, 2020).
That is to say, the profile of bioenergy generation allows a greater efficiency in the use of resources, reallocating energy distribution throughout the period and resulting in a reduction of the risk of deficit without worsening the conditions of the water reservoir. It is almost equal to the annual electricity consumption of a country like Ireland, for example. However, we would begin to benefit from less than 20% of the technical potential of this generating source in 2030, demonstrating the possibility of a positive response that bioelectricity can provide to the expected expansion of the free market.
Dissemination of Information
- Calculator: The SUCRE Project’s Legacy in a Free Online Tool
- Data Storage and Traceability
- Dissemination Material
The “Data Management Plan of the SUCRE Project” aims to use and connect different data management and storage platforms depending on their specific characteristics. The “e-LN LIMS” system is the adaptation of an Enterprise Laboratory Platform, which will meet the different needs of the project. The technological solution of the software includes the functionalities of Laboratory Information Management System (LIMS) and Electronic Laboratory Notebook (ELN).
The full content of the SUCRE project is available on the LNBR website, from basic information about the project and work, to news and downloadable documents covering events, presentations, articles, references and tools. About 800 copies of each booklet were distributed at events and gatherings in the sugar cane sector. The project was featured in 12 publications on the Facebook profile of UNDP, the project's managing body together with LNBR/CNPEM.
FINAL COMMENTS AND CONCLUSIONS
Regarding the recycling route alternatives, the field tests in the partner mills enabled the SUCRE team to identify the two most developed commercial alternatives: baling and integrated sugar cane (straw is brought together with sugar cane and separated at the mill in a cleaning system). By playing with different values for the route parameters, the team selected the straw recovery rate (in t straw/ha), transport distance and operating efficiency of the equipment (h of effective operation per day) as the most important parameters that influence costs and environmental impacts and were decisive in determining the the best straw harvesting route for each individual case. In the former, the preferred solution chosen by the mills recovering and using straw was the rotary drum screen, and for the latter the straw grinder (either with knives or hammers).
The various units tested in the SUCRE revealed low efficiency in the former related to the. The main obstacles in the current Legal and Regulatory Framework for the expansion of the surplus power generation in the sugar energy sector have been identified with the help of UNICA and contracted external specialists. UNICA must continue its efforts for the improvements in the Brazilian energy sector's legal and regulatory framework, which is perhaps the most critical bottleneck for the expansion of renewable electricity generation by the Brazilian sugar energy mills.
Disponível em: http://www.epe.gov.br/sites-pt/publicacoes-dados-abertos/publicacoes/PublicacoesArquivos/publicacao-160/topico-168/. Disponível em: http://www.epe.gov.br/pt/publicacoes-dados-Abertos/publicacoes/balanco-energetico-nacional-2019. Perdas de solo e nutrientes por erosão em Argissolo com resíduos de cultura de cana-de-açúcar.
Análise de seis sistemas de coleta de palha na colheita mecânica de cana-de-açúcar. Análise de viabilidade técnica e econômica da coleta de palha de cana-de-açúcar após ração e colheita plena. Avaliação de perdas invisíveis em colhedoras de cana-de-açúcar picada e alternativas para reduzi-las.
