Power plant perspectives for sugarcane mills

doi:10.1016/j.energy.2009.02.004

Energy

Volume 34, Issue 5, May 2009, Pages 689-698

https://doi.org/10.1016/j.energy.2009.02.004 Get rights and content

Abstract

Biomass, integral to life, is one of the main energy sources that modern technologies could widely develop, overcoming inefficient and pollutant uses. The sugarcane bagasse is one of the more abundant biomass. Moreover, the fluctuating sugar and energy prices force the sugarcane companies to implement improved power plants. Thanks to a multiyear collaboration between University of Rome and University of Piura and Chiclayo, this paper investigates, starting from the real data of an old sugarcane plant, the energy efficiency of the plant. Furthermore, it explores possible improvements as higher temperature and pressure Rankine cycles and innovative configurations based on gasifier plus hot gas conditioning and gas turbine or molten carbonate fuel cells. Even if the process of sugar extraction from sugarcane and the relative Rankine cycles power plants are well documented in literature, this paper shows that innovative power plant configurations can increase the bagasse-based cogeneration potential. Sugarcane companies can become electricity producers, having convenience in the use of sugarcane leaves and trash (when it is feasible). The worldwide implementation of advanced power plants, answering to a market competition, will improve significantly the renewable electricity produced, reducing CO₂ emissions, and increasing economic and social benefits.

Section snippets

Biomass and sugarcane

Biomass, integral to life, is one of the main energy sources that modern technologies could widely develop, overcoming traditional and non-commercial uses: the challenge is in the correct management and sustainable conversion not in the availability [1].

From a chain point of view, biomass typologies can be divided into energy cultures and residues. The residues, if used in situ, are subjected only to the last three part of the biomass chain (pre-treatment, conversion, and end use) entailing

The case study: a typical Peruvian sugar power plant

The case study refers to Pucalá plant situated near Chiclayo city, Department of Lambayeque, in the north coast of Peru. The sugarcane plant has a capacity of 200 t/h (i.e. 4800 t_cd (tonnes crushed per day)), a medium–large-size plant [6], [7], [8], [9], [10], [11].

During 2003 the company had 2500 employees, cultivated 11,437 ha, produced 914,975 t_cm (tonnes of cane milled) and 89,030 t of raw sugar (114 t of cane per hectare (t_c/ha), 80 t of cane milled per hectare (t_cm/ha) and 7.78 t of sugar

The standard cogenerative power plant

Upgrading the steam cycle (using the technical data of actual standard steam generators, e.g. two Thermax Babcock & Wilcox Limited, travelling grate, membrane walled, with screw feeder and pneumatic distributor, bagasse/coal/biomass fired boiler with a capacity of 90 t_cm/h, and a production of steam of 88 bar and 515 °C and a boiler efficiency guaranteed of 70.56% on bagasse, installed in Kakatiya Cement Sugar & Industries Ltd. in 2002) the electric power produced, is greater than the current

The gas turbine cogenerative power plant

The gasification allows obtaining a fuel gas suitable for the higher temperature Brayton cycles. Efficiency and reliability of gasification systems has been a priority, among others, during all of European Commission research programs (18 projects supported in the Fifth Framework Programme, specific calls in the FP6). The status of gasification has been reviewed recently from EC, USA, IEA [14], [15], [16], [17]. “A careful analysis of these reviews shows that there are still two main problems:

The fuel cells cogenerative power plant

Moreover to increase the electricity generated, an innovative configuration where a high-temperature fuel cell (BIGFC: biomass integrated gasification with fuel cells power plant) replaces the gas turbine is analysed. The fuel cells overcame the Carnot's theorem avoiding negative entropy increase associated with the combustion necessary for gas turbines. Molten carbonate fuel cells (MCFC) are considered as the more appropriate technological choice because of: use of hydrogen and carbon monoxide

Cost analysis of the plant

The global costs of the power plant are estimated taking into account the data (€/kW, etc) of similar power plants [8], [10], [14], [18], [23], [26], [28], [29], [31], [32], [33], [34] and the following assumptions: power plant life of 20 years, 6000 h mean operational hours, and 5% internal rate. It has been considered a capital cost of gas turbine and fuel cells power plants of 3000 and 5000 €/kW, respectively.

Usually big size plants have lower cost per kW. The higher costs of this plant are

Conclusions

On the back of high energy prices, the global sugar industry will make significant investment to modernise their operations. The power production potential through bagasse cogeneration has yet to be fully exploited in the sugar industry, and very high yield can came out from new power plant configurations and technologies.

Sugarcane companies can become electricity producers, having convenience also in the use of sugarcane leaves and trash (when it is feasible). Table 11 shows the electric kWh/t

Acknowledgements

The authors acknowledge the kind support of the Industrial Pucala S.a.c., the University of Santo Toribio de Mogrovejo in Chiclayo, and the University of Piura in Piura.

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Modeling and techno-economic analysis of a hybrid sugarcane plant fed by vinasse biogas and bagasse surplus for electricity generation
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The growing demand for electricity from renewable energy sources has motivated sugarcane producers to improve the power generation capacity of their plants. In this regard, the present work aims to contribute to the energy recovery process from two sugarcane byproducts: bagasse and vinasse. A novel hybrid combined cycle is devised to use the bagasse surplus generated during the sugarcane season to produce high enthalpy steam for a dedicated condensing turbine. A gas turbine, fed by vinasse biogas vinasse, is used to provide thermal energy to the steam bottoming cycle. Concomitantly, steam for the sugar and ethanol is produced by the existing sugarcane cogeneration system. This approach allows to increase the plant's electricity generation. From a prescribed milling capacity, a conventional sugarcane plant is modeled and validated at steady-state regime. Then, a hybrid plant, designed to consume the bagasse surplus and the vinasse biogas, is presented, and compared to the conventional plant. During the off-season, in the absence of vinasse and biogas, an off-design option is proposed to keep the system running full-time. Results showed that the hybrid plant electricity generation (kWh_el) is 7.2–41.5% higher than the conventional plant. The economic feasibility of retrofitting a typical sugarcane plant (live steam parameters at 68 bar/480 °C, for example), by means of a hybrid combined cycle, points to an internal rate of return of around 22.3% and payback period of 5 years. A parametric analysis was carried out showing that, for a process steam consumption below 540kg of steam per tons of sugarcane milled, there will always be leftover bagasse of the season, regardless of the conventional plant steam profile. The production of vinasse required for the hybrid system ranges from 310 to 375 L by tons of sugarcane milled (TC), values within the range of existing sugarcane plants (156–910 L/TC). In addition, the plant operating time can be extended in the off-season, from 200 to 330 days per year, with electrical efficiency achieving around of 27% in this period. In conclusion, the proposed system moves towards the advancement of clean and sustainable electricity generation in the sugarcane industry.
Strategies to improve the environmental efficiency and the profitability of sugarcane mills
2021, Biomass and Bioenergy
The Brazilian sugarcane industry is relevant in the country since the colonial period. Nowadays, there are sugarcane mills all over Brazil in a number over 350, which are responsible for generating jobs for the population and valuable products for the society. The development of this industry was is mostly due to governmental incentives, through several mechanisms. The last governmental program that aimed to boost ethanol production was the RenovaBio program. This program aimed to help the country to reduce greenhouse gas emissions by 2030. Moreover, the RenovaBio also collaborates economically for the development of the ethanol industry by creating a new product, the decarbonization credit (CBio). This aspect is interesting because it provides a new possibility to increase ethanol company's profits. Additionally, it shows that through improving process efficiency in all of the production steps (from agriculture up to product distribution) with positive impacts on environmental it is possible to increase profits. In this review, it will be discussed the potential of the CBio market and also suggestions to optimize ethanol and to increase ethanol production, reduce costs and improve environmental efficiency.
Techno-economic analysis of a hybrid combined cycle applied to sugarcane plants
2020, Energy Conversion and Management
Citation Excerpt :
Results have shown that, for a natural gas mixing ratio between 15 and 20%, co-firing these two fuels in GT is a good choice in terms of the power plant efficiency. Bocci et al. [32] carried out a case study at a sugarcane mill in Peru. The authors evaluated the use of gasifiers, GT and molten carbonate fuel cells.
Hybrid combined cycles, fueled by natural gas and biomass, have been present in several power plants. As shown by different authors, it is possible to increase the overall efficiency of these plants by means of waste heat recovery from exhaust gases of gas turbines. The main disadvantage, for some cases, is the higher natural gas consumption, making some plants economically unfeasible. The present work applies the concept of a novel hybrid combined cycle (HCC), adapted for sugarcane mills, burning sugarcane bagasse and natural gas. In order to evaluate the potential of application of this concept, a new hybrid configuration, starting from an existing plant, is proposed. A thermodynamic performance study has shown an electrical efficiency improvement (from 6.8% to 17.8%) for the same amount of bagasse originally burnt, thus allowing the plant to operate throughout the year, increasing the electricity generation (from 108.9 to 323.0GWh_el) as well as meeting the same steam demands for sugar and ethanol production processes. The economic evaluation, considering investments, operating expenses and plant requisites, has pointed to an internal rate of return (IRR) of 22.89%. Furthermore, this new configuration does not depend on a large natural gas consumption (gas share of 11.4%), making the plant’s economic feasibility less dependent on fluctuations of natural gas prices. Finally, a sensitivity analysis of four different hybrid plants have shown the techno-economic feasibility of hybrid combined cycles applied to sugarcane mills, including during the off-season period.
Exergy analysis of a grid-connected bagasse-based cogeneration plant of sugar factory and exhaust heat utilization for running a cold storage
2019, Renewable Energy
In this study, energy and exergy analysis of a 16 MW cogeneration plant of a sugar factory located in India is carried out. Bagasse leaving the mills with 50% moisture is fed directly into the boiler as fuel. Maximum energy loss (23.021%) as well as maximum exergy destruction (68.219%) is found in the boiler furnace. The fuel moisture alone accounts for 11.89% energy loss due to the absorption of huge portion of combustion heat for its vapourization. Therefore, the effect of reducing bagasse moisture content on this analysis is examined through computer simulation. Reducing moisture content of bagasse from 50% to nil would increase the power output, the cogeneration energy efficiency and the cogeneration exergy efficiency by 3597 kW, 3.66% and 3.02% respectively. It is also found that 6.342% of fuel energy is lost through the exhaust gases. To utilize a portion of this waste heat, a vapour absorption refrigeration system is integrated with the considered plant. It is found that the proposed cooling system would produce a refrigerating effect of 594.714 TR with a COP of 0.721 and can, therefore, be used for preserving large quantities of vegetables in a cold storage.
Prediction of the fibre content of sugarcane stalk by direct scanning using visible-shortwave near infrared spectroscopy
2019, Vibrational Spectroscopy
Knowledge of the fibre content in sugarcane stalks is important for breeding programmes and non-destructive measurements for its applications. This study aimed to use portable visible-shortwave near infrared (Vis/SWNIR) with a wavelength range of 570–1031 nm to evaluate the fibre contents of cane stalks. Fibre models were established by partial least squares (PLS) regression using spectra obtained from interactance mode with an absorbance unit of log (1/R). The models were constructed using a sample set of three sample sections (i.e., bottom, middle, and top of the sugarcane stalk). The samples were scanned with different integration times (200, 300, and 400 ms), and the spectra were pre-treated using different pre-processing techniques. The fibre content models were established based on both combined sample sections (CSS model) and individual sample sections (ISS model) obtained from the combination of three sample sections and an individual sample section, respectively. The results showed that the models that were developed using raw spectra with integration time of 300 ms had the best performance. This model had coefficients of determination of the prediction set (r²) of 0.75, 0.81, 0.81 and 0.71 and root mean square errors of prediction (RMSEP) of 0.81, 0.63, 0.80 and 0.73%fibre for the CSS model and bottom section, middle section, and top section of the ISS model, respectively. These results indicated that the models could be used for screening. Moreover, it was observed that the bottom section model had the lowest RMSEP. The model can be used as a rapid protocol for predicting the fibre content of sugarcane stalks, making it a useful method for a breeder to screen the fibre content in the field when monitoring during breeding programmes.
Sugarcane bagasse cogeneration in Belize: A review
2018, Renewable and Sustainable Energy Reviews
Citation Excerpt :
Furthermore, a Peruvian plant in the north coast of Peru was studied by Bocci et. al. by analyzing plant data in tandem with global power plant data to investigate energy efficiency [32]. The authors put forth a comprehensive analysis of power plant perspectives for sugarcane mills.
Sugarcane is the most important crop for the economy of Belize. Sugar is Belize's largest contributor to the agricultural sector with exports approximating US$70,000,000 for the year 2015. The biomass residue from the sugar production process, bagasse, is used to generate electricity through cogeneration. The single cogeneration plant in the country contributes about 15% of electricity to the national grid. Belize currently imports about 42% of its electric energy needs from Mexico, and to date, this is the country's most reliable energy source. With energy needs of the country projected to rise at a rate of 4% per annum, and with the costly import of energy, there exists the need to explore the expansion of co- generation energy technologies to increase local energy generation output to the national grid. The current work reviews the state of bagasse cogeneration in Belize and assess its potential for further expansion.

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Power plant perspectives for sugarcane mills

Abstract

Section snippets

Biomass and sugarcane

The case study: a typical Peruvian sugar power plant

The standard cogenerative power plant

The gas turbine cogenerative power plant

The fuel cells cogenerative power plant

Cost analysis of the plant

Conclusions

Acknowledgements

Energy

Applied Thermal Engineering

Applied Thermal Engineering

Biomass and Bioenergy

Applied Thermal Engineering

Biomass and Bioenergy

Fuel

Biomass and Bioenergy

Journal of Power Sources

Biomass and Bioenergy

Journal of Power Sources

Journal of Power Sources

Biomass and Bioenergy

International Journal of Hydrogen Energy