Optimizing ethanol and bioelectricity production in sugarcane biorefineries in Brazil

In sugarcane biorefineries, the lignocellulosic portion of the sugarcane biomass (i.e. bagasse and cane trash) can be used as fuel for electricity production and/or feedstock for second generation (2G) ethanol. This study presents a techno-economic analysis of upgraded sugarcane biorefineries in Brazil, aiming at utilizing surplus bagasse and cane trash for electricity and/or ethanol production. The study investigates the trade-off on sugarcane biomass use for energy production: bioelectricity versus 2G ethanol production. The BeWhere mixed integer and spatially explicit model is used for evaluating the choice of technological options. Different scenarios are developed to find the optimal utilization of sugarcane biomass. The study finds that energy prices, type of electricity substituted, biofuel support and carbon tax, investment costs, and conversion efficiencies are the major factors influencing the technological choice. At the existing market and technological conditions applied in the upgraded biorefineries, 300 PJ y⁻¹ 2G ethanol could be optimally produced and exported to the EU, which corresponds to 2.5% of total transport fuel demand in the EU. This study provides a methodological framework on how to optimize the alternative use of agricultural residues and industrial co-products for energy production in agro-industries considering biomass supply chains, the pattern of domestic energy demand, and biofuel trade.     

Natural-gas-powered thermoelectricity as a reliability factor in the Brazilian electric sector

The introduction of natural-gas-powered thermoelectricity into the Brazilian generation sector can be considered as a very complex energy, economic, regulatory and institutional revision. Brazil is a country with very specific characteristics in electricity generation, as approximately 80% of the generating capacity is based on hydroelectricity, showing strong dependency on rain and management of water reservoirs. A low rate of investment in the Brazilian Electricity Industry in the period of 1995–2000, associated with periods of low rainfall, led to a dramatic lowering of the water stocks in the reservoirs. With this scenario and the growing supply of natural gas, both from within Brazil and imported, natural gas thermal electric plants became a good option to diversify the electrical supply system. In spite of the Brazilian Government's efforts to install such plants, the country was faced with severe electricity rationing in 2001. The objective of this work is to show the need to continue with the implementation of natural gas thermal electricity projects, in a manner that allows flexibility and guarantees greater working reliability for the entire Brazilian electricity sector. Taking into account the world trend towards renewable energy, the perspectives of usage of biofuels in the Brazilian Energy Matrix and in electrical energy generation are also analyzed. The very issue of electrical power efficiency in Brazil and its challenges and strategic proposals from the standpoint of Government Programs and results provided so far are presented. The technological constraints in order to put on stream the thermal electric plants are also analyzed. The article concludes with a positive perspective of the usage of natural gas as to be the third pillar in the Brazilian Energy Matrix for the years to come.     

Influence of biomass waste from agro-industries on obtaining energetic gases assisted by chronoamperometric process

The generation of energy by thermoelectric plants powered by biomass in Brazil has grown by ～3% in the last three years. In 2016, 8.8% of the electric energy in Brazil was generated using biomass as an input. However, the generation of residues and the possibility of reapproaching have motivated the planning and uses of electrochemical processes to evaluate the obtained gases (mainly hydrogen and carbon monoxide) as clean energy sources. Although thermochemical processes using biomass as an energy source already exist, few reports regarding the study of this process through electrolysis are available. Herein, we describe a water electrolysis process using sugarcane bagasse, rice husk, and malt bagasse as biomass residues to obtain gases with potential uses as clean energy sources and analyze the mass concentration influences on the behavior of the electrochemical solution. Tafel and cyclic voltammetry analyzes showed a tendency to decrease the kinetics and current of the system with the increase of the biomass residue concentration in the solution. In contrast, sugarcane bagasse concentrations of 0.1%–1% increase the current. The faradaic efficiency and partial current density analysis confirm the results obtained from cyclic voltammetry for hydrogen production, with less faradaic efficiency for hydrogen and reduced current values in the system when the biomass residue concentration is higher. The production efficiency of carbon monoxide formed at the anode increases with the concentration for sugarcane bagasse (2.01–5.21 μA/cm²) with 1% of the biomass in solution.     

Life cycle assessment and life cycle costing of bioethanol from sugarcane in Brazil

Brazil has always been the pioneer in the application of bioethanol as a main fuel for automobiles, hence environmental and economic analyses of the Brazilian ethanol industries are of crucial importance. This study presents a comparative life cycle assessment (LCA) on gasoline and ethanol as fuels, and with two types of blends of gasoline with bioethanol, all used in a midsize car. The focus is on a main application in Brazil, sugarcane based ethanol. The results of two cases are presented: base case—bioethanol production from sugarcane and electricity generation from bagasse; future case—bioethanol production from both sugarcane and bagasse and electricity generation from wastes. In both cases sugar is co-produced. The life cycles of fuels include gasoline production, agricultural production of sugarcane, ethanol production, sugar and electricity co-production, blending ethanol with gasoline to produce E10 (10% of ethanol) and E85 (85%), and finally the use of gasoline, E10, E85 and pure ethanol. Furthermore, a life cycle costing (LCC) was conducted to give an indication on fuel economy in both cases. The results show that in the base case less GHG is emitted; while the overall evaluation of these fuel options depends on the importance attached to different impacts. The future case is certainly more economically attractive, which has been the driving force for development in the ethanol industry in Brazil. Nevertheless, the outcomes depend very much on the assumed price for crude oil. In LCC a steady-state cost model was used and only the production cost was taken into account. In the real market the prices of fuels are very much dependent on the taxes and subsidies. Technological development can help in lowering both the environmental impact and the prices of the ethanol fuels.     

Improving bioethanol production from sugarcane: evaluation of distillation, thermal integration and cogeneration systems

Demand for bioethanol has grown considerably over the last years. Even though Brazil has been producing ethanol from sugarcane on a large scale for decades, this industry is characterized by low energy efficiency, using a large fraction of the bagasse produced as fuel in the cogeneration system to supply the process energy requirements. The possibility of selling surplus electricity to the grid or using surplus bagasse as raw material of other processes has motivated investments on more efficient cogeneration systems and process thermal integration. In this work simulations of an autonomous distillery were carried out, along with utilities demand optimization using Pinch Analysis concepts. Different cogeneration systems were analyzed: a traditional Rankine Cycle, with steam of high temperature and pressure (80 bar, 510 °C) and back pressure and condensing steam turbines configuration, and a BIGCC (Biomass Integrated Gasification Combined Cycle), comprised by a gas turbine set operating with biomass gas produced in a gasifier that uses sugarcane bagasse as raw material. Thermoeconomic analyses determining exergy-based costs of electricity and ethanol for both cases were carried out. The main objective is to show the impact that these process improvements can produce in industrial systems, compared to the current situation.     

A mathematical,economic and energetic appraisal of biomethane and biohydrogen production from Brazilian ethanol plants' waste: Towards a circular and renewable energy development

The high production of sugarcane in Brazil and its application of ethanol and sugar production results in a higher generation of vinasse and bagasse. The treatment of these residues can be carried out using anaerobic co-digestion procedures. Besides promoting waste treatment, it enables energy exploration through biogas and hydrogen generation. Bioenergy use can also generate steam in sugar and alcohol plants by burning, sugarcane milling, fueling vehicles for the transport of products, among others. These energy applications allow total and efficient, energetic exploring of sugarcane. Hence, this study estimated the production of methane, hydrogen, thermal and electrical energy generated from vinasse and bagasse in the autonomous and annexed Brazilian ethanol and sugar plants. Three scenarios present the use of biogas generated: Scenario 1: energy use of all methane from biogas; Scenario 2: hydrogen production from the remaining methane, after considering the energy autonomy of the ethanol plants; Scenario 3: hydrogen production from all the methane generated. All the scenarios which considered the use of methane led to energy self-sufficiency in the sector. However, only annexed plants present economic feasibility for implementing the project. Scenario 2 is highlighted in this study, once beyond the sector's energetic self-sufficiency, the operational conditions enabled the storage of 9.26E+07 Nm³.d^?1 of hydrogen, equal 3.04E+08 ton per year. CH₄ and H₂ production seen in a global scenario of circular economy and energy security have high benefits, contributing to the gradual transformation of an economy dependent on non-renewable resources into a circular and renewable economy.     

Household consumption of electricity in Brazil between 1985 and 2013

This article describes the electricity consumption in Brazilian residences between 1985 and 2013 through linear regressions. The explanatory variables considered were the number of households, effective consumption of families as a proxy for family income, and electricity tariff for households. To deal with the power generation crisis of 2001 we have introduced a dummy variable in the form of a step function. With such explanatory variables, we were able to account for the reduction of household electricity consumption caused by the policies conducted in 2001 and their permanent consequences. The regression presented coefficient of determination of 0.9892, and the several statistic tests conducted assured the existence of long-term relation between the electricity consumption in residences and the explanatory variables. The obtained elasticities for the household consumption of electricity with respect to number of residences, family income and residential tariff of electricity were 1.534±0.095, 0.189±0.049, and −0.230±0.060, respectively. These results allowed understanding the evolution over time of the household consumption of electricity in Brazil. They suggest that the electric sector in Brazil should pursue an active policy to manage demand of residential electricity using tariffs as a means to control it.     

Supercritical steam cycles and biomass integrated gasification combined cycles for sugarcane mills

Back in 1970s and 1980s, cogeneration plants in sugarcane mills were primarily designed to consume all bagasse, and produce steam and electricity to the process. The plants used medium pressure steam boilers (21 bar and 300 °C) and backpressure steam turbines. Some plants needed also an additional fuel, as the boilers were very inefficient. In those times, sugarcane bagasse did not have an economic value, and it was considered a problem by most mills. During the 1990s and the beginning of the 2000s, sugarcane industry faced an open market perspective, thus, there was a great necessity to reduce costs in the production processes. In addition, the economic value of by-products (bagasse, molasses, etc.) increased, and there was a possibility of selling electricity to the grid. This new scenario led to a search for more advanced cogeneration systems, based mainly on higher steam parameters (40–80 bar and 400–500 °C). In the future, some authors suggest that biomass integrated gasification combined cycles are the best alternative to cogeneration plants in sugarcane mills. These systems might attain 35–40% efficiency for the power conversion. However, supercritical steam cycles might also attain these efficiency values, what makes them an alternative to gasification-based systems. This paper presents a comparative thermoeconomic study of these systems for sugarcane mills. The configurations studied are based on real systems that could be adapted to biomass use. Different steam consumptions in the process are considered, in order to better integrate these configurations in the mill.     

Alternative energy sources in the Amazon

This paper discusses the evaluation of energy potential of palm oil for the generation of electricity in isolated communities. In Brazil, the energy sector culture has historically been directed almost exclusively toward major projects geared to meet the demands of those sectors of society that have the greatest economic and political influence. Prioritizing industrialization and an accelerated urbanization, they have oriented the national energy system toward centralized production of enormous blocks of energy adapted to meet major urban concentration consumption but incapable of satisfying the needs of a large part of the population that inhabits the rural areas. These small- and medium-sized communities are sometimes isolated from the developed urban centers and not connected to the conventional electricity networks. In this scenario, the Amazon region stands out due to its huge territorial extension and low demographic density, which is scattered among islands and other locations not easily accessible. As a rule, these areas lack electricity, and, when they do have it, supply is precarious and provided through fossil fuels for electricity production     

Comparative analysis for power generation and ethanol production from sugarcane residual biomass in Brazil

This work compares the technical, economic and environmental (GHG emissions mitigation) performance of power generation and ethanol production from sugarcane residual biomass, considering conversion plants adjacent to a sugarcane mill in Brazil. Systems performances were simulated for a projected enzymatic saccharification co-fermentation plant (Ethanol option) and for a commercial steam-Rankine power plant (Electricity option). Surplus bagasse from the mill would be used as fuel/raw material for conversion, while cane trash collected from the field would be used as supplementary fuel at the mill. For the Electricity option, the sugarcane biorefinery (mill+adjacent plant) would produce 91 L of ethanol per tonne of cane and export 130 kWh/t of cane, while for the Ethanol option the total ethanol production would be 124 L/t of cane with an electricity surplus of 50 kWh/t cane. The return on investment (ROI) related to the biochemical conversion route was 15.9%, compared with 23.2% for the power plant, for the conditions in Brazil. Considering the GHG emissions mitigation, the environmentally preferred option is the biochemical conversion route: the net avoided emissions associated to the adjacent plants are estimated to be 493 and 781 kgCO₂eq/t of dry bagasse for the Electricity and Ethanol options, respectively.     

Extended sugarcane biomass utilisation for exportable electricity production in Mauritius

The availability and exportable electricity-production potential of bagasse and sugarcane residues are estimated for various technologies which determine steam production and utilisation at cogenerating sugar factories. Almost 565 kg of fibrous sugarcane biomass (expressed as kilogrammes of bagasse at 50% moisture) are potentially available for exportable electricity production for every tonne of cane milled. A “bagasse proper only” strategy would utilise 28% of the fibrous cane biomass and can potentially produce between 60 to 180 kW h of electricity per tonne of millable cane. Use of cane tops and leaves as a bagasse extender would utilise another 32% of the sugarcane biomass and the electricity output could range between 146 and 401 kW h/t of millable cane. The extreme case where 100% of the fibrous sugar cane biomass is utilised has the potential of producing up to 678 kW h/t of millable cane.     

Sustainable expansion of electricity sector: Sustainability indicators as an instrument to support decision making

The aim of this paper is to put forward a proposal for a methodology to analyze the sustainability of the expansion of electricity generation. To do so, an approach is needed that takes into account, in an integrated perspective, the technical, socioeconomic, environmental and technological factors of the various alternatives for sector expansion. In this regard, multicriteria analysis (MCA) is proposed as an evaluation tool. It will be applied to a situation that involves the selection of the following expansion alternatives: small hydropowers, wind energy, generation from sugarcane bagasse, biodiesel, urban solid wastes, natural gas and nuclear energy. The methodology involved the development of indicators encompassing technological, environmental social and economic dimensions, for each of the aforementioned expansion alternatives, and the results were very interesting, from a multicriteria point of view, in their capacity to internalize socioenvironmental, technological and economic aspects in the decision making process for electricity generation expansion. It may well prove to be a useful tool for supporting this decision, although efforts are required to standardize the methodology with regard to its evaluation procedures.     

Life-cycle greenhouse gas emissions and energy balances of sugarcane ethanol production in Mexico

The purpose of this work was to estimate GHG emissions and energy balances for the future expansion of sugarcane ethanol fuel production in Mexico with one current and four possible future modalities. We used the life cycle methodology that is recommended by the European Renewable Energy Directive (RED), which distinguished the following five system phases: direct Land Use Change (LUC); crop production; biomass transport to industry; industrial processing; and ethanol transport to admixture plants. Key variables affecting total GHG emissions and fossil energy used in ethanol production were LUC emissions, crop fertilization rates, the proportion of sugarcane areas that are burned to facilitate harvest, fossil fuels used in the industrial phase, and the method for allocation of emissions to co-products. The lower emissions and higher energy ratios that were observed in the present Brazilian case were mainly due to the lesser amount of fertilizers applied, also were due to the shorter distance of sugarcane transport, and to the smaller proportion of sugarcane areas that were burned to facilitate manual harvest. The resulting modality with the lowest emissions of equivalent carbon dioxide (CO_2e) was ethanol produced from direct juice and generating surplus electricity with 36.8 kgCO_2e/GJ_ethanol. This was achieved using bagasse as the only fuel source to satisfy industrial phase needs for electricity and steam. Mexican emissions were higher than those calculated for Brazil (27.5 kgCO_2e/GJ_ethanol) among all modalities. The Mexican modality with the highest ratio of renewable/fossil energy was also ethanol from sugarcane juice generating surplus electricity with 4.8 GJ_ethanol/GJ_fossil.     

Key prospects and major development of hydrogen and bioethanol production

Cheap Production of bioethanol from renewable lignocellulosic waste has the imperative potential to economically cut burgeoning world dependency on fossils while reducing net emission of carbon dioxide (CO₂), a principal greenhouse gas (GHGs). This paper highlights key benefits and status of bioethanol production technologies, aiming mainly on recent developments and its key potentials in Pakistan. Most sector of Pakistan economy heavily rely on the energy and power that is being produced using traditional approaches like from oil and hydel. However, the sedimentation in dams cut-down the energy generation and overwhelmed severe energy crisis that are witnessed since last decade. Thus, Pakistan must go to avail alternative sources of energy like hydro, biomass and solar so that energy security can be ensured to recover the tremendous loss of economy. Renewable biomass is abundantly available in Pakistan which can be used to produce bioethanol and electricity. Currently, 22 distilleries are producing the ethanol from sugar cane bagasse and out of these only 8 distillation units are producing motor fuel grade ethanol. The current bioethanol production of country is about 403,500 tons/year along with 2423 tons of biodegradable waste available in major cities. In addition, Pakistan produces 6.57, 0.5, 0.66, and 2.66 million tons of sugarcane, corn, rice, and wheat straw per annum, respectively. This biomass can produce 1.6 million liters of bioethanol which can produce approximately 38% of Pakistan's electricity annually. Despite having large potential, Pakistan is still producing a few volumes of ethanol from sugarcane bagasse. The production of bioethanol can be boosted using (I) pretreatment of agricultural biomass by alkali (II) enzymatic and bacteria-based hydrolysis of the biomass (III) post-hydrolysis using pressurized steam above 100 °C (IV) Fermentation of the biomass@ 7–10 h and (V) and (VI) distillation of bioethanol. This study recommends (1) increase R&D capacities mainly in the west and central regions of Pakistan, (2) initiate mega-projects to promote integrated bio-ethanol production at agriculture farms by providing 1/3 subsides, (3) purchase of bioethanol directly from the major agricultural farms, (4) produce bioethanol related manpower from the key research institutes as specified in this study.     

Relationship between the economic cost and the reliability of the electric power supply system in city: A case in Shanghai of China

This paper presents a model to quantify the impact of electric power outages on GDP by using Cobb–Douglas production function to develop an economic relationship between the reliability of the electric power supply system and the cost of electric energy unserved. Our findings show that average costs for providing a stable power supply are much lower than disruption costs, which is supported by recurring to the data available of Shanghai. Estimated by using Shanghai’s macroeconomic data of 1990–2006, this relationship indicates that the impact of electricity service disruption on Shanghai’s GDP is about 48.18 × 10⁸ CNY in 2006, matching an alternative “back-of-envelope” estimate of 50.91 × 10⁸ CNY. The estimated costs per kWh unserved are 1.81–10.26 CNY in 1990–2006, mirroring the increasing importance of electricity in the period’s economic development. These results demonstrate the usefulness of our approach for quantifying the reliability benefits of investments in electricity infrastructure.     

Reduction of irreversibility generation in sugar and ethanol production from sugarcane

Sugarcane is one of the most important industries of the Brazilian economy, and its main products are sugar and ethanol. Most of the industrial plants produce both products in an integrated process, in which the sugarcane bagasse is a by-product that can be used as a fuel in the cogeneration system. The bagasse is used as the only fuel of the plant, supplying all energy required for the process, and also producing electricity surplus that may be sold to the grid. In this paper, exergy analysis is used to assess an integrated sugar and ethanol plant with its cogeneration system. The plant was divided into eight sub-systems to evaluate the irreversibility generation in each separately. Data from typical sugarcane factories in Brazil, which produce sugar and ethanol, were used in the process simulation. The analysis has shown that the sub-systems with the highest contribution for the total irreversibility generation of the plant were co-generation, juice extraction and fermentation. Some improvements are proposed, including process thermal integration and the introduction of more efficient equipments for prime mover and steam and electricity generation. The analysis indicated that the total irreversibility could be reduced by 10% should those changes be implemented.     

Reforming the Energy Market and Utilization of Electrical Energy

The main objective of the present study is to provide an overview of reforming the Turkish energy market, including the electricity production and consumption values of Turkey and restructuring in the eight European Union countries. Turkey's electricity demand has been growing very rapidly. It has increased from about 47 TWh in 1990 to some 142 TWh in 2003, and it is expected to continue for the foreseeable future. Besides this, Turkey's total electricity capacity increased from 16,318 MW in 1990 to 31,846 MW in 2002. Restructuring of the electricity sector in the country has started with the establishment of the Energy Market Regulatory Authority (EMRA) upon the law (no. 4628) that came into force on March 3, 2001. The Energy Market Regulatory Board, which runs the EMRA, was commissioned on November 19, 2001. In May 2002, the EMRA issued drafts of the Energy Market Licensing Regulation and the Electricity Market Tariffs Regulation, and these regulations went into effect in August 2002. The Electricity Market Implementation Manual was also issued by the EMRA in April 2003. At present, not only the electricity sector, but the whole Turkish energy sector is in a dynamic change.     

Wind energy in Brazil—present and future

In Brazil, the power generation is predominantly hydroelectric, corresponding approximately to 91.4% of the installed capacity. The energy crisis in the Brazilian electric sector meant the end of the centralized generation and the launching of a decentralized generation approach aiming to add to the existing plants through small- and medium power capacity. Such a condition matches the wind energy characteristic profile. In northeastern Brazil is one of the most promising areas for wind exploitation, where the largest wind speed occurs exactly when the rate of flow in Sao Francisco river, which accounts for all the power energy supply of the northeast region, is low. Thus, during this critical period, the wind farms can produce electrical energy, saving the Sao Francisco waters and on top of that with no environmental risk, thus contributing to the overall reduction of CO₂ emission in the atmosphere. Because of those factors, the National Electrical Energy Agency (ANEEL), the Brazilian regulatory authority, has approved 77 projects for construction of wind farms, attracting foreign investment, besides the installation of wind turbine industries. The increasing use of the wind energy is prevailing over the absence of a specific legislation for the sector, but the National Congress has already taken some measures such as the act bill no. 2905/2000 and the temporary measure no. 14/2001.     

National hydrogen energy program in Brazil

To face the 1973 energy crisis and allow a reduction of fossil fuels imports. Brazil has developed an important alcohol program, suited to secure a major share of liquid fuels supply to be used in transportation sectors.National energy resource agencies point out that emphasis should be put on biomass and electricity.Having the second largest hydropower potential in the world, the Brazilian dilemma is that one-third of this potential is situated in the far Amazon region, whereas consumption centres are in the Southeast region. Thus, hydrogen presents itself as an excellent carrier for our country.The energy system in Brazil should be oriented towards a system based on electricity and hydrogen. With the availability of off-peak hydroelectricity at a low cost and new, very large plants starting operation, the situation appears quite favourable for water electrolysis and hydrogen production development. The production of electrolytic hydrogen, which can be transported and stored, is specially interesting because it allows a heavy electricity utilization well-fitted to production management. Its use would modulate and optimize electricity uses.Hydrogen production would be used in the chemical industry and for energy purposes.Relevant aspects of the Brazilian hydrogen energy program are described.     

Combined production of second-generation biofuels and electricity from sugarcane residues

This paper describes a preliminary analysis of two technological routes (based on hydrolysis and on gasification + Fischer–Tropsch conversion process) of biofuels production from cellulosic materials. In this paper it was considered the integration of the two alternative routes to a conventional distillery of ethanol production based on fermentation of sugarcane juice. Sugarcane bagasse is the biomass considered as input in both second-generation routes. Results show that the integration of gasification + FT process to a conventional distillery is slightly more efficient (from an energetic point of view) and also offers the advantage of products diversification (ethanol from the conventional plant, plus diesel, gasoline and more surplus electricity regarding the hydrolysis route). Considering typical Brazilian conditions, at this stage it is not possible to foresee any significant advantage of any of the alternatives, but potentially the gasification route would have an advantage regarding avoided GHG emissions depending on the emission factor of the electric sector in which cogeneration units will be installed.