The Brazilian experience of sugarcane ethanol industry

Biomass has gained prominence in the last few years as one of the most important renewable energy sources. In Brazil, a sugarcane ethanol program called ProAlcohol was designed to supply the liquid gasoline substitution and has been running for the last 30 yr. The federal government’s establishment of ProAlcohol in 1975 created the grounds for the development of a sugarcane industry that currently is one of the most efficient systems for the conversion of photosynthate into different forms of energy. Improvement of industrial processes along with strong sugarcane breeding programs brought technologies that currently support a cropland of 7 million hectares of sugarcane with an average yield of 75 tons/ha. From the beginning of ProAlcohol to the present time, ethanol yield has grown from 2,500 to around 7,000 l/ha. New technologies for energy production from crushed sugarcane stalk are currently supplying 15% of the electricity needs of the country. Projections show that sugarcane could supply over 30% of Brazil’s energy needs by 2020. In this review, we briefly describe some historic facts of the ethanol industry, the role of sugarcane breeding, and the prospects of sugarcane biotechnology     

The ethics of biofuels

The rapid development and adoption of biofuels has been driven by a wide range of targets and other policy instruments, but first‐generation biofuels have been widely criticized. In light of the development of new biofuel technologies that aim to avoid the problems of the past, the Nuffield Council on Bioethics conducted an 18‐month inquiry on the ethical, social and policy issues raised by both current and future biofuels. The Council concludes that many biofuels policies fail to take consideration of important ethical principles, such as protecting human rights, environmental sustainability, climate change mitigation, just reward, and equitable distribution of costs and benefits. It proposes an overarching ethical standard for biofuels, enforced by a certification scheme for all biofuels produced in and imported into Europe and ideally worldwide.     

Climate change, biofuels and eco-social impacts in the Brazilian Amazon and Cerrado

While global technical progress is relatively linear, there is wide variation in its environmental and social impacts at the local level, with cycles of expansion and retraction or boom and bust, of long or short duration. Analysis of previous open-ended stages of extraction and agro commodities in the Amazon indicates a general gravitational trend for technical progress to increase productivity and permit transformation of increasingly generic forms of material or energy, rather than relying on the specific physical or chemical properties provided by nature. While increased demand favours frontier expansion in the periphery when there is no other alternative, technical progress ultimately favours spatial reconcentration of production in central countries. The agroenergy stage now beginning involves rapid frontier expansion and offers various environmental and economic opportunities, but also generates a series of negative ecosystemic and socio-economic impacts, which are both direct and indirect, for tropical regions. The Amazon and the Cerrado are particularly vulnerable. Interacting with climate change and land use, the upcoming stage of cellulosic energy could result in a collapse of the new frontier into vast degraded pasture. The present and future impacts can be mitigated through crafting of appropriate policies, not limited to the Amazon, stressing intensified and more sustainable use of areas already cleared, minimizing new clearing and consolidation of alternatives for sustainable use of natural resources by local communities. Coping with these scenarios requires knowledge of complex causal relationships.     

Algal biofuels

The world is facing energy crisis and environmental issues due to the depletion of fossil fuels and increasing CO₂ concentration in the atmosphere. Growing microalgae can contribute to practical solutions for these global problems because they can harvest solar energy and capture CO₂ by converting it into biofuel using photosynthesis. Microalgae are robust organisms capable of rapid growth under a variety of conditions including in open ponds or closed photobioreactors. Their reduced biomass compounds can be used as the feedstock for mass production of a variety of biofuels. As another advantage, their ability to accumulate or secrete biofuels can be controlled by changing their growth conditions or metabolic engineering. This review is aimed to highlight different forms of biofuels produced by microalgae and the approaches taken to improve their biofuel productivity. The costs for industrial-scale production of algal biofuels in open ponds or closed photobioreactors are analyzed. Different strategies for photoproduction of hydrogen by the hydrogenase enzyme of green algae are discussed. Algae are also good sources of biodiesel since some species can make large quantities of lipids as their biomass. The lipid contents for some of the best oil-producing strains of algae in optimized growth conditions are reviewed. The potential of microalgae for producing petroleum related chemicals or ready-make fuels such as bioethanol, triterpenic hydrocarbons, isobutyraldehyde, isobutanol, and isoprene from their biomass are also presented.     

Anaerobic fermentation of glycerol: a path to economic viability for the biofuels industry

Although biofuels such as biodiesel and bioethanol represent a secure, renewable and environmentally safe alternative to fossil fuels, their economic viability is a major concern. The implementation of biorefineries that co-produce higher value products along with biofuels has been proposed as a solution to this problem. The biorefinery model would be especially advantageous if the conversion of byproducts or waste streams generated during biofuel production were considered. Glycerol-rich streams generated in large amounts by the biofuels industry, especially during the production of biodiesel, present an excellent opportunity to establish biorefineries. Once considered a valuable 'co-product', crude glycerol is rapidly becoming a 'waste product' with a disposal cost attributed to it. Given the highly reduced nature of carbon in glycerol and the cost advantage of anaerobic processes, fermentative metabolism of glycerol is of special interest. This review covers the anaerobic fermentation of glycerol in microbes and the harnessing of this metabolic process to convert abundant and low-priced glycerol streams into higher value products, thus creating a path to viability for the biofuels industry. Special attention is given to products whose synthesis from glycerol would be advantageous when compared with their production from common sugars.     

The economics of current and future biofuels

This work presents detailed comparative analysis on the production economics of both current and future biofuels, including ethanol, biodiesel, and butanol. Our objectives include demonstrating the impact of key parameters on the overall process economics (e.g., plant capacity, raw material pricing, and yield) and comparing how next-generation technologies and fuels will differ from today’s technologies. The commercialized processes and corresponding economics presented here include corn-based ethanol, sugarcane-based ethanol, and soy-based biodiesel. While actual full-scale economic data are available for these processes, they have also been modeled using detailed process simulation. For future biofuel technologies, detailed techno-economic data exist for cellulosic ethanol from both biochemical and thermochemical conversion. In addition, similar techno-economic models have been created for n-butanol production based on publicly available literature data. Key technical and economic challenges facing all of these biofuels are discussed.     

Bonkers about biofuels

Biofuels have been touted before, but failed to deliver. What's needed to get it right this time around?     

Bioprocessing for biofuels

While engineering of new biofuels pathways into microbial hosts has received considerable attention, innovations in bioprocessing are required for commercialization of both conventional and next-generation fuels. For ethanol and butanol, reducing energy costs for product recovery remains a challenge. Fuels produced from heterologous aerobic pathways in yeast and bacteria require control of aeration and cooling at large scales. Converting lignocellulosic biomass to sugars for fuels production requires effective biomass pretreatment to increase surface area, decrystallize cellulose and facilitate enzymatic hydrolysis. Effective means to recover microalgae and extract their intracellular lipids remains a practical and economic bottleneck in algal biodiesel production.     

The Brazilian seagrasses

Based on a critical review of the literature, and on abundant material recently collected along the coast of Brazil, a synthesis of the occurrence and distribution of the Brazilian species of seagrasses is presented. Two species of Hydrocharitaceae, namely Halophila baillonii Aschers. and H. decipiens Ostenf., and three species of Potomogetonaceae, Halodule emarginata den Hartog, H. wrightii Aschers. and Ruppia maritima L. s.s., were found. Ruppia maritima was found all along the Brazilian coast, from about 3 to 32°S latitude, in brackish water ponds and lakes, with salinities varying from 0.3 to 28?.. The other species are restricted to normal seawater ($\text{±35?.}$), although Halodule wrightii was also found in hypersaline waters (45?.). This last species is the most common seagrass in Brazil. The species of Halophila are restricted to warmer waters and were not found further south than Rio de Janeiro State, being especially common on the NE coast at depths down to 62 m. During the course of these studies, Halophila baillonii was found for the second time in Brazil since its original collection in 1888. A critical comparison of a large number of plants leads us to the conclusion that Halodule brasiliensis Lipkin cannot be distinguished from H. wrightii, and H. lilianae den Hartog cannot be distinguished from H. emarginata. Reproductive structures of H. emarginata are described for the first time.     

The Brazilian flaviviruses

Ten flaviviruses occur in Brazil: Bussuquara, Cacipacoré, dengue 1, 2 and 4, Iguape, Ilhéus, Rocio, Saint Louis encephalitis and yellow fever. Aspects of sylvatic maintenance cycles and human diseases caused by these viruses are analyzed. Large dengue outbreaks are occurring in Brazil and there is a risk of yellow fever urbanization.     

How biotech can transform biofuels

For cellulosic ethanol to become a reality, biotechnological solutions should focus on optimizing the conversion of biomass to sugars.     

The Brazilian ethanol program

Brazilian needs for petroleum as a primary energy source grew from 13.2% in 1940 to 41.7% in 1977. This resulted in a much greater dependence on foreign sources and prompted the Government to initiate a detailed study of alternatives. The National Alcohol Program established in 1975 is just one of the options being examined. The National Energy Balance forecast shows that annual anhydrous alcohol consumption for automotive purposes should increase from 1.74 × 10⁶m³ to 4.7 × 10⁶ m³ in the period from 1978 to 1987. This paper presents the main objectives of the National Alcohol Program in the context of the overall Energy Program, points out the problems connected with alcohol production and utilization, and reviews the serious problems related to its distribution to the consuming centers. Finally, the indirect benefits resulting from the implementation of the National Alcohol Program are shown, underlining the saving of foreign currency, the substantial increase in employment opportunities, the reduction in regional and individual income discrepancies, and the expansion of capital goods production, together with the improvement of national technology in the agricultural and industrial sectors.     

The hard choice for alternative biofuels to diesel in Brazil

This paper selects biofuel scenarios to substitute diesel in Brazil based on oil reserves increase, diesel imports, CO₂ emissions, crops agronomic yields, byproducts marketing and social impacts. This hard task still considers that agricultural practices in developing countries have large social impacts. Brazil presents high consumption of diesel oil in transport; low agronomic yield of traditional vegetable oil crops, which demand large cultivation areas contrasting with microalgae and palm oils which present high productivity. Concerning technologies, thermal cracking and transesterification of vegetable oils present a difficult economic situation related to vegetable oils price, food competition and glycerin market; BTL technology, meaning thermal gasification of biomass to liquids, faces problems related to low density of biomaterials and low viscosity of synthetic biodiesel produced. Biorefinery algal integrated systems and co-solvent technology to introduce up to 8% of ethanol into diesel seem to be feasible routes to reduce diesel consumption.