Research Article
Ankitha Jain
Abstract
Bioethanol gained growing attention as biofuel in the recent past. Its production steadily increased over the years attesting on 87.2 billion liters worldwide in 2013, with the United States as the top producer (ca. 60%), followed by Brazil.Ethanol is mainly produced from sugar cane (Brazil) and corn or other cereals (US), but these sources induced criticisms as for social sustainability, being directly competitive with the food and feed chain. Therefore, a second generation concept was introduced for biofuels, by developing processes for their production from waste biomass or energy crops not competitive with agriculture. However, currently in the US and Europe most bioethanol is still produced as first generation. For example, it was estimated that in 2011, 40% of corn harvested in the US was used as a feedstock for bioethanol production, compared to just 7% a decade earlier.Early examples of second generation bioethanol production are available, such as the Proesa process developed by Mossi & Ghisolfi group in Italy [1]. This process commercially operated since 2013 for the production of 40 kton/year of bioethanol (60 kton/year at full capacity) starting mainly from Arundo Donax, a common cane which can be harvested locally with good yield. The same technology has been exported in Brazil (65 kton/year, from sugar cane transformation wastes) and US (60 kton/year from non-food competitive biomass). In April 2013, a commercial ethanol plant started being built in Florida using sweet sorghum as a feedstock. The plant is being built by Southeast Renewable Fuels LLC using the process technology of Uni- Systems do Brasil Ltd.In spite of these emerging commercial experience in biorefinery, a consolidated expertise is still lacking. In particular, in developing countries it will be a challenge to balance large-scale industrial development with small-scale local value chains, which would be required to ensure environmental, economical and social sustainability. Therefore, to become a viable alternative, biofuels should be economically competitive, show environmental benefits, and provide a high net energy gain.On the other hand the research is very active in the biorefinery field. Simple queries on Scopus reveal that the word “biorefinery” is included in 3,646 references, “biofuels” in 37,193 documents and “bioethanol production” returns 4,859 references. As for bioethanol uses, the commercial practice is presently focused on the use of bioethanol as blend for gasoline or directly as fuel, to meet the most recent regulations on the fuel pool quota from renewable sources. Also in this case the research broadens the application potential of bioethanol, focusing mainly on hydrogen/syngas production by thermocatalytic processing (e.g., steam reforming) or on chemicals such as diethyl ether or ethylene.To date, comprehensive information on the economic sustainability of these ethanol conversion processes is still lacking. Indeed, in spite of huge efforts in developing materials and innovative ideas, the economical assessment of the proposed solutions is fundamentally lacking and this prevents the analysis on the real breakthrough potential of these technologies. Furthermore, no idea on the size of possible plants is given, to assess their real sustainability and possibility of integration in the social framework of different countries. Only few