The potato plant (Solanum tuberosum) is a perennial plant of the Solanaceae or nightshade family. It is commonly grown for its starchy tuber and is therefore the world's most widely grown tuber crop and the fourth largest crop after rice, wheat, and maize. The origin of the potato plant is in South-America mainly in the Andes. Potatoes spread to the rest of the world after European contact with the Americas in the late 1400s and early 1500s.
Potatoes are generally grown from the eyes of another potato and not from seed. They are planted as a row crop using seed tubers, young plants or microtubers. In most cases three steps of plowings including harrowing and rolling are necessary before the land is in suitable condition for planting potatoes. Commercial harvesting is typically done with large potato harvesters which also pre-clean the tubes. Further inspection and separation occurs when the potatoes are unloaded from the field vehicles and put into storage.Recently bio-ethanol is produced by using waste potatoes which are a co-product of the food industry. For instance waste potatoes are used as feedstock in Finland where oy Shaman Spirits Ltd in Tyrnävä (near Oulu) uses 1.5 million kilograms of waste potatoes per year for ethanol production [1-2].
Cellulosic Feedstock.Besides the so called first generation feedstock which is received from sugar and starch crops, cellulosic feedstock is a promising source for bioethanol production in the future. Since the technology for converting cellulosic feedstock into ethanol is not yet competitive, this feedstock is a second generation feedstock. Bioethanol production from cellulose is expected to significantly expand in the future, when technologies will improve. Subsequently, cellulosic wastes and biomass that is specifically cultivated for energy purposes will be discussed in detail.
Primary cellulosic wastes are produced during production and harvesting of food crops such as e.g., straw, corn stalks and leaves. Also residues from forestry such as e.g. wood thinning from commercial forestry belong to primary cellulosic wastes. These types of biomass are typically available in the field or forest and must be collected to be available for further use. Thereby attention has to be paid as there are longterm economic and environmental concerns associated with the removal of large quantities of residues from cropland. Removing residues can reduce soil quality, promote erosion, and reduce soil carbon, which in turn lowers crop productivity and profitability. But, depending on the soil type, some level of removal can be also beneficial. Establishment and communication of research-based guidelines is necessary to ensure that removal of residue biomass is done in a sustainable manner [3-4]
Secondary cellulosic wastes are generated during the production of food products and biomass materials. This biomass include nut shells, sugar cane bagasse, and saw dust, and are typically available at e.g. industries for food and beverage production as well as at saw and paper mills.
Tertiary cellulosic wastes become available after a biomass-derived commodity has been used. A large variety of different waste fractions is part of this category: organic part of municipal solid waste (MSW), waste and demolition wood, sludge, paper, etc.
Cellulosic energy crops
Feedstock from dedicated cellulosic energy corps is a promising source for ethanol production in the future. There are several advantages for the cultivation of cellulosic energy crops, such as perennial
herbaceous plant species and short-rotation woody crops (SRWC) . Firstly, the change of land from intensive annual crop production to perennial herbaceous species or to SRWC progressively increases the content of soil organic matter. In contrast, shifting land from natural cover to intensive annual crop production typically decreases soil organic matter steadily. Secondly, the roots of perennial crops protect soil from erosion. Thirdly, these crops generally require less fertilizer, pesticide and less energy input for crop management, especially since it is not necessary to plow the field each year.
Today, there is already some use of short-rotation woody crops for industrial purposes. For example, eucalyptus trees are grown for pulp markets and to supply charcoal for the steel industry in Brazil. In Europe and the United States, poplar trees are cultivated to provide fiber for the pulp and paper industry. Nevertheless, efforts to evaluate and develop energy crops are still in a relatively early stage of development when compared to conventional crops where cultivation and plant breeding has been under way for many years. The relatively early phase of energy crop development reflects a situation where tremendous opportunities exist to use advanced plant science and agronomy to dramatically increase biomass yields.
In temperate climates the cultivation of willow (Salix sp.) is suitable as SRWC. Willow trees and shrubs are very productive. In short-rotation coppice (SRC) plantations they can achieve high biomass yields by harvesting the young sprouts. The plant quickly regenerates with vigorous growth of new shoots and branches from the remaining tree trunks. SRWC can be harvested every few years. For instance, willows in SRC plantations can typically be harvested every 2–5 years over a period of some 20–25 years. Research on genetics and breeding has drastically increased the yields. In Europe most experience with willow plantations has been made in Sweden, where this crop is produced on approximately 14,000 hectares.
Besides willow, also hybrid poplar trees (Populus sp.) are cultivated in SRC plantations as they have similar fast-growing and high productive properties.Parallel to willow and poplar trees in Europe, eucalyptus (Eucalyptus sp.) plantations are grown in tropical regions.
Along with woody cellulosic energy crops also perennial grass species are a promising opportunity for future feedstock production. Miscanthus (Miscanthus sinensis, M. sacchariflorus, Miscanthus x giganteus), switchgrass (Panicum virgatum), and reed canary grass (Phalaris arundinacea) are examples of perennial crops that can be harvested every year. They have been the focus of considerable.
- AGQM (ARBEITSGEMEINSCHAFT QUALITÄTSMANAGEMENT BIODIESEL E.V.) (2006):Internet: http://www.agqm-biodiesel.de/3.html [12.06.06]
- ARMSTRONG S.R. (1999): ETHANOL Brief Report on its Use in Gasoline. – Internet:http://www.ethanol.org/pdfs/health_impacts.p df [02.08.06]
- ARNOLD K. RAMESOHL S. FISCHERDICK M. MERTEN F. (2005): Synopsis of German and European erperience and state of the art of biofuels for transport. – Study commissioned by the German GTZ; Wuppertal Institute;91 p.
- AUSTRALIAN GOVERNMENT (2005): SettingNational Fuel Quality Standards – Proposed Fuel Quality Standard for Fuel Grade Ethanol. – Austrian Government Position; Canberra; July 2005; 13 p.