In the last episode we discussed the problem of whether the cultivation of energy crops in competition with the production of food crops occurs. This must be affirmed in part, be obtained so long in the vegetable oils and starch, which are then processed into ethanol or biofuel or biodiesel on.
producing plants but also large amounts of cellulose, the formation the plant stand is used. Cellulose can be disrupted by a few organisms and digested, so that here there is no competition with food crops. The production potential is huge and is with up to 5 times the current petroleum consumption.
The problem lies in the fact that cellulose according to chemically prepare, so you can gain energy from it which are preferably in liquid form. For this, the cellulose, which forms long chains of molecules are converted into smaller fragments and then converted specifically to oil or gasoline-like compounds. There are various ways to decompose the plant parts by heat (pyrolysis).
at temperatures up to 200 degrees can be broken down the cellulose in the basic molecule of sugar and then fermented in a conventional manner to produce bioethanol. Between 400 and 600 degrees can be a bio-oil production, which can then be further processed to gasoline or diesel. Above 700 degrees, finally obtained a gas mixture consisting mainly of hydrogen, carbon monoxide five, can be produced from the so-called Fischer-Tropsch synthesis specifically turn liquid fuels (and many other compounds).
Figure: The bio-oil from biomass are
Largest disadvantage of the latter action the high cost of the synthesis process. Therefore, in the days of cheap oil also made relatively little effort to go that way. This changes the time. As expected low oil prices finally a thing of the past, this process is moving back more to the center of attention. is promoted by the development
progress in industrial chemistry. Today, thanks to a much better understanding of the structure of matter and modern computer technology equal better ways to improve such processes also from a cost point significantly.
The direct production of bio-oil from solid plant material is now the cheapest way to get liquid fuels. However, the substances thus produced without chemical processing forthe use in internal combustion engines are less suitable because they are acidic and therefore lead to severe corrosion in the engines. Therefore, such oil can be processed like petroleum refineries accordingly, which in turn leads to higher costs.
However, there are promising approaches to simplify also the steps by using modern techniques. It will be followed completely new WdeG, for example digestion of plant material using ammonia, which means that the resulting bio-oils are not acidic and can be processed more easily.
Another, still little-used way to win fuels, is the deliberate cultivation of oil plants in steppe and semi-deserts, ie areas where traditional agriculture is not possible. Here, the physic nut (Jatropha) and Rizinusbohnen be mentioned, as are the plants only low demands on soil and water availability, so that they can be grown there without competing with other food crops.
pictured Jatrophanüsse - fuel of the future?
The targeted soil with Terra preta could help to drive increased revenues. Another advantage of using these plants would be the opportunity to secure rural livelihoods in developing countries, many, or even create new ones.
Relatively new to the narrowed winding is the so-called hydrothermal carbonization, with the b eliebige parts of plants by pressure and temperature within a few hours to petroleum-like substances and coal can be converted, a process for which the nature millions need of years. The Beschreibng Verfahfrens this is the subject of our next article.
questions and suggestions will be answered under our email address terrapreta@web.de
Working Group Terra preta in the group of energy and environment
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