In the last episode we had dealt in detail with the pyrolysis as a way of making charcoal. In the meantime, we have become known for more information on this subject, so we think it appropriate, add it first before we deal with the hydrothermal carbonization as announced.
In recent years, as a result of the looming shortage of oil, the widely discussed energy from plants. In the first place one thinks of substances such as vegetable oils and the so-called bio-alcohol, which by the fermentation of sugar or starch Beets, sugar cane and various types of grain to ethanol is produced.
This alcohol can be used for normal petrol engines to a small percentage of the fuel mix in use in modified engines up to 100% as a substitute for gasoline. Methanol can also fulfill this role, but this is more of petroleum and gas produced and is therefore no alternative to replace conventional fuels. Moreover, methanol is highly toxic, making them difficult to use in addition. With the chemical processes that are relatively energy intensive, one could also directly synthesize methanol from carbon dioxide and water, but opens up the possibility only if we can win rates in the future, large amounts of energy from renewable sources.
vegetable oils can be used as diesel substitute in adapted engines or come in chemically-processed form, usually as rapeseed oil methyl esters (biodiesel) to the market.
But is not that much more for these products "organic" because their production often leads to increased environmental damage. And the production of these fuels may require more energy use, for example fertilization, pest control, transport and processing as in the final product is even mentioned. In the extreme case you needed for production a higher energy than on benefits can be pulled back. So that kind of production is only possible where the cultivation of the plants is subsidized by the state strong. Whether it makes sense, however, is another question. Ecologically, it is questionable in any case to go this way and completely absurd is it, when to be cleared, for example, the production of palm oil in tropical countries intact forest ecosystems to make way for palm oil plantations, as in Indonesia, but not only there, happens.
complicating factor is yet another point of view: energy plants are a serious competition with food crops is, for where they are grown, can not simultaneously food plants are grown. Therefore the energy crop production have been criticized, though not always fairly.
An exception to this as the so-called mixed fruit crops, where about false flax and peas are grown on the same area, the camelina oil for the production and peas as a vegetable. However, oil crops and cereals are suitable for this cultivation method (see illustration)
(pictured) mixed cropping with false flax and barley
But this situation is not without alternative because there is the possibility of plant residues to use for energy. Thus, Straw, waste wood, plant stems and even animal waste can be processed. But because
have especially liquid fuels, the widest range of applications, but most parts of plants have fibrous consistency, it needs an intermediate step, the plant production on the one hand and the production of liquid or gaseous fuels combines with each other.
we need procedures that allow it to generate cash directly from plant residues and gaseous fuels. These methods, which in the previous article described pyrolysis are very similar, have the potential to process annually amounts of biomass, which today's crude oil production not only meet, but surpass it even.
Because they can convert virtually any organic material into valuable useful elements, also eliminates the disadvantage that the raw material could eventually compete with food crops, because in addition to crop residues may also treat all the plants are used, which thrive on agricultural otherwise unsuitable soils .
However, most of the conversion process are not yet technically or even large-scale disposal. In the laboratories of the world are working flat out, techniques that work on a small scale already, prepare for industrial use.
Here is still a lot of research to be done, though the recent successes are encouraging. In particular, the development of suitable catalysts and the exploration of the optimal process control, our scientists provide some interesting challenges.
principle of the pyrolysis
In the next episode we will introduce some of these methodologies.
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group Terra preta in the group of energy and environment
