MODELOVÁNÍ ENERGETICKÝCH TOKŮ V ZEMĚDĚLSKÉ ROSTLINNÉ VÝROBĚ

Modelling of energy flows in plant production in agriculture

Modelování energetických toků v zemědělské rostlinné výrobě

Halbich Čestmír

Adresa autora:

ING. Halbich čestmír, CSc., Department of information technologies,

Faculty of economics and management, Czech University of Agriculture Prague,

165 21 Prague 6 - Suchdol E-mail halbich@pef.czu.cz

Anotace:

V příspěvku je popsán velmi jednoduchý model energetických toků v zemědělské prvovýrobě. Jako vstupní energie jsou zvoleny např. energie motorových paliv, energie nutná k výrobě hnojiv a další. Jako jediná výstupní energie je uvažována v modelu energie obsažená ve výsledném produktu. Jako určitý paradox se jeví skutečnost, že čím ”sofistikovanější” je výsledný produkt, tím menší je jeho obsah energie získané z 1 ha zemědělské půdy. Závěrem se dá říci, že každá zemědělská produkce může vyprodukovat více energie, než kolik do ní vstupuje, navíc přispívá k tvorbě a ochraně krajiny.

Summary:

A very easy model of energy flows in plant production in agriculture is described in the contribution paper. As an input energy has been chosen for example the energy of power fuels, the energy necessary for the production of fertilisers and other energies. As the only output energy is in this model reflected energy included in the eventual product. The fact that the more sophisticated the product is, the smaller is the capacity of energy obtained from the agriculture land per 1 hectare, seems as a paradox of certain kind. To conclude it is possible to say that every agriculture production can put out more energy than was put in it, in addition it contributes to landscape creation and protection.

Klíčová slova:

skleníkový efekt, model toku energie, poměr vstupní a výstupní energie, energie z biomasy,

více sofistikované technologie, precizní zemědělství

Key words:

greenhouse effect, energy flow model, NET energy ratio, biomass energy production, more sophisticated technology, precision agriculture

1. Introduction

As has already been mention in some authors former papers, the current situation can be regarded as everything but not a success of the Euroatlantic civilisation. Further there has been mentioned that the invention of agriculture some 10 000 years ago had started evolution leading to the topical economic and environmental problems. In their conclusions there stood an optimistic opinion that agriculture (generally each its production can have a positive NET energy ratio) can contribute to the solution of current problems. A further described model states concrete numbers and energy flows in plant production.

The main goal of the IS is known - to increase the profit of the company. In the contemporary world, a whole range of small companies based their information systems on Linux and its applications [5]. Linux seems to be a representative of the ”more sophisticated technology”, further just MST. A characteristic feature of our age is a globalisation of the world economics, the world of the continuous changes and also the usage of the MST, which together bring a higher added value. In the area of the agriculture there are at least two sets of MST there ,see [3]. The first is the common MST (for example IT, IS), the second MST is the special agricultural MST, (for example precision agriculture, exact agriculture systems (include exact fertiliser application, geographical information systems and others) and maybe genetically engineered foods). According to many authors such as [4], see Fig. 1 it is clear, that the MST are being developed considerably faster then current technologies and seat larger and larger place within the worlds turnover.

Although the term MST is not too frequented in specialized literature it shows the way of the demanded trend, when more and more per cents of the entire human production are being taken just by the MST (also the increase of their extent is bigger than of the other technologies). The MST decrease the amount of waste per a unit of production, the exploitation of limited natural sources, increase the wealth of humankind, the labor productivity, the amount of added value per unit of the human labor and the rate of satisfying human needs.

The above mentioned MST are ones of the means to reach the SD. Besides it is necessary to decrease radically the exploitation of limited natural sources. According to the authors opinion, it is possible (and demanded) to shift satisfying of parts of the human needs to immaterial.

Changes of the value adding structures

Fig. 1. Trends in contemporary technologies and economy (examples)

Fig.2. The Model of the energy flows in plant production in the agriculture

2. The model of the energy flows

The model has been constructed on the base of the matter that the Earth is in fact a closed system until we are able to export our problems into the universe. And even the constructed model, see Fig 2, is closed. Although the energy of sunshine (EF as free energy) enters the energetic audit of the model, it is not count on it. The model does not work without this energy but it is an outside, free energy and we does not have to pay for it. It also has mainly positive results (except the greenhouse effect that does not cause but takes part in it). Thanks to the greenhouse effect, the already closed earth system becomes closer (closed even for heat radiance emitted by the Earth).

From the civil engineering point of view, the operation of sun energy conversion into agriculture products is absurdly low. On 1 m2 of tract land 800 Wh of sun energy for some 1400 hours a year. At the result production of some 250 GJ per hectare for a biomass of hybrid poplar, the operation of obtaining energy is cca 0,6 % (to compare, operation of a diesel engine is cca 40 %, steam turbine cca 30 %, solar cells cca 10%). In spite of that it is still advantageous to exploit the energy of biomass because the technology of exploitation is quite cheap, approachable and besides helps to create and protect the cultural landscape, solves unemployment.

Nevertheless, a certain paradox emerge in agriculture, when more sophisticated products have lower NET energy ratio then less sophisticated, see Table 2. It is paradox only partly because MST in agriculture lead to the increase of NET energy ratio of concrete technologies, see for example [6], when EI is decreased almost at zero, (input energy) of fertilisers at stable output energy EO of the product (wheat in the concrete). We can find many examples. In Table 2 there are then mentioned some of the numerical values of EI EO and NET energy ratio obtained from foreign sources. We recognise various opinions on the greenhouse effect. Be it in operation already or not, if we acquire majority of energy by fossil carbon burning, the greenhouse effect will surely emerge.

Table 1 Energy balances for biomass production on plantations (GJ per hectare)

3. Conclusion

Biomass provides a clean, renewable energy source that could dramatically improve our environment, economy and energy security. Biomass energy generates far less air emissions than fossil fuels, reduces the amount of waste sent to landfills and decreases our reliance on foreign oil. Biomass energy also creates thousands of jobs and helps revitalise rural communities. The acquisition of energy from biomass is a way to reduce results of the greenhouse effect because during the acquisition of energy by burning the biomass the CO2 is released only in such extent as it had recovered from air while growing.

Table 2 NET energy ratio for different values of sophistication of products

References

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