**6. Conclusion**

192 Modeling and Optimization of Renewable Energy Systems

Amon et al. (2007) found that area methane yield tends to increase with increasing number of cut and fertilization levels. The biomass yields seem to be more important factor to achieve high area methane yield. According to Gerin et al. (2008), extensity of management of permanent grasslands leads to decrease in yield of dry matter and substrate biogas yield. However, too high intensity does not necessarily have to produce satisfactory results either.

1st cut 2nd cut 3rd cuts 4th cut

2 cuts 2 cuts 2 cuts 4 cuts 4 cuts 4 cuts N0P0K0 N40P0K0 N80P0K0 N0P0K0 N40P0K0 N80P0K0 **Counts of cuttings/Rate of fertilization (kg ha-1)**

Fig. 6. Area biogas yield (m3 ha-1) from permanent grassland under different management

1st cut 2nd cut 3rd cuts

N0P0K0 N50P40K100 N150P40K100 **Rate of fertilization (kg ha-1)**

Fig. 7. Area biogas yield (m3 ha-1) from permanent grassland under different management

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**m3 ha-1**

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intensity, 2009, Nicov locality, Czech Republic

intensity, 2009, Černíkovice locality, Czech Republic

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**m3 ha-1**

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Utilization of permanent grasslands for production of biogas represents a system with different final adjustment in comparison with utilization of forage for feeding purposes. The basic management of permanent grasslands abides preserved, however optimization of this process can differ from traditional use of biomass. The chapter shows that the term grassland is very wide and includes varied groups of stands. Therefore, it cannot be provided any all-purpose instructions for biogas produce from permanent grasslands. It is also necessary to point out that optimal management, which would cover both productive and non-productive functions of this vegetation, does not exist.

According cited literature and our own results, it is evident that for determination the optimal management of permanent grasslands for production of biogas it is necessary to take into consideration an influence of locality, species composition and other reciprocal biological relations. The system of biogas production from the permanent grasslands can fulfil productive as well as non-productive functions of grasslands. Considering the type of stand it is possible to modify the management towards maximization of production or strengthen their environmental value.
