Biogas production: current state and perspectives
Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. 
Trace compounds of biogas from different biogas production plants
Biogas composition and variation in three different biogas production plants were studied to provide information pertaining to its potential use as biofuel. Methane, carbon dioxide, oxygen, nitrogen, volatile organic compounds (VOCs) and sulphur compounds were measured in samples of biogases from a landfill, sewage treatment plant sludge digester and farm biogas plant. 
Enhancement of biogas production from solid substrates using different techniques––a review
Biogas, a clean and renewable form of energy could very well substitute (especially in the rural sector) for conventional sources of energy (fossil fuels, oil, etc.) which are causing ecological–environmental problems and at the same time depleting at a faster rate. 
Utilization of Plantain (Musa species) Leaves for Biogas Production
Aim: To determine the relationship between the volumes of biogas that can be produced using different biomass/water ratios. Study Design: Biogas was produced by the anaerobic digestion or fermentation of plantain leaves. A practical laboratory scale experimental design was used to find out the effect of biomass/water ratio and retention time on the volume of biogas generated using sun-dried and ground plantain leaves as the feed stock. 
Utilization of Genetic Algorithm to Optimize Biogas Production from Livestock Waste to Use in a CHP Plant in Agricultural Farms
The optimization of biogas production with respect to external influences and various process disturbances is essential for efficient plant operation. However, the optimization of such plants is a challenging issue due the underlying nonlinear and complex digestion processes. One approach to solving this problem is to use the flexibility and power 
 Weiland, P., 2010. Biogas production: current state and perspectives. Applied microbiology and biotechnology, 85(4), pp.849-860.
 Rasi, S., Veijanen, A. and Rintala, J., 2007. Trace compounds of biogas from different biogas production plants. Energy, 32(8), pp.1375-1380.
 Sreekrishnan, T.R., Kohli, S. and Rana, V., 2004. Enhancement of biogas production from solid substrates using different techniques––a review. Bioresource technology, 95(1), pp.1-10.
 Aiwonegbe, A.E., Akinyomi, J.O. and Ikhuoria, E.U., 2015. Utilization of plantain (Musa species) leaves for biogas production. International Research Journal of Pure and Applied Chemistry, pp.1-7.
 Kamalinasab, M. and Vakili, A., 2014. Utilization of Genetic Algorithm to Optimize Biogas Production from Livestock Waste to Use in a CHP Plant in Agricultural Farms. Biotechnology Journal International, pp.1149-1164.