1. Schenk, J., Schley, P., Hielscher, A.: Biogas composition and upgrading to biomethane. Gas Energy 3, 34–42 (2012)
2. Sterner, M., Schmidt, J.: Bioenergy and renewable power methane in integrated 100% renewable energy systems. In: Limiting global warming by transforming energy systems, pp. 104–126. Kassel University Press (2009)
3. Deutsche Energie-Agentur: Integration erneuerbaren stroms in das erdgasnetz: Power to gaseine innovative systemlösung für die energieversorgung von morgen entwickeln. Technical report, Deutsche Energie-Agentur (2012)
4. Garmsiri, S., Rosen, M.A., Smith, G.R.: Integration of wind energy, hydrogen and natural gas pipeline systems to meet community and transportation energy needs: a parametric study. Number 10 in The 3rd World Sustainability Forum 2013 (2013)
5. Varone, A., Ferrari, M.: Power to liquid and power to gas: an option for the German Energiewende. Renew. Sustain. Energy Rev. 45, 207–218 (2015). https://doi.org/10.1016/j.rser.2015.01.049