1. European Metrology Programme for Innovation and Research (EMPIR) project: “Metrology for biomethane”, available at: http://empir.npl.co.uk/biomethane/
2. Characterisation and cleaning of biogas from sewage sludge for biomethane production
3. European Biogas Association (EBA) Statistical Report of the European Biogas Association 2018 Brussels Belgium, 2018, available at: https://www.europeanbiogas.eu/wpcontent/uploads/2019/05/EBA_Statistical-Report-2018_AbrigedPublic_web.pdf
4. A list of the EU-wide existing best practices for the biogas transport in the natural gas grids REDUBAR WP06 D19/M, available at: https://ec.europa.eu/energy/intelligent/projects/sites/ieeprojects/files/projects/documents/redubar_best_practices.pdf
5. Absolute diode laser-based in situ detection of HCl in gasification processes