Many sites for biogas production in Latvia currently do not have sufficient heat load to provide power production in co-generation mode. The alternative to relatively inefficient power production could be production of bio-methane which is known as one of the most important renewable option for gas supplies. After removal of contaminants bio-methane is of quality of natural gas and can be delivered to power plants and industry using the natural gas supply infrastructure. For analysis of environmental benefit of using bio-methane the environmental impact of the proposed solution has to be assessed. The aim of the study is to make life cycle assessment of the system for bio-methane supply to industrial plant via the natural gas grid. The analysed system includes bio-methane production and transport to the natural gas pipeline including the infrastructure. Functional unit was 1 MWh of bio-methane energy injected into the natural gas transmission pipeline. Life-cycle model was created and analysed with software 'SimaPro'. ReCiPe and Eco-Indicator'99 were used as characterization methods to analyse the life-cycle environmental impacts. Results show the influence and contribution level expressed in mid-point categories as well as in a single-score indicator. The largest impact is created by use of fossil energy sources in production of bio-methane. The results can be used to design renewable energy supply systems and for the comparison of alternatives.