Background Global climate changes caused by greenhouse gas emissions (GHG) are currently being debated around the world. Over the next 20 years, world carbon dioxide emissions are expected to increase by 1.9% annually, mainly due to the burning of fossil fuels (coal, oil and natural gas) for energy production. The reduction of CO2 emissions is the central objective of the European Commission's energy policy. In order to achieve this aim, the EU considers that it is essential to develop renewable energies as a clear alternative to fossil fuels. The anaerobic digestion (AD) process has direct environmental benefits; it contributes to the supply of a ‘clean energy’ while reducing the negative impact of organic waste on the environment (odours, leaching, soil and water pollution and pathogens). AD avoids the release of CO2 and CH4 into the atmosphere, and moreover, the biogas produced can replace the use of fossil fuels with associated GHG reduction. The biogas can also be upgraded and additional environmental benefits can be obtained. Furthermore, the use of upgraded biogas (bio-methane) in remote areas, via injection into the natural gas grid, and the use as a clean transport fuel will significantly contribute to the increase of biogas in the energy supply. Objectives The goal of the BIOGRID project was to demonstrate the feasibility of producing a substitute natural gas (biomethane) from biogas. The other main objectives were to: Increase and optimise digester gas production through the co-digestion of organic wastes; Demonstrate a novel biogas upgrading system based on the combination of biological and cryogenic technologies to capture and store the CO2 in the biogas and to remove other contaminants (SH2, volatiles and moisture etc.); Determine whether the process developed by the project represents a cost-effective alternative to the CO2 capture technologies commercially available for use on biogas upgrading plants; Demonstrate the feasibility of using algae biomass in the anaerobic process for biogas production; Study the gas requirements, safety regulations and national and European legislation to determine to what extent the gas produced can be added to the natural gas grid or be used as fuel for vehicles; Demonstrate the feasibility of using biomethane remotely via injection into the natural gas grid and using it as transport fuel; and Perform an economic and environmental analysis in order to determine the viability of producing bio-methane with CCS from anaerobic digestion of organic wastes.Results The BIOGRID project combined biogas production with carbon capture and storage technology. It demonstrated the concept, ‘Carbon-negative bio-energy’ in which biogas obtained from organic waste is purified through a combination of biological and cryogenic technologies to obtain biomethane, a renewable energy similar to natural gas that can be used both as a non-pollutant fuel and also to be injected into the Spanish natural gas grid. The technologies used for obtaining biomethane also remove other contaminants, such as hydrogen sulphide (H2S), volatiles and moisture. Though the process developed by the project was shown to be a viable alternative to the CO2 capture technologies commercially available for use on biogas upgrading plants, this process proved not to be cost effective. Given that it was a prototype, the high investment costs from the cryogenic upgrading unit made the project plant (which has a 10m3/h capacity) unprofitable. The project estimates that a minimum processing capacity of 500 m3/h and a closer location of the plant to the distribution natural gas network would make the technology economically feasible. Furthermore, biogas production was optimised and increased through the co-digestion of organic wastes. The project demonstrated that it is feasible to use algae biomass in the anaerobic process for biogas production. Algae growth, however, was found to be less effective than expected. The project also carried out studies of biogas production – namely, requirements safety regulations and national and European legislation – in order to determine the specifications and requirements for adding biogas to the natural gas grid or using it in vehicles. The reproduction potential is very high, both in biogas production using waste from other sectors and in other Spanish distribution natural gas networks – and for all compressed natural gas vehicles. From agricultural waste, the total biogas potential is 7 669 million m3/year and the total biomethane potential is 5.17 bcm/year.n Spain the total conventional natural gas consumption was 28.7 bcm in 2013. Theoretically, 18% of biomethane could be injected and transported into the distribution natural gas network using the technology developed. An economic and environmental analysis was also carried out in order to determine the viability of producing biomethane with CCS from anaerobic digestion of organic wastes. The project represents a starting point in the promotion of four new R&D projects related to renewable natural gas that the beneficiary has initiated. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).