Towards a circular CO2 economy: novel pilot plant produces synthetic natural gas from water and carbon dioxide in a waste water treatment plant near Barcelona.
The energy company GAS NATURAL FENOSA steps up its business strategy to produce renewable gases compatible with the natural gas supply. The company is now taking the next step in renewable natural gas production, in collaboration with the Catalonia Institute for Energy Research (IREC) and the INERATEC GmbH, a spinoff of the Karlsruhe Institute of Technology (KIT). They have designed, built and implemented a demonstration plant on the production of synthetic natural gas (SNG), next to a biogas enrichment pilot plant operated by Cetaqua (Water Technology Centre). Both plants are now located on a waste water treatment plant in the metropolitan area of Barcelona (EDAR Riu Sec, Sabadell, 200.000 inhabitants). The core technology of this process is a compact chemical reactor system, delivered by INERATEC, equipped with a novel catalyst formulation of IREC.
This so-called Power-to-Gas process converts and stores the surplus of electricity coming from renewable resources, such as photovoltaic and wind power, into methane. In the last four years, Spain has produced 40% of its electricity from renewable sources, clearly lead by wind power. The main advantage of this strategy is that the renewable gas can be transported and stored in the existing gas infrastructure and transported throughout Spain. The gas storage capacity in Spain is in the order of 30 TWh, which implies the potential storage of the renewable electricity produced from Spanish wind turbines during half a year.
The current synthetic natural gas production process is based on hydrogen production via electrolysis and its reaction with carbon dioxide coming from industrial biogas. In the process, only tap water and carbon dioxide from biogas are used as raw materials. The compact INERATEC plant is designed for decentralized production, fits into a shipping container, and can be extended modularly. In the present case, the pilot plant has a production capacity of 100 Nm3 of natural gas per day and is scalable according to demand. IREC’s catalysts have the versatility to produce synthetic natural gas either directly from clean biogas or from the carbon dioxide released by a membrane biogas upgrading plant, which is also located on the water treatment plant implemented and operated by Cetaqua. The methanation reaction is carried out at mild pressure and temperature conditions. The current Spanish legislation is strict and requires a high methane content of 95% to be injected to the gas grid. In this line, the methanation process and gas analytics were developed specifically to comply with the Spanish legislation.
The operation of the demo plant started on May 2018 and is expected to be in operation in Barcelona one and a half years. The demo plant on synthetic natural gas production is a part of the Synthetic Fuels – Combustibles Sintètics (CoSin) project with code COMRDI15-1-0037 led by Gas Natural Fenosa. Co-funded by the European Regional Development Fund 2014-2020 within FEDER Catalonia’s Operative Program and Catalonia Trade & Investment under the RIS3CAT Energy Community.