DEFINE THE ROLE OF 'RENEWABLE' GASES
The role of 'renewable' gases in the energy transition
The Paris agreement and the commitments that Europe is making in its 2050 strategy pursue a carbon neutral society by 2050. By then, the energy sector must be fully decarbonised, which means that there is no place for raw fossil fuels.
'Renewable' gases: biogases, electrogases and decarbonised gases.
In this context, the role of the so-called 'renewable' gases are being discussed:
- Organic origin gas (Biogases). They are derived from decomposition of organic material, such as waste, sewage sludge, biomass, etc. This gas can only be used as a fuel locally (for the production of electricity and local thermal uses), since it cannot be introduced massively into gas networks. Currently, biogases are the only gases truly renewable with proven development and affordable costs, but their potential is very limited and restricted to local use, so they can only be an alternative for certain markets.
- Renewable electricity origin gas (electric gases). This option consists of using electricity generated with renewable energies to synthesise hydrogen through the electrolysis of water. The hydrogen obtained in this way is so called "electroH2", clean Hydrogen or green hydrogen.
- "ElectroH2" has a direct use in thermal and electricity production processes but, in relation to its transport and later use, the current networks only accept around a 10% of "electroH2" mixed with natural gas. Higher concentrations, or transport of only H2, requires a substantial modification of all gas networks and the adaptation of the final usage installations.
- From "electroH2", by incorporating CO2, it becomes synthetic methane, or "electromethane" similar to fossil-derived natural gas. In order to be carbon neutral, this gas requires that the CO2 incorporated in its production comes from direct capture from the atmosphere, which requires immature and very expensive technology. If the CO2 came from a previous emission of another process, the neutrality of emissions to the atmosphere would not be guaranteed and could not be considered as clean gas.
- Fossil origin gas (decarbonised gases). Fossil-derived natural gas used in thermal processes with CCS/CCU produces decarbonized gas (through combustion) or blue H2 (through water steam reform). These gases cannot be considered clean because CO2 emissions are released in their production (at least 10%). The viability of these options depends on their availability, in terms of technical-commercial development, and access to underground storage, transmission networks, cost, social acceptance, etc.
Since the technology for obtaining clean and decarbonised gas is still emerging and expensive, the main action in this regard should focus on R&D work.
The competitiveness of these technologies will depend on their future technological development. Within the existing options, these gases should only be used where there is no carbon neutral alternative (i.e. renewable electricity).