442 / 2018-09-01 17:06:08

Innovation in Green Gas Technologies and Systems

全体主题 > 生物质燃气

All countries need to decarbonise energy, agriculture and transport. Renewable electricity has long been understood in terms of technology in the mainstream media and is readily commercialised. Grid stability associated with increasing levels of intermittency of renewable electricity is a challenge. The concept of renewable gas or green gas is not as advanced nor understood. However, it offers solutions to decarbonising thermal energy, transport and agriculture and can also facilitate (and provide ancillary services) to intermittent renewable electricity. Six European gas grids have committed to carbon neutrality by 2050. The technologies employed initially involve upgrading of biogas (produced from slurries decarbonising agriculture) for gas grid injection. For example, Denmark is already at 12% green gas in the gas grid based on agricultural residues. The green gas industry will expand to gasification of woody crops with methanation, to fermentation of both macro- and micro-algae (to both biomethane and biohydrogen) and finally will employ power to gas systems. Green gas can facilitate intermittent renewable electricity due to the dispatchable nature of biogas and its ability to operate in demand driven mode. Pulse feeding of digesters results in peaks (and troughs) of methane output which can be timed to coincide with periods of maximum demand for electricity. Alternatively, when intermittent electricity is in excess supply it may be converted to an electro-fuel. Initially this may be hydrogen and but use of the Sabatier Equation allows capture of CO2 and production of renewable methane for gas grid injection. The sustainability of such systems is of issue in terms of decarbonisation. Hydrogen produced from carbonised electricity will have a higher carbon footprint than the electricity from which it is produced. Green gas has a significant role in the circular bioeconomy and when coupled with algae can facilitate valuable products (such as alginates, hydrogen, ethanol, volatile fatty acids) and energy vectors (such as advanced gaseous biofuel systems not requiring land). This paper will explore advances in technology and systems which, integrate green gas technologies in the future energy grid and in the circular bioeconomy.