Contains the full lesson along with a supporting toolkit, including teachers’ notes.
Biogas and biomethane
Biogas is produced by the anaerobic breakdown of organic matter in an oxygen free environment. Biogas typically consists of methane (CH4 ≈ 55%) and carbon dioxide (CO2 ≈ 45%) with some water (H2O), hydrogen sulphide (H2S), trace particulates and other compounds. When biogas is injected into the natural gas grid or utilised as a transport fuel, it must be upgraded to biomethane (>97% CH4) by removal of CO2. Its use as a fuel is an attractive option because it is renewable and so reduces our dependence on fossil fuels.
Biomethane is a suitable form of renewable fuel for Ireland as it has a similar composition to natural gas and there is already a natural gas distribution network in place. Therefore, biomethane has the potential to be injected into the network without the requirement to develop significant infrastructure. It is estimated that biomethane could provide 7.5% of Ireland’s natural gas demand by 2020; this would contribute significantly to the Government’s renewable energy commitments. Biomethane offers an environmentally friendly alternative to traditional fossil fuels such as oil, coal, diesel and petrol.
Furthermore, biomethane can be produced from a number of organic resources. This would bring some extra benefits; using agricultural waste to produce biomethane would reduce both air pollution and water pollution. The residue remaining after biomethane production can be used as fertiliser, indirectly reducing energy costs.