The gas industry is already feeding gas from biogas into the gas network. The plan for the future is to use the network of gas pipelines as a composite system in which natural gas, biogas as well as hydrogen and synthetic methane produced from renewable electricity are combined to form one huge energy source. The natural gas pipelines in Germany have a total length of more than 505,000 km and are already transporting double the amount of energy than the entire electricity grid.
Much more promising is the option of converting renewable electricity into gas and storing it in the gas pipelines. This would make it possible to use demand side management (adjusting the demand for electricity to the amounts being generated at that time), for instance at times when the wind is blowing so hard that more electricity is being produced than can be taken up by the grids, or to render the production side more flexible. It would also be possible for excess electricity to be converted into other forms of energy. One option here is power-to-gas technology. This technology uses electricity to split water into hydrogen and oxygen (electrolysis). The hydrogen is then fed into the gas network. In a second step, additional chemical reactions can be triggered to produce methane from the hydrogen. The gas that is produced in this way can then be used for industrial purposes, for heating, and for transport. It can also be used to power turbines, which convert the energy back into electricity.
Multiple conversions do, however, result in high levels of energy loss. This is why this solution is not yet economically viable. In the medium-term, however, power-to-gas technology could provide an affordable solution for storing large amounts of electricity in way that is economically viable. It would also forge a strong link between the gas network and electricity from renewables.