Renewable, synthetic energy sources are one of the central pillars of an integrated energy transition, alongside the direct use of renewable power and temporary storage of this power in batteries. These energy sources make it possible to seasonally store excess solar and wind energy and subsequently use it in many different ways for sector coupling, be it for heat supply, transportation or industry. The key technology for this is called power-to-gas (PtG), which involves using energy for electrolysis to break down water into oxygen and hydrogen. Additional synthesis processes can then be used to convert the hydrogen gas into methane – a gaseous energy source – convert it into liquid fuels or even convert it back into electrical energy.
So far, investments in Germany have been hampered by a number of obstacles. One problem is that electrolyzers are classified as end users of green power and subject to all of the corresponding taxes and levies. Another problem is the lack of an effective system of carbon pricing. And to reduce the current high cost of investing, a large-scale market launch is needed – with more installations and, in particular, larger ones. Nonetheless, electricity and gas grid operators are already carrying out initial projects. The intention is for power-to-gas plants to use both energy supply grids, paving the way for a hybrid infrastructure as sector coupling advances. Storing renewable energy in gas grids can help to relieve and stabilize the electricity grids as well as cutting the costs of grid expansion.