power to gas

Power to gas is a conversion process that transforms electrical energy into chemical energy stored in gases, primarily hydrogen or methane. The core technology relies on electrolysis: passing electrical current through water to split H₂O molecules into hydrogen and oxygen. A single electrolyzer converts electricity and demineralized water into these two gases at the cathode and anode respectively. The hydrogen can be stored directly in pressurized tanks or pipeline networks, or further processed through methanation to become synthetic methane (CH₄), which integrates into existing natural gas infrastructure.

The primary driver for power to gas installations is grid balancing. When wind or solar generation exceeds demand, operators face either curtailment (wasting energy) or storage. Electrolyzers can absorb excess power within minutes, converting kilowatts into storable chemical form. Industrial-scale systems operate at 50 to 100 megawatts of electrical input, though smaller units down to hundreds of kilowatts exist. Hydrogen emerges at pressures around 30 to 50 bar in alkaline electrolyzers, while proton exchange membrane (PEM) systems deliver higher pressures, reducing downstream compression costs.

Efficiency losses are substantial. Water electrolysis achieves 60 to 75 percent electrical-to-chemical efficiency under normal operating conditions. Methanation, which adds a second conversion step using hydrogen and captured CO₂ to synthesize methane, introduces additional losses of 10 to 15 percent. End-to-end efficiency from grid electricity to stored methane therefore sits around 50 to 65 percent. This gap remains the technology's central limitation: you store less energy than you input, making it economically viable only when generation curtailment would otherwise occur.

Integration and use cases

Hydrogen from power to gas finds direct use in industrial processes: ammonia synthesis, steel reduction, and petroleum refining already consume hydrogen at scale. Injecting hydrogen into natural gas networks is possible up to 15 to 20 percent by volume without modifications to appliances and turbines; beyond that threshold, infrastructure upgrades become necessary. Synthetic methane (also called power to methane or PtM) avoids this constraint because it behaves identically to fossil methane, using existing pipeline systems, storage caverns, and end-use appliances without modification.

The technology remains dependent on favorable electricity pricing. Power to gas installations operate during periods of negative or very low wholesale prices, typically a few hundred hours per year in mature renewable markets. Capital costs for electrolyzers range from 400 to 1,500 USD per kilowatt of electrical input, depending on technology and scale. Without subsidies or carbon pricing mechanisms that penalize curtailment, most projects struggle to achieve acceptable returns. Long-term viability hinges on the volume of renewable generation and the rigidity of existing gas demand and storage infrastructure.