PtX needs sustainability rules: additional renewable power is key to protecting the climate

Fuels produced from electricity – known as power-to-X (PtX) – are not necessarily sustainable or climate-friendly. They have a positive climate protection effect only if they are produced using additional renewable power and CO₂ that is captured from the air or from biomass use. Mandatory sustainability criteria with a high level of ambition should therefore apply to PtX production from the outset. This will also provide long-term investment security for PtX plants.

Which criteria should apply to sustainable PtX production? An impulse paper produced by the Oeko-Institut for Friends of the Earth Germany (BUND) provides answers.

1. Additional renewable power: the key to protecting the climate

PtX fuels can only help to protect the climate if they are produced using additional renewable power. Otherwise, PtX could have a worse carbon footprint than fossil fuels such as natural gas or diesel.

In Germany’s current electricity mix, which produces 474 g CO₂ per kilowatt hour (kWh), the CO₂ intensity of PtX ranges from 700 to 1,100 g CO₂/kWh, depending on its efficiency. By comparison, direct combustion of natural gas produces around 240 g CO₂/kWh; the corresponding figure for conventional diesel is approximately 300 g CO₂/kWh. However, PtX production has the potential to be almost 100% carbon-neutral – provided that it is based entirely on additional renewable energies.

2. The CO₂ source: a key factor for sustainability

The second criterion of relevance to the climate protection effect of PtX is the origin of the CO₂ that is used in the production process. In PtX technologies, power is used to produce hydrogen, which is processed into gas or liquid fuels (e-methane, e-fuels, etc.) in combination with CO₂. Sustainable biomass use and air are the only sources of CO₂ which do not produce greenhouse gas emissions; this, then, is the only option for achieving a carbon cycle that removes CO₂ from the atmosphere.

However, if the CO₂ used in PtX production comes instead from industrial processes, there is a risk that industry’s emission reductions will slow down. PtX plants have an operational lifetime of 20 years and more. During this period, industrial facilities supplying CO₂ for PtX would have no incentive to cut their carbon emissions. What’s more, if CO₂ emissions from industrial processes were to acquire value as an input for PtX production, this could well undermine the effectiveness of the European Union’s Emissions Trading System (EU ETS), whose purpose is to reduce carbon emissions from power plants and industry over the long term.

“Putting a price on CO₂ when we are meant to be cutting carbon emissions creates the wrong incentives and could counteract emissions trading,” says Peter Kasten, a PtX expert at the Oeko-Institut. Any use of industrial CO₂ for PtX production must be properly regulated, in the Oeko-Institut’s view.

And he continues: “We should not make the same mistakes with PtX as with biofuels. Only if it is ensured from the outset that power-to-X fuels genuinely reduce greenhouse gases should they be promoted. This also ensures that industry knows which strategies to invest in over the long term.”

3. Water and land: monitoring environmental and social hotspots

Besides CO₂, water is an essential input for hydrogen production. If PtX production is located in countries where water is already a scarce resource, this may negatively affect the sustainability of PtX fuels. The environmental and social dimensions of using land for additional renewable energies such as solar and wind must also be considered when measuring the overall footprint of PtX.

The social and environmental impacts of PtX production at the local level must therefore form part of sustainability monitoring. This is the only way to safeguard compliance with sustainability criteria for PtX technologies.

The impulse paper was funded as part of P2X, a Copernicus project supported by the German Federal Ministry of Education and Research (BMBF).

Not to be taken for granted: climate protection and sustainability through PtX – impulse paper by the Oeko-Institut

Positionen zur Nutzung strombasierter Flüssigkraftstoffe (efuels) im Verkehr: study by the Oeko-Institut (Positions on the use of electricity-based liquid fuels (e-fuels) in transport)

CO₂ emissions from PtX and fossil fuels: a comparison – infographic by the Oeko-Institut

Power-to-X: an overview of inputs, processes and products – infographic by the Oeko-Institut