Sustainable hydrogen: the fourth pillar of the energy transition

Sustainable, low-carbon hydrogen is the fourth pillar of the energy transition after renewable energies, energy efficiency and electrification. In practical terms, this means that without low-carbon hydrogen, it will be impossible to achieve a climate-neutral economy. Efficiency measures should be carried out, energy consumption reduced and renewables-generated electricity utilised directly in those sectors where this is feasible. These measures are enhanced by the use of renewable hydrogen as a potential energy source and input for industrial applications.

Depending on how it is produced, different colour names are assigned to hydrogen:

• Green hydrogen: This is produced through a process known as electrolysis of water. The electricity used for electrolysis must be generated from additional renewable energies. Green hydrogen will be the centrepiece of the hydrogen supply in the medium to long term. This will require a further major expansion of electricity generation from renewables in Germany, Europe and other countries.
• Blue and turquoise hydrogen: This is produced from natural gas using a process known as steam reforming. Most of the CO2 emitted during hydrogen production is captured and sent for long-term storage underground; alternatively, it is stored permanently as solid carbon. This type of low-carbon hydrogen may be of relevance in the short to medium term.
• Grey hydrogen is produced using electricity that mainly comes from fossil fuels. Its greenhouse gas emissions are therefore relatively high compared with hydrogen produced using natural gas, so it cannot be classed as sustainable. The CO2 emitted during hydrogen production is released into the atmosphere.

For all colours in the hydrogen palette and all production locations, whether in Germany or abroad, ambitious sustainability standards must be applied. Environmental and socioeconomic criteria such as working conditions, land rights and water availability need to be considered in this context.

As hydrogen is likely to remain a scarce and costly resource in future, it should mainly be used in applications where no other decarbonisation options can be expected.

• This applies particularly to the steel and chemical industries, aviation and shipping; in some cases, hydrogen may also serve as a substitute for natural gas in large-scale heat and power cogeneration.
• Hydrogen is a comparatively costly climate change mitigation option; for that reason, more cost-effective alternatives should be deployed first. In other words, hydrogen is not the key to transforming the transport or heat sector. Battery electric vehicles and heat pumps are far more efficient than the use of hydrogen and hydrogen-based applications. Hydrogen can merely complement electricity-based technologies in the transport and heat sectors.

International partnerships must be established at an early stage in order to achieve a secure and sustainable hydrogen supply for Germany. Germany itself cannot produce more than a very small percentage of the renewables-generated electricity required for hydrogen production.

Infographs on the topic of hydrogen (Flickr)  

Hydrogen: Information and services from the Oeko-Institut

The Oeko-Institut’s experts are engaged in a range of projects that focus on the production and sustainability of PtX materials. They provide advice to decision-makers on legislative and regulatory initiatives, analyse and assess sectors with potential for hydrogen use and conduct research on the required sustainability criteria.

Further information

Electricity-based fuels: the future of PtX

Online magazine eco@work, Issue 3/2020: Power-to-X: Why do we need PtX?