Power-to-X: Using electricity from renewable sources in a variety of ways

The term Power-to-X (also: Power2X) is used to describe all technologies that are employed to create other forms of energy or products using wind or solar power. The main products are heat (power-to-heat) and particularly green hydrogen (power-to-gas). Green hydrogen, in turn, may be used as the basis for methanol, ammonia, fuels and other chemicals that were previously manufacture with fossil raw materials. Industrial companies are therefore able to consistently structure their products and processes in a climate-friendly manner.

INHALT:

The X stands for the different products and forms of energy that can be produced using electricity. The list is almost endless because many additional products can be made from these.

 The main forms of power-to-X are:

• Power-to-heat: Generation of heat from electricity using electrode boilers or heat pumps, for example.
• Power-to-gas: Generation of gas from electricity, which usually means the production of (green) hydrogen through electrolysis – but it can also include further processing into methane.
  
• Power-to-liquid: General term used for the production of liquids (e.g. fuels) using electricity. Hydrogen is an intermediate product in this process.
• Power-to-fuel: Production of fuels using electricity, e.g. kerosene (see power-to-liquid)
• Power-to-ammonia: Production of ammonia using electricity – a process that also creates hydrogen as an intermediate product.
• Power-to-chem: General term used for the production of commodity chemicals using electricity.
  

Additional carbon is required, which is obtained from CO2, for almost all products made with hydrogen. One exception is ammonia: Nitrogen drawn from the air, which itself is almost 80% nitrogen, is used to make that.

A variety of conditions need to be met for power-to-X to deliver climate-protection and environmental benefits:

• Exclusive use of energy from renewable sources
• Sufficient generation of energy from renewable sources (no competition with other uses)
• CO2 (if required) from sustainable sources, e.g. biogas
• Best possible utilisation of by-products (oxygen, heat)
• Sustainable water use / no exploitation of scarce resources

The relatively high conversion losses associated with the generation of electricity for power-to-X from fossil fuels make these processes more harmful to the climate and the environment than the respective conventional technologies.

Many industrial processes rely on crude oil, natural gas and coal as their sources of energy. But fossil hydrocarbons are also needed as the raw material for many products and manufacturing processes.

 Products that can be manufactured using power-to-X without fossil fuels include:

• Plastics made using synthetic methanol
• Fertilisers made using synthetic ammonia
• The use of hydrogen to replace coke and natural gas to extract iron from iron ore (reducing agent)

The simplest and to date most widespread power-to-X technology is the generation of heat (power-to-heat). It’s possible to generate heat for small projects using resistance heaters and electrode boilers for larger ones.

The use of heat pumps to generate heat is significantly more efficient.

Green hydrogen is important to the energy transition as a future technology. It fulfils the following functions:

• It offers flexibility: Electrolysers take up wind and solar power when lots of it is generated
• Long-term energy storage
• Movement of large amounts of energy across long distances through pipelines
• Intermediate product for many power-to-X technologies

Different energy transition scenarios vary greatly where their hydrogen requirements are concerned. Fundamentally: Direct electrification is the more efficient technology. Hydrogen is employed where direct electrification isn’t possible for a variety of reasons and where such other technologies as solar thermal energy or the utilisation of waste cannot be used to produce the desired results.

Largely easy-to-electrify technologies include:

• Room heating and hot water (heat pump, also: solar heat)
• Car traffic

Technologies that are difficult to electrify include:

• Shipping
• Air traffic

Applications where the hydrogen molecules themselves are required constitute technologies that cannot be electrified at all:

• The production of steel
• The production of ammonia
• The production of methanol

Strengths: Power-to-X technologies can enable industry to become climate-neutral. They constitute an alternative to fossil raw materials and limited biomass resources. The running costs for the actual generation of energy are low, which consequently means that it becomes possible to plan products and energy for extended periods of time.

Weaknesses: The efficiency of power-to-X is low when compared with direct electrification (e.g. in mobility) because it requires many conversions that are associated with losses. Each conversion step (e.g. electrolysis, CO2 capture, methane generation) also requires investments that have so far necessitated subsidies for most applications.

Opportunities: Power-to-X reduces dependence on imported fossil fuels and encourages local value creation. Germany also has the opportunity to gain a technological lead and export plant technology. Therefore power-to-X and green hydrogen are creating business opportunities for industry in Germany.

Risks: A risk exists in that countries with cheaper renewable electricity will also be able to operate power-to-X technologies at lower costs. It’s a risk to which industries in Germany are exposed (e.g. fertilizer industry). A further risk obtains in that the expansion of renewable energies in Germany will not progress fast enough to meet the rising demand for electricity.

The sector still faces several challenges that need to be overcome before power-to-X becomes widespread in Germany. But it’s a technology of the future and it’s important to start the ball rolling now so as not to miss boat down the line.

Author: Eva Augsten