Power-to-X

Power-to-X is a powerful tool for the future of industry in the context of the energy transition. Its diverse possible applications offer the long-term potential of transforming the carbon-based chemical industry to use climate-neutral processes.

Using renewable electricity directly after it is generated is particularly efficient, since no energy is lost as a result of converting it into other forms of energy or storage. If the sun shines a lot and it is frequently windy, however, these renewable energy sources frequently produce a surplus of electricity. With the help of Power-to-X technologies (P2X) such as Power-to-Gas (P2G), Power-to-Liquids (P2L) and Power-to-Chemicals (P2C), the surplus power can be stored, transformed into other substances and used at a later point in time. These technologies therefore represent an important component of the energy transition. In addition to storing electricity, they also offer the potential of providing industry with “green” raw materials, making it possible to manufacture everyday products sustainably. Some P2X technologies also facilitate the shift from fossil-based to renewable resources since they can be integrated into existing supply chains and infrastructures. Furthermore, they play an important role for sector coupling: they ensure that sustainably produced electricity is used flexibly and efficiently in the heating, transport and industrial sectors. Thus, a secure, affordable and environmentally sound energy supply for the future can be achieved. Power-to-X technologies are of particular interest for the chemical industry – especially in terms of industrial carbon and nitrogen production – since a large proportion of all chemical feedstocks can be synthesised from hydrogen, CO2 and nitrogen from the air, using electricity generated from renewable sources. The process can therefore replace the use of fossil raw materials in the future and make a key contribution towards paving the way to a climate-neutral industrial sector. Power-to-X technologies are scientifically proven and are available – although their utilisation is currently still associated with higher costs than using fossil resources that are harmful to the climate.

 

For some Power-to-X processes, CO2 or nitrogen are also needed alongside electricity. There are various possible ways to obtain the required CO2: on the one hand, it can be captured from concentrated sources such as the processing of biogas or from industrial processes. It is also possible to extract CO2 directly from the atmosphere, creating a CO2 cycle. As it is one of the main components of the atmosphere, nitrogen can be obtained using an air separation unit.

Overview of a climate-neutral industrial network for the future, in which Power-to-X technologies play a key role

Power-to-Gas technologies convert electricity into the gases hydrogen or methane. In electrolysis, which is the basis of every Power-to-Gas technology, electricity breaks water down into hydrogen and oxygen. The hydrogen produced can be used to convert CO2 into methane. The gases produced in this way can then be transported independent of the power grid. Methane, the main component of natural gas, can be transported using the existing natural gas pipelines without any technical modifications and hydrogen can also be added to the natural gas pipeline to a limited extent. Since pure hydrogen is needed for many new technologies, however, a mixture of natural gas and hydrogen is insufficient. In order to meet the growing demand for pure hydrogen, the capacity of the pipelines must be increased in the future.

Once it is converted into hydrogen or methane, electricity from renewable energy sources can thus also be stored for periods when there are lulls in solar and wind power generation. Although short-term storage facilities can balance the fluctuations of solar and wind energy production for a restricted period of time, this system is stretched to the limit in the event of long down times due to weather conditions. The approx. 450,000-kilometre-long gas pipelines and 47 natural gas storage facilities in Germany store up to 200,000 gigawatt-hours of natural gas – in contrast to this, all the pumped-storage power plants in Germany have a combined energy capacity of 40 gigawatt-hours.

In addition to using hydrogen and methane to power combustion engines and to generate heat and recover electrical energy in fuel cells, hydrogen, in particular, can be used as a raw material.

In their joint project REFHYNE, Shell and several partners are installing, testing and operating a 10-megawatt PEM electrolyser in order to produce green hydrogen for the refinery plant.

Power-to-Liquid technologies are designed to manufacture liquid products for use as fuels. As in the case of Power-to-Gas, this initially involves converting electricity from renewable sources into hydrogen using electrolysis. There are subsequently several options for producing fuels: the processes that have been the subject of most research and are already well-established are methanol and Fischer-Tropsch synthesis. Via methanol synthesis, methanol is synthesised from the hydrogen that is produced, together with CO2, and the methanol can then be further processed to obtain diesel fuel. Via Fischer-Tropsch synthesis (FTS), various hydrocarbons can be produced, which are used as sustainable diesel, kerosene and petrol in combustion engines or as base chemicals such as ethylene or propylene in industrial production. Power-to-Liquid processes are a suitable means of supplying sustainable synthetic fuels for transport sectors where electro-mobility has hitherto reached its limits. For instance, batteries are currently still nowhere near capable of supplying the power density needed for long-haul flights, meaning that demand for sustainable fuels for combustion engines will continue to exist in the future.

 

Power-to-Chemicals technologies are also based on the production of hydrogen using electrolysis. In contrast to P2G and P2L, however, they are not designed to use the products for energy but as raw materials, in order to supply sustainable feedstock for the chemical industry. Currently all chemical products are still based on fossil resources. However, as the availability of these resources becomes increasingly limited, and in the interests of climate protection, sustainable alternatives are needed in order to guarantee future supplies of medicines, plastics and fertilisers. By combining various processes, a large proportion of the chemical value chain can also be realised based on hydrogen, CO2 and nitrogen and can thus reduce demand on resources. The production of syngas, methanol and ammonia offer much debated approaches to providing alternative building blocks for the chemical industry.

Syngas can be produced either using hydrogen and CO2 at high temperatures or directly from water and CO2 by means of co-electrolysis. By choosing different reaction conditions, it is also possible to produce methanol from hydrogen and CO2 (methanol synthesis). Alongside the elements hydrogen (H), carbon (C) and oxygen (O), nitrogen is another important component in many products, such as medicines and fertilisers. Although nitrogen is available everywhere, since it is main element of air, it can only be used in this form with a very high energy input. To allow further utilisation of nitrogen, it is therefore used in the Haber-Bosch process involving hydrogen to produce ammonia (NH3). This chemical compound can be more easily integrated into further production processes and is therefore extremely important for industry. The process can also be made sustainable by changing over from hydrogen produced from fossil fuels to renewable hydrogen.

Info booklet

With information about the initiative, the participating stakeholders, technologies and solutions for a climate-neutral industrial sector.

Info booklet