Why the chemical sector needs so much hydrogen

Whether as seasonal energy store or great white hope for zero-emissions aviation, hydrogen has long become an integral component of carbon neutrality. Furthermore, hydrogen is already an important commodity in the chemical sector. At present, this branch of industry is by far Germany’s biggest hydrogen user. According to the Hydrogen Compass, the country’s chemical plants consumed 1.1 megatons (MT) of this gas in 2021. This translates into 37 terawatt hours (TWh) of energy and accounts for about two-thirds of the hydrogen used in Germany.

A roadmap for the hydrogen economy

Based on data from the Hydrogen Compass task force, the chemical industry’s need for hydrogen could rise to over 220 TWh before contractually agreed carbon neutrality is achieved in 2045. The team consists of experts from the Chemical Engineering and Biotechnology Society (DECHEMA) and the National Academy of Science and Engineering (acatech), who have been tasked with designing a roadmap for building the hydrogen economy.

The project has received 4.25 million euros in subsidies from the budget of the German Ministry for Education and Research and the German Ministry for Economic Affairs and Climate Action. The scientists have been charged above all with evaluating existing studies in order to give players in business, administration and politics a shared understanding of the potential future look of the hydrogen economy and of the steps required to create it.

Chemicals produce 15 percent of German CO₂ emissions

One of the areas addressed by the project is the chemical industry. According to the Hydrogen Compass, it accounts for annual greenhouse gas emissions of around 112 metric tons of CO₂ equivalent, not including refineries. This represents approximately 15 percent of Germany’s total emissions, although the sector is only responsible for roughly seven percent of aggregate energy consumption.

The apparent mismatch of energy demand and emissions can be traced back to the use of fossil fuels as basic material. The chemical industry uses coal, oil and gas not just to produce energy, but also breaks these resources down into their elements ­ primarily carbon and hydrogen in order to recompose them. This is how the sector produces basic materials such as ammonia and methanol, which are then further processed into plastics and artificial resins, fertiliser and paints, personal hygiene products, cleaning agents and medicine.

All these products contain fossil fuels, with some even consisting entirely of them. According to the Hydrogen Compass, greenhouse gases resulting from combustion or consumption at the end of the production cycle account for half of the sector’s emissions. Additional greenhouse gases are produced from various conversion processes.

Green hydrogen is key to a sustainable chemical sector

Therefore, even if the chemical sector sourced its energy solely from sustainable sources, it would not even be able to cut its emissions in half. The inverse conclusion is that the chemical industry could more than halve its emissions by switching from fossil (grey) to sustainable (green) hydrogen.

To date, hydrogen is produced nearly exclusively from fossil fuels. Germany’s share of roughly five percent hydrogen from renewables puts the country in quite a commendable position on the international playing field.

The challenge is that, although the differences among prices of hydrogen obtained by various methods (see info box) have decreased in recent years, conventional production still has the lowest cost and – most importantly – the by far greatest installed capacity.

Chemical industry: the first stage of the hydrogen economy?

It is thus important to determine where low-emissions hydrogen should mainly be used as long as demand cannot be met without the grey category. Using grey hydrogen to heat buildings or generate electricity would do a disservice to the climate since fossil fuels yield more energy with similar emissions. However, the same would hold true if the chemical sector had to use grey hydrogen because the green grade was used by gas-fired power plants or heating systems.

And two more reasons also speak in favour of using low-emissions hydrogen in the chemical industry for the time being. First, whereas there are ways to generate electricity and heat that are more efficient than using hydrogen, this gas is an irreplaceable basic material for numerous industrial processes and products. Ammonia and methanol as well as virtually all the aforementioned products that are essential in everyday life feature an “h” in their chemical formula.

Second, aviation also lacks a feasible decarbonisation option that can do without hydrogen. However, while hydrogen jet engines are only just being developed, many processes employed in the chemical industry require basically no innovation at all in order to replace grey with green hydrogen. After all, the two are fully interchangeable.

Chemical industry enables negative emissions

This way, plastics could actually become permanent carbon sinks. If sustainable hydrogen is used together with carbon from biomethane to produce durable products such as garden furniture, car body parts and paint, the integrated carbon extracted from the atmosphere by plants during growth forms permanent bonds.

The same applies to syngas, an intermediate product made of hydrogen and carbon monoxide, which results directly from solar energy or, e.g., from pyrolysis from residential waste with biogenic content.

Waste plastic and other reusables can be recycled by various means to spur the circular economy. Chemical methods enable production of syngas also from mixed waste and composites. If renewable energy is used in the process, the resulting products can at least be considered emissions-free.

RWE is testing this concept as part of the FUREC project in the Netherlands. This involves producing hydrogen from residential waste. However, according to the Hydrogen Compass, only 35 percent of the waste plastic is being recycled, with the remainder being fired in power stations.

Chemical sector also needs hydrogen for energy supply

A wide range of  chemical processes requiring low-temperature heat are fairly easy to decarbonise: heat pumps as well as (steam) electrode boilers, in which heat is generated by conducting electric current through water, can be operated using green energy.

However, natural gas, which can only be supplemented by (sustainable) hydrogen but will likely be supplanted in the long run, is still required for high-temperature processes north of 300 degrees Celsius. Such processes can currently only be run in a carbon-neutral manner with synthetic fuels or by capturing the carbon dioxide emissions they produce. Green hydrogen could be the solution.

Conclusion: chemical industry needs hydrogen at nearly all levels

Besides the ‘basic requirement,’ which totals 37 MWh today, the chemical sector will need hydrogen in other areas as well. These include intermediates and basic materials which may already contain hydrogen that is not necessarily pure. Added to this is the energy used, in particular to generate high-temperature heat.

The manifold hydrogen applications in the chemical industry explain why the researchers working on the Hydrogen Compass reach the conclusion that demand will rise more than six-fold to over 220 TWh by 2045/2050. The scientists actually forecast the need peaking at as much as 283 TWh, corresponding to 7.5 times current consumption.