Carbon nanofibers in the hydrogen industry
With our carbon nanofibers (CNFs) fabrication technology, we develop materials engineering solutions for use in the cleantech industry.
Currently, we focus on improving membrane-electrode assembly (MEA)—a component in high-efficiency water electrolyzers and fuel cells. The component enables the conversion of electricity into hydrogen and vice versa. Thus, it’s a key component in storage and transmission of renewable energy and decarbonizing of industry, transportation, and heating.
With a clever use of carbon nanofibers, we can reduce the use of rare and expensive noble metals by 50–70 percent, while doubling or tripling the active surface area of the proton-exchange membrane (PEM) or anion exchange membrane (AEM) used in MEA.
Is your company interested in building more efficient electrolyzers or fuel cells? We are your technical partner. Contact us and we’ll tell you more.
What is cleantech?
Clean technology, or cleantech for short, refers to technology that simultaneously fulfills two objectives: First of all, it significantly reduces (i) the use of non-renewable materials and energy, (ii) waste and mismanagement, and (iii) emissions and pollution. Secondly, it is competitive with its conventional counterparts, if not superior to.
The term green technology, or greentech for short, is often used interchangeably with clean technology. One might argue that there are subtle differences between them. The problem is that nobody seems to agree on what these differences are. In practice, they refer to the same thing.
Cleantech can be used for many good purposes. The most worthwhile is perhaps the reduction of greenhouse gases in general and carbon dioxide (CO2) in particular.
Carbon neutrality
Human emissions of greenhouse gases have given rise to global warming, leading to devastating climate changes. To not ruin the world we have inherited and must pass on to future generations, we must achieve carbon neutrality—a state of net-zero greenhouse gases measured in terms of carbon dioxide equivalence.
More than 130 countries—including the United Kingdom and the European Union (except for Poland)—and many companies, cities, and financial institutions—have agreed to reduce emissions to net-zero by 2050.
Hydrogen (H2) has an essential role in achieving this goal. According to a report by the Hydrogen Council in collaboration with McKinsey & Company, hydrogen can contribute 20 percent of the total abatement needed in 2050. But then it has to be green hydrogen or low-carbon hydrogen.
Green hydrogen and low-carbon hydrogen
About 95 percent of commercial hydrogen in the US is produced by steam methane reforming (SMR) of natural gas. The process results not only in hydrogen but also in massive emissions of carbon dioxide.
The production of one metric tonne of hydrogen produces up to 13 tonnes of carbon dioxide. SMR is as far from clean technology as it gets.
Another dirty method is the gasification of carbon-based raw materials, such as oil, coal and biomass. By its very nature, this also gives rise to significant carbon dioxide emissions.
The only commercially viable method of producing hydrogen that does not give rise to carbon emissions is the electrolysis of water. Electrolysis of water is the process of running a current through water to split water molecules into their constituent parts: hydrogen and oxygen.
Hydrogen produced by water electrolysis is not enough to contribute to carbon neutrality. The electric power used in the production must also have been produced with no greenhouse gas emissions or at least substantially lower emissions than conventional fossil fuel power generation. Such hydrogen is called low-carbon hydrogen. If the electricity originates from a renewable source, it is called green hydrogen.
The European Union uses definitions that can be expressed as follows:
Grey hydrogen is produced with a carbon footprint greater or equal to 36.4 gram carbon dioxide equivalent per megajoule (regardless of the energy source).
Low-carbon hydrogen is produced with a carbon footprint lower than 36.4 gram carbon dioxide equivalent per megajoule.
Green hydrogen is low-carbon hydrogen where the energy source is renewable.
Green hydrogen to rescue
Green hydrogen is critical to enabling a carbon-neutral energy system. Electricity can be converted into energy-rich hydrogen, that can be stored for long periods in large volumes, can be transported long distances, and can be tapped as fuel or converted back into electricity when needed. This has many positive implications. Two examples:
Storing energy as hydrogen when low-cost surplus energy is available and releasing it when needed enables continuous grid operation with solar panels, wind turbines, wave power plants, and other renewable energy sources that are intermittent.
Transporting energy as hydrogen through pipelines or boats makes it possible to extract highly competitive renewable energy in places that would otherwise be out of the question due to their remoteness.
Storing and transporting energy is not the only way green hydrogen (or at least low-carbon hydrogen) can lower carbon emissions.
Heavy industry becomes green industry
Green hydrogen and low-carbon hydrogen are critical for decarbonizing industries.
First and foremost, the carbon emissions from industries using grey hydrogen would decrease significantly if they used green or low-carbon hydrogen instead. Take ammonia, for example. It is the second most commonly produced chemical in the world. More than 80 percent is used as feedstock for fertilizer. The rest are used in making paint, plastic, textiles, explosives, and other chemicals. Ammonia production in 2018 was 176 million metric tons and generated around 500 million tons of carbon dioxide. A large part of these emissions comes from hydrogen produced by steam methane reforming. That method emits 13 tons of carbon dioxide per ton produced hydrogen.
Secondly, green hydrogen or low-carbon hydrogen can be used as a new feedstock to lower carbon emissions. A great example of this is the steel industry. Each ton of steel produced in 2018 is estimated to emit 2.2 tons of carbon dioxide—equating to about 11 percent of global carbon dioxide emissions. But it is possible to make fossil-free steel by using green hydrogen instead of carbon or coke. Green hydrogen makes it possible to remove oxygen from the iron ore, which is a prerequisite for steel production.
Thirdly and lastly, green or low-carbon hydrogen can be used for high-grade industrial heating. An example is the cement industry, which accounts for 8 percent of global carbon dioxide emissions. Emissions can be reduced by a third by using green hydrogen to heat the cement kilns. (The remaining two-thirds come from the chemical reaction that produces cement and must be captured and stored or reduced by other means.)
Decarbonizing of transportation
The industry is not the sole significant source of carbon dioxide emissions. Transport is an equally big culprit, which needs to be decarbonized. Again green or low-carbon can be used.
Hydrogen can be used as a fuel for heavy-duty trucks, coaches, long-range passenger vehicles, and trains. It can also be used as feedstock for producing synthetic fuels for maritime vessels and aviation.
Rapid increase in demand for hydrogen
According to the report, Hydrogen for Net-Zero by Hydrogen Council and McKinsey & Company, green and low-carbon hydrogen can be used to avoid 80 billion tons (80 GT) of cumulative carbon emissions from now through 2050. With an annual abatement potential of seven billion tons (7 GT) in 2050, hydrogen can contribute 20 percent of the total abatement needed in 2050.
But then production over the upcoming 30 years must increase more than seven times-from 90 to 660 million metric tons. And in just eight years (2030), production will need to increase by more than 50 percent.
Rapid growth of production capacity
To meet the strong growth in demand for hydrogen, production capacity needs to be expanded rapidly. And indeed, we see a rapid growth in announced or started projects to build hydrogen production facilities. In fact, the growth is so fast that the Hydrogen Council’s growth forecasts have had to be bumped up every year in recent years.
In the report, Hydrogen for Net-Zero, Hydrogen Council and McKinsey & Company writes that players have announced more than 18 million tons of green and low-carbon hydrogen production through 2030. (See figure below.) Additional announcements include nearly 13 million tons of green and low-carbon hydrogen production capacity with deployment beyond 2030. The total green and low-carbon hydrogen production volume announced in 2021 exceeds 30 million tons—more than 30% of the current global hydrogen demand.
Skyrocketing demand of membrane-electrode assembly
Green hydrogen and low-carbon hydrogen are produced by electrolysis. Put simply, that is running electricity through water and gathering the released hydrogen. The apparatus in which this is done is called an electrolyzer.
Conventional technology—alkaline electrolysis—is quite inefficient. The hydrogen produced contains only 45–65 % of the energy input. Much better efficiency is provided by PEM electrolysis. Up to 84 % of the energy can be recovered, and the figure is expected to reach 86 % by 2030. Thus, the new electrolyzers being built will mainly use PEM electrolysis.
The critical component of a PEM electrolyzer is the membrane-electrode assembly (MEA). It is the unit where the electricity in contact with water becomes hydrogen and oxygen. Each production plant has vast numbers of these. Thus, the rapid growth of production capacity implies that the demand for MEA will skyrocket.
Operation of membrane-electrode assembly
The membrane-electrode assembly (MEA) has at its heart a proton-exchange membrane with catalytic metal particles on its surfaces, followed by porous material to diffuse the released gases and outermost flat plate electrodes.
The conversion from electricity to hydrogen occurs at the contact surfaces between the catalytic particles and the membrane. The more contact surfaces there are, the more hydrogen can be produced. The difficulty lies in getting the nanoparticles in the right place.
Why membrane-electrode assembly is expensive
Currently, one method used is to mix the catalytic particles into ink that is applied between the membrane and the porous material. The problem is that only a few of the catalytic particles end up right on the membrane. A vast majority is inside the ink and does not come into contact with the membrane. They are entirely wasted.
It wouldn’t be a big problem if it weren’t for the catalytic particles, being rare and expensive noble metals. On one side of the membrane, platinum is used, which on January 10, 2022, costs 853 USD per troy ounce—that’s about 25.000 EUR/kg. On the other side, it’s even worse. It uses iridium, which is very rare. Less than eight metric tons are mined yearly. And the price on January 10, 2022, is 6,100 USD per troy ounce—that’s about 175.000 EUR/kg.
How Smoltek reduce the price
The solution from Smoltek fixates nanoparticles of the catalyst metals on carbon nanofibers embedded into the membrane. This dramatically reduces the amount of noble metal needed while practically every piece of them is put to use.
This is how we can reduce the use of rare and expensive noble metals by 50–70 percent while doubling or tripling the active surface area of the proton-exchange membrane (PEM) or an ion exchange membrane (AEM) used in MEA.
Achievements so far
This requires the ability to fabricate, on the surface of the porous material, nearest the membrane, a forest of erect carbon nanofibres in rows and columns. The nanofibres must be uniformly distributed at a distance optimized to facilitate the transport of reactants to the nanoparticles and gas away from them.
Of course, it also requires that particles of platinum and iridium, measured in nanometers, can be created and attached to the surface and tip of the carbon nanofibre.
Furthermore, the carbon nanofibres must have low electrical resistance to allow current to flow between the electrode and the catalyst nanoparticles.
On top of all that, the carbon nanofibers must be corrosion resistant because of the membranes which create an acidic electrolyte in contact with water.
Smoltek has developed and patented the technology to do all this.
Are you interested in partnering with us?
Our next step is to industrialize our solution for carbon nanofiber enhanced membrane-electrode assembly (CNF-MEA for short). We are therefore looking for industrial partner(s) that, in close collaboration with us,
- builds and test prototypes with different combinations of geometry, protection, catalyst, and substrate for CNF to grow on,
- tests long-term durability of the most promising solutions,
- develops a high volume production concept, and
- produces a test series of CNF-MEA to be used in actual production.
Is your company a potential partner? Contact us today, and let’s arrange a meeting to discuss it further.
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