Researchers at all levels are working on alternative mobility concepts, from batteries to hydrogen to methane. They are not always in agreement with the strategies of politicians. In Austria, Sebastian Kurz,the ÖVP’s leading candidate, continues to generate debate. He wants to make Austria the number one hydrogen nation and establish hydrogen fuelling stations throughout the country by 2025.
Against the backdrop of the climate debate, microbiologist Heribert Insam sees an urgent need for action. At the same time, however, he urges us to think things through and weigh up all the advantages and disadvantages of the various energy sources. Insam is head of the Institute for Microbiology at the University of Innsbruck and is researching the potential of methane production in biogas plants. Methane is a combustible gas that occurs in nature but which also can be reproduced from renewable raw materials. It is used mainly to generate electricity and heat.
Insam sees methane from renewable sources (biomethane) rather than hydrogen as the more viable fuel source.
Diversity keeps systems stable
The scientist considers it a political mistake that Austria made when it decided twenty years ago to stop funding biogas plants. At that time, with a quota of 70%, Austria was the leader when it came to the production of renewable sources. A proportion that was largely based on hydropower. Since then, the number of biogas plants in Austria has ceased to increase and has remained constant at around three hundred. In Germany, however, there are 9500 biogas plants as well as large-scale photovoltaic and wind energy plants across the country, the researcher states.
“Diversity is an important factor when it comes to keeping systems stable. Even countries that had only opted for nuclear power have since become well-established in this respect. Energy should also not just come from high-tech sources, as these are increasingly susceptible to failure. Biotech is more resilient and should be part of the mix that we use to safeguard our energy supply.” Heribert Insam
The researcher sees the major potential of hydrogen as an energy resource due to its suitability for the production of methane.
Methane (= natural gas) distribution networks readily available
Problematic issues with hydrogen are:
- The lack of infrastructure in terms of management and storage;
- The low level of efficiency from the source to the wheel (approx. 25%) ;
- The low level of energy density – tanks need to be three times larger and pressure levels must be three times higher in comparison to what methane requires;
- The small-sized molecule – H2 – is easily lost due to ‘slippage’ in the pipelines;
“Creating an infrastructure for hydrogen takes about 15 years. New pipelines need to be built, and all the roads would have to be opened up again. We need technologies that are already available.” Heribert Insam
As a result of research in Austria and Europe, there is sufficient know-how and subsequently the necessary infrastructure is already available in order to be able to further promote transportation using methane, the researcher says. No new pipelines would have to be built for the transportation of methane, existing natural gas pipelines could be used more intensively.
Existing infrastructure for natural gas production could also be used for the production and storage of methane.
Production takes place in natural gas reservoirs. “Hydrogen is fed into the porous rock of former natural gas reservoirs and the microorganisms living in it convert the hydrogen into biomethane,” the microbiologist explains.
At the same time, the natural gas deposits could also be used to store methane. This would solve the storage problem.
According to Insam, this is a method with enormous potential because it would be able to be used to cover a considerable part of the demand for energy. Simultaneously, CO2 emissions are also likely to be reduced.
Methane from a biogas plant
Another way to produce methane is by using a biogas plant which utilizes agricultural and biological waste. Here, microorganisms are also responsible for the production of methane. The resulting biogas is composed of about 60 % methane and about 35 % of carbon dioxide.
In a more advanced form of methane production, excess electricity from photovoltaic and wind power plants could be utilized as well. This is because it enables methane content to be increased by 95 %. This particular percentage is required so that biogas can be fed directly into the existing natural gas network.
Hydrogen is generated from excess electricity and water during an electrolysis process. This hydrogen – together with the carbon dioxide present in biogas plants – is converted into methane by special microorganisms (archaea).
Insam also sees the advantage in the use of an existing infrastructure for this production method. Insam: “Biogas plant operators are happy about this because they are getting an upgrade this way. This is an all round win-win-win situation.”
High level of energy potential
Methane is a very large molecule in comparison to hydrogen. The advantage of its size is that molecules cannot escape so easily from pipelines. ” This is where smaller hydrogen molecules are at a disadvantage, they are extremely susceptible to slippage. Much is still lost even when they are being burnt up in the engine,” the scientist explains.
A further disadvantage is the low level of energy density in hydrogen. Methane has three times the amount of energy density. In order to reach the same level of energy density when using hydrogen, the pressure in the respective tanks would have to be about three times higher at 700 bar, which in turn would necessitate thicker walls as well. This would result in heavier tanks, which would be of particular importance when it comes to personal transportation.
“Last but not least, hydrogen is highly inefficient in terms of transportation. First, H2 has to be generated by electrolysis, which then, after an elaborate transportation process, is converted back into electricity in the electric vehicle via a fuel cell. The efficiency level is a meagre 25 % from the generation of electricity to the drive wheel. This requires twice as many wind turbines and photovoltaic systems as other propulsion technologies”. Heribert Insam
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