Last Updated on 14/08/2020 by Piero Mattirolo
Re-publication of an article by Mario A. Rosé on Agronotizie.
L’European Green Deal (Italian text in This Page), strongly supported by the Von der Leyen administration, is the manifesto that the European political class proposes as a recipe for:
“... build a Europe in which there will be no local pollution, nor loss of biodiversity, nor global impact on the climate, nor energy poverty, businesses will be competitive, the just and prosperous society, and no one will be left behind”.
Read with a critical spirit, purely technical and devoid of ideological bias, the document looks more like a utopian wish list than a guideline, because there is a lack of concrete actions to achieve the set objectives. The content includes several claims that are not supported by any evidence, For example:
“The rapid decrease in the cost of renewable energy, combined with a better definition of support policies, has already reduced the impact of renewable energy on household energy bills” (sic).
The historical series of ARERA (Regulatory Authority for Energy, Networks and Environment), reproduced in the photo 1, deny this claim, at least as far as Italian families are concerned. In the boom years of renewables, an upward trend in the total price is clearly observed, caused by the combined effect of taxes – which remain constant or slightly growing – and system charges that also increase when the price of energy falls.
The role of hydrogen in the Green Deal
Apart from the point-by-point examination of the Green Deal, in this article we will limit ourselves to analyzing one of the “mantras” of ecological rhetoric: the hydrogen economy. We will then verify the potential of biomass gasification processes and whether they can therefore represent a concrete opportunity for Italian farms.
In the renewable energy sector, the "new hydrogen economy" is the hottest topic of the moment. The most recent news comes from Germany and concerns the inauguration of a train -of Franco-German production- equipped with compressed hydrogen cylinders that feed fuel cells and a fleet of hydrogen buses -of Belgian production- in the town of Hürth (near Cologne). Certainly the new train Coradia iLint it does not emit smoke from its chimney, but it is not clear whether the hydrogen it uses is produced by the German Linde- can be considered "clean". The hydrogen that will power the buses, instead, it is the by-product of a chemical industrial center, but the cited article does not specify whether it is the residual hydrogen from the production of caustic soda - in principle "clean"- or the production of polyethylene or PVC - petroleum-derived products. It is also not clear whether the higher cost of a hydrogen train or bus compared to the simple electrification of the lines is economically justified or through an LCA (life cycle analysis). The image income for French and German politicians, on the other hand, is indisputable. The Green Deal was immediately brought up in the press, despite his 25 pages the word hydrogen appears alone 3 times, specifying -without defining it- that it is "clean hydrogen". In reality, a study of the IEA (International Energy Agency, figure 2) shows that the hydrogen currently on the market is anything but clean: the 73% of world production comes from natural gas, the 26% from coal and only 1% could be assumed to be "clean hydrogen" to which the text of the Green Deal. The IEA study shows that, at the moment, the cost of producing hydrogen with renewable energy - understood as only photovoltaic and wind power, leaving out all other forms- it is prohibitive.
The author has already expressed some perplexities on the much chat “hydrogen economy” in the articleHydrogen from biomethane, biomethane from hydrogen. Here it is useful to remember that thermodynamics is not an opinion and its laws cannot be derogated from with a European directive. If there will be a business on”clean hydrogen” in the future, we can be sure that it will develop only thanks to public subsidies, ultimately paid out of our pockets.
Why so much interest in hydrogen if, as we will see later, the efficiency of its use does not justify it? The Photo 3 gives us a clue on which countries will be the main beneficiaries of the substantial grants that will be awarded in the name of the Green deal, and what is the share of Italy. Draw the reader their own conclusions.
Hydrogen production technologies
L’European Alliance for Clean Hydrogen (Cast) was inaugurated with a meeting of experts and officials on 8 July 2020. From her declaration it seems that the only technology to produce “clean hydrogen” both electrolysis of water, using surplus wind and photovoltaic energy. The reason why the author so categorically states that a hydrogen-based economy cannot be competitive without state subsidies is that, at the present day, there are only three ways of producing hydrogen on an industrial scale:
- Electrolysis of water.
This is the solution proposed during the oil crisis that characterized the 1970s. The reason is due to the very simple concept – only apparently– able to catalyze the favor of politicians and public opinion. The solution consists in storing the excess solar photovoltaic and wind energy in the form of hydrogen and oxygen. The exploitation alternatives are: the sale of oxygen to industries for their production processes and the distribution of hydrogen to replace natural gas, or recombine hydrogen and oxygen in fuel cells to meet peaks in electrical demand. The reasons why both alternatives failed in the years of the oil crisis they are commercial as well as thermodynamic and have nothing to do with dark conspiracies of the oil lobbies, Masonic lodges or “strong powers”. As for oxygen, there are cheaper and more efficient methods to obtain it directly from the atmosphere, where needed, without the need to separate it from the water, compress it and transport it in cylinders. On the other side, hydrogen cannot replace natural gas for a long series of technical reasons (see the author's article cited above). As for the peak electricity generation or, as in the case of the trainCoradia iLint, the replacement of fossil fuels in the transport sector, the overall efficiency of the cycle does not justify the proposed solution. The efficiency of electrolysis, with the best technologies currently available, he was born in 70%. It means they would be needed 6,299 kWh of electricity for each kilogram of water to produce 1,24 Nm3 in H2 e 0,622 Nm3 of O2 (Ref[i]). The electrical generation efficiency of fuel cells ranges from 40% al 60% (Ref.[ii] e[iii]). The overall efficiency of the entire cycle is therefore between 28% and the 42%. In practice, it is also necessary to consider the electricity consumption to produce the demineralized water necessary for hydrolysis, for pumping it into the cells and, finally, to store H.2 and the O2 in high pressure cylinders. Therefore, the real yield of the cycle would be even lower, but let it be there’ECHA che l’IEA overlook this aspect of the process. By way of reference, remember that an endothermic biogas cogenerator has an electrical generation efficiency of the order of 38%-42%.
- Hydrogen by-product from the chemical industry.
The production of caustic soda is carried out by electrolysis of a common salt solution (ClNa) in water, obtaining hydrogen and chlorine as a by-product. The production of some plastics also generates hydrogen as a by-product. Industrial by-product hydrogen is certainly a resource to be used where available, but it certainly cannot meet the energy demand of an entire continent. In Italy, hydrogen by-product from the Marghera petrochemical plant represents yet another example of a resource wasted due to too many contradictory laws and bureaucratic immobility (if you see, by the same author, the story of the hydrogen vaporetto built in Venice).
- Reaction between carbon and water.
Carbon can react with water at high temperatures, according to the following reactions:
- Water gas displacement reaction, schematically represented by: CO + H2O → CO2 + H2. The reaction is catalyzed by Fe2THE3 o Cr2THE3.
- Coal gasification, C + H2O → CO + H2, it is a reaction that occurs between coal and water vapor at temperatures higher than 1000 °C. It was used between the late 19th and early 20th centuries to produce town gas.
- Reforming del gas naturale. The CH reaction4 + H2O → CO + 3H2 occurs between methane and water vapor at a temperature between 700 e i 1100 °C.
Since plant biomass is composed of approximately 50% C, 6% H, e 41% THE (Ref.[iv]), their gasification at temperatures higher than 1000 °C, with added steam, performs the three reactions described above. The result is a rich mixture of H2, call syngas, from which it is relatively easy to separate carbon dioxide (CO2). The biomass gasification process is however more complex and inefficient than the reforming of natural gas, reason why the industry prefers the latter. If the policy decides to encourage the gasification of biomass and penalize the reforming of natural gas, then a new market would open for farms, that of”clean hydrogen” produced with their lignocellulosic waste.
From a purely thermodynamic point of view, biomass gasification is cheaper than water electrolysis because it uses the heat produced by burning a fraction of the biomass. According to a study published by the Iea(Ref.[v]), the production of hydrogen by gasification of biomass is feasible on condition that the process does not use air but pure oxygen and steam, because atmospheric nitrogen would end up in syngas, and being a slightly soluble inert gas, it is very difficult to separate from hydrogen.
The study in question analyzes data from three pilot plants (of the Universities of Vienna, Stuttgart e l’Energy research center Netherlands) in which gasification is carried out with the steam generated by the combustion of biomasses by indirect heating, using air as an oxidizer but at the same time avoiding that atmospheric nitrogen ends up in the syngas. These technologies produce syngas with a content of H.2 between 27 e 45%. The study of’IEA also analyzes the performance of a new technology, this TO BE (Sorption Enhanced Reforming), which uses quicklime (OCa) injected into the gasifier together with the biomass with the aim of eliminating CO2 during gasification and favor the production of hydrogen. During prototype tests at the Universities of Vienna and Stuttgart, technologyTO BE has produced syngas with 73% in H2. The overall efficiency of biomass gasification is 69%, therefore almost equal to that of water electrolysis, with the advantage of not depending on the imbalances between solar / wind generation and grid demand. The economic study indicates that, at the current state of research, biomass gasification is economical only if the price of hydrogen is greater than 2,70 euro / kilogram.
From Photo 2 we observe that hydrogen from coal, or from natural gas, it is still the most competitive. L'”clean hydrogen” touted by the ladyVon der Leyen and by Mr.Timmermans, based exclusively on electrolysis of water using excess wind and photovoltaic energy, it is competitive only if subsidized with public money. Arouses suspicion, or at least perplexity, the fact that the EU intends to allocate substantial public funding to electrolysis technology, when the EU itself considers hydrogen and biomethane come equivalent energy carriers.
The technology to produce biomethane is much cheaper, and biomethane is 100% compatible with existing infrastructures: therefore why to allocate massive resources to hydrogen? It also seems strange that biohydrogen produced bydark fermentation – a technology very similar to that of anaerobic digestion– as well as the gasification of biomass have not been minimally considered by the political class of Brussels. The most advanced biomass gasification technologies are capable of producing syngas with a high hydrogen content, with the same energy efficiency as electrolysers, but they are still in the experimental stage, so they do not represent an opportunity for farms in the short to medium term.
From a purely technical point of view, we can prove with mathematical certainty that a conventional diesel train, converted to run on biomethane, would have the same overall efficiency as theCoradia iLint Franco-German. This conversion is perfectly within the reach of the workshops of theItalian Railways, it would require only a modest expense – among other things, not subject to the payment of royalties to foreign companies– and the purchase of biomethane by the Group FS it would favor local agro-energy companies.
Bibliography[i] University of Naples, Energy technologies course, Hydrogen technology module.
[ii] Marina Ronchetti; Fuel cells. State of development and prospects of technology; Enea publication, 2008.
[iii] US D.O.E.,Fuel cells fact sheet.
[iv] Channiwala S.A., On biomass gasification process and technology developments. PhD Thesis, Mechanical engineering department, Iit, Mumbai 1992). The values obtained by Channiwala are reported on the website of theBiomass energy foundation.
[v] Matthias Binder, Michael Kraussler, Matthias Cuba, and Markus Luisser; Hydrogen from biomass gasification, Iea Bioenergy; ISBN 978-1-910154-59-5, 2018.