By Oriol Casal (Cetaqua)
Recently, the H2 MED project has gained a lot of coverage on the news. For the first time, a green H2 pipeline is envisioned to transport green H2 cross-country as an energy vector, 2 million tons per annum, 10% of REPowerEU’s goal by 2030, with a capital cost of 2,5 billion euros. But in the first place, why is that necessary? Would it not be better to invest in strengthening the European electricity grids interconnections? And what potential role could biological methanation, a technology developed in the LIFE NIMBUS project, play in this context?
Energy, whether in the form of electricity (electrons moving from a high potential to a low potential status) or in the chemical form, such as natural gas, oil, coal, hydrogen or biomethane, is seldom consumed where it is generated. Thus, it must be transported. At urban areas, energy can be found usually in two forms: low-voltage electricity and low-pressure natural gas/town gas. However, there is a substantial investment in infrastructure that the public is not seeing and is there: power plants, transformer stations, LNG regasification plants, natural gas underground storage reservoirs, pipelines wide enough to fit a crouching adult and stretch for thousands of kilometers and compression stations.
Transportation becomes tricky as distances grow, and sometimes can render unviable certain projects due to losses and investment, such as renewable wind parks offshore, where wind is the strongest. Renewable electricity is transported by alternate current grid at high voltages, with new developments in high voltage direct current transportation, with a higher efficiency.
However, the moment that not only transportation is desired, but storage is also necessary, is where electro-fuels, such as H2 and synthetic natural gas, become the center of attention. At high renewable ratios in the electricity mix supply and demand cannot be longer managed and storage is necessary. The H2MED aims at making southern countries in Europe net exporters of green energy, by transforming wind and solar electricity into green H2 and pumping it to the north.
H2 is a nightmare both for storage and transportation: it is the tiniest molecule, meaning that it diffuses through all metal alloys and in some cases can make them brittle and fragile. That is why in the European Union it cannot be injected into the natural gas and it is capped at a maximum 5% volume by norm. Furthermore, it not only diffuses but it is also very explosive, much more than natural gas, which means that with most certainty it will never replace methane in home applications. On top of that, its energy content per volume is much lower than methane (approximately three times lower), meaning that pipelines need to be wider and/or work at higher pressures. All these factors make pipeline transportation heavy capital projects, and raising voices are questioning the real profitability and return on projects such as the H2MED.
Creator: Paul Langrock | Credit: © Paul Langrock / Greenpeace
Copyright: © Paul Langrock / Greenpeace
However, if green H2 is processed onto another energy carrier, its transportation becomes much simpler and standard. It can be processed onto ammonia, methanol, gasoline, diesel or any desired hydrocarbon. However, the easiest choice on all potential molecules is the one that has been used now for over a century: natural gas. In the LIFE NIMBUS project, biological methanation is explored to produce carbon neutral biomethane out of green electricity, which can be readily injected into the existing grid following European regulation and sold at a premium (since it is biomethane) in most European countries. Or, alternatively, it can be directly used as it is done in the LIFE NIMBUS project to fuel transportation without retrofitting existing buses, becoming an added value product: Compressed Natural Gas.