Biomethane-hydrogen: future green gas

Detailed study
21 December 2022

LOD takes part to nationwide experiment on the odorizability of the biomethane and hydrogen blend to be used in the household network

Increasingly, we are hearing about biomethane and hydrogen as energy sources for the near future, crucial for facilitating decarbonization in view of zero climate impact.

Actually, biomethane and hydrogen are already usable today: scientists and engineers are working to produce them with renewable energy, store them while bringing in as little energy as possible, and reduce the costs of their distribution. 

However,what is hydrogen and how mayit be used as an alternative to natural gas in the household network? Let's find out.


Hydrogen characteristics and classes

What is hydrogen?

Hydrogen is the lightest and most abundant chemical element in nature. It makes up nearly 90 percent of the visible mass in the universe. It is present in water, compounds and organic substances. We also find it in various natural gases and in the atmosphere.

Some of the main characteristics of hydrogen are following:

  • odorless
  • colorless
  • tasteless
  • flammable  

Its calorific value of 33.33 KWh/Kg - higher than that of natural gas, which is 13.1 KWh/Kg - makes it costly to transport it to the network.Therefore,many researchers, companies and investors are trying to figure out how toproduce it and use it bestas renewable energy. In fact, it may be defined as an "environmentally friendly" gasconsidering thatits use produces no carbon dioxide emissions, making it a key element in for planetary energytransition.

Five hydrogen classes

At the moment, hydrogen is classified into five classes according to the mode of production

  • Brown: Brown hydrogen is obtained by gasifying coal. More than 20 kg of carbon dioxide is emitted per kilogram of hydrogen produced.
  • Gray: more than 90 percent of the hydrogen produced is "gray." This element has industrial uses, for example in chemistry. It can be the production waste of a chemical reaction, or it may be extracted from methane (which is made of hydrogen and carbon [CH4]) or other hydrocarbons. The carbon dioxide generated is released into the environment. Therefore, this mode of production is not acceptable from a clean energy perspective. For its production, more than 9 kilograms of carbon dioxide are emitted per kilogram of hydrogen.
  • Blue: "Blue" hydrogen is the element extracted from fossil hydrocarbons. Unlike what happens in the case of "gray" hydrogen, carbon dioxide resulting from the process is not released into the air: it is captured and stored. It generates 9-10 kg of carbon dioxide per kg of hydrogen produced.
  • Purple: "Purple" hydrogen is extracted from water using power generated by a nuclear power plant, i.e., zero CO2 emission.
  • Green: "green" hydrogen is extracted from water using power generated by a power plant fed with renewable energy, such as hydroelectric, solar or photovoltaic. It has a very low environmental impact and generates zero CO2 emissions. We expect it to become more widespread in the coming years, as its cost becomes competitive and its use economically viable.  

How to produce hydrogen

Hydrogen production is based on breaking the bond between the hydrogen atom and the oxygen atom of the water molecule (H2O). 

Energy is required to break this bond and accumulate hydrogen. This energy is supplied by means of renewable sources or fossil fuels. If the electrolytic cell is placed near a plant using renewable sources, part of the electric power production, for example the part in excess of the network transport capacity, can be used to power it. In this way, the hydrogen produced serves as chemical "storage," which can be used later, when needed, as a raw material in steelmaking processes or as a fuel to provide high-temperature heat.    

The scientific and technological community has been working for a long time on how to make green hydrogen easier to produce and cheaper.

Where is hydrogen to be used

The possible end uses of hydrogen, particularly green hydrogen, are the following:

  • in the chemical industry and petroleum refinery, as a feedstock replacing gray hydrogen;
  • in industries where high temperature heat is needed, such as cement, steel and glass, to substitute fossil fuels used to date;
  • as a fuel for commercial vehicles;
  • for electric powergeneration.

Biomethane and hydrogen: a winning blend for the domestic network

We have already talked about biomethane, its benefits and about rules for feeding it into the network.

Letus now understand moreabout advantages and limitations in using hydrogen in the home network.

Miscela biometano-idrogeno e la distribuzione nella rete domestica

L’idrogeno è adatto a essere trasportato nei gasdotti esistenti e ad essere miscelato con il biometano. Gli utilizzi più diffusi sono nei settori:

  • siderurgico;
  • aviazione;
  • marittimo.

Il biometano e l’idrogeno rappresentano le fonti energetiche rinnovabili per l’evoluzione energetica europea.

Biomethane-hydrogen blend and its distribution in the household network

Hydrogen is suitable for transportation in existing pipelines and for blending with biomethane. The most common uses are in the following fields:

  • steel industry;
  • aviation;
  • maritime industry.

Biomethaneand hydrogen represent renewable energy sources for the European energy policies

Advantages of using hydrogen in the network

Hydrogen is: 

  • the highest energetic density fuel: 1 kg contains the same energy as 2.4 kg of methane or 2.8 kg of gasoline;
  • easy to store and transport by taking advantage of existing infrastructure;
  • zero CO2 emissions.    

Benefits from hydrogen use in Europe will be obvious by 2050 and will have a positive impact onthe labor market, the economy in general, and, most of all, the planet. In thenear future, it will beused for vehicles, to heat rooms and homes, and, of course, forindustrial purposes as well.

Limitations and costs of using hydrogen in the network  

Currently, there are several obstacles that slow down the development of hydrogen, such as:

  • high production, handling and transportation costs;
  • slow process inupdating regulations.

Current projects for using natural gas in the household network

Several projects are being developed in Europe to use hydrogen in the household network as well.

From here, it is possible to monitor online the progress of active projects not only in Europe, but around the world, referred to as Hydrogen Valleys. 

What is the Hydrogen Valley

The Hydrogen Valley is an incubator and accelerator of innovative projects concerning hydrogen and technologies for its development. It is basically a project (usually funded by local, national, and international grants) that brings different industrial and research initiatives together to carry out pilot projects along the entire hydrogen value chain (production, transport, distribution, and end use with storage.

Let'sunderstand better about someof these projects details.

UK: natural gas-hydrogen mixture in Keele University campus network

United Kingdom is the country where field testing is at a more advanced level. In October 2019, after a preliminary study phase, a natural gas-hydrogen mixture, with increasing concentration up to 20 percent hydrogen, was introduced into the Keele University Campus network. 

The test, which was completed successfully in April 2021, was carried out on a modern gas distribution network with polypropylene piping and involved more than 100 residential buildings and 30 universities.

Boiler manufacturers were immediately involved with appliances installed in the test area by setting up a demonstration heating plant to monitor parameters continuously. 

In September 2020, the first 100% hydrogen home boiler was installed and commissioned in a demonstration house in Spadeadam as part of the H2 project. 

Ultimately,the UK has successfully demonstrated that natural gas-hydrogen blendsmay be distributed safely to end users inside existinggas networks. 

Portugal, Spain and France connected through a green hydrogen network

Another interesting project is a"green" hydrogen corridor that will connect the Spanish Peninsula toFrance thanks to the "H2Med" project. The ambitious interconnectionproject, which will link Portugal, Spain, and France, will be operational in2030 and will have the capacity to transport up to two million tons of cleanhydrogen by 2030, accounting for about 10 percent of European consumption

Italy: Hydrogen Valleys for networked hydrogen experimentation kick off

With National Recovery and Resilience Plan (NRRP) grants, protocols for the implementation of Hydrogen Valleys have also started in Italy. These projects are geared toward creating real hydrogen supply chains by combining production, infrastructure and use in one place. 

Five regions are involved in the early stages of implementing this part of the NRRP:  

  • Piedmont
  • Friuli-Venezia-Giulia
  • Umbria
  • Basilicata
  • Puglia  


The Green Hydrogen Valley in Puglia, between Brindisi, Taranto and Cerignola, envisions the building of three green hydrogen production plants with a total capacity of 220 MW, powered by photovoltaics, creating up to 300 million cubic meters of renewable energy each year. The hydrogen produced will also be dedicated to industry through fuel injection into Snam local gas network and may be used for sustainable mobility.  

Friuli Venezia Giulia

In Friuli Venezia Giulia, thanks to a partnership with Croatia and Slovenia, the project to create the Hydrogen Valley of the Adriatic has begun. The collaboration will not only contribute to the transition to an integrated ecosystem involving energy, industry and transport, but will also allow cooperation on research and innovation, for the development of new solutions, such as the construction of stations for hydrogen refueling and transport.



The Lombardy Region recently kicked off the H2iseO project, allocating 75.5 million euros for the activation of hydrogen-powered rail service. With this project, the first hydrogen-powered rail line will be built in Italy along the Brescia-Iseo-Edolo route. The trains will use fuel cell, a special technology capable of producing light and electric power out of hydrogen.

Emilia Romagna

In recent months, Castelfranco Emilia (MO) has witnessed the beginning of the first national experiment for the use of hydrogen in a municipal gas distribution network. A mixture of methane and hydrogen has been injected into a portion of the Emilian municipal gas infrastructure managed by Inrete Distribuzione Energia, the Hera Group company that ensures natural gas and electric power distribution activities.

There are other projects going on at the moment, ranging from the distribution of combustible gas (methane) produced out of renewable sources to the distribution of Hydrogen-Natural Gas blends, and the direct supply of pure Hydrogen for "hard to abate" users or automotive use.  

Experimentation in the odorization of the biomethane-hydrogen mixture

Our laboratory, thanks to its know-how and investments in the field of rhino-analysis, took part to preliminary experimental tests of odorizability on the biomethane-hydrogen mixture for the Castelfranco Emilia project. It performed tests on samples of CH4-H2 mixtures at different concentrations, with excellent results. 

LODcontinues contributingin the area of research, whileconsolidating knowledge in the world of domestic fuel gases by taking part to workshopsand by being actively involvedin the drafting of European and national regulations, constantly updated.

LOD: Laboratorio Olfattometria Dinamica

Spin-off dell’Università degli Studi di Udine