Frequently asked questions on hydrogen

Hydrogen is present everywhere in nature, but it’s always bonded to other chemical elements. When we talk about hydrogen for energy, we’re referring to molecular hydrogen (H2), which is practically absent on Earth and is produced by processes that require energy to break its chemical bonds with other elements. Once produced, the energy contained in the hydrogen molecule can be converted into electricity (with devices called fuel cells) or into heat (with combustion processes) depending on its end use. Since it’s not found in nature, molecular hydrogen is not an energy source but an energy vector (or energy carrier) capable of storing energy to be used at a later time.

On Earth, hydrogen is mostly found in chemical compounds, which means it’s bonded to other atoms. There are several chemical processes that can separate hydrogen atoms from more complex elements to produce molecular hydrogen: for instance, hydrogen can be found in fossil fuels and in water. But making hydrogen from fossil fuels like oil, coal, or natural gas results in the production of carbon dioxide (CO2) as the main by-product of the process. Alternatively, hydrogen can be made with a process called water electrolysis: hydrogen and oxygen atoms are separated using electricity, producing H2 and obtaining oxygen as the only waste product.

Hydrogen is classified according to the chemical process that produced it, each of which is associated with a color. “Brown” hydrogen is obtained through coal gasification, and it is the one that pollutes the atmosphere and the environment the most because it emits 25 kg of CO₂ for every kg of hydrogen it produces.

“Grey” hydrogen is obtained from natural gas through the process of steam methane reforming and it has an environmental impact of 11 kg of CO₂ for every kg of H₂. If it’s then associated with another process to capture and store carbon dioxide, preventing it from being released into the atmosphere, it’s called “blue” hydrogen. However, due to the current technology’s limitations or due to CO₂ leaks from the storage systems, this process still emits an estimated 3-6 kg CO₂ / kg H₂.

Hydrogen can also be obtained with electricity through the process of electrolysis, which separates the atoms of hydrogen and oxygen contained in water molecules. If the electricity used comes from a nuclear power plant, it’s called “pink” hydrogen; it doesn’t release carbon dioxide into the atmosphere, but it produces radioactive waste. If, instead, the electricity used to produce it comes from renewable sources, it’s called “green” or “renewable” hydrogen, and doesn’t produce the CO₂ emissions.

Hydrogen has been in use for several years already – especially in the industrial sector, in oil refining, and in the production of fertilizers and ammonia. It’s also used in the food industry to make the so-called “hydrogenated fats” present in several food items.

Nowadays, most of the demand for hydrogen is produced in the same place where it’s consumed (like oil refineries, for example, which make it for their own consumption), so there isn’t an actual market for it because hydrogen is not exchanged between different operators.

In 2021, around 94 Mt (million tons) of hydrogen were consumed worldwide; the vast majority of it was “grey”, which means that it was produced from natural gas (Global Hydrogen Review 2022, IEA). Italy’s demand for hydrogen is estimated to be around 0.5 Mt; it’s mostly used in the ammonia and chemical refining industries (Hydrogen Monitor EU – 2018 demand).

Only green hydrogen made from renewable sources can be considered completely clean and sustainable because it doesn’t create any carbon dioxide emissions.

Hydrogen has been used for decades in numerous industrial applications. Unlike other substances like gasoline or methane, hydrogen is very light, even lighter than air, so in the event of leaks or accidental releases, it rises quickly and is dispersed into the atmosphere. However, since it’s a highly flammable gas, when it’s in high concentrations, it can be potentially dangerous if it’s ignited. Just like other substances used in industry, safety standards were put in place years ago regarding its production, storage and use, so that allow hydrogen can be used safely.

Fuel cells or turbines can be used to make electricity from hydrogen. The efficiency of these processes varies from 35% to 60%. If we also consider the production efficiency of producing hydrogen by electrolysis, using green hydrogen to produce electricity is not an efficient solution. In fact, it’s much better to use renewable energy made from the sun or the wind the very moment it’s produced; when it’s necessary to store it so that it can be used at a later time, it’s better to use batteries, which have an efficiency of around 85%.

There are several ways to transport molecular hydrogen. It can be transported by tube trailers when it’s stored in cylinders, or through dedicated pipelines (potentially even in liquid form, but costs are very high at present).
As an alternative to molecular hydrogen transport, a more efficient option is distributed hydrogen production by electrolysis very close to where it is needed. It’s actually better to transport the energy obtained from a renewable source through the power grid, which would also provide energy for an electrolyzer to produce hydrogen in the location where it’s needed.

Yes, if technological improvements and market growth can lower its production costs.

Electrification is the best way to decarbonize most of the sectors that use electricity in our daily lives. The best use of hydrogen is in the industrial sectors that are hard to abate, which means in those areas where electrification is technically difficult and not very competitive: these sectors usually require a large amount of energy, making it difficult to cut their greenhouse gas emissions. This includes industrial sectors that produce steel, ceramics or cement, industrial chemistry, foundries, and long-distance transportation by air or sea.

There are some technologies that use hydrogen to heat buildings; however, heat pumps and direct electrification systems are five times more efficient in terms of green energy consumption.

In both cases, the vehicle has an electric engine. The energy required by the engine of an electric vehicle is provided by a battery, which is previously charged through the power grid. In a hydrogen vehicle, instead, the hydrogen in its tank is used by a fuel cell to produce electricity to power the engine. In an electric vehicle, the system’s efficiency depends on the battery’s efficiency, while in a hydrogen vehicle, you have to consider both the efficiency of the electrolyzer that produces hydrogen as well as the efficiency of the fuel cell that converts it into electricity. Today, an electric vehicle is still 2.5 times more efficient than a hydrogen car.

No. Electric cars are better not only because they cost less to buy and fix, or because there isn’t a network of hydrogen fueling stations (unlike the power grid, which already exists), but also because electric vehicles are 2.5 times more efficient than hydrogen ones in terms of kilometers per kWh of green energy.

Currently, neither renewable hydrogen nor blue hydrogen are competitive in terms of cost compared to grey hydrogen. According to the forecasts made by Bloomberg NEF, however, green hydrogen will become competitive compared to grey and blue hydrogen by 2030. This will be possible thanks to the scaling up of the electrolyzer industry, its progressive automation and innovation, which will create increasingly efficient electrolyzers. 

An electrolyzer is an electrochemical device made of membranes and electrolytes; when it is powered by electricity, it can break the chemical bonds in a water molecule, separating hydrogen and oxygen, which can then be collected and stored.

A fuel cell is an electrochemical device similar to an electrolyzer. It’s made of membranes and electrolytes that are sometimes identical to the ones found in an electrolyzer, but it reverses the process: it uses hydrogen to create electricity. The molecules of the fuel (H₂) and of the combustive agent (usually oxygen, O₂) are broken down into positive ions and electrons, which then go through an external circuit, generating an electrical current. The H⁺ and O^- ions then combine, creating water (H₂O) as its only waste product.

Digital networks will play a central role in managing, coordinating and monitoring the production, as well as the distribution and delivery, of hydrogen for its various uses. Using innovative software will make it possible to detect anomalies and to identify potential risks. This way we can intervene early with preventive maintenance before any damage is done. Identifying inefficiencies in real time leads to improved performance and greater plant efficiency.