hydrogen (H), a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements

 

Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula H₂. It is colorless, odorless, tasteless, non-toxic, and highly combustible

hydrogen (H), a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the family of chemical elements.

Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula H2. It is colorless, odorless, tasteless

 non-toxic, and highly combustible. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter.

 Stars such as the Sun are mainly composed of hydrogen in the plasma state. Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons.

In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 years later during the recombination epoch, when the plasma had cooled enough for electrons to remain bound to protons.

Hydrogen is nonmetallic (except it becomes metallic at extremely high pressures) and readily forms a single covalent bond with most nonmetallic elements, forming compounds such as water and nearly all organic compounds.

Hydrogen plays a particularly important role in acid–base reactions because these reactions usually involve the exchange of protons between soluble molecules. In ionic compounds, hydrogen can take the form of a negative charge (i.e., anion) where it is known as a hydride, or as a positively charged (i.e., cation) species denoted by the symbol H+. The H+ cation is simply a proton (symbol p) but its behavior in aqueous solutions and in ionic compounds involves screening of its electric charge by nearby polar molecules or anions. Because hydrogen is the only neutral atom for which the Schrödinger equation can be solved analytically

 the study of its energetics and chemical bonding has played a key role in the development of quantum mechanics.

Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. In 1766–1781, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance,

 and that it produces water when burned, the property for which it was later named: in Greek, hydrogen means "water-former".

Industrial production is mainly from steam reforming of natural gas, oil reforming, or coal gasification.

 A small percentage is also produced using more energy-intensive methods such as the electrolysis of water.

 Most hydrogen is used near the site of its production, the two largest uses being fossil fuel processing (e.g., hydrocracking) and ammonia production, mostly for the fertilizer market. It can be burned to produce heat or combined with oxygen in fuel cells to generate electricity directly, with water being the only emissions at the point of usage. Hydrogen atoms (but not gaseous molecules) are problematic in metallurgy because they can embrittle many metals.

Hydrogen is a clean alternative to methane, also known as natural gas. It's the most abundant chemical element, estimated to contribute 75% of the mass of the universe.

Here on earth, vast numbers of hydrogen atoms are contained in water, plants, animals and, of course, humans. But while it’s present in nearly all molecules in living things, it’s very scarce as a gas – less than one part per million by volume.

Hydrogen can be produced from a variety of resources, such as natural gas, nuclear power, biogas and renewable power like solar and wind. The challenge is harnessing hydrogen as a gas on a large scale to fuel our homes and businesses.

 Why is hydrogen important as a future clean energy source

A fuel is a chemical that can be ‘burnt’ to provide useful energy. Burning normally means that chemical bonds between the elements in the fuel are broken and the elements chemically combine with oxygen (often from the air).

For many years, we’ve used natural gas to heat our homes and businesses, and for power stations to generate electricity. In the UK, 85% of homes and 40% of the country’s electricity currently relies on gas; in the US, 47% of households rely on natural gas and 36% on electricity1.

Methane is the main constituent of 'natural gas' from oil and gas fields. We’ve continued to use natural gas because it’s a readily available resource, it’s cost effective and it’s a cleaner alternative to coal – the dirtiest fossil fuel that we historically relied on for heating and to generate electricity.

When natural gas is burnt, it provides heat energy. But a waste product alongside water is carbon dioxide, which when released into the atmosphere contributes to climate change. Burning hydrogen does not release carbon dioxide.

What is the difference between blue hydrogen and green hydrogen?

Blue hydrogen is produced from non-renewable energy sources, by using one of two primary methods. Steam methane reformation is the most common method for producing bulk hydrogen and accounts for most of the world’s production. This method uses a reformer, which reacts steam at a high temperature and pressure with methane and a nickel catalyst to form hydrogen and carbon monoxide.

Alternatively, auto thermal reforming uses oxygen and carbon dioxide or steam to react with methane to form hydrogen. The downside of these two methods is that they produce carbon as a by-product, so carbon capture and storage (CCS) is essential to trap and store this carbon.

Green hydrogen is produced by using electricity to power an electrolyze that splits the hydrogen from water molecules. This process produces pure hydrogen, with no harmful by-products. An added benefit is that, because this method uses electricity, it also offers the potential to divert any excess electricity – which is hard to store (like surplus wind power) – to electrolysis, using it to create hydrogen gas that can be stored for future energy needs.

Is hydrogen already being used as a fuel

Yes. There are already cars that run on hydrogen fuel cells. In Japan there are 96 public hydrogen refueling stations, allowing you to fill up just as you would with petrol or diesel and in the same time frame as a traditional fuel car. Germany has 80 of these hydrogen stations and the United States is third with 42 stations.

Hydrogen is also an exciting lightweight fuel option for road, air and shipping transportation. The international delivery company DHL already has a fleet of 100 ‘H2 panel vans’, capable of travelling 500kms without refueling.

 What are the potential brakes to speeding up hydrogen use as a clean energy?

For hydrogen to be a viable alternative to methane, it has to be produced at scale, economically and the current infrastructure needs to be adapted.

The good news is that hydrogen can be transported through gas pipelines, minimizing disruption and reducing the amount of expensive infrastructure needed to build a new hydrogen transmission network. There would also be no need for a culture change in our home lives, as people are used to using natural gas for cooking and heating, and hydrogen energy equivalents are emerging.

 What is National Grid doing to advance hydrogen as an alternative green fuel?

We’ve committed to achieving net zero by 2050, which means we need to start preparing to change our gas usage over the coming years. One of the ways we propose to do this is through hydrogen.

In the UK, the current National Transmission System (NTS) transports natural gas across the country and people, businesses and industry rely on our network.

The NTS is a unique and complex network that uses steel pipes to transport natural gas at high pressures. We need to fully understand the impact that high-pressure hydrogen exposure could have on the pipes, before the network can be converted. Extensive testing and detailed trials are needed to establish what modifications we may need to make to safely transport hydrogen.

Hydrogen in the NTS – we’ve already run several projects looking into the physical capabilities of the NTS transporting hydrogen. These projects have not just looked at the impact hydrogen could have on our pipework, but also on all associated equipment such as compressors and valves, as well as the ways that a hydrogen network may need to operate differently in future.

In the US, one of the first and largest clean hydrogen projects – The Hybrid Project, located on Long Island – was launched in 2021. By blending green hydrogen into the existing distribution system, it will help to decarbonize the existing gas networks and is expected to heat approximately 800 homes.