What Hydrogen Is and Why It Matters
Hydrogen as an element, a molecule and an energy carrier, and the role it may play in lowering emissions.
8 min
Activities: 0 of 2
Hydrogen is the first element in the periodic table. Its atom has one proton and one electron, so it is the simplest and lightest atom there is. On Earth, hydrogen atoms almost never exist alone. They join in pairs to form the hydrogen molecule, written H2. When engineers say "hydrogen", they mean this H2 gas.
Hydrogen is everywhere, but almost always bound to other atoms. It is in water (H2O) and in every hydrocarbon you have handled: methane (CH4), crude oil, condensate. Free hydrogen gas is very rare in nature. So we have to make hydrogen by breaking it out of water or hydrocarbons, and that takes energy.
Why hydrogen matters for the energy transition
The energy transition is the shift from an energy system based mainly on fossil fuels to one with much lower greenhouse gas emissions. When hydrogen reacts with oxygen, in a flame or in a fuel cell, the product is water. No carbon dioxide (CO2) is released at the point of use.
That makes hydrogen interesting for jobs that are hard to do with electricity alone:
- industrial processes that need hydrogen as a chemical, such as ammonia and refinery hydrotreating;
- making steel without coal;
- high-temperature heat in heavy industry;
- storing energy for long periods, for example in underground caverns;
- heavy transport and shipping, often through hydrogen-based fuels such as ammonia.
The benefit depends completely on how the hydrogen was made. Hydrogen made from natural gas without capturing the CO2 has a large carbon footprint. The rest of the course returns to this point many times.
Why oil and gas people are well placed
Hydrogen projects need people who understand high-pressure gas, process plants, rotating equipment, pipelines, permits to work and process safety. Most hydrogen today is made from natural gas, in plants that look very much like gas processing and refinery units. Your experience is a strong starting point. What is new is a set of properties that make hydrogen behave differently from methane, and these are covered in detail in Module 2.
Why is hydrogen described as an energy carrier rather than an energy source?