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The Kallanish Glossary aims to be a useful resource for complex industry specific terminology. We are constantly adding to our glossary, so if you have a suggestion or amendment please do get in touch.
HEV (Hybrid EV)

Hybrid electric vehicles (HEVs) are powered by an internal combustion engine (running on petrol or diesel) but also have a battery-powered electric motor that serves to complement the conventional engine.

Home energy storage

Local energy storage technologies for home use are the lesser known relatives of battery-based grid energy storage and support the concept of distributed generation. When paired with on-site generation, they can virtually eliminate blackouts in an off-the-grid lifestyle.


Hydrogen is the chemical element with the symbol H and atomic number 1. With a standard atomic weight of 1.008, hydrogen is the lightest element in the periodic table. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all baryonic mass.  The 3 most common types of hydrogen are: 

  1. Grey Hydrogen: The most common form of hydrogen, it's created from fossil fuels and the process releases carbon dioxide which is not captured.
  2. Blue Hydrogen: Blue hydrogen uses the same process as grey, except this time the carbon is captured and stored.
  3. Green Hydrogen: Green hydrogen is made by using a process called electrolysis to split water into hydrogen and oxygen. If that process is powered by a renewable energy source, such as wind or solar power, then the hydrogen is referred to as being green.
Hydrogen Storage

Hydrogen can be stored physically as either a gas or a liquid. Storage of hydrogen as a gas typically requires high-pressure tanks. Storage of hydrogen as a liquid requires cryogenic temperatures. Hydrogen can also be stored on the surfaces of solids, by adsorption, or within solids, by absorption.


Hydrometallurgy involves the use of aqueous solutions for the recovery of metals from ores, concentrates, and recycled or residual materials. Processing techniques that complement hydrometallurgy are pyrometallurgy, vapour metallurgy, and molten salt electrometallurgy. Hydrometallurgy is typically divided into three general areas:

  • Leaching
  • Solution concentration and purification
  • Metal or metal compound recovery

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