Hydrogen Energy

Hydrogen - An Introduction

We all know what is hydrogen, ever since we were school going kids, we have been taught in our chemistry subject about hydrogen. This section is just to revise that part and set the stage for something very new and interesting!

If we see in an elemental form, hydrogen is the simplest and most abundant element in the universe.

It is also the most vital element, because it combines with oxygen to form water.

Talking about its atomic structure, it consists of just one proton and one electron.

In the gaseous form, hydrogen is a colorless, odorless and tasteless gas.

At standard temperature and pressure, it exists as a gas.

Over here, we are going to focus only on hydrogen as a gas and its important applications.

Colors of Hydrogen

Yes, you read that right. Hydrogen is a colorless gas, but still it is known by colors! There are seven types of hydrogen - green hydrogen, blue hydrogen, gray hydrogen, pink hydrogen, yellow hydrogen, black and brown hydrogen. But, are these just colors or do they hold some significance? Read on...!!

Types of Hydrogen
Sr. No	Type	Process
1	Green Hydrogen	Water Electrolysis
2	Blue Hydrogen	Steam Methane Reforming with Carbon Capture and Storage
3	Gray Hydrogen	Steam Methane Reforming without Carbon Capture and Storage
4	Pink Hydrogen	Water Electrolysis Powered by Nuclear Energy
5	Yellow Hydrogen	Water Electrolysis Powered by Solar Energy
6	Black Hydrogen	Black coal
7	Brown Hydrogen	Brown coal

Types of Hydrogen

Sr. No

Type

Process

Green Hydrogen

Water Electrolysis

Blue Hydrogen

Steam Methane Reforming with Carbon Capture and Storage

Gray Hydrogen

Steam Methane Reforming without Carbon Capture and Storage

Pink Hydrogen

Water Electrolysis Powered by Nuclear Energy

Yellow Hydrogen

Water Electrolysis Powered by Solar Energy

Black Hydrogen

Black coal

Brown Hydrogen

Brown coal

Types of Water Electrolysis

Types of Water Electrolysis
Sr. No	Method	Principle	Technology Status	Remarks
1	Alkaline Water Electrolysis	OH^- conduction through alkaline electrolyte	Commercial	Mature, inexpensive
2	Proton Exchange Membrane Water Electrolysis	H⁺ conduction through polymer electrolyte	Commercial	High efficiency and current density
3	Solid Oxide Water Electrolysis	O^2- conduction through ceramic electrolyte at high temperature	Early Commercial	Highest electrical efficiency
4	Anion Exchange Membrane Water Electrolysis	OH^- conduction through anion exchange membrane	Emerging	Combines advantages of AWE and PEMWE
5	Microbial Electrolysis Cell Water Electrolysis	Microbial oxidation of organics with external voltage	Under Research	Hydrogen production coupled under wastewater treatment
6	Capillary-Fed Water Electrolysis	Thin-film water delivery via capillary action to electrodes	Emerging	Reduces bubble losses and improves efficiency
7	Photoelectrochemical Water Electrolysis	Semiconductor absorbs sulight to drive electrolysis	Under Research	Direct solar-to-hydrogen conversion (yellow hydrogen)
8	High-Pressure Water Electrolysis	Electrolysis under elevated pressure	Commercial Niche	Produces compressed hydrogen directly