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How do you make Hydrogen from Water?

Tuesday, 10th September 2024

Introduction: How do you make Hydrogen from Water?

Hydrogen is very abundant however to get pure hydrogen we need to extract out everything else around it, or extract the Hydrogen out of everything else!

Water is H2O, H Hydrogen and O Oxygen. So we need to get the Hydrogen out of the water.

Using a Voltage applied to the water via an Anode (Positive) and Cathode (negative) bubbles are formed, these are bubbles of Oxygen and Hydrogen.

Now school level science has already created the 2 gases, we need to extract the H2 from the Oxygen though. Using Membranes, the small Hydrogen atoms can pass through these and the larger Oxygen atoms can’t – eureka! we have our basic system, correctly termed as a ‘Hydrogen Electrolysis system’.

What are the stages of a Hydrogen Electrolysis system?

  1. Obtain Pure Water - Pure water is needed, thus a filtration system, and water polishing to remove the ions, thus giving ultra clean deionised water.
  1. Pump water through a Cell - The water is pumped to the electrolyser which will consist of the Anode, Cathode and membrane called a ‘Cell’; one of these doesn’t produce enough Hydrogen so these “cells” are stacked together to allow for a good level of Hydrogen to be extracted. These membranes have been expensive and fragile due the materials of construction and expensive production techniques - now more economic membranes are readily available such as the Proton Exchange Membranes (PEM). Making the H2 Electrolyser more attractive for Hydrogen production.
  1. Extract the Hydrogen using cylinders - The Hydrogen comes via a pipe from the Stack to a Hydrogen separator, what’s to separate? There are still small amounts of water with the Hydrogen gas. By filling a cylinder with this the water stays at the bottom of the cylinder and the gas floats above the water, called Hydrogen Separation. This gives us 99% Hydrogen, and this can be used to fill cylinders. The gas is already at around 30 Bar pressure after the electrolysis process - ideal for filling cylinders. Further compression can be implemented to fill higher pressure cylinders and further purification could take place to remove even more water which can produce 99.999% pure Hydrogen - as needed by of markets such as Fuel cell systems.
  1. Recycle excess water - Water happens to the excess water from the H2 separation? This can be feed back to the initial Water supply and re used.
  1. Pump oxygen back to the supply tank - What happens to the O2 that is produced, the other side of the membrane we still have water and Oxygen gas, this can be pumped back to the initial water supply tank. Where the Oxygen gas floats above the water and can be feed out of the top of the tank and potentially be used similarly to the Hydrogen extraction and separation.
  1. The water supply is constantly being used as the Hydrogen is extracted, thus topping this up is a constant.
  1. Thus, the overall system is 1 feed of water, 2 outlets of Hydrogen gas and some water and a second outlet of water and Oxygen gas. The Hydrogen can then be converted back to water! Humans will use the hydrogen in Industry and in vehicles and the result is it converted back to water.

The advantage of Hydrogen production is that the Hydrogen can be stored and used at a later date. It can be used directly in the internal combustion engine or in fuel cells to produce electricity on demand. The crucial advantage is no battery is needed to store the energy as with solar energy or wind energy that is not used directly.

Expand your knowledge further with this Alicat white paper on Nel Hydrogen, where you will see the following recommendation from Nel, a global hydrogen company:

“This has helped us simplify our test setups, increase reading accuracy/reduce variability, [and] is much easier for our technicians performing the test.”

– Philep Levesque, Nel Hydrogen manufacturing engineer

Product Overview: How to measure the amount of Hydrogen produced

With Flow and Pressure sensors Premier Control Technologies can provide the instrumentation to measure the water flow, measure the Hydrogen flow and the pressure of both the water system and the High Purity Hydrogen Gas produced. You will find some instrument recommendations below:

Alicat Coriolis Flow Meters

Alicat Coriolis Flow Meters

The Alicat CODA Coriolis Flow Meter range offers direct mass flow measurements for exceptional accuracy in a broad array of precision ultra-low flow and high pressure applications.

  • Flow Rate: 0.08 – 300,000 g/h
  • Response Time: < 100 ms
  • Maximum Operating Pressure: 275 bar

Rheonik Coriolis Flow Meters

Rheonik Coriolis Flow Meters

The Rheonik Coriolis Flow Meters satisfies requirements for a higher pressure range - the high pressure ratings of up to 1379 bar and a wide fluid temperature range of -196°C and 350°C mean that the meters can be used in a variety of Hydrogen applications.

Pressure Measurement and Control

Our comprehensive range of pressure products spans mechanical pressure switches to electronic pressure control.

1. Equilibar Back pressure regulators

Equilibar Research Series

Equilibar back pressure regulators are well suited to Gas, Liquid and dual phase solutions. Reliable and simple to use with various materials of construction and tailor made for specific flow and pressure regimes, put us to the test! A perfect product example would be the Research Series. And if you would like to know how an Equilibar Back Pressure works, you can watch a video on YouTube here.

2. Alicat Pressure product range

Dual Valve Pressure Controller

Alicat pressure products include standard pressure transducers and more advanced pressure controllers for use with your standard, vacuum, differential, closed loop and closed volume pressure applications. Dual valve pressure controllers are able to vent pressure within your process to offer no overshoot of system pressure.

3. Drastar single and two-stage pressure regulation

DR60 Dual Pressure Gauges

Drastar's single and two-stage pressure regulation offers both high and low pressure processes covering a wide range of flow rates.

4. Pressure guages

PCT Pressure Gauges

Mechanical pressure gauges come in many shapes and sizes and we can build to your specification.

Related article

Controlling and measuring the flow rate of Hydrogen and Helium

Get in touch

If you have any questions please do get in touch on sales@pctflow.com or call us on 01953 609930.