The Color of Hydrogen: Green

Posted on October 10th, 2018

When you think of renewable energy sources, be sure to include green hydrogen. Its support of renewable energy sources such as wind and solar offers numerous benefits and opportunities. The following examines the basics of hydrogen, how it’s used, how it’s made and what makes the use of green hydrogen so compelling.

Hydrogen: What?

Before we get to the green part, consider basic hydrogen. Naturally a gas, hydrogen is special in many ways:

  • Henry Cavendish is credited with its discovery more than 250 years ago
  • It is atomic number 1 on the periodic table of elements
  • It has the lowest atomic weight at 1.008 (nitrogen is 14.007, oxygen is 15.999)
  • Atomic hydrogen (H) is the most abundant element in the Universe
  • Nearly all hydrogen on Earth is in the form of water (H2O)
  • It is colorless, odorless and tasteless but highly flammable.

Hydrogen is used in a multitude of diverse applications including the refining of crude oil, the production of fertilizers and chemicals (e.g. hydrochloric acid, hydrogen peroxide and ammonia), food production, the cooling of large electrical generators, fuel for fuel cells, cryogenics and welding.

Hydrogen: How?

Steam Reforming

Today, more than 95% of the hydrogen produced comes from the processing of natural gas, oil and coal using steam reforming. In this process, the fossil fuel is broken down using 700-1100°C steam. While steam reforming is the most economical way to produce large quantities of hydrogen, it also produces 9 to 12 tons of CO2 and other greenhouse gases (GHG), depending on the feed material, for every ton of hydrogen gas produced.


Electrolysis is the use of electricity to separate water into hydrogen and oxygen. The simplest electrolysis arrangement consists of passing a direct current (DC) through water between two electrodes. When the current flows, hydrogen gas bubbles appear at the cathode (-) and oxygen bubbles appear at the anode (+). Because pure water is a very poor electrical conductor, electrolytes are often added to the water to increase the flow of current and consequently hydrogen production.

Electrolysis is not nearly as efficient as steam reforming, but it produces no greenhouse gases.

Advanced Hydrogen Production

Research has been ongoing for decades in search of ways to more efficiently produce hydrogen. Today’s research concepts include:

Advanced electrolysis – These techniques aim to improve the efficiency of traditional electrolysis by utilizing new types of electrolytes including solid polymer, solid alkaline exchange and solid ceramic oxide membranes.

Microbial biomass conversion – This is the use of microorganisms that break down biological materials such as sugars and biomass and produce hydrogen as part of the process.

Thermochemical water splitting – As the name implies, this process requires heat and chemicals to split water into hydrogen and oxygen. Temperatures in the range of 500°–2,000°C can be generated by solar towers or parabolic mirror set ups while the chemicals are used to facilitate the water’s break down.

Hydrogen: Why?

Hydrogen is called a “zero-emissions fuel” since it produces only water vapor when burned with oxygen. As a fuel, it is used to power a variety of vehicles, from trains to fork lifts, it is used for electricity generation and for storing energy. Unfortunately, the broad use of clean hydrogen has been hampered by economic challenges, including the cost of  bulk production without greenhouse gases and the lack of large-scale distribution and storage systems.

Hydrogen: Green

The intermittent operation of renewable wind and solar electric facilities has created a situation that didn’t exist a decade ago; sometimes they generate too much electricity and other times they generate none. The millions of small- and medium-scale wind and solar generating systems can generate more electricity than may be needed on sunny, breezy days when the demand for air conditioning is low. The storage of excess electricity in substantial quantities, however, has always been technologically and commercially challenging.

Enter green hydrogen as a means for storing energy and electricity. It’s produced from water using otherwise unusable renewable electricity to power an electrolysis process. Green hydrogen can be stored in small or large quantities and easily turned back into electricity in fuel cells when wind or solar sources aren’t producing.

Green hydrogen also has an interesting range of possible uses:

  • Utility-scale renewable energy storage
  • Fuel for distributed generation and backup power
  • Blending into the natural gas in the pipeline network
  • Fuel cell electric vehicles (FCEVs)

Moreover, green hydrogen storage can be sized to accommodate the hydrogen produced over weeks, months or a season.

Is Green Hydrogen for You?

A recent research report from the financial services company, Morgan Stanley, contained the headline, “Green hydrogen could revolutionize energy production, helping utilities run more flexible power grids while reducing fossil fuel emissions.” This growing interest in green hydrogen is fairly new, however electrolyzers and fuel cell systems are already available that can produce and store enough green hydrogen to power large commercial buildings and factories.

ENGIE firmly believes that hydrogen is the key that will unlock the full potential of renewables and carbon-free energy solutions. Let us at ENGIE MEP Services show you how advanced solutions, including existing building commissioning, integrated controls, Distributed Energy Resources (DER) and green hydrogen can reduce your energy costs and increase reliability, resilience, value and comfort.