Is hydrogen energy green or blue?

What is hydrogen energy? It might be more accurate to call “hydrogen energy” a fuel-transfer technology. Unlike renewable fuels (wind, solar, hydropower), the energy inputs are greater than the resulting energy. So it’s inefficient. But many are touting hydrogen energy as part of a net-zero emissions future. Is hydrogen energy green or blue? Or is it a different shade altogether?

The idea of a global society with net-zero emissions was once as far-fetched as flying cars, the need for solar panel recycling, solar rooftops, or an all-electric auto industry.

But now that vision is coalescing along some divergent energy pathways. Wind energy installation has leveled off to some degree, at least compared to solar installs. Currently, coal plants are being decommissioned faster than they are being built. Energy storage is growing because a battery can instantly transfer power when the grid dips or blacks out. (By the way, solar batteries also operate to store energy for use during peak pricing hours. The savings appear small. But “smart” battery systems like the Tesla Powerwall are designed to charge and discharge to capture those savings automatically.)

And that brings us to hydrogen, the most abundant chemical in the universe. Hydrogen is colorless, tasteless, odorless, and a highly flammable gas.

Hinderberg airship explodes
Hydrogen transportation used to be kind of dangerous.

The main environmental issue in hydrogen fuel production is carbon emission. Most hydrogen fuel production does not capture carbon. But that’s changing.

Why capture CO2?

Okay, let’s get basic for a second.

CO2 is one of the greenhouse gases that causes climate change. Today, there are over 400 parts per million of CO2 in the Earth’s atmosphere.

Prior to about 1870, CO2 was under 280 ppm. For many thousands of years, CO2 was around 280 ppm. Even during and after the ice ages of the past million years, CO2 always stayed under 300 ppm.

What about black, brown, or gray hydrogen?

If we’re talking hydrogen energy, that means we’re also talking about carbon capture. That is, unless we’re talking about “brown,” “black,” or “gray” hydrogen.

Today, nearly all hydrogen is produced without putting the byproduct into carbon-capture storage (CCS), over 95%.

Brown hydrogen is made through the gasification of coal. Black or gray hydrogen are made using thermochemical processes. But none are capturing carbon dioxide (CO2).

All these are valid forms of hydrogen energy, but they’re not “clean” energy. (And at MOXIE, we’re all about that clean energy!)

Thermochemical processes (brown, black, and gray)

As we said, over 95% of hydrogen is produced by fossil fuel without carbon capture. These processes are called thermochemical and include gasification (coal) and gas-phase processes that use methane, refinery gas (a mix of methane and ethane, sometimes propane and butane), and naphtha. As a greenhouse gas, methane is at least 25 times more potent than CO2, so its use is a step in the right direction.

The other thermochem processes are steam methane reforming and partial oxidation. All three types produce syngas, a mix of hydrogen and carbon monoxide (CO). Sometimes thermochemical processes are stacked on each other in a series.

Thermochemically produced hydrogen creates about 10 pounds of CO2 for every pound of hydrogen. That’s why it’s crucial to capture CO2 and that’s why black, brown, and gray hydrogen production is a problem for Earth’s climate.

What is the difference between blue or green hydrogen energy?

Let’s be real, hydrogen energy has a long way to go to get to net-zero emissions. Less than 5% of hydrogen energy produced today is blue or green. But hydrogen has potential and some clean aspects.

With “blue” hydrogen, carbon emissions are captured and stored (CCS).

Currently, many oil and gas companies, like British Petroleum (BP) are banking on, hyping up, and moving ahead with massive blue hydrogen projects.

BP’s CEO, Bernard Looney, touted his company’s H2Teesside Plant on LinkedIn: “98% of emissions don’t reach the atmosphere.”

The BP hydrogen factory will use steamed methane to produce 1 gigawatt of hydrogen. Mr. Looney promised to make his company net-zero emissions by 2050. 1 GW is about 20% of Great Britain’s 2030 hydrogen target. BP will store millions of tons of carbon dioxide byproduct under the North Sea.

The other kind of clean hydrogen energy is called “green.” It doesn’t use fossil-fuel but instead produces hydrogen fuel with wind, hydropower, or solar energy.

Blue vs. Green Hydrogen

Blue hydrogen uses fossil fuel to produce the fuel and puts the CO2 into CCS, like the North Sea spot. For many, the issue with this method is the use of fossil fuel. Continued dependence on oil and gas is exactly in line with the fossil fuel industry’s game plan.

Green hydrogen removes fossil fuels from the process and focuses renewables, like solar power, onto the production of hydrogen.

The problem is getting solar energy diverted from the grid, where it powers homes, farms, and businesses, to this kind of inefficient hydrogen fuel. Again, green hydrogen is not the perfect answer for getting us to net-zero emissions.

Hydrogen vs. Electric car

Hydrogen-fueled vehicles

Most discussion of hydrogen fuel focuses on powering big rigs. Hydrogen has (literally) explosive power. Relative to electric fuel cells, hydrogen fuel is contained in a small package and refueling takes a few minutes. In cargo transport, space and weight are key factors for profits. So a heavy, bulky electric Lithium-ion battery costs more money.

Advantages of Hydrogen

  • Water vapor emissions
  • Infinite supply of hydrogen
  • Fast refuel
  • Quiet drive



  • Lower efficiency
  • Highly flammable
  • Lack of filling stations
  • Expensive

 Hydrogen car

Hydrogen Energy Market

The hydrogen fuel landscape is rapidly changing.

This year, Volvo and Daimler AG (Mercedes-Benz, Freightliner, and more) finalized a 50/50 partnership to produce hydrogen fuel cells. The joint venture is called Cellcentric GmbH & Co. KG and will mainly focus on developing hydrogen fuel components for long-haul trucking. The new company will start test driving hydrogen cells in the next few years and begin large-scale production after 2025.

The two companies assured customers that in all other aspects of the automotive industry, Volvo and Daimler will remain competitors.

Blue, green, or something in between?

The exhaust from hydrogen fuel is indeed clean. Water vapor? We’ll take that over diesel exhaust, right?

But the production of hydrogen energy, whether it’s green or blue, takes some mental gymnastics before we can call it truly clean energy. (Even carbon capture storage is a bit dicey. Some geologists warn that gasifying rock may cause earthquakes.)

The final verdict? Yes, green hydrogen has limitless potential but a long way to go. Blue hydrogen is gearing up, but despite fossil-fuel industry hype, questions remain about CCS and efficiency.

What do you think?

Is hydrogen a viable bridge-fuel technology on the road to net-zero? Or is it too dangerous to pursue for long-haul trucking? Is hydrogen energy “clean” if it’s blue or green (or any other color)?

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