Taste the energy rainbow: What’s with all the colors of hydrogen?

The growing acceptance of hydrogen as a transportation fuel for long-haul trucking comes with a big question. Where does the hydrogen come from?

Just like grid electricity created by smoke-belching coal power plants reduces the environmental benefit of battery-powered vehicles, hydrogen fuel’s value in reducing the warming of the planet is tied to the color assigned to its carbon intensity.

Hydrogen is the most plentiful element in the world. But harnessing it for use as an energy source is where the difficulty lies. Hydrogen is a carrier, not a source, of energy, said Alex Haynes, head of business development at Petrofac, which designs, builds and maintains energy infrastructure.

Energy to produce hydrogen comes from multiple sources, including solar, electricity, hydro, nuclear power and natural gas. The specifics of the production process, including the energy source it uses, determine the color assigned.

Green means go

Green hydrogen is the cleanest option. It is produced by splitting water into hydrogen and oxygen molecules, a process called electrolysis.The hydrogen can be used to make electricity. Oxygen is vented into the atmosphere, typically as harmless water vapor.

Electrolysis is electricity-intensive. And the cost of electricity is what makes hydrogen fuel so expensive, more than $16 a kilogram (just over a quart), according to a 2019 study. When the electricity is powered by renewable sources, such as solar or wind, CO2 ceases to be a byproduct.

This is why Nikola Corp. (NASDAQ: NKLA) sees its recent deal with Arizona Power for deeply discounted electricity as a breakthrough to its plans to build hydrogen fueling stations. Nikola plans to produce Class 8 hydrogen-powered fuel cell trucks in 2023. 

Blue and gray

Blue hydrogen is produced when natural gas is split into hydrogen and CO2 either by steam methane reforming (SMR) or autothermal Reforming (ATR) with the CO2 captured and stored. Capturing the greenhouse gases mitigates the environmental impacts on the planet. The “capturing” is done through a process called carbon capture usage and storage (CCUS).  

Gray hydrogen is made using a similar process to blue hydrogen — SMR or ATR is used to split natural gas into hydrogen and CO2. But the CO2 is released into the atmosphere.

Pink and yellow

Pink hydrogen is made via electrolysis using nuclear energy as its power source.  

Yellow hydrogen is a solar-exclusive output of electrolysis. Green hydrogen, by contrast, can use a combination of renewable sources.

Transitional future

The future of hydrogen is a transition from gray, through blue, to green hydrogen, Haynes said. Green hydrogen is still mostly an ideal. Carbon capture through blue hydrogen is likely for the next three decades, he said.

“There is great potential in both the blue and green hydrogen, and both will play an important role in energy transition,” Haynes said. 

Nikola plans a network of 700 hydrogen stations by 2028. That might be ambitious, especially if it hopes to use green hydrogen as the fuel. Pablo Koziner, Nikola president of energy commercialization, said making green hydrogen in one location cheaply and trucking it to other high-cost energy markets is likely. 

But if a zero-emission fuel cell truck is doing the hauling, it is a minimal carbon setback.

“I am more interested in the carbon intensity than I am in the color of the hydrogen,” Koziner told FreightWaves.

Hyliion Holdings Corp. (NYSE: HYLN) is also looking at hydrogen as a future fuel source. It is focused on launching an electric hybrid Class 8 truck that uses renewable natural gas for power.

“From my end, [I am] still a strong believer in fuel cells and hydrogen,” Hyliion CEO Thomas Healy told FreightWaves. “The question is when will [hydrogen] make sense? Hydrogen needs to decrease from $16 per kilogram to $2 or $3. Stations need to be built out. And then we need to start making green hydrogen, not gray hydrogen or dirty hydrogen.”

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