Here’s a riddle for you: What’s colorless but most often referred to by its colors?
The answer: hydrogen. Often referred to as a “clean-burning” fuel, because it generates near-zero carbon greenhouse gas emissions at the tailpipe, hydrogen is the most abundant chemical substance in the universe. It’s also colorless, odorless, and burns with a near-invisible flame. So why does nearly every Google search or news story about hydrogen turn up terms like “green,” “blue,” and even “pink”?
A rainbow of production processes
Hydrogen as a fuel source isn’t found freely in nature. It must be extracted from naturally occurring compounds, typically through energy-intensive processes. And though there are multiple ways to make hydrogen fuel — all resulting in the same molecular hydrogen — the lifecycle greenhouse gas intensity of each production method varies. Energy experts and engineers started labeling these processes by color to make it easier for the rest of us to understand the differences.
Whether this color designation makes it simpler is up for debate. There’s no universal standard for hydrogen color labeling, and different organizations and countries sometimes use different definitions. Still, if you’re considering hydrogen as a potential fuel source for your electric power needs, it’s good to have at least a basic understanding of the terminology. So, here’s a quick look at the most common “colors of hydrogen” and their meanings.
The cleanest H2: green hydrogen
Not surprisingly, green is the color chosen for the hydrogen production method, resulting in zero net greenhouse gas emissions. Green hydrogen is made by using electricity from renewable sources, like solar or wind power, to electrolyze water. Electrolysis is a chemical reaction that separates water molecules into their two components — hydrogen and oxygen — and nothing more. This type of production is costly, so only a small percentage of hydrogen is made this way.
The rest of the hydrogen spectrum
No black-and-white solution
Clear as mud? Don’t worry about remembering exactly what each color means. The key takeaway is that not all hydrogen is created equal, especially when looking at it from a carbon footprint and sustainability perspective. More companies are turning to sustainable solutions to help lower their carbon footprint. Renewable hydrogen and hydrogen blends are among several alternative fuels customers consider to achieve their sustainability goals. In fact, we already offer generator sets capable of operating on 100% hydrogen — including fully renewable green hydrogen. Here’s a look at our 35-plus years of hydrogen experience, products with hydrogen-blending capabilities, and other hydrogen-related projects currently underway.
Hydrogen Infrastructure and Integration Specialist
As the Hydrogen Infrastructure and Integration Specialist at Caterpillar, Steven Parente has responsibility for product definition and technical sales support of hydrogen infrastructure products. Furthermore, he leverages years of experience in hydrogen technologies to provide technical leadership for a diverse portfolio of hydrogen projects across the enterprise.
Steven has spent more than 16 years in the hydrogen industry where he has gained subject matter expertise in hydrogen production, compression, storage, and dispensing. He began his career as a process engineer, designing and commissioning steam methane reforming plants for hydrogen and syngas production. His accomplishments as process engineer include the development of a novel, compact hydrogen production system to provide a reliable, on-site production solution for small hydrogen consumers. He progressed through engineering management roles, leading increasingly larger engineering teams through engineering, procurement, and construction of hydrogen systems globally. As the hydrogen for mobility market rapidly evolved, he led a team in the development, testing, and deployment of hydrogen refueling systems designed to serve light and medium duty transportation sectors, primarily in California, China, and Europe.
Steven holds a bachelor's degree in chemical and biomolecular engineering and a master's degree in business administration, both from the Georgia Institute of Technology.
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