Blue, green, gold — what do all the colors of hydrogen even mean? Photo via Getty Images

Repeated association of specific colors in defined contexts deeply reinforces themes in the human brain. It’s why most students and alumni of Texas A&M University scoff at the sight of burnt orange, and you’d be hard-pressed to find the home of a Longhorn adorned in shades of crimson or maroon.

The color-coding of hydrogen energy production exemplifies one such ambiguous classification methodology, as the seemingly innocuous labeling of hydrogen as green (for hydrogen produced from renewable sources) and black (for hydrogen produced from coal) initially helped to quickly discern which sources of hydrogen are environmentally friendly or not.

But the coding system quickly became more complicated, as the realization that hydrogen extracted from natural gas (aka grey hydrogen) or coal (again, black hydrogen, or sometimes, brown hydrogen, depending on the carbon content and energy density of the source coal) could be extracted in a less harmful way, by introducing methods of carbon capture and storage.

These cleaner methods for hydrogen extraction earned the lofty color coding of blue, just one shade away from green in the rainbow spectrum and a safe distance from the less delightful and inspiring colors grey, brown, and black.

Then along came pyrolysis — a method for producing hydrogen through methane cracking, plainly, the decomposition of methane, CH4, into solid carbon and hydrogen gas, without the introduction of oxygen. This method results in significantly less (if any) creation of carbon dioxide as a by-product. Logic would lead one to categorize this process with a color that lies further away from black than exalted cousin, green hydrogen.

However, the solid carbon that remains after pyrolysis retains over one-third of the original energy available from methane and could tip the GHG scales negatively if not utilized in an environmentally responsible manner, so it’s not a clear-cut winner in the game of lower-carbon energy production. Thus, it is nestled between green and blue and often referred to as “turquoise hydrogen” production.

Other hydrogen production methods — pink, purple, and red — defy rainbow logic as they have all proven to result in higher GHG emissions than the original “clean” queen, green hydrogen, despite following a similar electrolysis process to separate hydrogen and oxygen from one another in its original composition as water. The source of electricity used in the electrolysis process determines the color-code here, as pink hydrogen is generated from nuclear power, red hydrogen is generated from nuclear thermal power, and purple hydrogen is generated from a combination of nuclear power and nuclear thermal power.

Yellow hydrogen seems to not yet have found a clear definition. Some argue it refers to green hydrogen produced exclusively from solar-powered electrolysis, while others claim it to be the child of mixed green/gray hydrogen. Artists should probably keep a far distance from this conversation, unless the energy produced from the steam coming out of their ears could perform electrolysis more cleanly than any of the green hydrogen solutions.

Finally, we have white hydrogen, the naturally occurring, zero-carbon emitting, plentiful element found in the earth’s crust – which is also the least understood of all the hydrogen extraction methodologies.

Remember, hydrogen is the first element in the periodic table, meaning it’s density is very low. Hydrogen knows no bounds, and once it escapes from its natural home, it either floats off into outer space or attaches itself to another element to form a more containable compound, like water.

Many believe white hydrogen to be the unquestionable solution to a lower-carbon energy future but there is still much to be understood. Capturing, storing, and transporting white hydrogen remain mostly theoretical, despite recent progress, which includes one recently announced Houston lab dedicated to hydrogen transport. Another Houston company, Syzygy has raised millions with its light-based catalyst for hydrogen production.

For example, Cemvita, a local Houston chemical manufacturing company, predicts a future powered by gold hydrogen: white hydrogen sourced from depleted oil and gas wells. Many wildcatters believe strongly in a new era of exploration for white hydrogen using techniques refined in oil and gas exploration, including reservoir analysis, drilling, and fracking.

Without a doubt, investigating further the various hydrogen extraction theories is surely a craveable new challenge for the sciences. But perhaps the current color-coding nomenclature for hydrogen needs refinement, as well.

Unless used in the scientific context of wavelength, color-based labels represent an ambiguous classification tool, as the psychology of color depends on modern societal norms. The association of colors with the various hydrogen production methodologies does very little to distinguish the climate impact each method produces. Additionally, the existing categorizations do not consider any further distribution or processing of the produced hydrogen — a simple fact that could easily negate any amount of cleanliness implied by the various production methods — and a topic for a future article.

For now, hydrogen represents one of the front-running sources for a lower-carbon energy future, but it’s up to you if that’s best represented by a blue ribbon, gold medal, white star, or cold-hard greenbacks.

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Lindsey Ferrell is a contributing writer to EnergyCapitalHTX and founder of Guerrella & Co.

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3 energy transition cos. in the running for Houston Startup of the Year

People's Choice

We're just two weeks away from the 2025 Houston Innovation Awards, presented by InnovationMap.com, and while an expert panel of judges will determine the winners in most categories, one award is up to the public.

Voting is now open for 2025 Houston Startup of the Year, the people's choice award. Six exceptional finalists are in the running for the title, including three from the energy transition sector.

From next-gen biobased materials to technology that creates chemicals without carbon emissions, these companies are shaping the future.

Read about all of the Startup of the Year finalists and their missions below, then cast your vote. You can vote once per day through November 12.

The winner, along with winners in all other categories, will be revealed live on November 13 at Greentown Labs. Tickets to the 2025 Houston Innovation Awards are available now — get yours today.

2025 Houston Startup of the Year finalists:

Eclipse Energy

Eclipse Energy, previously known as Gold H2, is a climatetech startup converting end-of-life oil fields into low-cost, sustainable hydrogen sources. The company completed its first field trial this summer, which demonstrated subsurface bio-stimulated hydrogen production. Eclipse Energy says Its technology could yield up to 250 billion kilograms of low-carbon hydrogen.

Rheom Materials

Rheom Materials is a next-generation startup developing biobased materials for a more sustainable future. Its two flagship offerings are Shorai, a sustainable leather alternative that is usable for apparel, accessories, car interiors, and more, and Benree, an alternative to plastic without the carbon footprint.

Solidec

Solidec is a chemical manufacturing company developing autonomous generators that extract molecules from water and air and convert them into pure chemicals and fuels that are free of carbon emissions. The technology eliminates the need for transport, storage, and permitting.

FlowCare

FlowCare is developing a period health platform that integrates smart dispensers, education, and healthcare into one system to make free, high-quality, organic period products more accessible. FlowCare is live at prominent Houston venues, including Discovery Green, Texas Medical Center, The Ion, and, most recently, Space Center Houston, helping make Houston a “period positivity” city.

MyoStep

MyoStep is a next-generation, lightweight, soft exoskeleton developed at University of Houston for children with cerebral palsy. The soft skeleton aims to address motor impairments that impact their ability to participate in physical activities, self-care, and academics, via an affordable, child-friendly solution that empowers mobility and independence.

Persona AI

Persona AI is a humanoid robotics startup that is creating rugged, autonomous robots for skilled, heavy industry work for various "4D" (dull, dirty, dangerous, and declining) jobs. In May, the company announced a memorandum of understanding with HD Korea Shipbuilding & Offshore Engineering, HD Hyundai Robotic, and Vazil Company to create and deploy humanoid robots for complex welding tasks in shipyards. The project will deliver prototype humanoids by the end of 2026.

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The Houston Innovation Awards program is sponsored by Houston Community College, Houston Powder Coaters, FLIGHT by Yuengling, and more to be announced soon. For sponsorship opportunities, please contact sales@innovationmap.com.

What to expect from the 2025 Greentown Labs' Climatetech Summit Houston

where to be

Greentown Labs' Climatetech Summit Houston will take place next Tuesday, Nov. 4, bringing together philanthropists, executives and innovators in the energy transition space.

John Arnold, co-founder and co-chair of Arnold Ventures, will participate in the keynote fireside chat with Greentown CEO Georgina Campbell Flatter. The conversation will explore "top priorities and opportunities in energy innovation today—with a special focus on how these dynamics are playing out in Houston," according to Greentown.

Other highlights will include:

  • Welcome remarks from Houston Mayor John Whitmire
  • A course led by TEX-E Executive Director Sandy Guitar
  • A philanthropy panel featuring Greentown Labs new Head of Philanthropy Stacey Harris
  • The Energy Jobs of the Future, featuring Sameer Bandhu, GE Vernova’s managing director, ventures and licensing
  • An Energy-transition Roadmap, featuring Monica Krishnan, Hermann Lebit and Bobby Tudor and moderated by Varun Rai
  • What is Climatetech? featuring Kyle Judah, Emerson Denka Wangdi, Laureen Meroueh and Head of Greentown Houston Lawson Gow

Ten Greentown Labs startups will also present their pitches at the event. Expect to hear from:

  • MCatalysis Inc. CEO, President, and Founder Michael D. Irwin. Dallas-based MCatalysis develops novel, high-efficiency industrial microwave processes and catalysts to produce low-cost, clean synthetic fuels and chemicals from waste carbon resources.
  • Pike Robotics CEO and co-founder Connor Crawford. Austin-based Pike Robotics provides next-gen robotic solutions for in-service inspection of floating roof storage tanks.
  • Helix Earth CEO and co-founder Rawand Rasheed. Houston-based Helix Earth retrofits commercial HVAC systems to improve energy efficiency.
  • 10DQ CEO Steven Reece. Greentown Boston member 10DQ has developed its Redox Loop Battery, which uses novel, water-based electrolytes to store energy in dense, low-cost, earth-abundant battery materials.
  • Janta Power CEO Mohammed Njie. Dallas-based Janta Power is developing 3D solar towers.
  • Neuralix business operations and product developer Annorah Lewis. Houston-based Neuralix offers a suite of rapid, customizable templates for the data lifecycle for the energy and manufacturing sectors.
  • Ententia co-founder Nishant Shah. Houston-based Etenitia develops enterprise AI platforms and systems that use domain expertise, rich multi-modal industrial datasets, and generative AI technology to power more effective and efficient business workflows.
  • Locoal CEO Miles Murray. Boerne, Texas-based Locoal is a waste-to-energy company that has developed a proprietary mobile containerized fluidized gasifier that diverts waste, converts it to clean energy and captures carbon in value-added co-products.
  • SpiralWave co-founder Adam Amad. San Francisco-based SpiralWave has developed novel electrochemical carbon capture technology that lowers costs.
  • Biatech founder and CEO Nathan Hartwig. Tampa-based Biatech has built an application-layer AI platform to help energy, mining and infrastructure operators optimize asset performance, reduce risk and improve decision-making.

In addition to the startup pitches, attendees will also be able to meet founders and Greentown members during the afternoon startup showcase. A networking reception at Axelrad Houston follows. A separate ticket offers admission to the showcase and networking event only.

See the full agenda here.

California company launches Tesla Megapack battery project in Houston area

power on

Oakland, California-based Nightpeak Energy announced earlier this month that its 150-megawatt battery storage project in Brazoria County, known as Bocanova Power, is now operating to address Houston’s peak capacity needs.

“This battery storage project will enhance grid reliability in the Alvin area while continuing to support integrating renewable energy,” Cary Perrin, president and CEO of the Northern Brazoria County Chamber of Commerce, said in a news release. “I believe we need energy storage now more than ever for its pivotal role in reducing strain on the grid while meeting fast-growing power demand in Texas and Brazoria County."

The project reached commercial operation in August, according to the release. The project utilizes Tesla's Megapack 2 XL battery storage system, and the facility operates under a long-term power purchase agreement with an undisclosed “investment-grade power purchaser.”

“Bocanova Power demonstrates the speed at which Nightpeak Energy is overcoming complex challenges to energize projects that support America's growing need for affordable, reliable, and secure energy,” Paris Hays, co-founder and CEO/CDO of Nightpeak Energy, added in the news release. “Unprecedented AI data center and manufacturing growth has only accelerated the need for these resources.”

Hays added in the release that the company has plans for more energy infrastructure projects in Texas and in the Western U.S.

Nightpeak Energy develops, owns and operates power plants that support the growing capacity needs of a decarbonized grid. It also owns and operates 240 MW of battery storage and natural gas generation facilities.

The company was founded in 2022 and backed by equity funding of up to $200 million from Dallas-based investment firm Energy Spectrum Capital.