These Houston startups raised more than a quarter billion dollars last month alone. Photo courtesy Venus Aerospace

Houston startups carried the fundraising momentum of Q1 and Q2 into July with several significant seed funding, Series A and Series B rounds.

From geothermal leaders to medtech innovators, these six Houston companies raised more than a quarter billion dollars last month alone, according to reporting by InnovationMap and our sister site, EnergyCapitalHTX.com.

Did we miss a funding round? Let us know by emailing innoeditor@innovationmap.com.

Altillion

Houston-based startup Altillion has secured $5 million in seed funding to accelerate the commercialization of its proprietary IRIS and ALIX technologies, which convert oilfield-produced water into valuable minerals, the company reported earlier this month.

San Francisco-based EIC Rose Rock and Houston-based Flathead Forge led the round. Altillion says the funding will go toward pilot facilities and commercial deployments as the company looks to scale in the U.S. Continue reading.

Buildforce

The U.S. is grappling with a current shortage of 50,000 electricians, according to the National Electrical Contractors Association. Photo via Unsplash

Houston-based Buildforce, which provides a tech-enabled staff platform geared toward electricians and electrical contractors, closed a $10 million Series A round led by Houston’s Saepio Capital last month.

Other investors in the round include Blue Heron Capital, Revolution’s Rise of the Rest Seed Fund, S3 Ventures and Chicago Ventures.

Buildforce says the funding will help fuel its national expansion and further development of its technology.

The startup, founded in 2019, connects electricians with electrical contractors for commercial and industrial construction projects. Continue reading.

Hephae Energy Technology Corp.

The company develops ultra-high-temperature tools to withstand the heat of geothermal reservoirs. Photo via hephaeet.com

Houston-area startup Hephae Energy Technology Corp. closed a $17.8 million Series A financing round last month to commercialize its geothermal technology.

The round was co-led by Pennsylvania-based Susquehanna Sustainable Investments, which invests in early-stage climatech companies, and Copenhagen-based Underground Ventures, which focuses on geothermal energy startups. Alfa8, Baruch Future Ventures, Centaurus Capital LP, Elemental Impact, Exa Ventures, Future Ventures, Grantham Foundation for the Protection of the Environment, New System Ventures and True North Institute joined the round, along with existing Houston-based investor Nabors Industries. Hephae reports in a news release that the Series A round brings the company's total capital raised to $24.7 million. Continue reading.

TYBR Health

The company's B3 GEL System is designed to protect tendons, ligaments and muscles while they heal from orthopedic surgery. Photo via Unsplash

Houston-based healthtech startup TYBR Health has raised a $30 million Series A round to scale its B3 GEL System, which helps protect tendons from scarring after surgery, the company announced last month.

The round was led by Minneapolis-based Vensana Capital and Cleveland-based Mutual Capital Partners, with participation from Denver-based Neovate Capital Partners and existing investors, according to a news release from the company.

TYBR Health said it plans to use the funding to broaden the B3 GEL System's clinical applications, expand commercialization and conduct studies to evaluate its ability to protect tissue and improve healing outcomes. Continue reading.

Venus Aerospace 

Venus Aerospace has secured funding from Mercury Fund, Lockheed Martin Ventures and others. Photo courtesy Venus Aerospace

Houston-based Venus Aerospace closed a $91 million Series B round last month and plans to scale the production of its hypersonic engine.

The round was led by Houston-based Mercury Fund with participation from Lockheed Martin Ventures, MESH, PEAK6, Draper Associates, Starboard Star Venture Capital, Green Sands Equity and other investors, according to a news release.

The investment comes about a year after Venus completed the first U.S. flight test of its high-thrust rotating detonation rocket engine (RDRE). The engine is expected to enable vehicles to travel four to six times the speed of sound from a conventional runway and is about 15 percent more efficient than traditional alternatives, according to the company. Continue reading.

Quaise Energy

A rendering of a Quaise Energy geothermal plant. Rendering via quaise.com

Houston-based Quaise Energy, a producer of utility-scale geothermal power, closed $134 million in a Series B round last month to advance its “superhot” geothermal power plant.

Climate-focused San Francisco-based investment firm Prelude Ventures led the round, with participation from JERA Co., Japan’s largest power generation company, and Idemitsu Kosan, one of Japan’s largest energy companies. Nearly all existing investors, including cleantech-focused investment firm Safar Partners, participated in the round.

The startup expects more equity and debt deals to close “imminently.” Quaise has raised $230 million since its founding in 2018. Continue reading.

The Venus Aerospace team in June. Photo courtesy Venus Aerospace

Venus Aerospace adds government, C-suite leaders following $91M raise​

new leaders

Fresh off its $91 million Series B, Houston-based Venus Aerospace has made several key additions and promotions to its leadership team.

The company says its expanded team will help it deploy its high-thrust rotating detonation rocket engine (RDRE), which completed its first U.S. flight test last summer.

"We flew the world's first high-thrust RDRE in just over four years on $80 million. We believe that makes it the fastest, most capital-efficient rocket engine program in history," Sassie Duggleby, co-founder and CEO of Venus Aerospace, said in a news release. "Adding this talent to our leadership team is how we bring that same discipline to the company itself, as we scale to meet the technical needs of defense and space customers who need range and speed legacy systems can't deliver."

The key hires include:

Lane Bodian, Vice President of Public Policy

Bodian previously served as the Principal Deputy Assistant Secretary of Defense for Legislative Affairs at the Pentagon.

Dan Rebnord, Director of Federal Government Relations

Rebnord most recently served as Senior Policy Advisor to a member of the Senate Armed Services Committee and previously worked in the Office of Legislative Affairs at the Department of Defense and as Staff Director for a national security subcommittee in the House of Representatives. Rebnord and Bodian will lead Venus' work with government stakeholders.

Tom Barron, Chief Operating Officer

Barron was promoted from his role as vice president of operations for Venus Aerospace. Before his time at Venus, he served as Special Assistant to the Secretary of Defense and consulted aerospace clients at McKinsey & Company. He also served as a U.S. Army Infantry and Special Forces officer.

Nick Cardwell, Chief Product Officer

Cardwell was promoted from his role as vice president of research and development. He previously held product and technology leadership roles at VC-backed tech companies in the San Francisco Bay Area and Austin.

Venus also named Cameron Taylor as its new vice president of operations, Sarah Boland Heine as its head of communications, Matt Stohr as its head of business development, and Sheila Menz as general counsel.

The company also announced a joint technology development agreement to advance the RDRE with defense giant Lockheed Martin last week. Through the partnership, Venus and Lockheed will focus on evaluating the RDRE's propulsion architecture in defense systems, specifically for precision fires applications where weapons are designed to accurately strike targets at long distances.

Lockheed Martin Ventures, the investment arm of the aerospace and defense contractor, is an investor in Venus Aerospace.

"Lockheed Martin is focused on rapidly delivering advanced capabilities that strengthen deterrence and provide decisive advantages for the warfighter," Tim Cahill, president, Lockheed Martin Missiles and Fire Control, said in a news release. "Our collaboration with Venus Aerospace allows us to evaluate a promising propulsion technology and determine how it can be integrated into future precision fires solutions. Efforts like this help accelerate innovation, reduce risk and shorten the path from emerging technology to operational capability."

Venus' RDRE is expected to enable vehicles to travel four to six times the speed of sound from a conventional runway and is about 15 percent more efficient than traditional alternatives, according to the company.

Venus says the reusable, affordable and scalable RDRE is designed with a "common propulsion architecture" that can work for multiple industries and mission types. The company has previously estimated that the hypersonic market is projected to surpass $12 billion by 2030.

Venus Aerospace has secured funding from Mercury Fund, Lockheed Martin Ventures and others. Photo courtesy Venus Aerospace

Venus Aerospace closes $91 million Series B to scale hypersonic engine

flight funding

Houston-based Venus Aerospace has closed a $91 million Series B round and plans to scale the production of its hypersonic engine.

The round was led by Houston-based Mercury Fund with participation from Lockheed Martin Ventures, MESH, PEAK6, Draper Associates, Starboard Star Venture Capital, Green Sands Equity and other investors, according to a news release.

The investment comes about a year after Venus completed the first U.S. flight test of its high-thrust rotating detonation rocket engine (RDRE). The engine is expected to enable vehicles to travel four to six times the speed of sound from a conventional runway and is about 15 percent more efficient than traditional alternatives, according to the company.

Venus Aerospace says the latest round of funding will allow it to move the RDRE from demonstration to deployment and meet customer requirements for the near-term defense and space industries. The company says that the reusable RDRE is designed with a "common propulsion architecture" that can work for multiple industries and mission types.

“This financing marks an important step in moving Venus from breakthrough demonstration to scaled capability,” Sassie Duggleby, co-founder and CEO, said in the news release. “Our customers need propulsion systems that go farther, can be produced reliably and are built on supply chains they can trust. We are advancing that capability with American engineering and manufacturing talent to strengthen U.S. defense, expand space access and support the future of high-speed flight.”

Venus Aerospace raised a $20 million Series A in 2022, led by Wyoming-based Prime Movers Lab. At the time, the company said it would put the funding toward three main technologies: a next-generation rocket engine, aircraft shape and leading-edge cooling system.

The company also picked up an investment from Lockheed Martin Ventures, the investment arm of aerospace and defense contractor Lockheed Martin, in November 2025—in addition to funding from other investors over the years.

“Since our initial investment, Venus has progressed very quickly in its technology development," Chris Moran, vice president and general manager of Lockheed Martin Ventures, added in the release. "Our reinvestment in Venus recognizes Venus’ accomplishments to date and focus on speed to manufacture, cost management and reduction of supply chain constraints. Venus is working effectively to position its propulsion system for the production scale required by defense programs.”

"Venus is exactly the kind of company Houston capital should be backing," Blair Garrou, co-founder and managing partner at Mercury Fund, added in the release. "It combines multiple frontier technologies, domestic manufacturing and clear commercial and national security relevance. We believe this team is positioned to lead an important new chapter in defense and space, and we are proud to support a company building breakthrough technology here in Texas."

Venus Aerospace and Houston clean tech startup Vaulted Deep were named to the World Economic Forum's Technology Pioneers community earlier this summer. Read more here.

Two Houston startups have been named World Economic Forum Technology Pioneers. Photo courtesy Venus Aerospace

Houston cleantech, space startups named to World Economic Forum cohort

top honor

Two Houston-based startups have been selected to join the World Economic Forum's Technology Pioneers community.

The two-year program aims to help mission-driven, early-stage start-ups scale their innovations through multi-stakeholder initiatives, co-creating partnerships and other gatherings for community members. One-hundred startups are selected each year from around the globe, this year hailing from 23 countries and working in AI, energy, space, biotech markets and more.

Cleantech startup Vaulted Deep was one of 11 energy and climate companies to be named to the cohort. Julia Reichelstein and Omar Abou-Sayed founded the company in 2023. Its technology injects excess organic waste underground to remove carbon dioxide from the atmosphere.

Last year, Vaulted Deep inked a 12-year deal with Microsoft to remove up to 4.9 million metric tons of carbon dioxide from the environment.

The startup has earned several accolades in recent years, including a No. 3 spot on Fast Company’s list of the World’s Most Innovative Companies of 2026. It was also recently named to market intelligence and advisory firm Cleantech Group's annual Global Cleantech 100 list for a second year in a row.

"Waste management is one of the world's great invisible infrastructure systems ... The need for new infrastructure is growing as disposal challenges become more complex and regulations evolve. Vaulted is building the first new disposal pathway for organic waste in decades by putting it deep underground, permanently," the company shared in a LinkedIn post. "This year, we're joining the World Economic Forum's 2026 Tech Pioneers alongside innovators working on the many interconnected challenges shaping our future."

Houston-based Venus Aerospace was also selected to join the cohort, along with six other spacetech companies. The company was founded in 2020 by Sassie and Andrew Duggleby.

The startup specializes in next-generation rocket engine propulsion as a cleaner alternative to traditional combustion engines. The company's rotating detonation rocket engine (RDRE) burns fuel more efficiently and completed a successful high-thrust test flight last year. Venus says it’s the only company in the world that makes a flight-proven, high-thrust RDRE with a “clear path to scaled production.”

"Frontier technologies matter most when they expand what people, industries, and nations can do," Sassie Duggleby, co-founder and CEO of Venus, said in a news release. "For Venus, RDRE does not just represent a more efficient engine. It is a foundation for faster movement, more capable space systems, and new forms of connectivity across the planet. Being named a Technology Pioneer validates the potential of this technology to help shape a future where distance is less limiting."

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This article originally appeared on our sister site, EnergyCapitalHTX.com.

Houston founders Laureen Meroueh, LaToshia Norwood, Sassie Duggleby, Nina Magon, Stephanie Murphy and Lauren Rottet were named to Inc. Magazine's 2026 Female Founders 500. Photos via LinkedIn and company websites

6 Houston entrepreneurs land on coveted Inc. Female Founders 500 list

the future is female

Six Houston female entrepreneurs and innovators were named to the 2026 Female Founders 500 list.

The annual list compiled by Inc. Magazine recognizes female founders based in the U.S. who have built businesses that have moved their industries forward. The group collectively generated approximately $12.3 billion in 2025 revenue and $12.2 billion in funding to date, according to Inc. Five Houstonians were named to the list last year.

"Each year, we are increasingly amazed by the extraordinary leaders on our Inc. Female Founders 500 list," Bonny Ghosh, editorial director at Inc., said in a news release. "The honorees on this year's list include innovators in AI, beauty and wellness trendsetters winning devoted fans, and nonprofit leaders making a real impact in their communities. Together, they're showing all of us what trailblazing female leadership looks like."

The Houston founders are:

  • Sassie Duggleby, CEO and co-founder of Houston space tech and engine company Venus Aerospace. Duggleby also serves on the Texas Space Commission board of directors.
  • Stephanie Murphy, CEO and executive chairman of Aegis Aerospace, which provides space services, spaceflight product development, and engineering services. Murphy also serves as chair of the Texas Aerospace Research and Space Economy Consortium Executive Committee.
  • Laureen Meroueh, CEO and founder of Hertha Metals, which has developed a cost-effective and energy-efficient process that converts low-grade iron ore of any format directly into molten steel or high-purity iron in a single step.
  • LaToshia Norwood, managing partner of L'Renee & Associates (LRA), a full-service project management consulting firm.
  • Lauren Rottet, president and founding principal of Rottet Studio, an international architecture and design firm focused on corporate, lifestyle and hospitality projects
  • Nina Magon, founder and CEO of Nina Magon Studio / Nina Magon Consumer Products, a residential and commercial interior design company. She also co-founded KA Residences earlier this year.

"Grateful to be recognized again on the Inc. Female Founders 500," Duggleby said in a LinkedIn post. "The best part of building Venus Aerospace has been working with an incredible team pushing the boundaries of flight—and helping bring more women into aerospace along the way.

Meroueh, whose company emerged from stealth last year, voiced a similar push for bringing more women into the fold.

"We've seen a 7x jump in female-led IPOs over the last decade, from just two in 2014 (less than 1% of all IPOs) to 14 in 2024 (nearly 9% of all IPOs). Progress is happening," Meroueh shared in a LinkedIn post. "Yet, less than 1% of venture funding in hard tech goes to female-founded companies. But as my friend Ana Kraft says, the right man for the job may be a woman."

Twenty-nine Texas female founders made this list, including Amber Venz Box, founder of the Dallas-based LTK shopping platform, and Cheryl Sew Hoy, CEO and founder of Austin-based Tiny Health, a fast-growing at-home microbiome health platform. See the full list of winners here.

Rice University lands $14M state grant to open Center for Space Technologies

on a mission

Rice University’s Space Institute soon will be home to the newly created Center for Space Technologies.

On Feb. 17, the Texas Space Commission approved a nearly $14.2 million grant for the Rice project. The Center for Space Technologies will target:

  • Research and development
  • Technology transfer and innovation
  • Statewide partnerships
  • Workforce development training
  • Space-focused education programs

The goal of the new center “is to fulfill an articulated need for research, workforce development, and industry collaboration,” said Kemah communications and marketing executive Gwen Griffin, chair of the commission.

State Rep. Greg Bonnen, a Friendswood Republican, authored the bill that set up the Texas Space Commission.

Since being authorized in 2023, the commission has funded 24 projects, with Rice and Houston-area companies accounting for nearly $75 million in grants to back space-related initiatives.

The grant to Rice brings the TSC's total investment to $150 million, fully committing the entire state appropriation from the Texas Legislature in 2023.

Other local companies that have received grants over the years include Aegis Aerospace, Axiom Space, Intuitive Machines, Starlab Space and Venus Aerospace.

The commission also awarded $7 million to Blue Origin earlier this month. See a list of the 24 awards here.
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CultureMap Emails are Awesome

2 Houston universities named best colleges of 2027 by Princeton Review

A-Plus Ratings

Back-to-school season is has returned in full force, and that means it's time for college rankings. Two Houston universities in particular are being hailed as the top of the class for 2027.

The high caliber schools — Rice University and University of Houston — earned new acclaim in The Princeton Review's ranking of the "Best 392 Colleges" for 2027.

The Princeton Review's 35th annual "Best Colleges" rankings are determined by a survey of 172,000 current college students that gave "candid feedback" about their schools and their experiences. The flagship guide does not rank the schools overall, but it does rank them across 50 different categories, including best-run colleges, best quality of life, happiest students, best athletic facilities, among others.

In all, 14 Texas institutions were highlighted in the overall list of the 392 best colleges.

Schools don't pay to be included in the guide, but The Princeton Review clarified that schools could pay for a "featured" designation. No Houston university paid to be featured in this year's guide. Trinity University in San Antonio and Southwestern University, a private school in the Austin suburb Georgetown, were the only two Texas schools that paid to be "featured."

Rice and UH have been on a winning streak in separate reports of the best universities worldwide, best graduate schools, and best online degree programs.

In addition to being included in the overall list, Rice was highlighted as one of the Best Value Colleges, Colleges That Create Futures, and it earned high marks in Princeton Review's Mental Health Honor Roll 2026. The home of the Rice Owls also starred in the regional Best Southwest list that contained 41 universities across Arizona, Colorado, New Mexico, Oklahoma, and Texas.

"Rice University stands out as a leading research university where academic diversity and a wide array of interdisciplinary institutes and centers make it easy for students to explore multiple areas of interest," the school's profile says. "At Rice, 'knowledge isn’t siloed — students are constantly crossing disciplines and interests in ways that feel natural rather than exceptional.'"

Rice earned the following rankings on 14 other lists:

  • No. 1 – Lots of Race/Class Interaction
  • No. 3 – Best College Newspaper
  • No. 9 – Friendliest Students
  • No. 11 – Best Quality of Life
  • No. 13 – Great Financial Aid
  • No. 14 – Top 50 Best Value Private Colleges
  • No. 17 – Their Students Love These Colleges
  • No. 18 – Top 20 Best Value Private Colleges Without Aid
  • No. 18 – Best Student Support and Counseling Services
  • No. 19 – Best College Dorms
  • No. 21 – Students Study the Most
  • No. 24 – Best Campus Food
  • No. 24 – Best College Radio Station
  • No. 24 – Best-Run colleges
The University of Houston also appeared in the Best Southwest, Best Value Colleges, and Colleges That Create Futures lists, and it was named a top Green College, which examined schools that "share superb sustainability practices, a strong foundation in sustainability education, and a healthy quality of life for students on campus

UH earned five more accolades:

  • No. 1 – Top 50 Undergraduate Schools for Entrepreneurship Studies
  • No. 1 – Top Undergraduate Schools for Entrepreneurship Studies in the Southwest
  • No. 8 – Most Politically Moderate Students
  • No. 15 – Financial Aid Not So Great
  • No. 42 – Top 50 Best Value Public Colleges
In the school's profile, students say they had an overall positive experience thanks to UH's excellent academic offerings and dedicated faculty members.

"Students confirm that 'the research and other academic opportunities... are very accessible to students who seek it out,'" the profile says. "This includes taking advantage of UH’s vast alumni network (more than 325,000 and counting), not to mention its location in the corporate center of Houston, where 'the opportunities that are provided are immense.'"

The 12 other public and private universities in Texas included in The Princeton Review's 2027 guide are:

  • The University of Texas at Austin
  • Southwestern University, Georgetown
  • Baylor University, Waco
  • Texas A&M University - College Station
  • Trinity University, San Antonio
  • Texas State University, San Marcos
  • Angelo State University, San Angelo
  • Texas Christian University, Fort Worth
  • University of Dallas, Irving
  • Southern Methodist University, Dallas
  • The University of Texas at Dallas, Richardson
  • Austin College, Sherman
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A version of this story originally appeared on CultureMap.com.

Houston named the No.1 emerging city for biopharma in inaugural report

Biopharma Leader

Houston is ranked No.1 on the first-ever Next 10 U.S. Biopharma Clusters report published by Genetic Engineering & Biotechnology News (GEN).

The report, which ranks the best emerging hubs for life science activities, considered patents, NIH funding, lab space, venture capital investments, and the number of jobs in regions in cities, states and “clusters” across the U.S. GEN touts Houston as the top city for the biopharma industry due to a surge in funding, job creation, medical innovations and startup success.

Here’s how Houston ranked in the report’s different categories;

  • No. 1 for NIH funding with 2,262 awards totaling more than $1.25 billion
  • No. 2 for emerging regions for jobs, with 28,000 jobs
  • No. 2 for lab space, with roughly 8 million square feet in the market
  • No. 6 for patents, with 2,760 patent families

According to BioHouston chairman Jeff Wade, Houston secured half a billion dollars in venture capital funding in 2025 and 2026 to date.

The report called out major biopharm news out of Houston in the last few months, including Bristol Myers Squibb selecting Houston for its $1 billion, 600,000-square-foot manufacturing site and Eli Lily selecting Houston for its $6.5 billion, 236-acre manufacturing site. Both facilities will be located within Generation Park, a 4,300-acre, master-planned commercial district near Lake Houston.

Houston startups like CrossBridge Bio and Duracyte were also mentioned in the report. CrossBridge, which develops antibody-drug conjugates for cancer, was acquired by Eli Lily in April for $300 million. Duracyte, a “living pharmacy” company, was launched out of Rice University’s biotech venture studio RBL LLC this spring and is backed by up to a $45 million Advanced Research Projects Agency for Health (ARPA-H) award.

The startup is working to commercialize its Hybrid Advanced Molecular Manufacturing Regulator (HAMMR) technology, a rechargeable, implantable device that can sense biological signals, monitor tumor environments and adjust therapeutic output in real time.

“There’s a lot of great talent, but the unique advantage that we have is we are able to benefit from a lot of unique clinical infrastructure and clinician insights,” Omid Veiseh, Duracyte co-founder and managing partner of RBL LLC, told GEN. “There are a lot of clinicians here who are eager to partner on investigator-initiated trials.”

The report also touted Houston’s Texas Medical Center, home to the University of Texas MD Anderson Cancer Center and Baylor College of Medicine, and international partnerships like the recently expanded TMC Korea BioBridge.

Other cities to make the list include:

  • No. 2 Minneapolis-St. Paul
  • No. 3 Denver-Boulder
  • No. 4 St. Louis
  • No. 5 Dallas-Fort Worth

States to make the list include:

  • No. 1 Ohio (including Cincinnati, Cleveland, and Columbus)
  • No. 2 Indiana (including Indianapolis)
  • No. 3 Florida (including Jacksonville and Miami-Fort Lauderdale)
  • No. 4 Georgia (including Atlanta and Augusta)
  • No. 5 Wisconsin (including Madison and Kenosha)

Regional state clusters to watch include:

  • Phoenix
  • Pittsburgh
  • Greater Richmond, Virginia
  • South Carolina
  • Utah

See the full report here.

Major Texas-based airlines ground humanoid robots as passengers

In The Air

Two major airlines based in Texas are drawing a hard line between human and humanoid: American Airlines and Southwest Airlines won’t permit human-like or animal-like robots to board flights as passengers.

Fort Worth-based American and Dallas-based Southwest recently adopted bans on robotic passengers after two incidents in which human-like robots joined flesh-and-blood passengers on Southwest flights.

In May, Aaron Mehdizadeh, owner of The Robot Studio rental company in Dallas, was heading from Las Vegas to Dallas Love Field with 3.5-foot-tall Stewie, according to CBS News Texas. Rather than shipping Stewie as cargo, Mehdizadeh bought the robot its own seat using a type of ticket often purchased for fragile items such as wedding dresses and equipment.

But because Stewie was technically a carry-on item, the robot wasn’t supposed to occupy a seat, according to eWeek. Crew members wound up disconnecting Stewie’s battery and relocating the robot to a window seat before takeoff.

Mehdizadeh pushed back on Southwest’s stance regarding the battery, telling CBS News Texas that Stewie’s power supply is a standard battery that’s similar to one for a laptop.

Stewie isn’t the only robot making mischief in the skies. In May, a 70-pound, human-like robot named Bebop caused a stir on a Southwest flight from Oakland, California, to San Diego.

The robot prompted a nearly one-hour flight delay after crew members realized it violated restrictions on large carry-ons and raised concerns about the battery, San Francisco TV station KGO reported. Dallas-based Elite Event Robotics owns Bebop.

Southwest seized Bebop’s lithium-ion battery, but the airline did let Bebop take the San Diego-bound flight.

Southwest’s new robot policy prohibits human-like or animal-like robots from riding in an airplane cabin or as checked baggage, no matter their size or purpose. All other robots, including toys, must fit in a carry-on size bag and comply with battery restrictions, the airline says.

In a statement sent to CultureMap, a Southwest spokeswoman says the airline “has taken a strong stance on this issue and has led the U.S. airline industry with our battery policy.”

“The robot policy is a further evolution of a [safety] journey we have been on for several months. This move was not in response to any single incident,” the spokeswoman adds. “To eliminate confusion, the policy applies to all similar devices, regardless of size.”

Lithium-ion batteries can overheat, catch on fire, or explode on airplanes.

American’s new robot policy, which took effect Monday, August 17, is similar to Southwest’s. The policy prohibits human-like and animal-like robots from sitting in a purchased seat, being stored in an overhead bin or traveling as checked baggage. The ban applies to U.S., international, and regional flights.

“While there have been no known events involving this type of robot on any American flight, this policy was developed following a comprehensive review of safety risks associated with these devices, including the large lithium-ion batteries that power them,” the airline said in an internal memo obtained by the View From the Wing travel blog.

American gate agents have been told not to allow a passenger accompanied by a robot to board a plane or to let a robot travel as a checked item, the memo say.

If a robot is discovered after check-in, American employees are supposed to follow the Federal Aviation Administration’s “undeclared dangerous goods” procedures. These procedures cover hazardous shipments like lithium-ion batteries, explosives, flammable liquids, and compressed gases that lack required warning labels or shipping documents.

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This article originally appeared on CultureMap.com.