Houston-based Rhythm Energy CEO and founder, PJ Popovic, discusses the landscape of Texas' energy market and how renewables should be incorporated. Photo courtesy of Rhythm

After experiencing the hottest day on record this past Fourth of July, PJ Popovic — CEO and founder of green energy retailer Rhythm Energy — explained what extreme temperatures like these mean for Texas’ energy market and the role renewables will play in addressing increased demand response.

Headquartered in Houston, Rhythm Energy launched two years ago and offers a variety of 100 percent renewable energy backed plans, from wind to solar. Popovic discussed with EnergyCapital where he thinks renewables fit into Texas’ energy consumption and grid reliability issues in an interview.

EnergyCapital: Let’s start with some background on Texas’ electricity and energy market. Can you explain ERCOT and PUC and the roles they play in our current market?

PJ Popovic: ERCOT first of all, it stands for Electric Reliability Council of Texas. So basically, the easiest way to explain it is it’s our transmission organization and it really coordinates movements of wholesale electricity in most of the state of Texas. It really manages the price of power and balances supply and demand. To make sure that we have power when we flip the light switch on, make sure that power is there. Besides ERCOT, we have something called transmission companies, which is if you know, centerpoint, or ENCORE as an example, they really transport the power and they're compensated by a fee on customers bills. So every customer bill, including the ones that we send with Rhythm, includes Centerpoint charge, which is really the cost of automated Centerpoint maintaining those, those transmission and distribution networks.

And then the Public Utility Commission — the best way and easiest way to explain it — is really responsible for regulating the whole electricity market. And besides the electricity market, they also regulate telecommunications and water and sewer utilities in Texas as well. And they are responsible for making sure we have a well functioning market. Lately there’s been a lot of news because of the market design changes, which really have to be okay with them because that really ties in to regulation of the market and they also resolve customer complaints. Maybe that's another function they do.

EC: What are renewables’ roles in Texas’ energy consumption? How do they play a part in the electric grid’s demand response?

PJP: We really talk a lot about the energy transition, and over the years, you're hearing that more and more in the news. One interesting thing about Texas is that we already went through a first phase — a huge phase — of energy transitions in the prior years. So we've kind of been there, done that.

When I think about energy transitioning, it's really a continuation and acceleration of what's already started. Texas has really secured the top spot right now, in being the biggest renewable provider or having the largest generation fleet powered by renewables in the United States, and really, there was a huge decline in coal, which didn't happen just in Texas, it was across the United States. It really was compensated and then some with the growth in wind and solar.

Renewables play an incredibly important role in Texas — with Texas being a very competitive, free market. It's able to attract a lot of investments and get renewables at scale, which ultimately does lower all of our electricity costs. Demand has been growing in Texas tremendously. Texas summer consumption, highest of the days, hit 79 to 80 gigawatts. Every single year Texas adds approximately one more gigawatt of demand. If you look at the grid growth, we're growing in summers, we're growing even more in winters between.

EC: Since the freeze and subsequent power crisis of 2021, have you noticed a shift in public opinion towards renewables?

PJP: Yes, we have as part of Rhythm. So the unfortunate reality is I think that renewables became a very political question and there's always the question like, “What is right thing versus what is left thing,” and that's the sad reality and I will come come back to it because just a long story short, renewables are and will become a major part of how we supply homes and businesses.

But the shift in public opinion was evident after winter storm Uri. We saw a combination of misinformation, lack of knowledge about how renewables work in the electricity kind of grid collapse we had during the winter storm. And there were a lot of questions about whether winds can support anything, whether it's going to be available when it's hot or cold.

There is still a lot of I would say speech that is not necessarily painting renewables correctly. For example, when we talk about dispatchable generation we tend to talk about gas power plants, about how we need gas power plants. One of the things that I think is beautiful about renewables is that really technology is evolving rapidly and it's advancing insanely fast. And when you talk about dispatchable generation, five years ago, yes, it was gas. But if you think about today, there are already batteries being installed in Texas, and if you think about the future, there's probably half a dozen or dozen different technologies that are going to be renewable based technologies that will potentially play the role of dispatchable generation.

EC: So, if solar continues to grow in market share and sizzling summers continue, why isn't solar taking a larger role in supporting Texas' grid?

PJP: Let's talk about the challenges as well of solar and renewables as they stand today. First of all, one thing I want to set clear, none of the situations we're in should be a surprise. It should not be a surprise at all that we question whether we're going to have electricity in, for example, cold winter days. We've been going through this transition for years. And what happened, we kept retiring dispatchable generation such as coal, which is a good thing, because of the pollution and other other impacts it has on our communities. At the same time, we kept building renewables and there is a continued retirement of generation acids today, and there is at the same time significant upward pressure on the low data centers, electrification and so forth. We also have really great incentives to build more renewables through the inflation Reduction Act, so you're gonna see that acceleration.

However, this is not sustainable. There are periods of time where we do need dispatchable generation, solar and renewables are not dispatchable so there is the famous saying, "if the wind is not blowing or the sun is not shining, we're not gonna get any electricity." So the changes in mix where you switch from more dispatchable generation to more just renewable generation is a dangerous one, if you do not have appropriate balance and appropriately view how much generation you need for some really specific hours or specific days with some extreme weather temperatures. So we're quite keen on getting appropriate market design that will incentivize the buildup of dispatchable generation. We love solar, we love wind intermittency, but not being able to turn it on and off is not a bug. It's a feature of that generation. We knew that all along. So the question is really, how do you compliment that with some dispatchable generation that will allow you to secure a well functioning and cost competitive grid?

​EC: What real incentives for consumers should be considered to improve demand response?

PJP: Demand response is one of those components that we really love because we believe that that's definitely again a feature of the grid of the future. I would say maybe before we even go about demand response, first of all, there's a number of solutions that need to be done on the generation side. And those solutions, we are firm believers, should not be locking us into a certain technology. I would say you have to have the right incentives to incentivize the build out to dispatchable generation. However, don't lock us into one technology because technology is rapidly advancing.

We in Texas have to take energy efficiency seriously. If you look at the growth of the load of the demand in Texas, our winters are growing more rapidly than summer peaks. So summer peaks, approximately two and a half gigawatts year over year growth. Winter peaks are growing three and a half gigawatts, and that's not sustainable because at one point you're not going to be able to build out enough generation and enough demand response to be able to supply power to those homes in the cold winter days if we have inefficient electric heating, which is what we're seeing in Texas. Energy efficiency standards have to be raised and that's something that's going to pay dividends in the next several years already.

Demand response is something we're quite keen to see more of. At Rhythm for example, we serve close to 20,000 solar customers with rooftop solar, a lot of them have batteries. So the pulling of those batteries is an example. Being able to dispatch those batteries provides electricity not just for those homes, but also sending the electricity back to the grid is becoming immense. And it's not only a question about what we have today, it's a question about the growth we're seeing in solar and battery installations. The homes are installing solar at a really rapid pace and we're getting to some serious size in terms of what we have behind the meters.

EC: What do you want people to know about how Rhythm addresses grid instability?

PJP: At Rhythm, we really take having a reliable and cost effective grid seriously, so there are a number of solutions we're putting in place and solutions that are coming up that we're going to hopefully be able to announce within the next couple of weeks. We started this 100 percent renewable company, to support energy, movement to renewables and we want to support specific assets that are built in Texas. We are huge believers that renewables are part of the overall solution because every megawatt hour we have from renewable generation is a megawatt hour we do not have to produce from coal or gas. We all know, especially after last year and this year's events, which is the war in Ukraine, how important that is because energy and commodity prices can skyrocket.

Rhythm supports that build up to renewables. At the same time we do advocate for really responsible solutions in the market. So we are actively advocating on behalf of our customers to make sure we have a reliable and well functioning grid. How do we do that? We do that through conversations around performance credit mechanisms, making sure we implement it in a way that benefits Texas consumers. We are the face of Texas customers, we have to explain anything that's not logical that gets implemented. So we take personal responsibility around how those solutions are being really developed and what makes sense for the consumer.

Lastly, we want to look beyond just global energy credits and look at the real products that can make a true difference. So we are investing money now in building new products that are going to incentivize customers to move consumption from those very expensive periods into cheaper periods. Move away from those expensive periods where we pollute a lot, when there is a lot of dirty generation, into periods where we have more renewables. We're going to do that through smart plans that are coming up. We're going to do that to plans where people get a clear financial signal incentive of changes in behavior that will benefit both the grid overall Texas market and their bills. So that's one thing I'm really excited about. We should be launching in a week and a half to two weeks.

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This conversation has been edited for brevity and clarity.

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Houston maritime startup raises $43M to electrify cargo vessels

A Houston-based maritime technology company that is working to reduce emissions in the cargo and shipping industry has raised VC funding and opened a new Houston headquarters.

Fleetzero announced that it closed a $43 million Series A financing round this month led by Obvious Ventures with participation from Maersk Growth, Breakthrough Energy Ventures, 8090 Industries, Y Combinator, Shorewind, Benson Capital and others. The funding will go toward expanding manufacturing of its Leviathan hybrid and electric marine propulsion system, according to a news release.

The technology is optimized for high-energy and zero-emission operation of large vessels. It uses EV technology but is built for maritime environments and can be used on new or existing ships with hybrid or all-electric functions, according to Fleetzero's website. The propulsion system was retrofitted and tested on Fleetzero’s test ship, the Pacific Joule, and has been deployed globally on commercial vessels.

Fleetzero is also developing unmanned cargo vessel technology.

"Fleetzero is making robotic ships a reality today. The team is moving us from dirty, dangerous, and expensive to clean, safe, and cost-effective. It's like watching the future today," Andrew Beebe, managing director at Obvious Ventures, said in the news release. "We backed the team because they are mariners and engineers, know the industry deeply, and are scaling with real ships and customers, not just renderings."

Fleetzero also announced that it has opened a new manufacturing and research and development facility, which will serve as the company's new headquarters. The facility features a marine robotics and autonomy lab, a marine propulsion R&D center and a production line with a capacity of 300 megawatt-hours per year. The company reports that it plans to increase production to three gigawatt-hours per year over the next five years.

"Houston has the people who know how to build and operate big hardware–ships, rigs, refineries and power systems," Mike Carter, co-founder and COO of Fleetzero, added in the release. "We're pairing that industrial DNA with modern batteries, autonomy, and software to bring back shipbuilding to the U.S."

Shell partners with UK-based co. for hydrogen electrolyzer pilot

ultra-efficient electrolyzer

Shell Global Solutions International, a subsidiary of Shell, which maintains its U.S. headquarters in Houston, has signed a collaboration agreement with London-based Supercritical Solutions to advance Supercritical’s ultra-efficient hydrogen electrolyzer technology toward a field pilot demonstration.

In the deal, the companies will collaborate on a paid technology feasibility study that will support the evaluation and planning of the pilot demonstration, according to a news release. Supercritical Solutions’ technology aims to deliver high-efficiency renewable hydrogen at a lower cost for the industrial hydrogen market.

"Signing this collaboration agreement with Shell is a major milestone for Supercritical Solutions and an important step on our commercialisation journey,” Luke Tan, co-founder of Supercritical, said in the news release. “We are directly addressing the cost and complexity barriers facing the renewable hydrogen market. We are excited to move forward with a company like Shell, whose global leadership has been proven to accelerate innovative technologies to market.”

Supercritical’s hydrogen electrolyser technology can operate at high temperatures and pressures of up to 220 bar without the need for an external hydrogen compressor, rare-earth materials or easily degradable membranes. The technology removes the typical compression step in the process while delivering hydrogen at industry standards. It requires significantly less energy than many traditional electrolyzers and is more cost-efficient.

This recent investment builds on an ongoing relationship between Shell and Supercritical. Supercritical was founded in 2020 and was runner-up in Shell’s New Energy Challenge, which helps startups and scaleups develop sustainable technologies, in 2021. Shell Ventures then invested in Supercritical’s Series A funding round in 2024 with Toyota Ventures.

3 Houston-area companies named to Global Cleantech 100

Energized

Three Houston-area companies—Amperon, Hertha Metals and Vaulted Deep—appear on this year’s Global Cleantech 100 list.

The unranked list, generated by market intelligence and advisory firm Cleantech Group, identifies the 100 privately held companies around the world that are most likely to make a significant impact in the cleantech market over the next five to 10 years.

For the 2026 list, Cleantech Group received more than 24,000 Global Cleantech 100 nominations from nearly 60 countries. Cleantech Group scored those companies and narrowed the contenders to 264. An expert panel reviewed those nominees, and the list was whittled down to the 100 winners.

Here’s a rundown of the three Houston-area honorees:

Amperon

Founded in 2018 by Sean Kelly and Abe Stanway, Houston-based Amperon offers an AI-enabled energy forecasting and analytics platform designed to help stabilize electric grids. Amperon received undisclosed amounts of venture capital from National Grid Partners and Tokyo Gas Co. Ltd. last year and announced a recent investment from Samsung Ventures earlier this month.

Hertha Metals

Founded in 2022 by Laureen Meroueh, Conroe-based Hertha Metals provides a single-step process for producing sustainable steel. Last year, the company emerged from stealth mode and raised more than $17 million in venture capital.

Vaulted Deep

Vaulted Deep’s technology injects excess organic waste underground to remove carbon dioxide from the atmosphere. Julia Reichelstein and Omar Abou-Sayed founded the Houston-based company in 2023. Last year, the startup raised $32.3 million in venture capital. Also in 2025, Vaulted Deep signed a 12-year deal with software giant Microsoft to remove up to 4.9 million metric tons of carbon dioxide from the environment.

Vaulted Deep also made the list last year, along with Houston-based Syzygy Plasmonics and Fervo Energy. Fervo was also named the 2025 North American Company of the Year by Cleantech Group.