SwRI, 8 Rivers Unveil Cost-Effective Power System with Liquid Oxygen Storage
- MM24 News Desk
- Oct 18
- 3 min read
Image Credit: SWRI
What if power plants could stockpile their own fuel when electricity is cheap, then use it later when prices spike? That's not a hypothetical question anymore. Southwest Research Institute and 8 Rivers just patented a system that does exactly that – and the fuel they're storing is liquid oxygen.
This innovation addresses one of the biggest challenges facing clean energy: how to make carbon-capturing power plants economically viable while dealing with wildly fluctuating electricity prices. The solution is surprisingly elegant, combining proven technologies in a novel way that could change how we think about power generation.
The system builds on the Allam-Fetvedt Cycle, a recently developed power generation process that combusts fuel like natural gas using an oxygen and carbon dioxide mixture. What makes this cycle special is its ability to capture essentially all carbon emissions, producing minimal greenhouse gases. It's the kind of technology we desperately need as climate concerns mount.
But there's a catch. The Allam-Fetvedt Cycle requires high-purity oxygen separated from air, which is mostly nitrogen with trace amounts of other gases. This separation process is energy-intensive, consuming roughly ten percent of a power plant's total output. That's a significant chunk of production lost just preparing the fuel.
Dr. Jeffrey Moore, an SwRI Institute Engineer and one of the system's inventors, saw an opportunity in electricity's price fluctuations. "Our idea is to generate oxygen during off-peak hours, when electricity is less expensive because demand is lower," he explained. "The oxygen can then be stored in liquid form and converted back into gas for use in the plant later. This boosts plant output while lowering operating costs."
Think of it like charging your phone overnight when electricity rates are lower. Except instead of storing electrons in a battery, you're liquefying oxygen and keeping it in cryogenic tanks until needed. When electricity demand and prices rise, the plant can use stored oxygen rather than diverting precious output to real-time oxygen generation.
To ensure this wasn't just theoretically clever but actually profitable, SwRI conducted comprehensive techno-economic analysis, modeling both plant performance and hour-by-hour costs across a full year. The numbers looked promising, and studies by Princeton University and the National Renewable Energy Laboratory suggest the economic benefits will only grow stronger.
Why? Because electricity price volatility is increasing as more renewable energy comes online. "The data show that in some regions prices may stay low for weeks, then spike for long periods, depending on renewable penetration," Moore said. "Right now, the grid is about ten to fifteen percent renewables. If that rises to thirty percent, the problems associated with fluctuations in wind and solar energy production will be exacerbated."
Here's the fundamental challenge with renewables: the sun doesn't always shine and the wind doesn't always blow, yet electricity demand continues regardless of weather conditions. When renewable generation drops suddenly, grid operators need backup power sources that can ramp up quickly. When renewables flood the grid with cheap power, traditional plants struggle to compete economically.
"This makes energy storage critical for overall grid reliability," Moore explained. "Currently, there's no large-scale energy storage system on the grid, though research is underway. This oxygen storage system is one way to effectively store energy, by generating liquid oxygen when power is cheap and using it later when prices are higher."
The beauty of this approach lies in its maturity. Unlike experimental energy storage technologies still in development, the individual components have decades of proven performance. "Air separation and liquid oxygen generation have been around for decades," Moore noted. "That's what got us to the moon. We're putting these tested individual pieces together at larger scales, to reach greater heights in clean energy production and improving net present value of the plant."
SwRI researchers are considering incorporating this technology into the Supercritical Transformational Electric Power Demo pilot plant at their San Antonio headquarters. The STEP facility ranks among the world's largest demonstration facilities for supercritical carbon dioxide power generation. Adding liquid oxygen storage and the Allam-Fetvedt cycle would make it even more fuel-efficient.
The implications extend beyond individual power plants. As renewable energy penetration increases across the grid, solutions like liquid oxygen storage become increasingly valuable. They provide a bridge between intermittent renewable generation and consistent power demand, making the entire grid more stable and reliable.
This patent represents the kind of incremental innovation that rarely makes headlines but fundamentally enables the clean energy transition. It's not about inventing entirely new physics or discovering exotic materials – it's about cleverly combining existing technologies to solve real economic and engineering challenges.
Power plants that can profitably capture their carbon emissions while adapting to volatile electricity markets? That's the kind of practical breakthrough that actually gets deployed at scale, transforming the energy landscape one facility at a time.
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