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Scientists use power generated by carbon dioxide to solve the global energy crisis

Sandia National Labs began working on the project more than 10 years ago, and now comes the time when scaling involves using super-critical carbon dioxide instead of steam for turning turbines. They

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Scaling up is the project’s next step after more than a decade of work by Sandia.

As proved by Sandia National Labs, which connected a closed-loop system to the local grid and supplied 10 kilowatts of power for almost an hour, supercritical carbon dioxide is in when it comes to turning turbines. …

In Sandia’s experimental system, a turbine is powered by carbon dioxide that has been compressed to the point where it is both a liquid and a gas. If scaled up to power plant levels and heated using nuclear, solar, or fossil fuels, supercritical CO2 can reach temperatures far higher than steam and could be much more efficient.

Ten kilowatts isn’t much; it represents around one-third of the daily energy consumption of the typical US home. Darryn Fleming, the principal researcher, stated that it is a big thing because the lab was able to link its test loop directly to the grid.

“The data that would have allowed us to connect to the grid took a very long time to obtain. Anyone in charge of an electrical grid must be very careful about what they sync to it because doing so could cause the grid to malfunction “Fleming declared.

The Rankine cycle, which turns water into steam that powers turbines, can be replaced thermodynamically by the Brayton cycle.

Only about a third of the power generated is turned into electricity due to the Rankine cycle’s inefficiency and energy loss when turning steam back into water. According to Sandia, Brayton cycles have a potential conversion efficiency of up to 50%.

Supercritical CO2 is heated in Sandia’s technology, and energy is then transferred through a turbine. The CO2 travels through a recuperator after leaving the turbine, where it cools off before being sent to a compressor. The CO2 is cooled by the compressor, re-pressurized, and then sent back through the recuperator to recover some heat before being sent back to the beginning. The US lab operator said that the system’s efficiency is partially due to the recouping procedure.

Although fully realized systems will reach even higher temperatures, Sandia only heated its supercritical CO2 to 600°F (316°C) for the experiment. The system is depicted by Sandia in schematics, and high-pressure CO2 is seen leaving the heater at almost twice the temperature.

Sandia had to find the appropriate control mechanism to manage its output before attaching the Closed Brayton-cycle test loop to the grid in April, and the researchers discovered it in an elevator component called a permanent magnet rotor.

The rotors, which work similarly to the Brayton cycle test loop Sandia employed in its experiment, are used to convert potential energy created by lifting an elevator vehicle into electricity as the car is lowered, according to the lab

According to a statement from Sandia, “this resemblance allowed the Sandia team to modify commercially available power electronics from an elevator components business to manage feeding electricity from their test loop into the grid.”

Logan Rapp, a mechanical engineer with Sandia, said that linking the lab’s test loop with the elevator bits was a significant advancement that “very clearly” defined the boundary between 10 kilowatts and a megawatt or more. According to Rapp, Sandia’s business partners are aiming for 1 to 5 megawatts, which could power 500–1,000 houses.

After completing a direct-to-grid test that was successful, the Sandia team is now attempting to achieve higher temperatures. The company intends to construct a two-turbine alternator producing system in 2023, which it claims will be more effective. By fall 2024, they hope to demonstrate a 1MW system.

According to Sandia spokesperson Mollie Rappe, Sandia experts are working to validate each component of the system separately so that interested businesses can improve the components as they see fit. This will help make commercial development more enticing.

Supercritical CO2 is nothing new to Sandia; the company has been developing such systems for more than ten years. Sandia claimed to be leading development at the time, however it refrained from calling supercritical CO2 generators practically inevitable. After eleven years, we’re beginning to get closer.