Supercritical CO2 Turbines a Leap in Efficiency

Wow. Who wuddah thunk that carbon dioxide was good?

Probably some plants already knew....

Neat flower. Thanks !

" . . . if you do doubt your courage or your strength, come no further, for death awaits you all with nasty, big, pointy teeth."

I always wondered what the obstacle was...

Guess I'm always skeptical about such promises. Has it been peer-reviewed? How much power does it take to get CO2 to that pressure? Like, is the 10 MW the net power produced?

GE has built prototypes, and based on the performance achieved they can expect about a 50% extraction rate or 50% efficiency rating, about a 10% improvement over steam turbine...they also have a much faster startup time of just 2 minutes, as opposed to steam which takes about 30 min...

Increasing the density of your expander fluid is the holy grail of turbine generation...like the waste heat recovery units Organic Rankine cycle used in industry today, and for probably 50 years or more....

This is the actual size of the 10MW Supercritical CO2 turbine ...

https://www.popularmechanics.com/technology/infrastructure/a20359/ge-minirotor-co2-powered-turbine/

There are many different for purpose turbine designs made by several companies...

https://www.turbomachinerymag.com/view/steam-is-here-to-stay-demand-grows-for-small-and-medium-sized-steam-turbines

..."As a working fluid, supercritical carbon dioxide is ideal – at the right temperature and pressure it behaves like a dense fluid (denser than water), allowing the Brayton cycle to work at higher efficiency – much higher than can be achieved via the Rankine cycle. Because supercritical carbon dioxide is so dense, the size of the turbine can be reduced, and simplified, from the size of a semi-trailer to something that could sit on an office desk."...

..."The carbon dioxide is recycled – and since we are no longer making steam, our water usage goes down tremendously (80-90%). Water use for energy production accounted for 583 billion cubic meters – 15% of the world’s water withdrawals. In the U.S. over 40% of all freshwater withdrawals are for thermal power generation. Seems to me freeing up this much water for other uses, especially in dryer areas, might be very welcome…."

Figure 1 The Rankine Cycle.

The Rankine cycle is normally operated with a change in phase (water to steam). We’ve long known that a different cycle, called the Brayton cycle, is more efficient.

Figure 2 The Brayton Cycle.

The Brayton cycle uses what we might call a gas turbine. It operates solely within the gas phase. The reason the Brayton cycle is more efficient is it lacks the phase change of liquid water to steam which ultimately robs some of your energy output.

For the Brayton cycle, the density of your working gas makes a big difference in your energy output. Supercritical fluids (gases heated and compressed until they behave like liquids) are much easier to compress….because of that the amount of work done during the compression phase is reduced; and the energy saved there greatly contributes to the turbine’s overall efficiency.

https://euanmearns.com/every-big-bit-helps/

A description of supercritical fluid...

https://stirlingengineforum.com/viewtopic.php?t=1168

Supercritical CO₂ is used for producing decaffeinated coffee (an oximoron, if you ask me...)

https://www.coffeereview.com/coffee-reference/coffee-categories/decaffeinated-coffee/carbon-dioxide-methods/

This is actually very old technology. See E.G. Feher: THE SUPERCRITICAL THERMODYNAMIC POWER CYCLE (Douglas paper <unreadable> 1967) and (same author and title) Energy Conversion, Vol. 8, pp. 85-90. Pergamon Press, 1968.