And now CO[SUP]2[/SUP] is also being used to help oil companies recover more oil from each well, you see we only ever manage to get about 60% of the oil from each oilfield to actually flow upwards into our waiting hands, the rest gets left behind as its just too difficult to get it out, even that 60% figure is high compared to the historical figure of as low as 40%. This is what the phrase recoverable resource as opposed to an oil reserve refers to, when an oil company states that they have found a reservoir containing X barrels oil or Y m[SUP]3[/SUP] of gas, that does not mean that this amount of jungle juice will emerge from the reservoir.Carbon Dioxide is good for a lot of things like adding fizz to your soft drinking in its gaseous form and keeping food cold in its solid form as “dry ice.”
What many people do not know is that the gas is also useful in its lesser known liquid form. You won’t see it in nature since it takes five atmospheres of pressure at slightly higher than room temperature, 31C, to take it to a super state.
Then it can be used to push turbine blades and thus generators connected to them to make power.
The objective of using supercritical CO2 (S-CO2) in a Brayton-Cycle turbine is to make it much more efficient in the transfer of heat. Wright points out that a steam turbine is about 33% efficient, but that an S-CO2 turbine could be as high as 48% efficient, a significant increase.
A closed loop supercritical CO2 system has the density of a liquid, but many of the properties of a gas. A turbine running on it, “is basically a jet engine running on a hot liquid,” says Wright.
Barber-Nichols S-CO2 turbine wheel
Photo: Sandia National Laboratory
Since the CO2 is pre-heated, less energy is needed to then heat it up to the turbine inlet temperature. By recovering some of the energy usually lost as waste heat, the recuperator can make a supercritical gas turbine significantly more efficient.
The recuperators on the S-CO2 systems work much the same way as a gas fired turbine except they are heating a noncombustible gas instead of air to be mixed with fuel.
Q: You indicated that a first-of-a-kind system producing a 10 MW system could be $20-30 million. Do you have a cost estimate for an “Nth of a kind at 50 MW?”
A: Our target is a cost of $1 a watt. If we can find the right industrial partners, we could produce the first units for non-nuclear power applications in three-to-five years.
Separately, Wright said that to use the turbines with small modular reactors (SMRs), they would have to be evaluated as safety-related equipment by the NRC or any nuclear safety agency elsewhere.
He wants to see a revenue stream from non-nuclear applications before spending money on the cost of a regulatory process that covers equipment for nuclear power stations.