The discussion point that geothermal sources in general have...

The discussion point that geothermal sources in general have emissions is worth exploring but I am not going to enter a lengthy debate on the matter. An initial reading of some of the sources provided here clearly indicates that CO2 is naturally released anyway from ground sources. This is not surprising - one's own observations of steam venting from the ground in certain parts of the world suggests that being the case.

We could all quibble about whether Vulcan's claim of net zero is 100% accurate. What is clear though is that Vulcan's process has the potential to be far less demanding on land footprint, CO2 involved in power/heat generation and lithium production (and therefore op ex). That's beyond question. Even if Vulcan's process emitted several grams/kWh would that overturn the business case or land them in a consumer affairs dispute? Hardly. It is a high school debating point.

We know that there are naturally occurring CO2 missions that come from the ground. We know that not all geothermal plants have the same design.

If this geothermal heat can be harnessed, as it has been in several parts of the globe for decades, that is a good thing because it emits a fraction of the CO2 generated by coal and gas fired power stations.

I am particularly drawn to the finding:
"Bertani and Thain (2002) argue that geothermal power production may cause a decrease in gas emissions through natural pathways from geothermal reservoirs. Consequently, they argue that “a very strong case can be made for subtracting the pre-development natural emission rate from the rate being released by the operation of the geothermal development”. In support of this, they state that CO2 emissions through natural pathways, i.e. soil and fumaroles, has noticeably and measurably decreased in Larderello as a result of geothermal power production from that field. These observations of decreased surface activity at Larderello are supported by pictures and descriptions from travelers that visited these areas prior to exploitation (see Figure 7). According to these accounts, the entire Larderello area was covered by active surface manifestations such as fumaroles, boiling pools, and steaming grounds, earning it the name Devil’s Valley. Over the last several decades, power production from the Larderello system has brought about pressure decrease in the reservoir and, as a result, the natural degassing from the system has almost completely ceased (R. Bertani, personal communication). Similarly, Frondini et al. (2009), citing Sammarco and Sammarco (2002), suggest that geothermal power production at Mount Amiata, Italy, may have resulted in decreased natural gas emissions at that site." (p.8 Greenhouse Gas Emissions from Geothermal Power ProductionThráinn Fridriksson, Almudena Mateos Merino, A. Yasemin Orucu, Pierre Audinet The World Bank)

Thanks Hegge123 for the sources.