Actual paper (not calling this a study since this appears to be non–peer-reviewed and only self-published): https://microgridai.centrefornetzero.org/ Be advised that this website relies on some Chromium-only trickery.
renewable microgrids [...] compared to nuclear small modular reactors
A 95% renewable microgrid with 5% gas backup - in line with the UK’s Clean Power 2030 target - was modelled at almost a third (31.7%) lower cost than scenario 1 in today’s prices. In this model, the gas is restricted to just under 80MW (2/3rds the size of the data centre) and the model correspondingly chooses a larger battery for storage, and increases the size of wind and solar technologies.
I'm confused; how does 5% equal 2/3 the size of the data center modeled?
(Edit: Someone else suggested this: "I think the gas can supply 2/3 of the power that the data centre requires for situations when there is no sun or wind but only makes up 5% of the total energy used over a year.")
They include a link to the model: https://github.com/ryanjenkinson/data-centre-modelling