Drax datacentre could create nearly twice the yearly emissions of all Gatwick flights
(www.theguardian.com)
Drax has been fuelled by biomass for some years now. Biomass is usually wood.
As with other energy hungry works - aluminium smelting, bitcoin mining etc - it makes sense to avoid transmission losses by building them immediately next to power stations. If run from the same source, they will be using the same fuel type.