From my perspective this is the central part of the scheme as described in Monbiot's intro:

The government’s plan for carbon capture and storage (CCS) – catching carbon dioxide from major industry and pumping it into rocks under the North Sea – is a fossil fuel-driven boondoggle that will accelerate climate breakdown.

Having worked in the industry I am familiar with the details of both pumping CO2 into North Sea depleted oil reservoir and such, and production of 'green' hydrogen. For pumping CO2 one requires existing pipelines. If these are not available near to industrial centres one needs to produce/construct miles of pipelines. Our steel industry is basically dead and therefore we would be forced to buy these outside the UK. Just think of the EROI in these circumstances where the steel pipeline needs to be manufactured, transported and constructed, together with pumping stations etc. So, yes, it is a fossil fuel-driven boondoggle

I've skimmed the details of Monbiot's alternative proposals, but I do agree with his analysis as per above.