Good point. But there are two problems with that claim.

One is about an order a magnitude, the other about a sign.

The first one: if you burn 1kg of pure Carbon, you get 3.67 kg of CO2 and 32.8 MegaJoules [1], which is the same as 32800 kJ or, 32800/3600 kWh. That's 9.11 kWh for each 3.67 kg of CO2, or 2.4848 kWh/kg. That's quite close to 2500 kWh/ton.

They are claiming it takes them 230 kWh/ton to reverse this reaction. You can see this is an order of magnitude wrong. Let's say they meant to say 2300 kWh/ton. If you divide that by 2500 kWh/ton you get exactly 92% that they claim.

But here's the second mistake: you need to put more, not less energy to split CO2, otherwise you'd get energy for free. 2300 kWh/ton is simply impossible. You need to use more than that, and actually more than 2500 kWh/ton if you don't want to violate the first principle of thermodynamics.

[1] https://en.wikipedia.org/wiki/Heat_of_combustion#Heat_of_com...