Having read through their workflow diagram, I'm really unclear why they can achieve 90% efficiency. Isn't that basically just a Carnot engine? If not, why not

Having read through their workflow diagram, I'm really unclear why they can achieve 90% efficiency. Isn't that basically just a Carnot engine? If not, why not? If it is, how can they possibly achieve 90% efficiency when the best Carnot-like engine I've seen is around 35%?