(But would not meet the energy conserving limit for hths 150)
I'm not really sure what you wrote here.
In simplest terms, an oil that has an HT/HS Viscosity of 3.5 cP or higher will not meet the energy conserving requirements stipulated in ILSAC GF5 spec.
There's some dubiousness about Renewable Lube around this. They claim the 0w30 is HTHS of 3.6-3.8 but also call it energy conserving. I've never gotten a clear answer out of them on this.
Then again, their basestocks and chemistry seem to be quite advanced so it's possible that the HTHS is a bit lower (3.2-3.4?) but the formula is so stout that it maintains that viscosity for a very long time.
The fact that their 15w40 is really a 5w40, and almost a 0w40, leads me to believe there is some very sophisticated engineering they keep secret.