Ok, did not know that. Still, 6% is far away from that of e.g. solar power towers. And as I said, you could still add plants with 6% efficiency underneath.
Also, what exactly is your argument about high-tech? I definitely don't call a bunch of mirrors on pillars and a brick tower with some water tube and steam turbines "high tech". It's less technology than the tractor, fertilizer machine, plant grinder, countless other agricultural machinery and chemical plant that biofuel requires.
Also, it takes less space, and it can be built in 100% dead desert where not even bacteria can survive.
I have the feeling that you have a strong emotional drive in defending this, that in not built on reason.