Quoted from frolic:
I'm pretty certain Andrew has posted on pinside that the idea is shelved for now.
We actually revisit this every 3-6 months, and did so only a week ago.
As and when the technology and cost make options like this commercially viable, then we will re-visit it again.
However, it is worth noting that we are constantly looking at new technologies and options - and some options may well become available sooner rather than later