Kind of missing the point on 24/7 efficiency.
My point was to modify the tower to generate power when the sun was not shining.
Right now the tower design would run at 60% efficiency during the day. What is that efficiency after dark when the tower is putting out 0 power? How does that impact the towers efficiency when measured over a 24/7 period?
If you are going to build a 2,600-foot tower that will obviously see usable wind at the upper altitudes wouldnt it make sense to capture some of that external wind?
Even if the turbines added provide just enough to power the mandatory hazard lights required by structures that large it would save on tapping the grid at night.
To have a 2,600-foot tower that fails to generate power after the sun goes down is a huge waste. External turbines capturing the winds common above 1,000 feet would greatly improve the towers 24/7 efficiency. There are already turbine designs in place for skyscrapers that could be easily modified for use on this tower.
To follow-up on the other thought. The darkened area at the top of the tower could warm the stack and maintain the heated air to the top. You do not want to have rising air cooling too much and potentially causing down drafts, which would hurt efficiency.
To my knowledge no one has ever built a chimney this tall, but at those altitudes the stack would be subject to cooling breezes. The potential for back drafts causing air flow stall at the top of the stack increases with the height of the stack.
A previous tower design using internal turbines actually used this cool air falling effect to generate power. The naturally cooling air was to be assisted by spraying water at the top of the tower. It was suggested to use the water for this in lieu of conventional irrigation because it would generate power and increase natural air moisture levels downwind of the tower.
