Hacker News Reader

Comment by brudgers | Hacker News Reader

In June, I drove across North Texas on I40 and marveled at the scale of the wind turbines. At those scales (Panhandle I and II generate 400MW according to Wikipedia), I suspect that per turbine materials cost is less of a limiting factor than site acquisition and infrastructure installation. I also wonder about modeling multi-unit installations as shifting wind direction and intensity changes local conditions and moves one kite turbine relative to its neighbors.

It's an interesting approach.

View on HN

There's also research about Dynamic position adjustments to benefit from air flows.

As I drove the landscape, I was looking at the spacing between turbine rows and thinking about dirty air and laminar flow (why Texas is a good place for wind farms). Probably because the previous week I'd watched a bit of Americas Cup on TV with a friend who sails.

In the long run, it might be possible to achieve higher energy density with kites due to dynamic repositioning. The economics of increased complexity for higher density might work out, but I suspect that the density would need to be significantly higher while maintaining similar consistency of output. Feathering a fixed turbine offline in high wind and spinning it up again as conditions become favorable looks quicker than cabling in and cabling out kites in similar conditions.

is "dirty air" nothing more than particulates suspended in the wind gusts or is it some special term of art? Just curious, is there a relationship between dirty air and laminar flow?

This may not be 100% accurate in nomenclature, but it gets the point across. Laminar flow is uniform and very easy to model mathematically, hence the reference to its "clean-ness" (e.g. clean [simple yet functional] design, clean [elegant] math proofs, etc). Its opposite: turbulence. laminar:turbulent::clean:dirty. You get turbulence/wake when there's something upstream of you disturbing the flow patterns. Air has less potential energy in it once it has been disturbed (the random motion of turbulence detracts from it's ability to generate pressure differences via flow manipulation). Riding in dirty air happens when the rich man's yacht in front of you sails upwind of your own personal rich-mans-yacht. Your vessel can still sail, but will sail a little bit slower, due to there being less available energy in the wind for you to tap into. This becomes a problem w/ turbines for obvious reasons (ask yourself why they don't just put multiple turbines all on a spoke for cost-of-installation savings, or even why they always seem to choose 3-bladed turbines [a very cool/interesting mathematical optimization problem!]).

Turbulence isn't always energy robbing, e.g. drafting in cycling and auto racing and distance running. Though it is hard to operate a sailboat like that...for what it's worth, my friend has a Sunfish these days.

The difference is which direction the energy is flowing. In sailing, you're extracting wind energy into kenetic energy. In drafting, you're expending energy from some other source to overcome the resistance of the air you're displacing to maintain your kinetic energy.

Reply on news.ycombinator.com