Sunday, July 27, 2008

Wind power

I like the idea of getting wind power to market. I like the idea because wind is plentiful in the US.

Can we really harvest what we need? A few issues of concern:
1. How much do the turbine networks cost?
2. How long do they last ?
3. How quickly can they be fixed and/or replaced?

The meteorology based concerns:
1. Can the turbine handle the low level jet, especially the vertical wind shear [turbine lifetime and overall "up" time]?
2. What is the probability that tornado's and/or damaging winds will occur over the lifetime of the turbine?
3. Can the turbine handle smaller scale events which may not meet severe weather criteria but may enhance the wind shear locally [outflow boundaries]?

Wind speeds need to be greater than 6.9 m/s at 80 m*. This is easily achieved in the Central US during the severe weather season. However blocking anticyclones routinely set up for spans of 1-4 weeks throughout the summer months (June, July, August). This effectively limits summer production. Turbulence in the Low level jet also affects turbine lifetime. The Plains is a turbulent hot spot. As a general rule turbines are not made to withstand strong winds. The height of the turbine and rotational and vibrational characteristics help determine the stress experienced by the entire structure*. It is possible that non-severe winds can damage a turbine. Given the data density of even surface stations it is likely that a network of turbines put upin the Plains would have difficulty being productive.

Maintenance costs are up to 3 percent and replacing blades is 15-20 percent of the initial cost of the turbine*. A German turbine had a design lifetime of 20 years ... it lasted 3 weeks*.

*some of these facts were found on the Danish Wind Industry web site.