Thoughts on deep water wind turbine platforms

[kristopher]

Lessons Learned by Offshore Oil Industry Boost Offshore Wind Energy
by Christopher D. Barry, P.E.
Maryland, United States

There is a significant energy resource in the form of wind offshore of much of the United States. For example, a recent study done at Stanford by Dvorak, Jacobson and Archer suggests that there is an exploitable wind resource of up to 200 terawatt hours (TWh) off the coast of California. Unfortunately, 90% of it is in waters more than 50 meters deep, so a lot of this energy is not regarded as economically viable with the current monopile tower technology.

In general, the offshore oil industry has found that the cost of a bottom founded platform is a function of depth cubed so the cutoff depth is a function of the value of the energy asset (whether it's oil, gas or wind). This is a cubic function because if the water depth doubles, the platform height (from the bottom to the water line) doubles, so the amount of steel in it doubles. Then if the platform doubles in height, the base dimensions have to increase, roughly linearly, because the overturning arm on the base increases at least linearly. (The weight the lower section supports also increases as well, which adds some more steel cost.)

Floating turbine prototype in Brindisi harbor

Fortunately, the offshore oil industry faced this problem in the late 80's, when the price of oil fell dramatically and the industry developed a number of options to economically exploit small oil fields in deep water. Most of these concepts are even more applicable to wind power, because ...

http://www.renewableenergyworld.com/rea/news/story?id=52760

[oldhippie]

1. Interesting........

I just listened to a podcast about this on my walk this morning. It was from the June 5 issue of the podcast from your same reference. Stephen Lacey was interviewing some engineer about the issues of deep water offshore wind. It was clear that the guy was trying to be upbeat and positive, and he mentioned that the offshore oil industry has tackled some of the problems, but there were still a lot of issues to be resolved to make it cost effective. I really like the podcasts from renewable energy world. I try not to miss any.

Kristopher, I must say you sure find a lot of interesting stuff. It keeps me reading a lot. I really enjoy your posts.

[kristopher]

2. There are some hurdles to overcome, that's for sure.

The biggest, of course, is economic. I don't totally disagree with an approach that forces competition, however there are some goals that need to be tackled by the government regardless of costs. If we'd have approached the lunar program with current Harvard MBA values at the forefront, we'd have never undertaken the challenge.

I think the deep-water solution is going to be found by combining technologies. Waves are formed by both wind and tidal forces, while the wind driven waves are little more dependable than the wind, the tidal waves (it's ocean sloshing in its basin between coasts) are extremely dependable. By combining the two types of generation into one unit, I think we might see cost effective expansion into deep water sooner than most expect. But then again, us old hippies do tend to be incurable optimists, eh?