HAWT or VAWT?

Picture: Wikipedia image of the Tassa 5KW VAWT.


This debate is a bit like the old "nature-or-nurture" controversy, or "paper vs. plastic," and I try not to get into it, except to point out that both Vertical Axis Wind Turbines (VAWTs) and Horizontal Axis Wind Turbines (HAWTS) must still obey Betz's Law and the Power Law, and the Laws of Supply and Demand, and therefore won't make enough power to pay for their own construction in Maine, except on the tops of mountains or on the seacoast or the middle of the Gulf of Maine, or on very tall towers.

But the question keeps coming up, primarily because lots of folks in Maine dislike the look of the large white, shiny (and very energy-productive) HAWTs that have begun to proliferate on our mountaintops.

People also continue to ask me, all the time, why we can't have "nice" little turbines, outside people's own homes, instead of on our beautiful mountains.

The answer of course is the same: they won't make enough energy to pay for themselves. And indeed, I've begun to be involved as an expert witness in litigation, as householders begin to sue contractors in Maine who oversell the productive capacity of small, "nice" household scale turbines.

There's nothing nice about being ripped off.

Some new research involving a breakthrough, sort of, in VAWT array design suggests that VAWTs might indeed command the future, or some of it at least. A Caltech researcher reversed the direction of turn of half the units in an array of VAWTs and was able to beat the usual spacing rules by an order of magnitude with no drop in power production, along the way overcoming the costs of the inherent lower thermodynamic efficiency of VAWTs in a sense by allowing greater placement of turbines per acre or hectare.

Thermodynamic efficiency is easy to understand: it's energy out divided by energy in, generally expressed as a percentage, and is a primary factor in the cost per unit energy of turbines. But land leasing or buying is also an input cost in wind power production, and so the latter can be used to offset the former.

This is just another example of why economics is as useful as physics or engineering or aerodynamics or anemometry in wind power production.

I think it's why I like wind turbines so much.

This technique provided a great reduction of turbine land use per unit power, and if it could be commercialized, the new idea would reduce the "sacrifice area" needed in Maine to make clean energy.

The formal report is available here, from the Journal of Renewable and Sustainable Energy

But, before all of our anti-wind activists get themselves all worked up about banning HAWTs, let's just identify a couple of minor lingering problems:

1. There is, as yet, no commercial VAWT design above a few KW of rated capacity, at least that I know of. We need MW-capacity, or better yet, multi-MW capacity turbines. We will have to build them. Not that this would be such a bad thing. It would provide for a new Maine industry. (But the last thing anti-wind activists want is a successful Maine wind power industry.)
   
2. VAWT arrays will still need to go on the tops of mountains or seacoasts or out in the Gulf. The Californian desert test site used looks to have Class 5 or 6 winds, just scanning the anemometric data in the paper. This kind of wind power density only exists in certain places in Maine, the kinds of places we're (surprise!) currently using for HAWTs. We will just require fewer acres to make the same amount of power, assuming we can design and build a commercial scale VAWT product as in 1) above.
   
3. If high-density VAWT deployment turned out to be successful, that might encourage more, rather than less, use of Maine's mountains and coast for wind power -- we'd probably just export even more of it to the "lower 47." And the economic friction that is currently slowing Maine wind power development, from permitting and legal costs and form lack of available capital, would be reduced overall, probably increasing the pace of all wind power development, HAWTs and VAWTs alike.
4. All of this requires that land leasing is a major factor in power production costs. I don't think it is. Planning friction is a major cost, but it's one that can easily be scaled up by activists, ie: you might get just as many complaints from a ten-acre VAWT proposal and you previously might have done from a hundred-acre HAWT proposal.
   

Not that any of these reasons will prevent the question coming up.

Indeed, since this research is published and publicly available, I can now confidently predict that in the next Maine wind power siting battle the following question will come up for planning board members and selectors to puzzle over,

"Why can't we have some of those nice high-density VAWTs I read about in Science Daily instead of all these nasty low density HAWTs that the company proposes."