A New Way to Skin the Renewable Energy Cat

Tom Konrad CFA

It’s not often that I come across a new type of renewable energy and think, “This could really work.”  But that’s what I thought when I heard the concept for the downdraft tower proposed by Clean Wind Energy Tower (CWET.OB.)

First, a couple caveats.  The concept is not new, it’s been around 25 years in draft form.

The physics is simple.  Build a very tall, hollow tower in a hot, dry climate; cool the air at the top with a mist of water (even salt water will work), and capture the resulting energy from the downdraft with an array of wind turbines arranged around the bottom.  Most of the water is condensed at the bottom of the tower, and (since it has been effectively distilled) used as fresh water, a valuable commodity in the dry regions that are appropriate for downdraft towers.

Because the tower needs to be extremely tall in order to make the downdraft strong enough to generate electricity economically, the tower also features vanes designed to direct prevailing winds down to the base to be captured by the same turbines.

The company expects that the combination of generation from prevailing winds and the induced downdraft wind will combine to give the tower a capacity factor in excess of 60%, much higher than typical solar or wind capacity factors, while most of the power will be produced in the afternoon and evening during spring, summer and fall, meaning that this power is likely to be more valuable to utilities than either wind or solar photovoltaic. 

The reason no one has attempted to build a downdraft tower before is that we did not have the technology to build a tall enough tower.  Now we do.  In particular, the Kroll self-erecting cranes used to build such skyscrapers as the Burj Dubai, along with other construction methods used to keep such extremely tall skyscrapers upright in strong winds and earthquakes.

I spoke briefly with Ron Pickett, CWET’s President and Stephen Sadle, the firm’s Chief Operating Officer at the Modern Energy Forum in Denver in early September, and I got the impression that the two men are used to success.  They, and two others of their team have worked together on four successful start-ups, from telemedecine to the incineration of municipal solid waste recycling.

This time they’re thinking bigger: The commercialization of a new clean energy technology.  Although they are careful to stress that they are simply combining and commercializing proven technologies, I find it hard to believe that they will be able to raise the funding necessary to build their demonstration tower in the current environment.  Bond investors are generally unwilling to fund anything that seems even remotely new, a problem that might have potentially been overcome  by a program like the DOE loan guarantees, but it’s unlikely that anything resembling that program will be authorized in the next few years considering the current Solyndra brouhaha.

I hope I’m wrong and they do get the money they need to succeed, since this downdraft tower concept has the potential to be a valuable addition to our clean energy arsenal, but at this point, I can’t recommend small investors buy the stock.

DISCLOSURE: No Position.

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