The second of the presentations I gave at this year’s Penguicon was titled ‘Alternative’ Alternative Energy Generation.

Alternative energy systems such as wind power and solar panels have become so familiar they really have become mainstream. But these aren’t the only alternative energy systems available. There are ‘alternative’ alternatives that offer other ways of harnessing energy from other sources and in other ways than the ‘mainstream’ alternative energy methods. Find out about river current power generation, wave power, kite wind power, etc.

The PDF of the presentation is here, and the links to articles about the various technologies discussed are after the cut.



[Originally posted on EcoGeek. This is a really cool development, and one of six recent USDOE ARPA-E grant winning projects. I’ve seen several kite-oriented systems in the last few years, and there are a lot of cool ideas in them, but this is the most fully formed and compelling one I’ve seen yet.]


Makani Power is one of six recent US Department of Energy ARPA-E grant winners for their Airborne Wind Turbine (AWT), a tethered flying wing that flies in endless loops around its anchor point on the ground and generates electricity from propellers on board. Makani believes it will be able to produce wind power that is 40% cheaper than conventional wind power and, more importantly, at an unsubsidized real cost competitive with coal-fired power plants.

Think of this as a really big wind turbine. But, instead of needing a big blade going back to the hub, which requires a lot of strength and a lot of weight, only the tip of the blade is used, in the form of a flying wing kite on a tethered line. The kite is flying loops just like the tip of a turbine blade. The tips are the fastest moving and most energy productive part of the turbine; this approach simply gets rid of the rest of the bulky, less-productive blade. The propellers on the wing are turned as it moves through the air, generating electricity and slowing the speed of the wing. The tether serves as both an anchor for the wing as well as the conductor to bring power to the ground for distribution.


The wing is able to self-launch and, since it is not carrying fuel or batteries, it has a very high thrust to weight ratio. The wing is turned vertically and the power-generating propellers act like helicopter rotors to power the wing to its operating altitude of 200 meters (656 feet). When wind at operating altitude drops below 3.5 m/s (7.8 mph), the speed needed to generate power, the wing re-orients into a vertical configuration (hover mode) and is winched back down to its cradle.

You can see a set of animated clips showing just how this works.

Once in flight, the wing is controlled by computer systems which steer the wing to keep it in flight and maintain power generation. “The autonomous controller is responsible for maintaining a stable flight path, while also maximizing power output. To do this, hundreds of times each second the controller calculates the wing’s position and heading from sensor data and adjusts the control surfaces (aileron, elevator, and rudder) to maintain the correct flight path. This fast response allows the wing to easily handle disturbances such as gusts. The control system has been proven, both in simulation and reality, to fly stable and reproducible paths.

We’ve seen other tethered power generation concepts, spinning blimps, and different versions of giant kites, as well as underwater kites, which are quite similar to the AWT. But the Makani system really seems to have everything pulled together in a complete system. The company has been testing a prototype 10 kW prototype, and will next move to the development of a utility-scale 1 MW system.

Flying at a higher altitude than turbine towers reach means that the less likely to harm birds or bats. Its maximum altitude is 600 meters (1969 feet), which is comparable with tall buildings, radio towers, and other structures, and aviation safety will be maintained with signals and lights in a fashion similar to other tall ground structures.

[Originally posted at EcoGeek. I have some further thoughts about this in response to a comment to the original story. Those are appended at the end.]


Concrete is not often the greenest material choice, particularly since concrete production is one of the largest single sources of carbon emissions globally. But, for wind turbine towers, the use of concrete bases can provide a number of significant benefits, including reducing the amount of concrete needed for the footings for a tower by more than two-thirds. Concrete bases can also be more economical to install and can provide faster construction times for wind towers and also can raise tower height to increase power production.

The wider footprint of the precast concrete base also adds stability to the foundation of the tower. With the precast concrete base, load is spread over a wider area, and a simpler ring footing can be utilized, which results in a 60% – 70% reduction in the concrete needed for the footing of the tower. This can result in a net reduction of the total amount of concrete used. The ring footing is easier to construct as well, since the problems associated with a mass pour can be avoided.

In addition to the construction benefits, the concrete bases increase the overall tower height to raise the turbine into more powerful winds or to allow the use of larger diameter blades. Metal towers are reaching limits for transportability and constructibility, but adding precast concrete tower base can add 30 meters (almost 100 feet) of height to the tower. This can allow larger diameter turbines to be used with existing metal towers.

Concrete tower bases can also be locally produced, rather than needing specialized manufacture as with steel towers. Precast concrete sections for these bases are actually more transportable, since they are produced in sections that are assembled together once on site. Concrete is also a sturdier product, which is less susceptible to damage and rusting and does not require regular painting like steel.

Atlas CTB White Paper (PDF)

via: North American Windpower

My additional comments are more broadly on the topic of information sources for blog writing than on the particulars of this article, but it is in reference to this article that I make my points, so it seems reasonable to add this here.

An EcoGeek commenter thinks we are “thoroughly debased of values and corrupted by advertising” because this article cited a whitepaper produced by a company that has developed this alternative for the market in the United States. In fact, much of my original source information for this article came from an article in North American Windpower magazine (an actual paper magazine that I was reading while waiting for my flight to Washington DC last week). But I could not find a link to an online copy of the article, so I used the manufacturer’s whitepaper as a source for further information, and provided a link.

To my mind, there is a lot of information in the whitepaper, and for some people who want to delve further (particularly people in the wind industry – I’d like to think that maybe there are a couple among the EcoGeek readership – who had missed earlier information about this particular approach), providing reference to source material was only meant to be beneficial. I felt that there was a lot of good information about the numerous benefits offered by these tower bases, and really had to pare things down to keep the article to a reasonable size.

Wind power has become one of my areas of specialty. I read the trade magazines and I’m conversant with issues in the industry. I think Hank didn’t stand up for me as much as he ought to have, particularly in this case, because, while I was repeating the information in the whitepaper and in the original magazine article, I happen to agree with the numerous benefits enumerated in those places. As I was reading the article, I was thinking this makes perfect sense. We may not always dig as deeply as we should, but this is a case where the writer understands and agrees with the information being presented, and I was not simply regurgitating the content of the whitepaper without understanding it.

I don’t believe I was unduly influenced by the manufacturer’s spin. Yes, I see a number of upsides to this. But I think that my own understanding of the engineering (admittedly coming from an architectural perspective, but not unaware of the issues involved) is good enough to see the benefits in pouring a ring foundation as opposed to a mass foundation. I also know that concrete requires less maintenance than exposed steel. I also know that there are real limits on the transportability of wind tower components. I’ve seen more than a few of them on the road in person. So there is an industry benefit to getting an extra 30 meters while being able to keep using existing steel towers. I can see some industry caution about marrying steel towers to these bases, because it is new. But there is always industry resistance to anything that is new. And I don’t think the engineering on these is so outrageous that it would be problematic.

Certainly, the whitepaper is going to have some measure of bias and positive spin in favor of the company. But this is some of the first information available about the particular development, and in order to bring information about new technologies and innovations to EcoGeek readers, we regularly work from industry press releases, marketing brochures, whitepapers, and other sources of information. I suppose I could wait ten years for the peer-reviewed case studies that analyze installations with these bases, and show how they have performed, but that’s missing the point.

We are going to use manufacturers’ information, including press releases and whitepapers, as well as other sources to learn about new and interesting and exciting technologies, and we’re going to use that information along with our own judgment, experience, and understanding to write about them. It’s pretty much how things work. The fact that interesting information comes from a whitepaper (as well as from an industry magazine article) does not diminish the fact that it is still interesting.

[Originally posted at EcoGeek. This is a cool way of further optimizing the investment in a wind turbine and extending its usefulness and productivity.]


A Colorado company is introducing a system that will allow wind turbines to generate power even when the wind is not blowing. The SmartGen hybrid gas-wind turbine enables wind turbines to produce energy at periods of low wind, by turning the turbine with compressed air generated at the base of the tower from a turbo-compressor that is run on natural gas or biogas.

Even more importantly, the SmartGen system can be retrofitted into existing wind turbines, allowing existing facilities to increase their performance. This is likely to be particularly compelling for installations seeking to extend their production while remaining free of fossil fuels. In areas where biogas production is also available nearby, a wind power facility that is generating renewable energy credits could likely also produce power from biogas in this manner as another form of renewable power and thereby remain 100% renewable energy based.

A smart clutch disengages the wind blades from the machinery when the compressor is engaged. The company also notes that the exhausted air from the air motor cools dramatically when it is released, which can help provide cooling for the generator nacelle and may even help prevent fires in the housing.

“Large wind turbines, even in good wind resource areas, typically generate rated power only 30% of the time because the wind blows intermittently or at a low wind velocity,” according to the company. Utilizing other fuels to keep the turbines generating power means that the system better employs the investment in equipment, instead of having it sit idle for much of the time.

via: North American Windpower


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