Green Reliability/Alternative Energy

Commercial grade wind turbines generally have a target design life of 20 years.  This goal is frequently elusive with key components like the gearbox often showing much shorter life in service.

Continuous condition monitoring and motion control are technologies which are beginning to improve the reliability of wind turbines.  Condition monitoring can reduce downtime by advance warning of the problem and in some cases making simpler repairs as opposed to full replacement.

There are many ways for advanced monitoring and control technologies to improve the reliability of wind turbines.  For more details, see the article at:,aid_254889&dfpLayout=blog

There is a great deal of development effort going toward the development of “gearless” wind turbines. The reason being that the Gearbox in wind turbines remains as one of the single largest reliability problems in the industry.

On wind turbines: “Current designs can’t be scaled up economically. Most of the more than 25,000 wind turbines deployed across the United States have a power rating of three megawatts or less and contain complex gearbox systems. The gearboxes match the slow speed of the turbine rotor (between 15 to 20 rotations per minute) to the 2,000 rotations per minute required by their generators. Higher speeds allow for more compact and less expensive generators, but conventional gearboxes—a complex interaction of wheels and bearings—need regular maintenance and are prone to failure, especially at higher speeds.”

“On land, where turbines are more accessible, gearbox maintenance issues can be tolerated. In rugged offshore environments, the cost of renting a barge and sending crews out to fix or maintain a wind-ravaged machine can be prohibitive. “A gearbox that isn’t there is the most reliable gearbox,” says Fort Felker, direct of the National Renewable Energy Laboratory’s wind technology center.”

“To achieve the power output of a comparable gearbox-based system, a direct-drive system must have a larger internal diameter that increases the radius—and therefore the speed—at which its magnets rotate around coils to generate current. This also means greater reliance on increasingly costly rare-earth metals used to make permanent magnets.”

For more information, see:
and another post here: Wind Turbines Gearbox Reliability

“Shedding some light on Bulbgate” (Gail Collins, New York Times)

This recent article in my local newspaper reminded me that media people do not necessarily have the scientific background to understand an issue.

Ever since the announcement that Incandescent light bulbs will be banned in 2012 I have wondered how to get this issue into the right perspective. I am all for energy efficiency when the facts are clearly presented but in this case we have people that passed math but slept through science. What should it tell us when the world’s oldest Incandescent light bulb has been burning for 109 years? Context, please.

A statement that needs to be questioned, because of the lack of scientific context, is: “Fluorescent and LED lamps will save more energy when we use them to replace Incandescent lamps”. The scientific fact is that if you put 100 Watts into an Incandescent lamp, you get 100 Watts out, part of it light and part of it heat. This is called in Physics as “Conservation of Energy”. The same is true for CFL’s and LED’s, the only difference is the proportion of heat to light. So then the question should be if we get heat as part of the output from a device that is intended to produce light, is that a bad thing. I say Yes and No. No, if the heat energy from the lamp offsets the energy being used to heat the surrounding air where the lamp is being used; Yes if the heat is undesirably adding to the surrounding environment. In the latter case, the question might be how often is the lamp turned on in a bright, hot environment compared to the dark and cool of the night? Does the heat from an Incandescent lamp impact the surrounding area noticeably more than the Fluorescent or the LED? My experience is that I have never been able to tell the difference.

What should be a bigger part of the conversation is this:”which technology is more reliable and which is less expensive?” I say, when not abused, the Incandescent lamp wins hands down. Statements from Proponents for eliminating the Incandescent bulb make out of context claims like “LED’s will last 25,000 hours (less than 3 years) instead of 1,500 hours (2 months) for the Incandescent bulb”. The absurdity of the statement is shocking. A LED chip alone may quite well last 25,000 hours but since an LED lamp includes numerous additional components, including multiple LED chips, collectively it will have a much lower life expectancy, and is very expensive. The Incandescent consists of ONE component and if treated right will survive well beyond the 25,000 hours. Let’s talk about the mistreatment of the device, what is the cause and how to avoid it.

The Incandescent lamp is an inexpensive and environmentally friendly device because it consists of a thin metal wire with a positive temperature coefficient (so it won’t run away and self destruct). Its’ Achilles heel is the fact that due to the positive temperature coefficient, it has a lower resistance when cold and if the rated voltage is abruptly applied the initial current is much larger than when the metal wire (filament) finally reaches operating temperature. This inrush of current causes a sudden heating of the filament which causes a wrenching change of dimension. In addition, since the filament is extruded and will have slight variances in cross section, it will have points along the filament that will be higher resistance and will become exceptionally hot. In time it will degrade and fail. The solution to this is to NOT apply the voltage abruptly; don’t flip the switch. Low cost dimmer controls (e.g. Lutron Corp) not only allow you to adjust the light output to the level you need and/or want (saving energy), it also applies and removes the voltage slowly, giving the filament time to heat (expand) and cool (shrink). Therefore all of my Incandescent devices are operated by a dimmer control. The time to turn a knob or slide the control versus flipping a switch is negligible, it becomes such a habit that I don’t even think about it. One caveat is that the control must NOT be a push on-push off variety because that will still makes an abrupt application of the voltage. Incidentally I have never had to replace a dimmer control because of the simplicity of the design whereas dimmable CFL’s and LED’s require you to throw out the dimmer part of the device when it fails because it is integral to the device. One last note here, since a 100Watt incandescent can be dimmed and will consume less energy, why is that not a good thing? Only dimmable CFL and LED lamps can do that but with a much higher cost and, due to the complexity of the controls, have lower reliability collectively. Why would you pay more for something that will fail more often?

Lastly, the way to save energy while getting the illumination that you want is to use it wisely. I sometimes get the impression that the drive to go to more efficient, expensive lighting sources is so that we can have more of them burning brightly in our house and not feel guilty. When young I did not really understand when my father berated me for not turning off the light when I left a room, but over the years I now do.

Last thought: How come they are not outlawing Candles? Geez, I hope not.

We are hosting a Free webinar on solar reliability on Tuesday April 5 from 9-11PDT. Here is more info on it.

Tuesday April 5th – Reliability in the Universe of Solar Products, by Ops A La Carte and Concurrent Design. Register at:

We have two more free webinars this quarter:
– Wednesday May 4th – Reliability and Quality Engineering Integration using DFSS and DFR Methods, by Ops A La Carte. Register at:

– Wednesday June 1st – How to Use HALT with Prognostics, by Ops A La Carte and the Ridgetop Group. Register at:

Wind Turbines have steadily grown in size to the point where the largest models have blades of more than 100 meters in diameter.  The Gearbox (which connects the rotor shaft to the generator) continues to be the component whose failure results in the most significant cost and downtime.  Therefore, the reliability of the gearbox is one of the biggest concerns in the wind industry.  At present, wind turbines are generally designed for a 20-year design life; however today’s gearboxes generally have an operational life of  7-11 years, per Sandy Butterfield, former NREL Chief Wind Turbine Engineer. 

Some estimate that the current risk of failure of the gearboxes may have an economic impact as high as $300 Million USD.  Gearbox failures are so expensive because of the high cost of repairing or replacing the gearbox, and due to the resulting downtime associated with the replacement.  The gearbox itself typically represents about 10% of the total cost of the wind turbine system.  With downtime, transportation of the gearbox, and labor, typical gearbox replacement costs range from $300K-$775K USD.

With these very high costs, improved reliability of the gearbox can truly have a huge economic payoff.  It comes down to the need for accurately predicting the aerodynamic and inertial loads transferred from the huge composite blades over a wide range of operating systems.  In many cases flexibility of components such as shafts, bearings, gears, etc. can become very important.

For further background, see the article:
“Wind Turbine Gearbox Reliability”  at: 
or request a copy from me:

Find more on Green Reliability at the Ops A La Carte site.

I am giving a presentation tonight (Sept 30) at the IEEE Reliability Society meeting at the HP Oak Room in Cupertino, CA. Email me if you want details on the event or need directions. It is a FREE event.  I started a linked-in discussion on this same topic and I posted a blog on our site about this so sorry if you are getting this from a few different angles.

Given the short notice, I’m guessing most of you will not be able to attend but I would like to start a discussion about this topic.   Here is a link to a few Green presentations we have given, including tonight’s presentation

Part of the motivation for this talk is that today, the topic of Green is discussed more and more. Every day we hear about companies “going green”. But what does this really mean? You can hardly go to a website today without finding claims such as “we are going green”. The problem is there are no common definitions of what “Green” is and if we treat it this way, then the “Green Revolution” will come and go and there won’t have been much of an impact on our environment.

Leading clean tech specialists Woody Clark and Thomas Friedman agree that we need to start doing something immediately and the govt needs to help. Both are using global warming as one of their principle scare tactics. Is global warming real? We won’t debate that here but what is real is that energy consumption is going up exponentially along with the growth of China and India and other developing nations. Both are saying that the US must take the lead!

Friedman criticized the Bush administration for not reacting to 9/11 from an energy point of view. According to Friedman, the US had a golden opportunity to reduce our dependency on oil and we blew it.

Now we must take the lead with alternative energy solutions. China and India are looking closely at us and will likely follow. But we need to show leadership. The wrong move now could be costly later on. But what do we need to do and how do we do it?

And EPEAT is the newest buzzword that is getting a lot of attention, but is this just another fad with no teeth?

Today there are no standards set for Quality/Reliability in the Green movement. If the product fails prematurely, they have means of disposing of it but why not work on preventing it from failing in the first place ?

Woody and Thomas never mention reliability in their books. There is a big gap and everyone in this room will be playing a roll of filling that gap in the next 10-15 years.

My talk addresses this very subject – “Going Green” has many implications, from the materials being used to the type of energy being used and the quantity being consumed. And each aspect of “Going Green” has reliability implications. In fact, any time we change material properties or design concepts, there are inherent reliability risks that need to be addressed.

PS – I am giving the talk again at the annual Accelerated Stress Testing and Reliability Workshop in New Jersey next week (THIS TALK AND THE ENTIRE CONFERENCE ARE AVAILABLE VIA WEBINAR if you would like to attend so let me know if you need details on this). I would very much appreciate any feedback/advice you can give me on this so that I can incorporate your opinions into my talk. Specifically, here are a few polling questions that I would like you to answer for my research:

1) Do you believe the Green movement today has real teeth or is it still a lot of talk without much action

2) Do you believe we need reliability and quality guidelines or standards for the green movement

3) Do you believe that Obama should regulate the industry so as to “fuel” the green movement and get us away from fossil fuels. One such way is either tax breaks for green or tax hits for non-green, the most obvious being to tax gasoline.

We will be participating in a Clean Tech event on Tuesday, June 23rd at the Plug and Play Center in Sunnyvale, California.  Go here for all the details.

We will be hosting a free “Green Reliability” Seminar/Webinar on Friday May 8th from 9am-12pm at De Anza College in Cupertino California.

It will also be available via webinar. Sponsors will also include De Anza CACT (Center for Applied Competitive Technologies) and IEEE.

The focus of the seminar will be on different ways reliability is playing an important role in the new push to go green, including the push for different materials, lower power consumption, and fewer failures (reducing the addition to landfills).

Details will follow.