The bad news about windfarms.... 14

[jmw]

Just Google Windfarms efficiency and you'll get all the latest reports.
Key at the moment is one by a conservation group, the John Muir Trust. It concludes:

Wind farm efficiency has been challenged by an environmental group, John Muir Trust. The con- servation group said its analysis found wind generation in the U.K. was below 20% of capacity most of the time, well below the 30% claimed by the industry. The report concluded that wind turbines "cannot be relied upon" to produce significant amounts of energy.

Try this link:

http://www.dailymail.co.uk/sciencetech/article-1374251/Wind-farms-working-just-21-capacity.html

or:

http://www.bbc.co.uk/news/uk-scotland-12985410

Of course, the BWEA says otherwise:

Myth: Wind farms are inefficient and only work 30% of the time
Fact: A modern wind turbine produces electricity 70-85% of the time, but it generates different outputs depending on the wind speed. Over the course of a year, it will typically generate about 30% of the theoretical maximum output. This is known as its load factor. The load factor of conventional power stations is on average 50%5 . A modern wind turbine will generate enough to meet the electricity demands of more than a thousand homes over the course of a year.

http://www.bwea.com/energy/myths.html

I liked best the defense by Jenny Hogan, director of policy for Scottish Renewables, who said:

No form of electricity worked at 100% capacity, 100% of the time.

JMW

http://www.ViscoAnalyser.com

 

[VEBill]

And in related news:

http://www.gizmag.com/vestas-v164-wind-turbine/18319/

7MW * 30% is still 2 MW.

 

[msquared48]

Is this the same Jenny Hogan who just had a baby last year and is a traffic announcer for a local TV station in Seattle?

Or not...

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[jmw]

Does a baby qualify as a "Scottish Renewable"? If so perhaps it is the same lady.

JMW

http://www.ViscoAnalyser.com

 

[BigInch]

Perhaps in Englanda, the BEWA is correct. Anywhere else its pretty much the Muir group that will be right. In Spain its between 13% and 18% depending on if its a windy year or not.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[msquared48]

I guess her first name is spelled Jenni... She is definitely Brit from the accent.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[ccfowler]

"No form of electricity worked at 100% capacity, 100% of the time."

While that statement is true, but a bit of perspective is needed:

I've known coal fired steam power plants to be operated at maximum load continuously (24 hours/day, 7 days/week) for several weeks at a time to serve an urgent need.

Base load nuclear plants normally operate at some very large fraction of full power for most of their operating time.

Anyone care to depend on wind or solar to serve in similar capacities when actually needed?

Anyone care to speculate on what forms of power production will continue to be needed to cover for the times when the wind isn't blowing hard enough or is blowing too hard?

Similarly, what about overnight or during cloudy times for solar power?

Solar, wind, ... will surely play roles in power production, but conventional power production will remain necessary for a very long time.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[owg]

ccfowler make a very good point. The numbers don't reflect the variable "when I need it or when it feels like it."

HAZOP at

http://www.curryhydrocarbons.ca

 

[BigInch]

Yes the real numbers do reflect that. It is why wind production in Spain is 13 to 18% of installed nameplate capacity. You have to know which numbers to look at. Installed capacity isn't one of the more descriptive numbers when it comes to actual power production.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[Sparweb]

Wind farms are designed to be economic on the energy production. They do not need to produce at maximum or near maximum power all the time to accomplish this.

This is very difficult to communicate to the lay public, journalists, and politicians who don't know the difference between power and energy.

Some allowance has to be made for tax incentives and loans made by governments, to all sides, when comparing the numbers. Some of these numbers are thoroughly buried. Others are waved in your face without rigorous evidence.

Steven Fahey, CET

 

[jmw]

Try this link:

http://www.dailymail.co.uk/news/article-1361316/250bn-wind-power-industry-greatest-scam-age.html

JMW

http://www.ViscoAnalyser.com

 

[MAGTiger]

Wind farms work great so long as they are 100% backed up by gas turbines spinning unloaded. Or as long as they are the tiniest fraction of the coal and nuclear plant base load. But then why would we buld then to supply the tiniest part of load. hmmm...

I guess they are best for the people selling them.

Neil

 

[jmw]

And the politicians. I believe Mr Camerron's father in law will be a beneficiary of the scam.

http://www.dailymail.co.uk/news/art...s-green-subsidy-wind-farm-nets-3-5m-year.html

And with the BBC pension fund invested heavily in the wider AGW scam rip offs along with the WWF's deal in South America, what chance has the poor taxpayer - except perhaps that the dominoes falling in the Middle East may topple ever closer to the UK.

And then there are the follow on links:

http://www.cawt.co.uk/index.php?mac...23bb5returnid=115&m23bb5returnid=115&page=115

JMW

http://www.ViscoAnalyser.com

 

[BigInch]

Wind farms are designed to be economic on the energy production. They do not need to produce at maximum or near maximum power all the time to accomplish this.

Obviously when they are only giving us 12 to 18% of nameplate generating capacity at the end of the day, or year as the case may be, there is very little economic anything going on anywhere, except for the huge tax credits that Marriott and the rest of the tax credit fund buyers are sucking up.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[DHambley]

Solar and wind farms don't make a profit by generating electricity at competetive rates. They make a profit by generating tax write-offs.

 

[BigInch]

I think you're right, however solar typically generates a much greater proportion of nameplate capacity, reaching 40% ranges for averages taken over very wide areas for relativly long time periods as well, so I don't put both in the same class. Not too bad when you realize that the power source is off for about 50% of the time anyway. It seems the Sun on the average can lay down a good power flux over a much greater area for a considerably longer time than what can be sustained by wind, except for those odd here and there nooks and crannies that always get a good blow. Solar also does not seem to be prone to such great parasitic loads, such as momentum loss of the spinning blades when combating inertia of the towers swiveling back and forth, or the power loss when they don't. For the most part it can be economically limited to 25 to 28% of max output. I also think there is a good amount to blame on the use of what is probably a very highly idealistic wind velocity distribution curve that they tend to use when calculating expected output of a wind farm, simply because the Releigh distribution doesn't really happen and because of blade inertial losses from variable wind velocities (speed and direction). If anybody has seen a study on wind turbine parasitic losses, I sure would like to know about it.
Solar is quite a bit more expensive, making it still not ready for non-tax-credit-related roll out, but they can do something about that. Prices have fallen a lot over the last two years.

Wind's greatest ad/disavantage IMO is that it makes a highly visible statement as to how much green paint their sponsers want the public to believe they have. In the meantime, reuse your bath towels during extended stays.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[cranky108]

The best use for solar panels, is to shade your car from the hot summer sun. So please install more of them in parking lots please.

 

[GregLocock]

I've spent a while monitoring solar output. Averaged over a day the worst day's output is about 40% of what you'd expect on average for that date and location. The best day I've seen might be 120% of average.

Australia's weather is probably a bit more predictable than most continents so those figures are not reliable for all locations. Incidentally optimum condition is the sun high overhead surrounded by clouds. The clouds reflect more light back downwards.

One big problem we have is that the output voltage falls off as the cells heat up, which is what happens when the sun shines on them.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[BigInch]

Electrical devices do like the cold temperatures. Maximum output is obtained on a similar cloudy day as you describe, but in winter with the air temp low, however still high enough to result in partly cloudy conditions. A bit of well directed wind helps the cooling as well.

Cranky, you're not wrong. The shade when make when placed above your own roof can reduce house temperatures and save some of that AC cost too.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[IRstuff]

Stands to reason, a typical shake roof with 1500 sf of area would be loaded with 532 kBTU/hr at solar maximum. If nothing else, the reduced solar load would prolong the life of the roofing material.

TTFN

FAQ731-376
Chinese prisoner wins Nobel Peace Prize