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Stanley
Local Historian & Old Fart


36804 Posts
Posted -  15/12/2007  :  07:03
I thought it might be a good thing to have a topic devoted to this important subject.


Stanley Challenger Graham




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stanley at barnoldswick.freeserve.co.uk
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Tizer
VIP Member


5150 Posts
Posted - 26/10/2010 : 16:27
"I've never quite understood why people like old windmills but hate the new turbines." (SG)

In my case it's not due to being nostalgic and averse to everything modern but because a wind farm somehow seems very inefficient in use of land and sky above it. I know they can produce a lot of electricity but good grief look at the size of them, so they should! It seems a bit like building WW2 battleships to fight a 21st century war. All the effort goes into erecting the darn things and nobody is bothered about creating a better way of harvesting wind energy. We ought to get Mr Dyson and his innovators on board and ask them to come up with something better. Have you seen his bladeless alternative to the ubiquitous fan? I don't know how it works but perhaps we could reverse the technology to generate electricity. Why does it have to be gigantic fan blades? (Rant over!!)

http://www.dyson.com/fans

Edited by - Tizer on 26/10/2010 16:28:04


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panbiker
Senior Member


2300 Posts
Posted - 26/10/2010 : 17:10
There is a bit of an explanation of how they work on your website link Tiz, or better to say hints at the technology, Mr Dyson says they use airfoil techniques. No real explanation of how you multiply air out to air in in such a small unit. The ring is static in the Dyson fan so how the airfoil principle works in this configuration beats me. Normally an airfoil as used in an aircraft wing is propelled trough the air by thrust creating lift by the pressure differentiation above and below the airfoil. Interesting technology but would like to know more. Does not appear to have any moving parts so it would be a bit difficult to run a turbine with it.

Edited to include this link: 

http://www.dyson.com/international/default.asp?lang=en

This does explain a bit more but what creates the moving air in the first place?

Edited by - panbiker on 26/10/2010 17:14:35


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pluggy
Geek


1164 Posts
Posted - 26/10/2010 : 18:28
If wind turbines made the same noise as Dyson vacuums, the NIMBYs would be up in arms.  How much power you can extract from moving air is directly proportional to the swept area of the blades, so to extract a lot of power from wind, you need a large swept area.  Interestingly increasing the number of blades within the swept area  can work against you.  Modern wind turbines with the almost universal 3 blades are far more efficient than the many bladed wind pumps so beloved of the western US




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Big Kev
Big


2650 Posts
Posted - 26/10/2010 : 19:13
http://gizmodo.com/5385011/how-dysons-blade+less-fan-works

 Pretty little video.

 My understanding is the fast moving air would create lower pressure in the ring therefore dragging more air, from outside, through it.

 


Big Kev

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pluggy
Geek


1164 Posts
Posted - 26/10/2010 : 19:25
Kind of a overhyped version of a decades old technology that presented itself in numerous forms.  The old Navy guys will probably the remember the steam ejector http://en.wikipedia.org/wiki/Injector which works on exactly the same principal. You squirt steam through it and it moves a larger volume of air, gas, oil, bilge water, effulent, you name it. The Dyson uses compressed air as a propellant and just moves air.

 


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Big Kev
Big


2650 Posts
Posted - 26/10/2010 : 19:28
That's about it. It's quite effective, have a look at this


Big Kev

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panbiker
Senior Member


2300 Posts
Posted - 26/10/2010 : 20:25
Thanks Kev, your link shows the same clip as mine from the Dyson website, which fails to mention that the gizmo does indeed have moving blades inside the ring. Knowing that, all becomes clear. They are simply using a more efficient blade based on airfoil technology and hiding it in the design of the product. Just looked at the prices for said technology, £200 - £300 for a fan - it needs to be efficient!


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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 27/10/2010 : 05:44
There used to be a windpump at the top of Wisick on I think Thornton Hall land. It was ruinous in the 1950s.


Stanley Challenger Graham




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Tizer
VIP Member


5150 Posts
Posted - 27/10/2010 : 12:46
Thanks chaps for all the explanations - I loved the American lady blowing up the bag! But it's more discussions like this above that are needed because the original point of the discussion may not bear fruit but the brainstorming and spin-off can lead to useful developments. A lot of the drives to develop new technology these days get taken up by the money men too early and `pushed' by the money when they should be `pulled' by the ideas. They end up going down a blind alley, like with some of the biofuel projects.


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Tizer
VIP Member


5150 Posts
Posted - 27/11/2010 : 17:10
Well here we are nearly 12 months later and the Earth is still warming, the glaciers and permafrost melting, and the weather getting increasingly extreme and unpredictable. What has changed most is the lack of interest from the news media and the resulting lack of concern and more scepticism from the public. The United Nations Climate Change Conference will begin in Cancun, Mexico, next Monday, 29th November 2010, but I'll bet you haven't heard much about it. Here are some snippets of what I believe to be interesting information on climate change...

As the recession started some people predicted that the economic decline would lead to a levelling out, or even a lowering of global temperature. Not so, we are still on the rising curve. Any lowering of temperature by reduced industrial activity has been outweighed by a shift of production from the West to the East, to countries like China and India where much of the energy comes from coal-fired power stations (one new power station comes on line each day in China). The moderation of the increase in carbon emissions in Western countries is largely due to us buying our goods from the East instead of making them ourselves, but manufacturing in the East is `dirtier'.

There is another little-noted factor to take into account when we consider total carbon emissions over the last 20 years or more. The emissions are still on an upward curve but it doesn't look as bad as it really is - using the total figure (even a total for Europe) is misleading. The reason is that in the late 1980s the political changes in the Soviet block led to a dramatic fall in industrial activity in those countries and this continued until very recently. The carbon emissions for the Soviet block fell in line with the fall in industrial activity and this depresses the curve for the total emissions. Thus if the Soviet political change had not occurred the total emissons curve would have risen even more steeply than it did. Those countries are now returning to activity, some of it still using `dirty' energy production and we may see the emissions curve turn upwards again. I don't see this discussed in the media or even among the more technical publications.

With the Cancun conference about to start the UN World Meteorological Organisation has released its latest Greenhouse Gases Report and this describes concerns over a rise in emission of another greenhouse gas, methane, from wetlands and permafrost. The wetland release is due to exceptionally warm temperatures at high northern latitudes in 2007 and heavy rain in tropical wetlands in 2007 and 2008. Release from permafrost similarly follows warmer temperatures and the permafrost contains enormous amounts of methane present in a form of ice (methane clathrate). Molecule for molecule, methane causes much more warming of the atmosphere than does carbon dioxide, CO2 (25 times more over a 100 year period) but usually less of it is released than CO2. The major concern is that as the permafrost melts there may be a `runaway' release of methane - the more methane released the more the permafrost melts. If the oceans warm there is also potential for vast quantities of methane clathrate in the deep ocean sediments to be released but this is a longer term danger.


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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 28/11/2010 : 06:03
I noted the same reports Tiz. I also heard a report that China is burning more coal than the rest of the world put together and consumes more steel than The US, Eu and Japan combined. They are doing what we did in the 19th century but on a vastly larger scale. Gaia will strike back! I also heard some discussion on World Service about increased levels of methane in the atmosphere, one of the most potent greenhouse gases. They suspect that the predicted release of methane from perma frost and sea bed has started with global temperature rise. We are all doomed....


Stanley Challenger Graham




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Tizer
VIP Member


5150 Posts
Posted - 28/11/2010 : 11:42
I posted the above because I thought it would be a good time to raise climate change again, not just with the upcoming Cancun conference but also to fit in with the severe cold weather! "The Earth can't be getting hotter, there's snow outside!".

I've been reading up on methane in the ground and the atmosphere. You might have seen geologist Iain Stewart on TV in Siberia poking a hole through the ice on frozen lakes then lighting the methane that rises out of the hole, nearly setting fire to himself (but then he's a volcano expert so he's used to it). Vast amounts of methane (CH4) are locked up in a crystalline form with water as a methane ice (technically, methane clathrate) in frozen wetlands and in sediments at the bottom of the oceans. The methane ice forms at high pressure and low temperature and is stable at -20C or lower but once the temperature rises above this figure it will be released. The low temperatures keep it locked up in the permafrost and the high pressures keep it deep in the ocean sediments. Atmospheric methane concentration plotted on a map of the world shows highest levels are in the northern hemisphere - in fact there is a gradient of increasing methane from the Antarctic to the Arctic. I assume this is because most is presently coming from land, not oceans, and the north has the most land, especially frozen wetlands. Other sources are swamps and flatulent animals, especially ruminants.

Methane doesn't last as long in the atmosphere as CO2 because it reacts with oxygen to form....water and more CO2 (both also greenhouse gases). However it is much more effective, molecule for molecule, as a greenhouse gas than CO2 - 72 times more effective over a 25 year period, and 25 times more over a 100 year period. A burst of methane release is more dangerous than a burst of CO2 release. The scientists are worried by the melting of the permafrost which is already forcing the Chinese to rebuild roads and railways in the north as they sink and buckle.

I picked up something interesting on CO2 recently that I didn't know about before. We often hear about CO2 being mopped up by the oceans which gives us an impression of the gas having a relatively short lifetime in the atmosphere. A large part of released CO2 does get absorbed by the oceans over about 300 years and another part reacts with calcium carbonate and this takes around 5000 years. But a final part reacts with igneous rocks and this takes hundreds of thousands of years. What it means is that of the excess CO2 we are producing now, some will remain in the atmosphere essentially forever (`forever' being longer than the likely existence of the human race). Some of the scientists have pointed out that we worry about building up stores of radioactive material with a `long' lifetime - we should be concerned about building up CO2 in the atmosphere with an even longer lifetime and which could be a more serious danger to mankind than the nuclear power station waste. (I'm not using this as an argument for nuclear power but to make a case for being more concerned about CO2.)

On a more optimistic note, scientists at the Universities of Hull and Liverpool (British science!) have found a way of using `dry water' (water droplets coated with silica nanoparticles which give the material the properties of a dry powder) to soak up and bind methane in manner similar to the clathrates mentioned above. With dry water the clathrate can be made at low pressure and only needs to be kept under -20C. This may not offer a practical way to soak up methane from the atmosphere but it will be used to recover natural gas from `stranded' gas wells and to store the gas which is currently flared off at oil wells.


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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 29/11/2010 : 06:24
Interesting info about longevity of CO2 in the atmosphere. I realise that you are coming at it from the CO2 angle but the situation being what it is with CO2 emissions not being controlled does strengthen the case for nuclear generation to bridge the gap until we find a better non-polluting way, fusion, solar etc. Mind you even those have problems, where does the waste heat go?


Stanley Challenger Graham




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frankwilk
Senior Member


3975 Posts
Posted - 29/11/2010 : 07:06
Can anyone remember the last time we saw a measurement being taken of the Ozone Layer on TV. It used to be every few weeks I haven't heard of it for a while now !!!! and CFCs ???



Frank Wilkinson       Once Navy Always Navy Go to Top of Page
Tizer
VIP Member


5150 Posts
Posted - 29/11/2010 : 16:43
"...where does the waste heat go?".......That's one of the downsides to unlimited, `free' heat from solar collection - we'll probably use it wastefully!

Frank, governments heeded scientists' warnings about ozone depletion and reduced CFC use after the Montreal Protocol (1987). CFC production has fallen from a maximum of about 1.2M tons a year to 70,000 tons (2007 figure). The ozone layer is gradually recovering but the CFCs have a lifetime of from 20 to 50 years so it's a slow process. The media has lost interest and we've accepted the reality of living with increased skin cancer and genetic damage due to lower ozone levels. Much of those bad effects are `not here' and affect other animals as well as humans, hence the lack of media interest. I still remember the intense sunburn on a visit to New Zealand in 1989! I always wear a hat in the sun now.


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