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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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pluggy
Geek


1164 Posts
Posted - 19/12/2007 : 19:18
37% is excellent thermal effficiency for any prime mover.  Utilising the waste heat would probably reduce the efficiency of the plant and increase the cost of the electricity.  The efficiency is largely a product of the difference in temperature between the hot sink (The boiler steam temperature)  and the cold sink (the tempearture of the condensor).  For the waste heat to be usable it would need to be at a much higher temperature than what a cooling tower can reduce it to.  Combined heat and power is fantastic on paper, its a logistical nightmare when you're trying to balance a highly variable demand for electricity against the very likely unrelated demand for heat.  You either cap the production of electricity when heat demand is low or you dump the excess heat to atsmosphere when you can't get rid of it, this on top of the reduced efficiency because the waste heat has to be useable makes combined heat and power unviable except in special circumstances.  Its a lot easier and cheaper just to waste it in cooling towers than try to use it.


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HerbSG
Senior Member


1185 Posts
Posted - 19/12/2007 : 19:57
One explanation offered in our area to explain why the blades are not turning is " there is a safe wind range, if the wind is too strong the blades are stopped"??????


HERB


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Tizer
VIP Member


5150 Posts
Posted - 19/12/2007 : 20:39
Those wind turbine blades always look like they are going slowly but I'm told the blade tips are whizzing round at over 100 mph. So I guess it gets a bit hairy when the wind picks up.

And I suppose it doesn't do to get too close to one of the tips. I can imagine a Harold Lloyd film with him getting caught on the end of a turbine blade!


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Julie in Norfolk
Senior Member


1632 Posts
Posted - 20/12/2007 : 00:21
I hate to bring up the Norfolk subject again, I do not assume that we are far ahead of others with trying to be green but I cite the following.

Swaffham I, Ecotech Centre

Swaffham I is the UK's first multi-megawatt wind turbine and one of a new generation of direct drive, variable speed wind turbines, brought to the UK by Ecotricity.

The turbine was installed at the Ecotech Centre in Swaffham, Norfolk in October 1999 and officially opened by the Environment Minister, Michael Meacher. It produces enough electricity for over 1,000 people - over a third of the population of Swaffham.

The Ecotech Centre is an environmental education centre and Swaffham I includes a viewing platform, which has already been visited by over 50,000 people. The unique public viewing platform, designed by Foster & Partners, is situated just below the hub and can be reached by climbing a 300-step spiral staircase inside the tower.

Swaffham I is superior to conventional electricity generators, in terms of energy efficiency and yield, as well as having minimal environmental impact. An official Millennium Product, this world leading wind converter incorporates unique design advancements and refinements to increase aerodynamic efficiency and reduce noise.

"This is the most significant wind project in the UK and I encourage people to come and take a look. It shows the way we are all wishing to go in terms of greater renewable energy, with wind power playing a part. What we are seeing here is what I would like to see all across the country. There is a sense of great power. Half the people of Swaffham are going to get their energy from this turbine. I think that is tremendous." - Michael Meacher, Environment Minister (at the time)



Vital Statistics

Swaffham I, Ecotech Centre

Ecotech Centre
Swaffham, Norfolk

Installed - 1999

Turbines - 1

Capacity - 1.5MW

Generation kWh - 3.5 million

Equivalent homes - 1,100

Hub height - 67m

Rotor diameter - 66m

Carbon dioxide (CO2)
savings - 3,161 tonnes

Sulphur dioxide (SO2)
savings - 37 tonnes

Nitrogen oxide (NOX)
savings - 11 tonnes

We now have 3 turbines at Swaffham and more than several off Yarmouth coastline. They do not supply a massed amount of power but they do supply a useful amount. I would also recommend the Swaffham Ecotech site as a place to take children or just to learn as adults. I have been there several times myself.


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softsuvner
Regular Member


604 Posts
Posted - 20/12/2007 : 06:28
Julie

Is this the one that you can see from the A 47? I've been past that one several times, and wondered what sort of view you would get from the top of the pillar. I will put this on my "places to visit" list. Thanks

Malcolm 


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frankwilk
Senior Member


3975 Posts
Posted - 20/12/2007 : 06:53
" I hate to bring up the Norfolk subject again "

We won't hold that against you Julie, I worked on the CCGT plant at King's Lynn.



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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 20/12/2007 : 07:16
Sorry Pluggy, you're wrong about 37% being excellent.  It's all relative and depends on the type of prime mover you are talking about.  The Gardner diesel was 50% efficient and Rolls spent years trying to beat that with the Eagle which they eventually sold to Perkins.  Newton and I built a CHP plant in his backyard 30 years ago that was about 85% efficient.  Fiat patented the same system we used many years later.  You are right that raising the exhaust temperature from a steam unit, either turbine or reciprocating reduces the efficiency of the unit itself but it's only done when there is a constant demand for the by-product.  Look at the power stations in NY and the old London units.  They supplied low pressure steam to the surrounding areas which was used to heat domestic hot water and heating in winter.  Not the most economical electricity but a more efficient overall performance.  The best places for CHP are swimming baths which have a heating load all the year round.  Many of them have generating sets sized not to match the total electricity load but the average heating load.  These are very economical and have a good pay-back time.

Even the old steam-driven mills were more efficient than the grid by far.  At the end of the war the government formed the National Industrial Fuel Efficiency Committee and their job was to persuade as many people as possible to buy mains electricity to raise the base load and finance the expansion of the grid and the building of larger generating units.  They were very successful but on the whole operated a gigantic fraud as nobody got cheaper electricity.  Look up Broughton Road Shed in the LTP and see what happened there.  A typical example of the general experience.  Bancroft survived because when the NIFE men called, the management sent for Newton and he asked whether they would gusrantee reinstatement of the engine if the bills didn't fall.  They went away.  When the shed was almost sold to a Rochdale firm of oil burner manufacturers I wsa asked to get out the figures for our energy costs.  Even running at 50% capacity our plant was half the cost of mains electricity for a 400Kva load.  In other words we were more than twice as efficient even though our unit fuel cost was much higher.  The average thermal efficiency of an old steam driven plant was probably 30/40%.  Makes a modern power station look daft delivering energy at 15/20%.  Hard to believe I know but unfortunately true.  The bottom line was the energy bill and that didn't lie.


Stanley Challenger Graham




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Tizer
VIP Member


5150 Posts
Posted - 20/12/2007 : 12:26
It's always useful to look at things from other folks point of view. There is a different perspective on climate change to be seen on the web site of the "Arctic and Small Island Developing States":

http://www.manystrongvoices.org/overview.html

Their recent press release begins:

"The world’s indigenous peoples do not accept the much advocated target of limiting the global temperature increase to 2 degrees Celsius. For indigenous peoples - including in the Arctic, small island developing states, forests, and dry-land and low-lying areas - this increase will mean the destruction of our cultures, livelihoods, traditional knowledge and communities.

"The limited access for indigenous peoples to financial resources is constraining our efforts to implement traditional and modern adaptation measures. Despite the adaptation work already pursued by a number of our communities, climate change and its consequences are outpacing our fight to survive. "



Edited by - Tizer on 22/12/2007 11:02


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Julie in Norfolk
Senior Member


1632 Posts
Posted - 20/12/2007 : 13:38
Who's fighting? just come here and say that without speaking.


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pluggy
Geek


1164 Posts
Posted - 20/12/2007 : 23:31
I always accepted the figures when I was doing my Marine Engineering as being somewhere near.  40% for a reasonable diesel under a variety of loads.   50% is very close to the theoretical maximum.   Turbines (steam or gas) are more efficient at high loads than reciprocating. At variable loads reciprocating are better.   Triple expansion steam engines are around 25 % under ideal conditions. Reciprocating usually have a much higher maintainance load. 

The most efficient electrical generation plants are diesels with their waste heat producing steam to drive turbine generating sets.   

The cost of power from the grid will have a lot more to do with the horrendous electrical losses involved in moving it down miles of cable than the efficiency of the engine generating it.  Birds sit on power lines for a reason - they're warm.  

CHP figures are cheating, it wouldn't be too difficult to get 90% +.  Heat is the lowest form of energy, its the bottom of the tree.   It could be argued that ordinary light bulbs are efficient, because the huge amount of heat they produce, warms the room they are located in, as does a TV set, computer or practically any other electrical appliance.  My office at work doesn't require heating at all, its done admirably well by the dozen or so servers it contains.  We have to use air conditioning in summer tho......


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Stanley
Local Historian & Old Fart


36804 Posts
Posted - 04/01/2008 : 07:57
News that one of the energy companies is putting proces up today.  One of the reasons cited is the $100 barrel of oil.  Piece on R4 yesterday where a US trader said that there never was a $100 barrel of oil.  It was a fake trade made by two traders so that they could frame the certificate.  I know the price of oil is rising and will eventually pass $100 but these 'milestones' if reported are used by the market to justify their actions.  It wouldn't hurt to find the traders and punish them......


Stanley Challenger Graham




Barlick View
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Tizer
VIP Member


5150 Posts
Posted - 04/01/2008 : 09:57
Tarred and feathered would seem appropriate, Stanley. And then a few days in the Barlick stocks if you still have them.


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pluggy
Geek


1164 Posts
Posted - 04/01/2008 : 11:29
 http://www.bloomberg.com/energy/

 With spot prices currently just under $100 a barrel it wouldn't have been much of an exaggeration to buy it at 100 bucks.  The oil prices are as much an indication of the low value of the dollar (and currencies in general ) with what is being dubbed the credit squeeze as to the value of oil.  Most commodies are trading at a high price, gold reached an all time high of $870 an ounce this week as well.  

Incidentaly the UK news is way behind on the global currency scene.  It first hit the news here in September, I lost quite a bit of money trading currencies when it hit the markets at the end of June and July when it first became an issue in the States.  Anything long dollar or pound took a nose dive, which is where I was.  I'm contemplating starting again now things are settling again. 

With the US (and UK) making noises about withdrawal from Iraq and Afghanistan its likely the currencies will recover and commodity prices will fall.


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pluggy
Geek


1164 Posts
Posted - 04/01/2008 : 12:13
Tarring and feathering is a little over the top for a fake trade when the real price reached $99.68 a barrel. Most trades in the global markets are 'fake' in the established sense of the word anyway. You 'buy' stuff on credit on the futures market and then lose or gain the profit or loss when you close the trade some time later. The money for the 'transaction' doesn't actually move anywhere.  Neither do many people actually buy or sell actual oil, its all market speculation.

Edited by - pluggy on 04/01/2008 12:17:04


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frankwilk
Senior Member


3975 Posts
Posted - 04/01/2008 : 12:37
I agree 100% traders don't lose.  But Please tell that to my Energy Supplier who is buying Spot



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