Both Sendai reactors (unit 1 and unit 2) have now been restarted. Sendai unit 1 has just started providing electricity to the grid. (August 14th)
So how will this affect Japans Carbon Dioxide emissions? And how would renewables (say wind) compare?
When nuclear was shut down in Japan it was replaced with an unholy mix of coal and gas (with about 7% oil) A rough estimate of the amount of Carbon Dioxide from the generation that replaced nuclear would be around 750Kg of Carbon Dioxide for every MegaWatt Hour of energy generated (750KG/MWh)
Sendai, during its last year of full operation generated just short of 13TWh of electricity (13000 GigaWatt Hours) So today, the first day of generation, Sendai unit one (half of the power plant) will have generated around 18GWh of energy. This will displace energy that would have otherwise been generated from the coal/gas/oil mix
So a rough estimate of the amount of Carbon Dioxide prevented from being dumped into the atmosphere by this single day of generation from half a nuclear power plant amounts to 18000 x 750 = 13.5 million Kg of Carbon Dioxide or 13500 Tonnes.
A single day of operation from half a nuclear power plant prevents the emission of 13500 Tonnes of carbon Dioxide.
Amazing isn't it?
How would a renewables option compare?
An 150m high 2MW wind turbine with a typical 25% capacity factor would intermittently produce 12MWh in a day. Or using same units as Sendai - 0.012GWh
So to match the single day output from half of Sendai nuclear power plant (and ignoring the problems of intermittency) would would need 1500 turbines.
Or to put it another way, for a single turbine to match a single days energy generation from half of Sendai nuclear power plant would take that turbine four years, one month and nine days.
Don't figures like that just knock you out?
Showing posts with label intermittency. Show all posts
Showing posts with label intermittency. Show all posts
Wind Turbine Design, Cube Laws, Efficiency and Cock Ups
Well, I have to 'fess up
to having made an error regarding the output characteristics of
modern day Industrial Wind Turbines.
A silly mistake at that.
But possibly a mistake that also reveals some interesting possibilities with wind turbines. Especially related to reducing their size, noise and increasing useful power output.
Crack Pottery? Possibly. But I've not been at the cider yet. (honest)
A silly mistake at that.
But possibly a mistake that also reveals some interesting possibilities with wind turbines. Especially related to reducing their size, noise and increasing useful power output.
Crack Pottery? Possibly. But I've not been at the cider yet. (honest)
First, in order for this post to make sense, let me summarise some things that ARE true.
- The energy in the wind is a cube of the speed. In other words if you double the wind speed – wind contains 8 x energy. Halve wind speed- wind contains one eighth the energy.
- The theoretical maximum amount of this raw wind energy that can be harvested is 59.3% (Betz's Law)
- In reality the most efficient turbines manage about 45% (at a wind speed of around 7-8 m/s).
All of the above are correct. (Or I really am in trouble!)
My mistake in some earlier posts was to assume the efficiency of a wind turbine was roughly constant across the operational wind
speed range (up to maximum output).
Sadly this is nowhere near true.
In reality the
efficiency (or how much energy the wind turbine can actually suck out
of the wind) drops like a stone as the wind speed increases.
For most industrial
wind turbines the highest efficiency (at around a wind speed of 7m/s)
is about 45%. But as the wind speed increases, the efficiency falls
to around 10% at a 90% loading.
The overall effect of
this is to roughly linearise the power output to the wind speed. So
instead of getting eight times the power out when you double the
wind speed you only get double the power out. The rest is spilled.
So what does this
matter if the
thing is only as efficient as a 19th century steam engine when confronted with a high wind?
It matters a lot.
Way back in 2002 at the
Lee Ranch wind turbine research facility in New Mexico, it was
discovered that 50% of the annual energy output of a wind turbine was
delivered in 15% of the time.
My own analysis done back in 2011
showed that for a three month period the whole UK wind turbine fleet
delivered 50% of its energy in 25% of the time. But remember that was
for the whole distributed fleet.
It would be reasonable to assume
that for a single facility, the Lee Ranch figures are roughly correct
for the UK too. Also, there is no reason to think any design change to wind turbines since 2002 will have significantly affected these Lee Ranch findings.
In order to harvest the
50% of the energy that is smeared out over 85% of the year you have
to compromise the turbines efficiency at higher wind speeds. The result today is an
enormous unreliable monster.
So, for a moment, let
us forget about the grindingly low 50% of energy generation that gets
smeared over 85% of the year. Let us concentrate on the other 50% that
arrives in 15% of the time (currently at an efficiency of a measly
10-15%).
For arguments sake, let us design a turbine
that may not cut in until the wind speed is 12 or 14 m/s but then
delivers an efficiency of 40%. It will (MWhr for MWhr) be very much
smaller, simpler and more robust than a conventional turbine.
OK
it will only operate for 15% of the time and it is truly intermittent. But
all wind is intermittent. Remember a conventional turbines output
during 85% of the year is pretty derisory anyway. Often it is so low
that it might as well not be there.
So, build smaller more
efficient turbines. Crucially, in order to make these turbines more efficient, they only operate at higher wind speeds. We then rely on gas backup for the rest. More predictable, less
environmental impact and more reliable (due to narrower operating
domain).
Tell me where I'm
wrong. (Seriously - I may well be)
Of course this is
still all window dressing. This (and the rest of RE) is just Care Bear fluff. Nuclear plant (with some gas) is the ONLY viable option to cut
GHG and air pollution.
But I hope that this is at least “interesting” fluff.
Junk Energy and Wind Turbines
The John Muir Trust is an honourable institution, dedicated to protecting wild places. It seeks to protect the remaining wilderness that is so diminished in our country. As a result of this focus, they commissioned a report of the affects of wind turbines upon this countryside and also (critically) how effective and worthwhile these turbines would be.
Their report, compiled by Stuart Young Consulting has just been published. It is totally damning. It can be found HERE
It shows that the national wind turbine output:
below 20% of capacity more than half the time.
below 10% of capacity over one third of the time.
below 2.5% capacity for the equivalent of one day in twelve.
below 1.25% capacity for the equivalent of just under one day a month.
Billothewisp did a similar though much smaller analysis ( See Here ) here for a 3 month period over winter 2010. The results were just as bad.
The John Muir Trust analysis covers over 2 years and is comprehensive and irrefutable. Stuart Young Consulting freely admit that they were surprised at how appalling these figures are.
How long are we going to have to put up with this scam?
All the wind turbine industry does is mercilessly ruin rural communities, while pandering to the fashion sense of vacuos green bigots. The only real winners are the carpet bagging developers who in turn line the the pockets of ruthless and amoral landowners who allow these things to desicrate their local communities.
The actual energy contribution from the whole of the wind turbine fleet is dismally unreliable, erratic and excruciatingly expensive.
One observation from the Stuart Young Consulting document says it all:
[quote]
It is clear from this analysis that wind cannot be relied upon to provide any significant level of generation at any defined time in the future. There is an urgent need to re-evaluate the implications of reliance on wind for any significant proportion of our energy requirement.
[unquote]
The politician who puts the country before this scam (and probably before his mates who are profiting from it) gets my vote.
The John Muir Website can be found HERE
The report by Stuart Young Consulting (pdf) can be found HERE
Billothewisps 3 month summary post is HERE
Hat tip to Charles For this Post over at nucleargreen.blogspot.com
Their report, compiled by Stuart Young Consulting has just been published. It is totally damning. It can be found HERE
It shows that the national wind turbine output:
below 20% of capacity more than half the time.
below 10% of capacity over one third of the time.
below 2.5% capacity for the equivalent of one day in twelve.
below 1.25% capacity for the equivalent of just under one day a month.
Billothewisp did a similar though much smaller analysis ( See Here ) here for a 3 month period over winter 2010. The results were just as bad.
The John Muir Trust analysis covers over 2 years and is comprehensive and irrefutable. Stuart Young Consulting freely admit that they were surprised at how appalling these figures are.
How long are we going to have to put up with this scam?
All the wind turbine industry does is mercilessly ruin rural communities, while pandering to the fashion sense of vacuos green bigots. The only real winners are the carpet bagging developers who in turn line the the pockets of ruthless and amoral landowners who allow these things to desicrate their local communities.
The actual energy contribution from the whole of the wind turbine fleet is dismally unreliable, erratic and excruciatingly expensive.
One observation from the Stuart Young Consulting document says it all:
[quote]
It is clear from this analysis that wind cannot be relied upon to provide any significant level of generation at any defined time in the future. There is an urgent need to re-evaluate the implications of reliance on wind for any significant proportion of our energy requirement.
[unquote]
The politician who puts the country before this scam (and probably before his mates who are profiting from it) gets my vote.
The John Muir Website can be found HERE
The report by Stuart Young Consulting (pdf) can be found HERE
Billothewisps 3 month summary post is HERE
Hat tip to Charles For this Post over at nucleargreen.blogspot.com
Labels:
intermittency,
John Muir Trust,
wind turbines
Wind Power: The Damning Results
Here is the results from some analysis of the 3 month NETA Wind Turbine metered output. This NETA data is independant and used to pay power generators. There is no wishful thinking or political slant on this data. This data is freely available and continuously updated HERE.
The snapshot I used is available HERE
The first graph below is a frequency plot of power output against half hour billing slots. It shows how often, within the 3 month period wind power contributed a particular power level (power level - X axis number of half hour periods - Y axis. (Sorry forgot to label the graph properly)
The most shocking outcome from this graph is that the most common output from the whole of the national metered wind power system is 300MW. That equates to 12% of their maximum rating of 2430MW. They were running at this level, or less for more than 30% of the 3 month period.
The graph indicates that while in the 3 month period the output fell to close to zero (less than 100MW ) for no less than (in-total) 147 hours, at no no time it ever reach anywhere near the often hyped maximum rating. In fact the total output never even reached 85% of this rating. The absolute maximum achieved was 2065MW (84.8%). This was achieved for (in-total) one hour in the three month period.
This graph below shows the half hourly power ratings linearly from low to high. Wind energy is governed by a cube law. Double the wind speed and get 8 times as much power (unfortunately the reverse is also true - halve the speed get 1/8th the power). Here you can see the cube law in action and how it skews the output so most of the time wind power generation is BELOW the Capacity Factor
The raw average (or capacity factor), which is arrived at by simply adding all readings up and then dividing by the number of readings gives an capacity factor of 25%. (608MW) On their website the BWEA suggest it is 30%. Often the figure gets inflated further. The press blindly accept what they are told.
This otherwise laudable Daily Mail Article falls into exactly this trap.
Remember these NETA figures include offshore as well as onshore sites so the Capacity Factor is certain to be even poorer for on shore turbines alone.
The BWEA suggest that the capacity factor taken in isolation is meaningless. I (sort-of) agree with this. As electricity generation cannot be stored, the duration of the power generation operation is as important (or arguably more so) than the averaged value.
In this three month period the wind output only managed to reach or exceed this capacity factor (25% - 608MW) for less than 40% of the time. If you use the much hyped BWEA figure of a 30% capacity factor, then this value was only reached or exceeded for 23% of the 3 month period.
Due to the cube law relating wind speed and power output, we find that half the 3 months energy arrived in less than 25% of the time leaving the other half to cover the remaining 75% of the period. This is actually an improvement on the single facility figures of about 15% found in the USA (Lee Ranch Sample Data (1/2 way down this page) .
This improvement from 15% to less than 25% is the contribution from the grossly overstated "if its not blowing here its blowing somewhere else" argument. Clearly, in the UK, the power averaging due to the geographic separation of the turbines falls very far short of the usual bland statement that "things even out".
This is a graph of nuclear power output over this 3 month period. Notice how steady it is as it provides us with essential, solid, predictable Base Load generation. The variation is where the Power generator is matching demand not the result of a lack of "fuel" or wind (interestingly, there does appear to be a drop-out. and that, my friends is exactly what spinning reserve is for!)
The mess below is the wind power output for the same period.
It is a chaotic unpredictable set of short duration spikes smeared over a grindingly low background. How anyone could suggest that this can be used to reliably provide 30% of our power is beyond me. There are those though who even suggest that this could be used for base load power generation.
God help us all if the likes of Chris Huhne is stupid enough to continue pushing us down this road.
Love & Kisses
Billothewisp
The snapshot I used is available HERE
The first graph below is a frequency plot of power output against half hour billing slots. It shows how often, within the 3 month period wind power contributed a particular power level (power level - X axis number of half hour periods - Y axis. (Sorry forgot to label the graph properly)
The most shocking outcome from this graph is that the most common output from the whole of the national metered wind power system is 300MW. That equates to 12% of their maximum rating of 2430MW. They were running at this level, or less for more than 30% of the 3 month period.
The graph indicates that while in the 3 month period the output fell to close to zero (less than 100MW ) for no less than (in-total) 147 hours, at no no time it ever reach anywhere near the often hyped maximum rating. In fact the total output never even reached 85% of this rating. The absolute maximum achieved was 2065MW (84.8%). This was achieved for (in-total) one hour in the three month period.
This graph below shows the half hourly power ratings linearly from low to high. Wind energy is governed by a cube law. Double the wind speed and get 8 times as much power (unfortunately the reverse is also true - halve the speed get 1/8th the power). Here you can see the cube law in action and how it skews the output so most of the time wind power generation is BELOW the Capacity Factor
The raw average (or capacity factor), which is arrived at by simply adding all readings up and then dividing by the number of readings gives an capacity factor of 25%. (608MW) On their website the BWEA suggest it is 30%. Often the figure gets inflated further. The press blindly accept what they are told.
This otherwise laudable Daily Mail Article falls into exactly this trap.
Remember these NETA figures include offshore as well as onshore sites so the Capacity Factor is certain to be even poorer for on shore turbines alone.
The BWEA suggest that the capacity factor taken in isolation is meaningless. I (sort-of) agree with this. As electricity generation cannot be stored, the duration of the power generation operation is as important (or arguably more so) than the averaged value.
In this three month period the wind output only managed to reach or exceed this capacity factor (25% - 608MW) for less than 40% of the time. If you use the much hyped BWEA figure of a 30% capacity factor, then this value was only reached or exceeded for 23% of the 3 month period.
Due to the cube law relating wind speed and power output, we find that half the 3 months energy arrived in less than 25% of the time leaving the other half to cover the remaining 75% of the period. This is actually an improvement on the single facility figures of about 15% found in the USA (Lee Ranch Sample Data (1/2 way down this page) .
This improvement from 15% to less than 25% is the contribution from the grossly overstated "if its not blowing here its blowing somewhere else" argument. Clearly, in the UK, the power averaging due to the geographic separation of the turbines falls very far short of the usual bland statement that "things even out".
This is a graph of nuclear power output over this 3 month period. Notice how steady it is as it provides us with essential, solid, predictable Base Load generation. The variation is where the Power generator is matching demand not the result of a lack of "fuel" or wind (interestingly, there does appear to be a drop-out. and that, my friends is exactly what spinning reserve is for!)
The mess below is the wind power output for the same period.
It is a chaotic unpredictable set of short duration spikes smeared over a grindingly low background. How anyone could suggest that this can be used to reliably provide 30% of our power is beyond me. There are those though who even suggest that this could be used for base load power generation.
God help us all if the likes of Chris Huhne is stupid enough to continue pushing us down this road.
Love & Kisses
Billothewisp
Labels:
intermittency,
reliability,
wind power
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