Monday, March 14, 2011

Nukes, Black Swan Events and Wind Turbines

Summary
Japan has recently been nailed with a one two punch of a massive earthquake (9.0 on the Richter scale) plus the subsequent massive tsunami when a length of one crustal plate sliding over another one lurched suddenly, and the main island of Honshu moved 8 ft closer to North American in a very short period of time. The fault line was "only" 150 km long, and a few km wide meters wide, but that's a lot of water that gets moved. The surge of water was between 7 to 10 meters in many places (25 to 33 feet). See http://www.dailykos.com/story/2011/03/13/956106/-Major-Update:-Catastrophic-Failure-of-Sea-Walls-in-Japan ... The good news.. it could have been worse, especially if the 400 km length of plate had shifted like it COULD have...

Unfortunately, this is a bit like a Michael Chrichton novel, where Murphy of Murphy's Law fame (if it can go wrong, it will) is constantly wrecking havoc by inserting chaos into someone's well-ordered life and societal plans. And so Japan got nailed, in the nukies, so to speak. No country practices earthquake and tsunami disaster prevention, civil defense and mitigation as well as the Japanese, as they KNOW they are on several earthquake faults, and they have a history with them. So, when the earthquake hit, many reactors in the country "scrammed" and went into shutdown mode ASAP via inserting the control rods into the reactors bringing the nuclear fission reactions to a halt. The lines carrying grid electricity in or (generally) out were severed, so the back-up diesels (13) kicked in, providing much needed electricity to the site. But about 55 minutes after the quake, a 7 meter tall wall/mound of sea water slammed into the Fukushima Daiichi complex (6 reactors), and it knocked out the diesel generation (probably shorting out the switchgear/wiring in the basement). So now there was a site electrical blackout, and that's when things got ugly real fast. All that remained was 8 hours worth of battery supplied electricity, and mostly enough to operate the controls and instrumentation and not much else. Then came the LOCA (Loss of Coolant Accident), which leads to a whole new level of grief and misery. Nukes are NEVER supposed to have a LOCA event happen ....

So 4 days later, two (Unit 1 and Unit 3) of the three active reactors have undergone a partial core meltdown (now we also know that Unit 2 may be in even WORSE shape), and a huge quantity of hydrogen was generated when the red hot fuel rods made of a zirconium alloy (a chemical relative of titanium) reacted with steam to make hydrogen gas. The H2 gas was vented from the steam system (otherwise the reactor core would have burst open as a result of the enormous pressure generated), and in each case, ignited in a spectacular fashion, blowing the top roof off of the reactor building. (Note: one ton of zirconium can make 88 lbs of H2 gasfrom 792 lbs of water, and each meter of fuel rod assemblies has at least 15.4 tons of zirconium in the fuel rod tubes for just the small reactor in Unit 1). Rumor has it that reactor #2 has also gotten damaged. And this is no where near the end of this ongoing immensely tragic tale.

The question of the day is why did Japan choose the nuclear path, and why was it willing to up the ante with 17 more of them (55 so far). And another question concerns the U.S. - why, given our humongous wind resources and need to create jobs, would the "nuclear option" be pushed so hard, especially when it produces electricity more subsidized and more expensively than can be made via onshore wind, and at an enormously greater risk while making FEWER (estimated 50% less) jobs per billion dollars of investment in installation? And this same problem (earthquakes under the reactors, tsunami's nailing coastal units) could and eventually will happen to our country. Just for comparison, if our wind potential was converted to electricity with commercial scale presently available wind turbine models, we could make 25 time our current production/usage of electricity; talk about more than a mouthful! Tapping only 8% of our commercializable wind can power up our country twice over - enough to account for storage losses (mostly pumped hydro), and the replacement of all natural gas and oil for heating, as well as most gasoline usage in cars (replaced with electric/plug in hybrid cars).

So, to paraphrase Clint Eastwood, "Well, punk, are you feeling lucky?" Who want's nukes? Speak up now, and the Federal, and many state governments are willing to tap into a $50 billion or more fund to make sure that in a decade (maybe more, maybe less), you too can have one. In NY, Nine Mile 3, rated at something like 1.6 GW and sure to cost over $18 billion, was planned for just north of Oswego, able to tap the enormous cooling capacity of Lake Ontario and the NY City electricity market. "Well, punk, what do you say?"

How About Some Attitude...
Sure beats wind turbines, any day, right? We wouldn't want to be around when they malfunction in a "wind meltdown". And besides, think of the horror of having to look at them, off in the distance all day long (well, you mostly get a break at night), usually spinning away. What's a little (well, maybe a lot, but then it's a bit like a crap shoot with regards to who gets nailed and to what extent) radiation induced alteration of your genetic code worth, anyway? It sure beats the grief and misery wrought by widespread wind turbine installation and having to gaze upon those infernal blights upon the viewscape, right? Don't you have a right to control the images you perceive as a result of light photons flowing through the air and impinging upon your eyes? Besides, your only other choices than nukes are zilch for electricity are coal burners, or maybe some gas burners (while the coal and methane last, as there are only finite supplies of those in the U.S., too) when you toss out the wind turbine option, along with your collective environmental sanity..... And don't you like the resulting mass unemployment when so many are idled because there is not much to be made that can be sold to those with money and/or available credit when the wind turbine option is ignored, and not used. After all, mass producing wind turbines might fix that situation somewhat (well, significantly for a couple of decades), and really upset the apple cart that results in most of our income and wealth getting shoved up to the wealthy, from you know who. We can't mess that scene up and employ mass quantities of the presently unemployed, now, can we?
OK, enough with the attitude...

Discussion
So what is a Black Swan Event? One version is some fairly rare event, where "the event is a surprise (to the observer) and has a major impact. After the fact, the event is rationalized by hindsight". Another refers to the risk embodied in "fat tailed risk statistical distributions", where risk is defined as the probability of an event times the severity/impact of that event. Examples of this include the current Great Recession, the Great Depression of 1929-1941, the 1919 Influenza epidemic that was set off by WW1, the massive meteor strike in Yucatan 65 million years ago, Chernobyl and of course, Japan's recent combination of earthquake-tsunami-Fukushima nuke disasters. One characteristic is that normal predictive statistics have zero relevance with Black Swan events. A rare event that has a massive impact is often a "game-changer", which can alter events from the time of the event onwards in an often dramatic manner. See http://en.wikipedia.org/wiki/Black_swan_theory; this also encompasses the problem of "you can't deal with what you can't predict". Most common events can be analyzed by "normal probability distributions" (it's called that for a reason), when lots of previous events form the basis for a prediction about what might occur in the near future, and this view slants how we attempt to analyze the risks of the things we do. But that has ZERO relevance for rare events, because there are never enough of these occurring to be able to analyze these via the "large number of samples" statistical approach. And the cure for the nuke version of a Black Swan Event - well, more "resiliance", less risk, a more widespread approach to making electricity, and one without nukes. It's basically impossible to take the Black Swan hazard out of nukes, environmental or financial.

This is more of a thought process problem. For example, to date there have been 6 partial of complete core meltdown events from commercial scale nukes:

1. Fermi 1 - Monroe (Detroit) Michigan, 1967 - 94 MW Liquid sodium coolant fast breeder
2. Three Mile Island - Harrisburg, Pa, 1978 - 802 MW water coolant reactor
3. Chernobyl - USSR/Ukraine, 1987 - 1 GW Graphite moderated reactor/boiler explosion
4. Fukushima Unit 1 - Japan, 2011 - 439 MW Boiling Water reactor (1970)
5. Fukushima Unit 2 - Japan, 2011 - 760 MW Boiling Water reactor (1974)
6. Fukushima Unit 3 - Japan, 2011 - 760 MW Boiling Water reactor (1976)

Even before the set of 3 units at the Daiichi site malfunctioned, there were 3 examples of "it can't happen here" happening. Each time, the accidents were rationalized as being "once in a lifetime", "once in a century events" or "once in a millenium" events, highly improbable, and 3 events is not enough to compile a decent statistical profile of accident probabilities. But, it WAS known and IS known that they OCCUR, and that the events following them can be (or in the case of Chernobyl, were) completely unacceptable. Not only were these examples of a massive squandering of financial resources, but the possible downside can lead to widespread poisoning of the environment and of people who might live there.

So, what is the price for a ruined life, or one with a 10,000 times normal probability of getting some nasty form of cancer? How about thousands of lives put at risk, or millions who will get nailed by cancers that they otherwise would not have contracted? And what about the afflicted offspring, who suffer a wide variety of maladies, such as compromised resistance to all kinds of diseases? Who pays for up and moving hundreds of thousands of people, and all that goes with that? And will the bureaucrats (governmental and/or corporate) who allowed, financed, supervised, inspected and the corporate owners who profited from this be suitably punished (for example, death by radiation poisoning in a 1 hour period, and viewed on You-Tube so as to be a dis-incentive to screwing up in the future) as the responsible parties to a nuke disaster? Well, that never seems to occur, except maybe in Russia, minus the You-Tube, of course.

And how does this translate into money? Well, not well, but it does translate. After all, there is a lot of money tied up in those nukes, and then major parts of the economy become dependent upon the electricity produced by those nukes, and they won't function without electricity from SOMEWHERE. Odds are, that nuke electricity is highly subsidized, and electricity customers become highly addicted to it; sudden withdrawal of that cheap stuff and replacement with more expensive stuff can have economic consequences (good and bad) and to varying degrees on various organizations and individuals.

Another hard to translate concept is nuclear proliferation. Nukes were originally made as part of the U.S. nuclear weapons mass production systems, which involved something like $2 trillion, back when a trillion dollars used to mean something. Numerous reactors in Hanford, Washington and Savannah River, Georgia were designed to mass produce Pu 239 (Hanford) or Tritium (Savannah), though there were back-ups to an amazing degree. The Soviets also replicated this arrangement, and this has been copied to a lesser extent by Israel, India, Pakistan, China, France and Great Britain, and maybe by North Korea. One way to stop the mass production of The Bombs (all fission, fusion (H-Bomb, neutron bomb and "county buster" (fission-fusion-fission combination)) is by stopping the production of plutonium and possibly tritium by shutting down nuclear reactors. Both Pu 239 and Tritium (hydrogen isotope composed on one proton and 2 neutrons) are made by exposing parent elements to neutrons of the correct energy (for example, U238 plus a neutron can give Pu239), and the mass quantities of neutrons are provided by nuclear fission of U235 or Thorium.

After all, if you are going to be a government with nuclear weaponry, it makes no sense to have just one Bomb; after you use it (assuming it works), you have no more, and odds are, revenge will not be long in coming, which is where having all those back-ups come in handy. Insane though it may be, and it is called MAD (Mutually Assured Destruction) for a reason, and the cost to do this is an enormous and onerous drag on the economy (all those resources used to make something which, when used, means the probable swift destruction via retaliation of the government/society that used it in the first place) - it doesn't matter, apparently. Just about anything will get sacrificed to mass produce the Bomb and associated delivery systems, Pakistan being the present poster child of that sad fact (Pakistan is really poor, most of it's people are, and yet so much was squandered to get it's present stash of 40 or so nuclear Bombs).

The Black Swan Event
Here is a "before picture" of the site, which unfortunately had the 13 diesel back-up gensets located next to the water.


Next, here is the after; the tsunami wall was rated for a 6.5 meter wave, but this one came in at over 7 meters, and it just took out the back-up gen sets, and more importantly, the electrical switchgear. Odds are, the water pumps needed close to 2 MW per reactor at 75 atm operating pressure (about 1100 psig). Under normal operating conditions, each reactor needs 15 million gal/hr for the small Unit 1, and about 25 mgh for Units 2 through 5, but its a big ocean.....


During the initial hour, much of the pressure in the reactors would have been bled down via the condenser water, with the cooling water pumps powered by the back-up diesels. But when those got trashed by the tsunami, the site went "dark" except to the 8 hours of battery power.

Here is a view of the plant arrangement, from an awesome article at http://www.dailykos.com/story/2011/03/14/956193/-What-the-Fukushima-20Big-2X-Update-w-photos-(UPDATED-2X):

In this diagram the "Mark 1 Containment Building" is on the left (cylindrical reactor in center, spent fuel storage "swimming pools" in blue above the reactor), and the electricity generation building/steam condenser building is on the right. The big pipes visible in the "before" picture are probably cooling water lines ending up at about a smallest size of 48" diameters.

Once the control rods (neutron absorbers) were inserted, the fission reaction was stopped, but the radioactive decay of the fission "daughter products" still continued. These isotopes are unstable, as they contain too many neutrons for the number of protons. Upon decaying, a lot of heat is generated when the energy is near or at the speed of light particles (electrons, various nuclei, gamma ray photons). In many cases, a freshly spent fuel rod will heat up at a rate of about 1 C per second unless promptly immersed in water, so in less than 17 minutes, such a fuel rod would be glowing red as it emanates heat. Here is an awesome article that goes into some detail on LOCA events and attempts at LOCA prevention: http://www.theoildrum.com/node/7638#more.

Here is an example - and for comparison, fission of U235 makes about 200 Million Electron-volts (Mev, the unit of choice for atomic energy of energy), and a blue light photon has about 2.6 electron volts of energy (480 nm wavelength which corresponds to a temperature of 30,000 C - see http://en.wikipedia.org/wiki/Electronvolt#As_a_unit_of_temperature). In this, n is a neutron, e- is an electron, t is the isotope half-life, and ph is a gamma ray photon(s), and the starting uranium atom has 92 protons and 143 neutrons before it "eats" a neutron:

n + U235 --> "U236" -> Rb90 + 2 n + Xe 144; 200 Mev

Rb90 (t= 2.6 mins) -> Sr90 (t= 29.1 yr) + e- + ph; 6.59 Mev

Since Strontium 90 has a long lifetime, the decay reaction more or less stops here as far as in the reactor heat generation goes.

Xe144 (t= 1.2 sec) -> Cs144 + e- + ph; 8.47 Mev
Cs144 (t= 1.01 sec) -> Ba144 + e- + ph; 4.9 Mev
Ba144 (t= 4 sec) -> La144 + e- + ph; 4.9 Mev
La144 (t= 40.7 sec) -> Ce144 + e- + ph; 5.5 Mev
Ce144 (t= 284 days)-> Pr144 + e- + ph; 0.32 Mev
Pr144 (t= 17.3 min) -> Nd144 (t=2.1 x 10^15 yrs) + e- + ph; 3.0 Mev

Neodynium (of magnet fame) is also very stable - it's half-life is about 1.5 million times the life of the universe.

n (t= 10 min) -> proton + e- + ph; 1.29 Mev (2 of these)

In this arrangement (about 6% of fissions), the decomposition of fast decaying isotopes would give off 37.46 Mev, or about 18.7% of the energy liberated by the fission reaction. Supposedly, about 7% or so of a reactor's energy is given off by the "hot daughters", but this may depend on the fuel rod "cycle" (some fraction of the fuel rod bundles are swapped out after about 9 to 15 months for storage in the "swimming pools", so a reactor very close to "refueling" would be thermally heated by decomposition reactions to a greater extent than would one that just started up). From the good folks at The Union (of Concerned Scientists) comes a great example:

from http://allthingsnuclear.org/post/3859682324/reactor-core-cooling

In this graph, the time scale (x) is logarithmic. For a reactor like the Unit 1, the water boil-off rate is going to be 92 gpm of water at 24 hours after shut-down, and probably 128 gpm at 0.1 days (2.4 hours). At 128 gallons/minute, the water level drop is about half an inch per minute, and there is only 196 inches of water above the top of the fuel rod assemblies. BTW, 92 gpm is about 23 tons/hr, a non-trivial amount.

Oops. No cooling means a major, if not epic amount of grief coming shortly. This happened in all three active reactors.

But, this is not the only source of grief. Those swimming pools also need cooling, otherwise, they too will begin to boil. And even if those rods have been cooling for a year, they still have a problem with heat removal. If not kept cool, they too can eventually catch on fire though it may take between a day to a week. Once that happens, they will spew some really nasty medium duration isotopes, such as Sr90 and Cs137 around, and if inhaled/ingested, these can basically give a person a constant X-ray from the inside. Totally not good.

The fuel assemblies in the reactor, if they get out of the water, then start to glow cherry red. The zircalloy tubing that holds the fuel pellets then starts to react with the steam, forming zirconia (which flakes off) and hydrogen gas:

Zr + 2H2O --> ZrO2 + 2H2

At 88 lbs of H2 per ton of Zr, this is about 15,600 cubic feet at standard pressure (like the outdoors), and probably equal in destructive potential to about a ton of TNT. A one meter length of fuel rods could lead to about 2/3 of a TON of hydrogen gas. The H2 gas has to get vented from the reactor (otherwise it would burst apart from overpressure), and when it is vented with steam into the top of the containment building, rapidly, it can collect in the upper section of the building (above the swimming pools). Add a spark (or initiated by ionizing radiation from radioactive impurities), and this is like a fuel-air bomb, with the following results (these are huge buildings of reinforced concrete, and not lightweight structures):

This is the before and after picture of Unit 3 Notice anything about where the fuel rods would have been placed in the pools (see reactor diagram)? Try this view:


Remember, "oops" is not something that is supposed to go with nukes. Nor are humongous explosions on/in/above the reactor building.

And this would never happen? The odds of this were supposedly 10^-5 reactor years; that is, one core meltdown if 100 reactors operated for 1000 years. Yeah, right; we just had 3 in 3 days.

In Conclusion
Perhaps the nuke probability estimates were a wee bit generous on the side of the nuke operators. However, if the public ever thought these would happen, nukes NEVER would have been allowed. There are massive subsidies as a result of POLITICAL decisions, many of them bought and paid for by corporations who had a big financial interest in the outcome of such wrangling. In the U.S., if the Price-Anderson Act never got adopted or ceased to get renewed, there would be no privately owned nukes, period. A recent Union of Concerned Scientists report (~143 pages) estimates the subsidies given to nuke owners as 7.5 cents/kw-hr - but all those have the Price-Anderson Act (very limited liability of owners to damages above $11 billion) as a prerequisite; no Price-Anderson Act, no nukes (see http://www.ucsusa.org/nuclear_power/nuclear_power_and_global_warming/nuclear-power-subsidies-report.html). Nukes are some classic "welfare queens", and that does not include the problem of where to put the trash (spent fuel rods), which STILL has no licensed facility to house them in the U.S. That also should be a "cease and desist" moment, especially when you look at what passes for the roof on Unit 1 at the Daiichi complex. Obviously, anything still in those pools is not stored safely, and will soon be making a royal mess of things once they catch on fire/emanate rad-waste nasties all over the region, depending on which way the wind happens to be blowing.

It is already less expensive to produce electricity from new wind turbines versus a new nuke, and that was before the "new" risk premium got added onto new nukes. Part of this is because wind turbines are "modular" (1.5 to 3 MW units), part of it is because a project time-line to so much quicker (1 to 3 years) versus a nuke (10 years) and part of this is just the capital cost per average delivered MW (about $2 million to $3 million per MW for wind, about $12 million for a new nuke - see http://climateprogress.org/2009/07/15/nuclear-power-plant-cost-bombshell-ontario/). The greater risk (financial, environmental, political, national "insecurity", etc) of nukes will now make them even more expensive. Odds are, there will never be a new nuke installed in the U.S. for at least the next decade.

And yet, those in favor of nukes have a near fanatical religious belief in their product. Odds are, no one can ever shake them from this belief. But it is the money guys that really matter, and they only believe in money. The You-Tubes of the TWO explosions over Units 1 and 3 have effectively ended the political basis of the financial subsidies and access to cheap and easy credit, and without those, nukes are toast.

Of course, just because wind turbines are now the lower cost way to make electricity without CO2 pollution, this does not mean that this path will be followed. The wind business needs security to make financial sense - of pricing, and of access to the grid. Without systems like those in Ontario or second best options like those of Quebec, few wind turbines will be able to be installed. But, get some version of setting prices for wind sourced electricity based on the cost to produce it and not the cost of coal or natural gas, and we could easily power up this country on wind electrically speaking, and still have plenty of potential wind sites to replace the natural gas used for heating and most of the liquid fuels used for transporting goods and people around. And at less cost than new nukes, new coal burners and various forms of solar energy.

Of course, if "the powers that be" (mostly unelected) don't have the will to do it, it probably won't be done, unless there is a really strong push from "below".

But, all that wind turbine manufacture and installation, and associated pumped storage installation might cause the wrong kind of Americans to be able to get jobs. And so far, there is no evidence that almost all of the Republicans and a lot of the Democrats find that to be an attractive idea. It would be nice if at least most of those Democrats "get with the program", and take this idea of significant renewable energy (in the U.S., mostly based on wind, not just "sort of" based on wind) up as a political issue as an economic development policy that also provide low risk, clean electricity. Who knows, enough of them might get elected so as to make the often environmentally insane Republicans not very relevant.

Otherwise, we can wait for our Fuku event... like the twin sets of twin nukes in California, placed atop/close to the San Andreas fault. Or the ones near St Louis, near the New Madrid fault. And what about if this is not just an accident. After all, you don't need to blow up the building, just block the cooling water access to the core, even when it is shut down and no longer "fissioning", just "decaying". The means to do a nuke in come from the nuke, a fact that has been well known for a long time, but is now evident for all to see.

A great saying to remember: "You can never foolproof anything forever, as fools are too clever". Another one is to register to vote. A supremely less dangerous way to make homegrown electricity than nukes (wind) can only be economically viable when the politics gets the pricing system right. And no subsidies or tax breaks or tax avoidance schemes need to be invoked, either.

DB

Friday, March 4, 2011

New Dudes (Wind Turbines) on the Block

.................... from http://www.nordex-online.com ..........................

Summary
There have been recent additions to commercial scale wind turbines in the recent past, which fit into the category of Low Wind Speed Turbines (LWST's). New additions include the Nordex N117, RE Power's MM114 turbine on a 143 meter tall tower, and Gamesa's new G97 turbine, which also has a tall tower option. These units can produce electricity on a subsidy free basis for less than 10 c/kw-hr from hub height wind speeds of 5.5 m/s. For comparison, most U.S. wind turbine installations occur in places with a hub height wind speed of more than 7 m/s at present, where wind speeds average twice the power of those at 5.5 m/s.

Introduction
The trend towards LWST manufacture and deployment seems to be picking up steam, as well as the offshore wind turbine business in Europe. In some ways, both are related pehnomena - Europe is serious about producing more electricity from wind, as this is a much less expensive way to do this than by using photovoltaics and solar thermal systems, especially in areas where the suns shines unobstructed for less than 75% of the time. In much of Europe, as is the case for Buffalo, the insolation rate (unobstructed by clouds) is at 50% (Buffalo) or less than that (northern Germany, Denmark, Nordic countries and especially England-Scotland-Ireland).

Also of note, onshore wind is generally less expensive than a new nuke or a new coal burner, especially one that has to stash the CO2 trash. The initial attempts at burning natural gas and then stashing the CO2 trash only seem to make sense for areas new where the CO2 can be used in oil fields (CO2 under severe pressure acts like a solvent for oil (a supercritical solvent) that can lower the viscosity of the oil-CO2 phase, and this get it to the oil well). Of course, the big unknown with Ngas is the price, which is essentially impossible to forecast 5 years from now due to POLITICAL and SOCIAL factors in countries either producing this gas from gas fields, or from those countries which have gas pipelines flowing across them (i.e. Ngas trolls).

So, if you want a source of electricity that will be reliable and predictable in price for at least the next 20 years, wind is one of the better ways to go. In Europe, they are willing to go for prices that are 13 Eurocents/kw-hr or more (17 to 20 US cents/kw-hr) from wind, and that is why there is the rush for offshore wind. The Black, Baltic, North and Mediterranean Seas, and the Atlantic are plenty windy, especially the North Atlantic/North Sea, where wind speeds averaging 9 to 10 m/s are quite common and quite well distributed over very large areas of water surface.

Of course, onshore wind is cheaper than offshore wind, but many of the good spots in Europe are already used up, or else have cities on them. Thus, more wind derived electricity must come from areas where the wind speed at 80 meters above the ground is less and less useful using conventional turbines. So, there are three solutions - use a conventional turbine on a taller tower (wind speeds increase as the tower height increases), use a turbine designed for slower winds (a LWST), and/or use a LWST on a taller tower. That way, more electricity can be derived from a given area of land.

Discussion
The electrical power output of a wind turbine is proportional to the cube of the wind speed at the hub height, and the square of the rotor blade radius (one rotor blade length). At any given site, the key to getting more power out of a given wind turbine is to use a bigger rotor blade for a given generator size and a taller tower, since the wind speed at a given site increases with the height above the ground. Of course, manufacturers of wind turbines have to be worried about the cost to make these systems, since a taller tower and a bigger blade costs more money to make. Items such as generators and transformers also increase in price as their capacity increases, just to complicate a very complicated puzzle of a device with at least 8000 components to it.

The LWST developments are aimed at making electricity a viable business for about 50% of the land area of the U.S. - most conventional wind turbines are only useful for about 15% of the U.S. land area, such as coastlines, ridgetops, the Great Plains and certain special spots that can be classified as "wind canyons (like Altamont, California). The choice 15% of fast wind areas tend to have an average wind speed of more than 6.9 m/s at 80 meters above the ground, and the vast majority of such areas are located at long distances from big load centers (like NY City), though there are exceptions. So anything that can utilize mellower winds (5.5 m/s to 6.9 m/s at 80 meters above the ground) can be placed closer to where the electricity is actually used, which is quite a valuable characteristic.

Most of these "mellower wind" zones have a lot of wind obstructions (hills, buildings, and especially trees), and wind speeds are slowed by the friction of a fluid (air) flowing over a rough surface). The change in wind speed versus height is known as the wind shear, and is quantified via a value called the surface roughness (z0) or else the wind shear exponent (a). In most areas of the U.S., the wind shear exponent is near 0.2, and this means that winds at 120 meters above the ground, wind speeds would be 8% faster than at 80 meters above the ground, and the power in the wind would average 27.5% more at 120 meters height versus 80 meters height. Going with the taller tower means that the capital cost rate of that turbine (as in $/MW-hr due to paying back the installed installation cost of the turbine) can drop by 20%, and overall operating cost can be 15% less. Of course, taller towers cost more to install, so this lessens the benefit somewhat. More importantly, you can get 20% more power out for a given site by going with the taller tower.

There are limits to this beneficial effect, but so far Enercon (Germany's largest wind turbine manufacturer) has settled on a 135 meter tall tower for their turbines (notably the E126 x 7.5 MW unit, and the E101 x 3 MW/E82 x 2.3 MW systems), but they refuse to sell their units in the U.S. market (you can buy them in Canada, however). Such turbine towers introduce another problem, which is the flexibility in steel, and the need to have very thick lower sections (which have more mass per unit length, and cost more since steel is sold on the basis of mass. Three solutions to this are the use of reinforced concrete towers (notably Enercon), the use of hybrid towers (bottom part is concrete, top sections are steel) and finally, sectioned steel columns that are assembled into cylindrical sections at the installation site. At present, a diameter of 4.2 meters (13 feet 9 inches) is about as large as can be transported by road (fits under bridges), and 50 tons is about the upper mass limit that most roads can handle. The concrete tower sections are usually precast in a factory, and assembled on site, and sometimes each cylindrical ring is made of more than on section. These concrete sections can be up to 1 ft thick, and the concrete towers (with steel reinforcement) are very rigid, and thus vibration problems are minimized. So, tall tower problem solved, and the problem now becomes which option to choose and how tall to install.


The New Dudes on the Block
Nordex recently announced their version of the LWST - the N117. This unit is based on their nacelle design of their 2.5 MW systems (they have installed more 2.5 MW units than any other company). It features a 58.5 meter radius blade (117 m rotor diameter), for a swept area of 10,751 meters (bigger than 2 football fields), a 91.5 m all steel tower and a 2.4 MW generator. This unit has been tuned for moderate wind speeds, and they claim that a net output of 40% (average of 960 kw) should be attainable in many places. At the top of the blade rotation, a clearance height will be 150 meters. No plans for taller towers have been listed, yet. The power ratio (rotor area divided by rated generator size) is 4.48 m^2/kw. See http://www.nordex-online.com/en/produkte-service/wind-turbines/n117-24-mw.html?no_cache=1 for more details. This would be made in Arkansas.

Gamesa recently introduced a stretch version of its G90 (90 meter) x 2 MW turbine - the G97 x 2 MW. With a rotor area of 7390 m^2, this unit has a power ratio of 3.69. Tower heights of 90 and they have a 120 m hybrid tower under development - see http://www.gamesa.es/recursos/doc/productos-servicios/aerogeneradores/catalogo-gamesa/catalogue-gamesa-g9x-eng.pdf. This would be made in Pennsylvania.

RE Power just announced (just in time for a major European wind energy trade show) that it will sell (in Europe, anyway) its 3.2 MW M114 (114 meter rotor diameter) with a 143 meter hybrid tower system. With a swept rotor area of 10,207 m^2, this unit would "only" have a power ratio of 3.19 m^2/kw, the 143 meter height could provide a 32% greater power output than a similar unit placed on a 90 meter tall tower. See http://www.repower.de/index.php?id=151&backPID=25&tt_news=3183&L=1.

These units supplement a field that only had the Vestas V100 and the RE Power MM100 - both 100 meter rotor diameters with 1.8 MW rated outputs, and with a power ratio of 4.36 m^2/kw. The V100 has tower height options of 78 and 95 meter heights, while the MM100 only comes with an 80 meter tower, so far:

Vestas V100 - see http://nozebra.ipapercms.dk/Vestas/Communication/Productbrochure/V10018MW/V10018MWUK/
REPower MM100 - see http://www.repower.de/MM100/?L=1


So, bottom line, the old excuse of "inadequate wind resource" for much of NY state has now been reduced to a status of Richard Pryor's famous phrase "Honky Jive". Here is how you can replace all polluting sources of electricity. We just need to get sensible pricing for electricity that is designed to facilitate renewable energy WITHOUT government subsidies (why use up all the day care money by subsidizing wind turbine installations with tax payer monies). Most countries of the world who have successful renewable energy programs have the customers (electricity consumers) footing all the bills.

So why can't NY State have a mature renewable energy pricing system instead of a gambling casino on which long term electricity prices are based on wildly fluctuating fossil fuel prices, and where huge external costs are not included in the prices of pollution based (coal, oil, natural gas and nukes) electricity (yes, that is a subsidy)? Well, the answer for now is not one that indicates intelligence on behalf of most NY State leaders, just ignorance, in spite of the efforts of a few.

DB

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