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PostPosted: Dec 16, 2007 5:29 pm 
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The thing about wind power that people don't know or don't remember is that it's cost is very location dependent.

But since it's mostly built for political purposes, it is rarely built in the best places or in the best ways.

Offshore is very expensive if the sea is deep for example. (There are a great many places with shallow offshore areas, but the local government there might not have the local political incentive for wind power.)
Or if the cable distance is long. Or some other things. The big turbine technology is still developing: usually bigger turbines work better offshore since you have to build less foundations for the same amount of megawatts. On the other hand, you need a bigger special crane that could cost a lot to rent and bring from somewhere.
Wind generator park cost structures will be very different in the future: both the technology and the whole effort scale will be different, and possibly carbon price will increase electricity prices.

People do all kinds of categorical statements nevertheless. "Wind project XX would have cost YY, clearly wind power is too expensive ever".

With the electron economy there will be a sizeable market proportion that can benefit from the not-constant wind power.

Hydropower with reservoir is the best pal for wind power. In many places wind power portion could be easily upped to significant percents of power production (over 10%) and it would require only minor conventional additions to the grid.

There are models and software where you can simulate a nation's electricity grid quite closely and produce different scenarios, with quite accurate results.


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PostPosted: Dec 16, 2007 6:11 pm 
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meiza wrote:
Hydropower with reservoir is the best pal for wind power.

It can also be said that "Hydropower with reservoir is the best pal for nuclear power."

For instance, if France had lots of hydropower with reservoir, its nuke plants wouldn't need to load-follow, and you would need fewer of them, because energy can be stored in hydro reservoirs.

But there are few countries in the world with even a fraction of the capacity needed to store the required amounts of energy -- be it from wind farms or nukes.

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PostPosted: Dec 16, 2007 6:46 pm 
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jaro wrote:
meiza wrote:
Hydropower with reservoir is the best pal for wind power.

It can also be said that "Hydropower with reservoir is the best pal for nuclear power."


Well that's the way we do it in Belgium...Our reservoir at Co is filled when our power plants would have to level down.

But like meiza said, wind power is very location dependent. And if you build your wind turbines at a very good location, it can have a rather good availability.

But I doubt anybody can be against wind power, you just have to take into account the disadvantages of wind...and even if it is costly, CO2 emission and fossil fuels will become more costly in the future. So if you can reduce a part of those, you are always in a win situation. (well that's my opinion, but I'm a half green-half nuke person)


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PostPosted: Dec 17, 2007 1:08 pm 
Kirk Sorensen wrote:
I know I sound like a broken record on this, but it would be better to take the money intended for this high-temperature gas-cooled reactor and devote it to the liquid-fluoride thorium reactor instead. The LFTR can fulfill the hydrogen mission AND close the nuclear fuel cycle, something that the gas reactor will never be able to do. Furthermore the LFTR won't require the expensive fuel qualifications program of the gas-cooled reactor.


Thermochemical production of Hydrogen using the Sulfur - Iodine cycle requires in excess of 850C. While Molten salt reactors have demonstrated very high temperatures, I seem to remember that hastelloy-N corrosion is accelerated above about 650 C, and this would necessitate the development of new corrosion resistant materials.

Essentially, the VHTR has some issues with fuel reprocessing, but at the moment it appears it will become the first reactor capable of sustaining an outlet temperature above the threshold for the SI Hydrogen cycle for long extended periods of time ( decades ), hence the interest in them. Furthermore, the Gen IV initiative is set up to facilitate cross-cutting research, and since a lot of the research into VHTRs are on high temperature brayton cycles and thermochemical hydrogen production, these projects will likely help the MSR as well.


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PostPosted: Dec 17, 2007 1:18 pm 
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There are hundreds of different approaches to thermochemical hydrogen generation, of which sulfur-iodine is one. Many others operate at lower temperatures, at the expense of some efficiency reduction.

The Brayton cycle used in the gas-cooled reactor is penalized vs. the Brayton cycles that could be used in the fluoride reactor by the inability to do multiple reheat. Multiple reheat improves efficiency, but improves the specific net work of the helium flow much more, which reduces turbomachinery size substantially.


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PostPosted: Dec 17, 2007 3:09 pm 
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Jonatan wrote:
While Molten salt reactors have demonstrated very high temperatures, I seem to remember that hastelloy-N corrosion is accelerated above about 650 C, and this would necessitate the development of new corrosion resistant materials.

It seems to me that your premise is that MSR technology is not allowed to progress beyond the achievements of ORNL in the sixties.

Four decades is a long time, and much has happened since then, in high-temperature materials development, especially in the area of composite materials.

In fact, there is nothing all that novel about composite materials such as Liquid silicon infiltrated Carbon-Silicon carbide composites (LSI-C/SiC), and the various pieces of equipment that have been manufactured using the material, for use in high-temperature applications (950°C to 1200°C).

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 Post subject: About He
PostPosted: Jan 26, 2008 3:26 pm 
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Wondering...isn't helium a finite resource?

David


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PostPosted: Jan 28, 2008 3:47 pm 
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The helium recirculating turbine concept is very attractive: inert, low neutron cross-section, high efficiency, etc.

Air turbines are better developed. Maybe we could afford to lose a few percent of efficiency, and make it up in equipment and siting costs by eliminating the large, low-temperature heat exchanger and water-feature on the back end of the thermal cycle.


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PostPosted: Jan 28, 2008 4:53 pm 
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rgvandewalker wrote:
Air turbines are better developed. Maybe we could afford to lose a few percent of efficiency, and make it up in equipment and siting costs by eliminating the large, low-temperature heat exchanger and water-feature on the back end of the thermal cycle.


If you're talking about open-cycle air turbines heated by a nuclear source, then you're probably looking at an efficiency of about 25% (vs. 50% for closed-cycle water cooled).

Probably too much of a hit for big municipal power plants, but may be alright for remote applications like military power.


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 Post subject: Wow
PostPosted: Jan 29, 2008 2:09 am 
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Wow, that's a lot more than I expected.

So, Hydrogen?


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 Post subject: Re: Wow
PostPosted: Jan 29, 2008 12:41 pm 
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rgvandewalker wrote:
So, Hydrogen?


My guess is that there would be a number of problems with hydrogen. First, there is the potential problem of Hydrogen diffusing into the salt mixture through the heat exchanger, which could be a chemical nightmare (HF). Second, you'd make it much more difficult to extract the Tritium diffusing into the Hydrogen working fluid. Third, the addition of a flammable gas just adds one more catastrophic failure mechanism to the plant.


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 Post subject: Re: Wow
PostPosted: Jan 29, 2008 2:41 pm 
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rgvandewalker wrote:
So, Hydrogen?


Nitrogen? Turbines intended for air can be bought off the shelf, Nitrogen is cheap, in no way dangerous, and works in a closed cycle almost as well as Helium.


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PostPosted: Apr 10, 2008 12:12 pm 
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More information about the "Next-Generation Nuclear Plant" and its funding woes, most of which are brought on by fuel qualification which wouldn't be necessary in a fluoride reactor.

Idaho lab's long range vision for NGNP

Nor would high pressure operation.


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PostPosted: Apr 10, 2008 12:40 pm 
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Kirk Sorensen wrote:
More information about the "Next-Generation Nuclear Plant" and its funding woes, most of which are brought on by fuel qualification.


Sounds like they've got that problem licked:

Quote:
March 10, 2008
Team achieves nuclear fuel performance milestone
Researchers at the U.S. Department of Energy’s Idaho National Laboratory, in partnership with three other science and engineering powerhouses, reached a major domestic milestone relating to nuclear fuel performance on March 8.

David Petti, Sc.D., and technical director for the INL research, says the team used reverse engineering methods to help turn the fuel test failures from the early 1990s into successes in 2008. “We wanted to close this loop for the high-temperature gas reactor fuels community,” he said. “We wanted to put more science into the tests and take the process and demonstrate its success.”

This work is important in Idaho because the Idaho National Laboratory is the U.S. Department of Energy’s lead nuclear research and development laboratory.

The research is also key in supporting reactor licensing and operation for high-temperature reactors such as the Next Generation Nuclear Plant and similar reactors envisioned for subsequent commercial energy production.

“Hats off to the R&D fuels team on this major milestone,” said Greg Gibbs, Next Generation Nuclear Plant Project director. “This is a major accomplishment in demonstrating TRISO fuel safety. This brings us one step closer to licensing a commercially-capable, high-temperature gas reactor that will be essentially emission free, help curb the rising cost of energy and help to achieve energy security for our country.”

The work is a team effort of more than 40 people from INL, The Babcock & Wilcox Company, General Atomics and Oak Ridge National Laboratory.

The team has now set its sights on reaching its next major milestone - achievement of a 12-14 percent burnup expected later this calendar year.

The research to improve the performance of coated-particle nuclear fuel met an important milestone by reaching a burnup of 9 percent without any fuel failure. Raising the burnup level of fuel in a nuclear reactor reduces the amount of fuel required to produce a given amount of energy while reducing the volume of the used fuel generated, and improves the overall economics of the reactor system.

After U.S. coated-particle fuel performance difficulties in the 1990s and a shift in national priorities, research on this type of fuel was curtailed for a time. Funding for the research resumed in 2003 as part of the DOE Advanced Gas Reactor fuel development and qualification program.

The team studied the very successful technology developed by the Germans for this fuel in the 1980s and decided to make the carbon and silicon carbide layers of the U.S. particle coatings more closely resemble the German model. The changes resulted in success that has matched the historical German level.

INL’s Advanced Test Reactor was a key enabler of the successful research. The ATR was used to provide the heating of the fuel to watch the fuel’s response. The fuel kernel is coated with layers of carbon and silicon compounds. These microspheres are then placed in compacts one-half-inch wide by two inches long and then placed in graphite inside the reactor for testing. The fuel element is closely monitored while inside the test reactor to track its behavior.

Source: DOE's Idaho National Laboratory


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PostPosted: Apr 10, 2008 1:08 pm 
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Not quite sure how you read it that way. Sounds like they had a big press release to say that they looked at old fuel failure data and now they're shooting for a higher burnup level in future tests. Still sounds like more fuel qualification.


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