The large coal burning part
(Faded) gets demolished.
<=======
HOW the modified power plant would work: The reactor (right) is in a sealed underground silo located in the power plant's coal storage yard.
STEAM: The heat comes from the bed (or pile) of atomic pebbles (the little red dots). The pebbles heat helium gas in the reactor to 1,300°F. The hot helium gas is circulated clockwise to carry the heat from the pebbles to the attached helium-to-water heat exchanger (a "fire-tube" water heater). The heated water (red) that exits through the bottom water pipe of the heat exchanger is supercritically hot (1,150°F), and under about 4,500 pounds per square inch pressure to keep the water from turning into steam.
NEXT, The heat is carried by the water through new, heavily insulated pipes to a new steam generator located in the power plant.
The STEAM GENERATOR: is also a type of heat exchanger. This time, the 1,150°F supercritical water is used to make the 1,000°F, 2,400 psi superheated steam needed by the power plant's turbine. The steam generator's steam pipes are connected to the three-stage steam turbine (devices 11, 9, 6) that spins the electricity generator (device 5). The "new" steam is identical to the "old" steam that used to be made by the coal boiler.
TRISO NUCLEAR PEBBLES: Two identical special 200 ton storage vault railroad cars, equipped with with elliptically-keyed wheels, (temporarily removed) would be temporarily welded to the rails next to the silo to supply and remove TRISO nuclear pebbles through pneumatic tubes connected to the car bottoms.
The Germans used an automated pneumatic transport system on their THTR-300 pebble bed reactor, blowing the radioactive pebbles through tubes to unload fresh, check how tired an individual pebble was, then either returning it to the reactor or placing it in a removal transport container. The U.S. MIT pebble bed reactor design is even more sophisticated. The pebbles would be held in metal clips on a conveyor belt storage system inside the railroad cars. A full load of 450,000 pebbles is about 112 tons - containing perhaps 9 tons of uranium. Every several years, when the "used pebble" railroad car becomes full, it would be taken to the pebble recycling center, emptied, refilled with fresh pebbles, then returned. More about TRISO pebbles.
THAT'S ALL THERE IS TO IT, FOLKS! What a simple way to end Climate Change. The only new items are the reactor, the two heat exchangers, and a small control and service building located in the now-unneeded coal yard. It should be pointed out that power plant water heaters and steam generators, while not trivial devices, are about 30% the size of conventional nuclear power plant steam equipment so they are much less expensive and can be built in several months almost anywhere.
Faded and lifted away slightly shows the now unused 10+ story high coal-burning portion of the power plant.
Conversion is that simple. Illustrating the Coal Yard Nuke idea, the above is an anatomically correct simplified coal burning power station schematic diagram from Wikipedia. This sketch shows what I hope PBMR, Ltd. would accept as an alternate application for their reactor. Their design: http://www.iaea.or.at/programmes/inis/aws/htgr/fulltext/29026679.pdf
Wikipedia original sketch image: http://en.wikipedia.org/wiki/Fossil_fuel_power_plant GNU Free Documentation License
Suggested Conversion Demonstration Projects
A Demonstration Facility will cause a flood of engineering feasibility studies to be made. If this is a bad idea, it will be caught for sure then.
Note: Several months of real-life running time will be needed to reveal any serious design errors and afterthoughts. Power plants typically have 70 year lives. Plants from the '50s can easily provide the needed running time while keeping developmental costs to a minimum. Companies like Babcock & Wilcox have over 50 years experience in designing nuclear steam heat exchangers and should be involved in these early projects. One ton of coal produces 2.86 tons of CO2.
Michigan: (Left) Initial single micronuke reactor pilot demonstration facility at the White Pine Electric Power Plant, at White Pine, in Michigan's Upper Peninsula. Three 1956 20 MWe (megawatt, electrical) coal burning units. Much of the plant's output goes to power a copper production facility. A perfect place to try out a 25 MWe Hyperion TRIGA-like micronuke on a single coal burning unit. In 2005, the facility burned a total of 74,910 tons of coal producing 215,000 tons of CO2. White Pine Electric
Michigan:
(Right)
Small single reactor demonstration
facility at the J. R. Whiting plant near Erie, Michigan.
On the western shore of Lake Erie, just north of Toledo and south of Fermi II
near Monroe, Michigan. Three 1952 100+ MWe coal burning units. One
coal burning unit could be repowered with a de-rated 180 MWe PBMR TRISO pebble
bed mininuke or all three could be driven by a single 331 MWe General Atomics GT-MHR
TRISO prismatic mininuke. In 2005 the facility burned about 1,000,000 tons
of coal producing
2,810,000 tons of CO2. J.R. Whiting
Florida's "Big Bend" Power Plant
Florida: (Left) Full scale demonstration facility at the huge Big Bend plant near Tampa, Florida. As many as 12 PBMR TRISO pebble bed mininuke conversion boilers. Three mininukes in parallel for each of the four early 1980's 450 MWe coal burners. In 2005 the facility burned about 3,700,000 tons of coal producing about 10,700,000 tons of CO2. Big Bend
For CO2 comparisons download the "Biggest CO2 Sources List .pdf" (Hint use the "Edit > Find" function to find your data).
According to CARMA, TECO's Big Bend coal-burning power plant makes 30,000 TONs (or 60 million pounds) of CO2 per day or 10,950,000 tons per year. And the Big Bend 4-unit plant is just one of about 50,000 multi-unit power plants in the world for a total of 143,000 units. Big Bend has about 1 million customers. They own their own coal mine but their additional expansions will be natural gas turbines which are only 2/3s as dirty.
At 1,800 megaWatts, Big Bend is a huge power plant - larger than the newest nuclear power plants. Areva's biggest and best nuclear plant, the EPR, is only 1,600 megaWatts. It will take about a dozen PBMR 165 megaWatt pebble bed TRISO-fueled reactors to convert Big Bend from coal to nuclear. Tampa could put in two EPRs next door to Big Bend. There is an excellent transmission line corridor already established along I-75 to feed the entire Florida Gulf coast. Since the ground in that area is already more radioactive than anything Areva's reactors could ever produce (the government won't let Tampons make wallboard out of the area's gypsum due to it's radioactivity), I can't imagine the locals opposing all the money two EPRs would bring in for 50 years.
Climate Change can't possibly be stopped without first cleaning up at least the world's 5,000 dirtiest power plants. It's unavoidable. Conversion from coal-burning to nuclear can be done quickly and should be done first because nothing else will reduce so much CO2 as quickly.
Some more technical: Nothing new needs to be invented. No new technology advances needed!
BUYING
THE REACTOR: PBMR,
Ltd. won't like this, but
I am suggesting we buy only the reactor made by PBMR,
http://en.wikipedia.org/wiki/Pebble_bed_reactor as shown at
right, not their entire gas-turbine electricity generation system as shown on their web site.
South Africa's Pebble Bed Modular Reactors, (Pty) Ltd. (PBMR)
make a 1,700°F gas-cooled reactor filled with helium. And, I think
they also have a process heat version designed. Inert and a good
carrier of heat, the helium in the reactor is pressurized to 1,300 psi to further
improve heat transfer. Since there is no liquid-to-gas phase-state change,
there isn't a violent
explosion hazard of
the type steam can produce. This kind of gas pressurization will make a
non-shockwave gas escape like a punctured tire. Both pebble bed and prismatic reactors use
helium at about this pressure.
The author believes no one knows more about how to
make a commercially successful circulating pebble reactor than PBMR. The
PBMR's project is supported by the South African government, Eskom, the
Industrial Development Corporation, and US companies Westinghouse and Exelon.
The commissioning of the first commercial pebble bed plant is scheduled for
2013.
Partner Westinghouse is calling it the first of the Generation-IV reactors.
Gen-III+ is probably most accurate with the VHTR/NGNP being tomorrow's Gen-IV
Pebble Bed.
"Pebble-bed Modular Reactor (PBMR) (Eskom): The
PBMR, which uses helium as a coolant, is part of the HTGR family of reactors and
thus a product of a lengthy history of research, notably in Germany and the
United States. More recently the design has been promoted and revised by the
South African utility Eskom and its affiliates. Westinghouse BNFL is a minority
investor. Prototype variations of the PBMR are now operating in China and Japan.
Eskom has received administrative approval to build a prototype PBMR in South
Africa, but has also been delayed in implementation by judicial rulings
regarding the reactor’s potential environmental impact. Certification procedures
in the U.S. have slowed, but never have been abandoned. At around 165 MWe the
PBMR is one of the smallest reactors now proposed for the commercial market.
This is considered a marketing advantage because new small reactors require
lower capital investments than larger new units. Several PBMRs might be built at
a single site as local power demand requires. Small size has been viewed as a
regulatory disadvantage because most licensing regulations (at least formerly)
required separate licenses for each unit at a site. The NRC also does not claim
the same familiarity with the design that it has with LWRs. Fuels used in the
PBMR would include more highly enriched uranium than is now used in LWR designs.
The PBMR design is considered a possible contender for the U.S. Department of
Energy's Next Generation Nuclear Plant (NGNP) program in Idaho. China has also
indicated interest in building its own variation of the PBMR. China and South
Africa have also discussed cooperation in their efforts." Details
regarding the PBMR design can be found on https://www.pbmr.com/. Information
related to certification of the PBMR can be found at
http://www.nrc.gov/reactors/advanced/pbmr.html
About 2,000 people are currently working on
construction of the PBMR demonstration reactor and it's facilities. It is on
schedule to start up in 2013. Also, at this time, PBMR has only a pilot pebble plant
said to be making
about 270,000 TRISO pebbles a year. TRISO particles can be crushed and the uranium
and thorium inside recycled. For sure, there are downsides and
difficulties associated with pebble bed reactors, some due to the the TRISO pebble itself.
Notice the serrated surface of PBMR's pebbles. The world doesn't realize it yet, but it is in desperate need of billions
of pebbles
every year. France, China, Germany, and the United States have made TRISO
pebbles in the past. Britain, Japan, Russia, and the United States have
also made TRISO prisms in the past.
It should be pointed out that Westinghouse already has a small NRC-certified 300 megaWatt conventional reactor, the IRIS - International Reactor Innovative and Secure, not hot enough to repower a coal-burning power plant but it would be an excellent mass-produced choice for providing the electricity needed to power Shell's clean shale oil recovery system. Hyperion and NuScale have even smaller reactors, Hyperion's is almost hot enough to repower a very small coal-burning power plant.
ADDITIONAL TECHNICAL ITEMS:
(A) Already in common use in conventional PWR reactors, an excellent way to interface a gas-cooled high temperature pebble bed reactor with an existing coal-fired steam plant turbine is to use "SUPERCRITICAL" HOT WATER - water under more than 3210 psi. Supercritical water is a gas with the density of the liquid having a very high volumetric heat capacity (right, olive colored area). Its a way to manage and transport heat energy when using several reactors in parallel to drive a single very large power turbine or a single reactor to drive several older small power turbines with different steam requirements. http://en.wikipedia.org/wiki/Supercritical_fluid
(B) If steam is above 700°F, and at it's natural pressure, it is usually called SUPERHEATED STEAM.
(C) The supercritical water heater is built as a dual-tube calandria (a drumless fire-tube & water-tube boiler that does not require expensive heavy forgings) in a tub filled with unpressurized liquid lead (green outline in power plant sketch above) to carry the heat between the helium pipes and the water pipes. This design is a work-around that might be a new invention. Because the helium in the reactor is under comparatively low pressure, the liquid lead heat conductor under atmospheric pressure will make water ingress into the reactor impossible in the event of a supercritical hot water leak, a key safety issue in a design that mixes HTGRs and supercritical water. These things always vibrate themselves to failure over their 50+ year life spans so we might as well design them to fail gracefully.
Since the pebble bed's supercritical water is twice as hot as is used in a conventional PWR nuclear plant, a very experienced company such as Babcock & Wilcox should be called upon to make the first few water heaters and steam generators.
1,150
Why use supercritical water? A cubic foot of water will carry 3,200 times as much heat as a cubic foot of air.
FUEL HANDLING: Two identical special 200 ton storage vault railroad cars, equipped with with elliptically-keyed wheels, (temporarily removed) would be temporarily welded to the rails next to the silo to supply and remove pebbles through pneumatic tubes connected to the car bottoms. The Germans used automated pneumatic transport systems on their pebble bed reactors, the U.S. MIT pebble bed reactor design is even more sophisticated. The pebbles would be held in metal clips on a conveyor belt storage system in the railroad cars. A full load of 450,000 pebbles is about 112 tons containing perhaps 9 tons of uranium.
PASSIVE COOLING: The gray rods sticking into the ground provide a passive conductive, rather than radiative, thermal path into the environment in the event reactor goes into Doppler thermal limiting mode. Also, the standard PBMR reactor has a 1 meter layer of graphite insulation located between the cylindrical vertical pebble chamber and the reactor wall to stop both neutrons and heat. This feature makes the Doppler mode efficient. The sheet metal loop to the right side of the reactor is a passive chimney-type heat exchanger to keep heat from accumulating in the silo. Using the duct system as the heat exchanger keeps the the silo air from escaping.
Installing and connecting the new steam generator heat exchanger and adding new controls are all that will change in the power plant. There will be a new small, separate, reactor operations building for the pebble bed reactor(s) located nearby in the coal yard. The remotely controlled reactor(s) will provide hot water for making steam as needed by the power plant. The power plant's original steam temperatures and pressures remain unchanged. Much simpler than the full PBMR system as presented in this document: http://www.iaea.or.at/programmes/inis/aws/htgr/fulltext/29026679.pdf
REACTOR/TURBINE MISMATCHES: According to PBMR, their reactor is capable of producing 180 megaWatts electrical. The magic of the Coal Yard nuke system is the concept of using them as central supercritical hot water heaters to produce enough heat to power one or more steam generators. Say you have several old, small turbines whose power does not add up to more than 180 MWe. As an example: an old plant with single 25, 50 and 75 MWe units could be powered by one reactor with its hot water output split into 25, 50, and 75 MWe steam generators. If different temperatures are needed, that can be done also. If you have a fairly new big 500 megaWatt electrical unit, three PBMRs running in parallel driving a single 500 MWe steam generator would be needed to max out that puppy. Using supercritical hot water gives us incredible flexibility in matching all those old steam plant turbine combinations.
Plants already running on supercritical steam could have several reactors arranged in a ring around a central boiler.
Nuclear reactors are extremely reliable. Nuclear submarines have only one. Also, since this is a pebble bed, it doesn't have to take a month vacation every other year for refueling.
COOLING WATER: Unlike conventional nuclear, upgrading a coal burning power plant to pebble nuclear does not increase the amount of cooling water needed. Notice in the drawing above, the turbine steam condensation system remains untouched so the amount of cooling water needed is unchanged. This is due to the fact that pebble reactors duplicate fire, conventional reactors cannot. Also, the stack losses are gone, and since a coal fired plant uses three-stage 1,000°F turbines as compared to conventional nuclear power plant's 550°F two-stage turbines, the efficiency has got to be higher than either of them. Might cover the cost of those expensive pebbles.
Coal Plants have plenty of life left in them.
An excellent investment in our future. Over half the U.S. fossil fuel power plant generating capacity was built after 1980. Since power plant life is considered to be as long as 60 years, we have 40, 50 or even more years of life left in our most recent (and largest) fossil fuel plants. Well worth the cost of conversion. Projecting 1980 through 2006 EIA values (growth = new power plants) to the vertical ordinate, we find about 0.3 + 1.0 = 1.3 T kWh, which, at 2 lb of CO2 per kWh, (Table 4) is about 1.3 BILLION tons of U.S., or 6.5 B World, CO2 every year.
See also:
The IPCC has identified 5,000 multi-unit fossil fuel power plants worldwide that are the really big CO2 polluters. If they are very big, they are fairly new. It is critical we concentrate on them first. They should be repowered rather than shut down. We can't put our energy-starved mega-cities on an energy diet at a time when we need more electricity for water desalination, plug-in hybrid cars, and summer air conditioning to fight ever-worsening Climate Change.
____________________________________________________________________________________________________
Original ESKOM Pebble Bed Modular Reactor and Helium Driven Electricity Generator
This is a gas turbine (think 747 jet engine) system, not a steam turbine system.
The
speed of
in helium is nearly three times the speed of
in air. This means closer turbine blade tolerances. In addition,
helium flows differently than air. Designing an efficient helium gas
turbine is a really big challenge. You can't just go to a catalog and
order a helium gas turbine with a proven track record. This is why Rod
Adams suggests using nitrogen (air is about 80% nitrogen) for his patented
This sketch is important because it shows the operating temperatures, pressures, mass flows, and heat exchanger and device capacities.
This appears to be an early design. Other PBMR literature indicates a 160 megaWatt generator. More information is available at ESKOM's web site, link below.
(From ESKOM web site.) http://www.eskom.co.za/nuclear_energy/pebble_bed/pebble_bed.html
Power plant coal yards provide
plenty of room for TRISO pebble bed reactors.
(Right, below, Looking North) Big Bend plant,
located on Tampa Bay's big southeast bend, showing it's enormous black coal
yard. Plenty of room for some small PBMR reactors to
be buried underground there. The white warm discharge water seen
just below the stacks is where manatees hang out in the winter to keep warm.
The small light colored building located at the upper right is the water
desalination facility that supplies
25% of Tampa's
drinking water. Desalination facilities consume extremely large amounts of
electricity. (From Google Earth.)
(Left, above, looking southwest) Underground and underwater pump/generators at the 1,800 megaWatt Ludington, Michigan, pumped energy storage facility on Lake Michigan's coast. Enough electrical energy to keep Detroit going for about 8 hours. (Author's photo.)
Available
Supercritical Water System.
1.
THERMAL MATCHING: Conventional nuclear reactors run at
about 550 degrees F. Pebble bed
reactors run about 1,600 degrees F and are cooled using a
gas, often helium. Since almost all coal-fired steam power
plants use 1,000 degree F, 2,400 pounds per square inch steam
(called superheated steam), I have to use
something that is even hotter, so I must use a PBMR
pebble bed reactor since that's the nearest thing to a
catalog item that will do the job.
At the Coal Yard Nuke sketch's extreme right, there is an underground silo with a pebble bed reactor (the little red dots are the pebbles) and a helium-to-water heat exchanger (not all that different in function from your residential gas hot water heater) with the reactor's very hot 1,600°F helium gas being blown through it. Because the pebble bed reactor can easily heat the water to 1,150 degrees F, the water has to be under very high pressure (3,200 psi) or more to remain water. This type of water is called "supercritical" water.
"Temperature as energy" is somewhat comparable to "voltage as energy" if the water volume (or electrical amperes) remains constant.
There are hot water lines running from the underground reactor silo to a new steam generating heat exchanger sitting on the boiler room floor to the right of the blue feedwater equipment.
Think of the high temperature, high pressure, hot water line coming from the reactor's water heater as a high-voltage power transmission line. Think of the new steam generator on the turbine room floor as something like a step-down transformer in an electrical substation. The hot water-to-steam generator is designed in such a way that it duplicates the steam the large original boiler (device 19 in the sketch) made. Obviously, the analogy breaks down as soon as you think about increasing temperature at the expense of volume as if it were a voltage-amperage tradeoff. But, within it's limitations, the analogy has some value.
A "refresher" note at the bottom of this web page describes a generic steam path through boilers and turbines and, as such, is a good illustration of the complexity of this situation in real power plants.
Old coal power plants are always a collection of different size boilers and generators made over a span of perhaps 50 years by different vendors to meet different budgets. This makes it extremely important to be able to match a nuclear reactor that runs best at it's own fixed set of temperatures to whatever turbine pressures and temperatures the power company customer happens to be running. Realize the turbine could be between 5 and 50 years old!
Different size and different temperature boilers in different coal burning power plants can be duplicated by simply changing the coils in the water-to-water steam generator. It's not that much different than changing the secondary coils on a transformer to get a proper voltage (or temperature) and current (or steam volume) match. Take a close look at how the coils are positioned in my sketch. They are almost a mirror image of the the original coal fired boiler.
Duplicating some boilers will cause the secondary coils to have more turns for hotter, dryer, higher pressure steam, duplicating other boilers will cause the secondary coils to have fewer, larger diameter pipes for great volumes of cooler, wetter, lower pressure steam. Another possibility are several different types of small turbines all "feeding" off the same steam generator or several reactors "pooling" their heat to drive one monster steam generator that, in turn, drives a monster ex-coal power plant turbine - Big Bend comes to mind.
The key is that the supercritical hot water be substantially hotter than any power plant steam a Coal Yard Nuke system will have to duplicate.
2. EFFICIENCY: Coal Yard Nukes might also be pushing the envelopes of both steam and nuclear power plant thermodynamics. Heat exchangers always exact a penalty but it may be insubstantial in a Coal Yard Nuke compared to the overall efficiency improvement. If we duplicate those Riley boilers exactly, the load on the plant's turbine condensing tubs will remain the same and the retention of untransferred BTUs in the reactor's helium loop instead of going up the smokestack (25% of heat?) means a boost in plant efficiency in addition to eliminating CO2 along with all those other noxious coal emissions.
This idea will eliminate about 60% of Global Warming's CO2 every year while improving power plant efficiency. What more could the world ask for?
The following describes a generic fossil fuel power plant's steam turbine connected to a hybrid nuclear power station's pebble-heated steam generator instead of a coal-heated boiler. - It is almost identical to a classic coal plant's steam path.
(A) The new steam generator makes identical steam pressures (1,000°F and 2,400 pounds per square inch) for the high pressure turbine stage (device 11) of the power station's electricity generator (device 5, above). Depending on heat availability and power needs, the steam is either expanded through the high pressure turbine (device 11, above) or by-passed and sent back to the steam generator for reheat.
(B) Either way, the steam is then returned to the steam generator for a reheat pass to become intermediate pressure steam (1,000°F, 552 psi, again, no change) for the intermediate pressure turbine (device 9, above).
(C) After leaving the intermediate pressure turbine, the steam, now expanded to low pressure, goes immediately into the double-ended low pressure turbine (device 6, above), exiting both ends of it's bottom at a slight vacuum into the condensing tub (device 8).
(D) There, in a cool environment that no longer supports steam, the spent low pressure steam will flash condense back into boiler feed water so it can be turned back into steam again by repressurizing it to 2,400 pounds per square inch (device 7) and pumping it back into the bottom of the steam generator. Big Bend's boilers do this at the rate of 23 tons, or 750 cubic feet - a 9 foot cube - of water a minute.
(E) The condensing tub is kept cool by a loop of 75°F in, 95°F out, cooling water (circulated by device 2) from either a 60°F cooling tower or a 60°F cooling body of water (as shown on the extreme left on the diagram).
(F) The electricity produced by the electrical generator (device 5) is carried by the 3 electrical phase wires to a step-up transformer (device 4) located next to the power plant. It takes about 1,000 volts per mile to efficiently push high-current electricity - so the step-up transformer will have to transform the three-phase electricity from the generator's perhaps 5,000 volts to perhaps as high as 500,000 volts to send the electricity via the high voltage transmission line system (device 3) to a load as much as 500 miles away. Lesser distances mean lesser losses.
Original power plant image: http://en.wikipedia.org/wiki/Fossil_fuel_power_plant GNU Free Documentation License
The Coal2Nuclear
concept:
"A terrific application for several [nuclear] heaters that can
produce 400 MW thermal at about 800 C is to replace similar sized boilers at
coal fired power plants. Like Jim Holm, I think that
Coal2Nuclear is the best way to make use of the investment at existing coal
fired facilities for items like steam plants, electrical distribution, and
cooling water. I think the conversion would be a heck of a lot cheaper than
trying to install the chemical facilities and plumbing required to capture and
sequester CO2. Preventing pollution is often cheaper than trying to cure it." --
Rod Adams,
http://www.atomicinsights.blogspot.com/
"Coal Yard Nuke" describes a general idea - not a particular type of coal storage yard or nuclear reactor.
More: In addition to the TRISO Pebble Bed Mininuke reactor
shown above, there are other possible Coal Yard Nukes:
1. Hyperion™ TRIGA-like MicroNuke.
Most cities have multi-building college, hospital, office, or factory complexes
that are burning coal or natural gas to power both their heating and air
conditioning systems.
Look for
smokestacks near you.
2. Liquid Fluoride Thorium Reactor is a very
low-cost, mud puddle simple reactor that has what it takes to be a Coal Yard Nuke. There are
no commercial versions at this time.
You may wish to read Coal, Section A, Part Three, "Why Coal2Nuclear," to get some background as to how the author arrived at the idea of repowering coal power