dallashistory

They are finishing the Twin Oaks power station and the nearby strip mine that was started by TXU, but never finished. The mega technology (such as the walking dragline excavators) descibed in this article is neat.

Basic Facts
Fuel source: Lignite
Operating capacity: 1,600 MW*
Years to begin operation:
Unit 1-2009; Unit 2-2010
Location: Robertson County
Supporting mine: Kosse
*Upon completion

http://www.groesbeckjournal.com/news/2008-10-09/Front_Page/Kosses_Big_Dig.html

Those big machines can be amazing. It just might be worth a trip down there, when they get it operational.
Google maps shows a scar east of Kosse, and I found the plant due south on the west side of the lake, but I haven't found any trackage yet. Of course, I have no idea how old the photo is.
The truth is I didn't realize there was any easily accessible coal is Texas. Do you know of any other open pit mines in the state?

Paul

Paul Brancato wrote:Those big machines can be amazing. It just might be worth a trip down there, when they get it operational.
Google maps shows a scar east of Kosse, and I found the plant due south on the west side of the lake, but I haven't found any trackage yet. Of course, I have no idea how old the photo is.
The truth is I didn't realize there was any easily accessible coal is Texas. Do you know of any other open pit mines in the state?

Paul

We don't have much in the way of coal reserves. What we do have quite a bit of is Lignite, which is between coal and peat in terms of quality.

http://en.wikipedia.org/wiki/Lignite

Also called brown coal or soft coal; it is very high in dirt content. That makes it impractical to ship even by rail for very far distances; so there is usual a powerplant near the strip mine to burn it; what is called a mine mouth power plant.

The coal may travel from the mine to the power plant either by rail or by conveyor belt. A boiler built for burning lignite needs a larger firebox on account of the lower energy content, and larger precipitators or baghouses to deal with the large amounts of dirt or ash.

While most lignite is burned in mine mouth power plants, some steam locomotives burned lignite as well. In order to do so, they had to have large fireboxes; the firebox in the Northern Pacific Z-5 class 2-8-8-4 for burning Rosebud coal (also lignite) were so big, a catered dinner for 12 was held inside the firebox of the first one; the largest locomotive in the world at that time.

Getting back to your question, there are several lignite power plants in Texas; all mine mouth plants. One that is easy to spot is TMPA's Gibbons Creek Power Station outside of Bryan/College Station Texas, Gibbons Creek Reservoir (the cooling lake for the plant's condensors) is easy to find in aerial photographs, as is the mine itself. Zooming in on the plant itself, you can see the large precipitator between the generating units and the smokestack. Coal comes in from the mine via conveyor belt.

Gibbons Creek station on Goggle Maps

The actual coal fired power plants in the state burn low sulphur coal from open mines in Wyoming; dedicated unit (or "ping-pong") freight trains run on a continuous basis back and forth between Wyoming and Texas supplying these plants. It was one of these that derailed in Cleburne last week.

I realized that lignite was a lower grade of coal, I just didn't know it was that much lower. I just assumed that the co-location of the power plant with the mine was a cost saving measure. Cheaper to build a new plant, which we need anyway, than ship a train load of fuel in every day for 40 years.
Which brings up another point. They say this new mine will last 30 to 40 years. Surely the life span of the generation plant is longer than that. Are there other sources of lignite close by? Or possibly it has a future burning good coal?
As for the locomotives, wasn't lignite the genesis of the Camel Back design? The fire box was too big to see around?
Paul

Paul Brancato wrote:I realized that lignite was a lower grade of coal, I just didn't know it was that much lower. I just assumed that the co-location of the power plant with the mine was a cost saving measure. Cheaper to build a new plant, which we need anyway, than ship a train load of fuel in every day for 40 years.

A 500 MW coal unit, baseloaded at all times, burns about a trainload a week. At least that is what I remember. Mulitply that by the number of such units in Texas, and yes, that is a lot of coal trains.

Paul Brancato wrote:Which brings up another point. They say this new mine will last 30 to 40 years. Surely the life span of the generation plant is longer than that. Are there other sources of lignite close by? Or possibly it has a future burning good coal?

Actually, 30-40 years, maybe 50 is a pretty good lifespan for a generating unit. Advances in powerplant design may advance so much in that time that it may no longer be as efficient as new units coming on line. So, in 30-40 years, they may be shut down, switched to burning coal brought in from up north, or even repowered. For example, a pair of units from the 1950s in Lake Charles, LA had their gas-fired boilers replaced with a pair of circulating fluidized bed boilers in the late 1990s; they "burned" petroleum coke from the nearby refineries, and provided in part steam to the same.

http://en.wikipedia.org/wiki/Fluidized_bed_combustion

A short distance away, a pair of units in a power plant that was built during WWII* and bought by the local industries was either replaced or mostly suplimented by a pair of cogen units.

Paul Brancato wrote:As for the locomotives, wasn't lignite the genesis of the Camel Back design? The fire box was too big to see around?
Paul

Close; they had a Wootten firebox, which burned anthracite waste.

http://en.wikipedia.org/wiki/Camelback_locomotive

* A side story. Since copper was in short supply during WWII, the bus bars that tapped the power from the generators were made out of silver. They didn't have to worry about theft as long as the units continued to run; when they were replaced with copper bus bars after the war, security guards were posted to ensure their safe departure from the plant! It was written up in the local paper.

The big banks of magnets used at Oak Ridge as part of the U-235 separation process used silver for their windings instead of copper becasue the copper was needed for other things (like cartridge cases, bullet jackets and such). The silver was withdrawn from the US Treasury Silver Depository at - West Point, NY. Returned post-war, with the loss of only a few ounces unaccounted for.

There is another lignite mine and mine mouth power plant even closer to DFW. It is Limestone power plant, by the town of Jewett, on I-45 South, just north of Buffalo:

http://maps.google.com/maps?hl=en&ie=UT ... 7&t=h&z=12

It is along Hwy 164. If you look off to the left between mile markers 185 and 188 while traveling south, you can catch a glimpse of the big excavators and the power plant itself. The excavators were working much closer to the highway a few years ago, you could clearly see the boom lite up at night when you drove by.

From the web:

The Limestone Electric Generating Station, owned by NRG Texas, is a large utility coal-fired steam electric power plant. The plant is equipped with a tangentially fired boiler to supply steam for a 913 MW turbine-generator. Limestone fires a blend of Texas lignite and Powder River Basin coal.

They are planning on adding a third unit to the plant.

Stole this from Wiki, but did check it against a print encyclopedia I trust (1970 edition of Britannica) and it looks pretty straight factually:

Types of coal

Believed approximate position of the proto-continents toward the end of the Carboniferous period; the light blue represents shallow seas where many of today's coal deposits are found, as opposed to deeper waters which gave rise to oil bearing rocks derived from marine species. The ice caps were known to be very large, lowering sea levels extensively by locking up oceanic waters into solid ice, though how large the ice caps became is a matter of debate. The position of most continental foundations in lower latitudes definitely created a series of successive shallow swamplike seas we burn for today's coal sourced electricity.As geological processes apply pressure to dead biotic matter over time, under suitable conditions it is transformed successively into

Peat, considered to be a precursor of coal, has industrial importance as a fuel in some regions, for example, Ireland and Finland.
Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Iron Age.
Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
Bituminous coal, dense mineral, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke.
Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically [b]altered bituminous coal and petrified oil, as from the deposits in Pennsylvania.
Graphite, technically the highest rank, but difficult to ignite and is not so commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant.
The classification of coal is generally based on the content of volatiles. However, the exact classification varies between countries. According to the German classification, coal is classified as follows:[2]
Name Volatiles % C Carbon % H Hydrogen % O Oxygen % S Sulfur % Heat content kJ/kg
Braunkohle (Lignite) 45-65 60-75 6.0-5.8 34-17 0.5-3 <28470
Flammkohle (Flame coal) 40-45 75-82 6.0-5.8 >9.8 ~1 <32870
Gasflammkohle (Gas flame coal) 35-40 82-85 5.8-5.6 9.8-7.3 ~1 <33910
Gaskohle (Gas coal) 28-35 85-87.5 5.6-5.0 7.3-4.5 ~1 <34960
Fettkohle (Fat coal) 19-28 87.5-89.5 5.0-4.5 4.5-3.2 ~1 <35380
Esskohle (Forge coal) 14-19 89.5-90.5 4.5-4.0 3.2-2.8 ~1 <35380
Magerkohle (Non baking coal) 10-14 90.5-91.5 4.0-3.75 2.8-3.5 ~1 35380
Anthrazit (Anthracite) 7-12 >91.5 <3.75 <2.5 ~1 <35300
Percent by weight

The middle six grades in the table represent a progressive transition from the English-language sub-bituminous to bituminous coal, while the last class is an approximate equivalent to anthracite, but more inclusive (the U.S. anthracite has < 6% volatiles).[/b]


Sorry the table for the German classifications didn't format as it does in the article.

The Reading and some other anthracite burning (and hauling) roads like the Lackawana (the famous road of anthracite travelled by Phoebe Snow) actually burned anthracite waste, known a "culm" IIRC, which burned clean and and hot, but had problems requiring a shallow fire-box that was also wide to get enough heating surface exposed.

In 1997 I arranged a tour of TXU's Monticello lignite coal operation near Mt Vernon, TX. [We ended up getting a lot more tour than we planned!]
You could catch glimpses of the open pit operation from I-30 back then. Not sure about today.

We took a company bus out to one big gouge in the earth where they were actively mining. There was a gargantuan tracked machine there called a cross-pit spreader that mined the lignite. It was like something out of a science fiction movie. HUGE!

After we returned from this part of the operation we got permission to ride an electric-powered coal train to the North Mine. Going north we rode in a cab-control caboose. Going south we rode in the cab of a GE electric locomotive. Later in the day we rode in the cab of a GE diesel locomotive to take an ash train out to the pits.

We saw everything but inside the actual power plant where the coal was burned. This was undoubtedly my best industrial tour ever.

P.S. In 1995, I got to "test drive" the former Santa Fe Alco S2 switcher at the unfinished Twin Oaks facility near Bremond. TXU was selling it off to bidders then. I was inspecting it for a museum.