As each year passes, it would seem that the coal seems being dug out would be harder and harder to get at. You’d always mine the easiest stuff first-right? Is it possible, that some other coalfield will take over the PRB’s dominance?
Have other coalfields played out?
Question posed in your title: Yes About 30 years without rather radical changes in the economy, technology, or law.
Yes, you mine the easiest first. That’s why the PRB was virtually untouched until the 1970s, because it was a long way away from everywhere and the coal is very low in heat value. Higher value coal closer to markets was mined first.
No, nothing is waiting in the wings to take the PRB’s place, not without rather radical changes in the economy, technology, or law. Observe that the PRB is about as far away as one can get from the demand location for coal in the U.S. without coming out the other side (and shipping by water). About the only really interesting field in the lower 48 might be the Kaiparowits Field in southern Utah, which has somewhere between 6 and 11 billion tons of economically extractable coal, or about 12-22 years of life at the same rate of extraction as the PRB. The Kaiparowits field was looked at closely for mine-mouth power plants in the 1960s and 1970s but the economics were tough due to its great distance away from everything, because it would require underground mining, and because mine-mouth plants couldn’t economically comply with Clean Air Act requirements for nearby National Parks (Grand Canyon, Bryce Canyon, Canyonlands, Zion, etc.). Law can be changed, but that takes a majority vote, and no credible person in the coal business is predicting there is majority vote out there in the public to amend the CAA to reduce its requirements. There is also a lot of lignite in North Dakota which has even worse heat value than PRB subbituminous (and even more water and ash content), and the economics are not very attractive.
Yes. Many fields have already reached their economic end. There’s often still coal remaining, but it is beyond economic extraction. Just a few of the fields in the Western U.S. that have been effectively mined out in my lifetime, that were once big producer
What changes in economy, technology, or law could extend the economic life?
Economy: if the price was to increase significantly causing power plants to switch to another method in the long term.
Technology: Finding cleaner fuels and begin using them quickly.
Law: Maybe reducing the numbers of coal fired power plants and eventually eliminating them.
Just my [2c]
You realize what you are saying is that you are looking for a change that would make it attractive to mine more of the PRB coal resource – in other words, make the coal cheaper FOB the power plant, but not any other coal or energy source cheaper at the power plant.
First, let me summarize what the economic limits of PRB coal are. The principal field in the PRB is the Gillette Field. It is mined along a north-south line about 80 miles in length, extending from about 20 miles north of the City of Gillette, Wyoming, to about 60 miles south. The coal-bearing strata outcrop east of the BNSF-UP Joint Line, and dip westward at about a 1 degree slope. Mining commenced at the outcrop of the seams beyond the clinker zone (where the coal has been burned in situ over time) and is proceeding westward down-dip. While there are multiple seams in the formation, only two seams are mined, the Anderson (or Upper Wyodak) and Canyon (or Lower Wyodak), and often they have no discernable parting between them.The other seams are either too thin or too deep or too intermittant to be economically mined.
The seam runs beneath the Joint Line, getting into deeper cover as it trends westward. Mining east of the Joint Line is relatively simple. The open-mine commences at the outcrop where there is very little cover. As the coal is excavated westward, the cover is cast into the prior mining zone. Because the coal seam is thick relative to the cover, there is plenty of room in the pit to cast the cover as the mine proceeds westward.
But to open a mine west of the Joint Line is a different matter. Because the Joint Line interrupts the mining progression, opening a mine requires excavation of a sizeable “box” to uncover the coal seam, and casting up a very large spoil pile which cannot be dumped back into an already mined area, which is a very expensive proposition.The c
I have the impression that the PRB over burden is unconsolidated material and it is all removed by drag lines and shovels. Am I correct on this?
Old Ben #1 in Southern Indiana started early in the 20th Century from the out crop of the seam. With the seam slopping down, by the 1980’s the overburden was, as I recall, at least 100 feet and the consisted of layers of limestone and shale that had to be blasted so it could be removed with the drag line. About that time, they began using the technique called cast blasting. I assume it had something to due withthe timing of the explosive detenations, and as a result there was a considerable increase in the amount of material blown into the adjacent mined out pit. As I understand, this process added years to the economic life of the mine.
So the question. Are the life of PRB forecasts based on the continued use of prevailing mining methods or do they reflect all methods that are or might reasonably become state-of the-art in the next 20-30 years?
Jay: In generalized terms, yes. Some of the mines that had low stripping ratios at least initially actually were able to employ dozer-scraper operations to remove the overburden. Mines with medium stripping ratios have typically been truck-shovel operations, and those with the highest ratios have typically been dragline operations. Most of the mines at one time or another have used two or more of these methods. A common technique is to use slot-dozer operation to shove overburden into the reach of a dragline. Usually a D10 or D11 ripper is sufficient to break the hard material, but sometimes downhole drilling is used. The coal seam itself is usually drilled and shot to reduce shovel time and make the crusher more efficient.
The forecasts employ trend lines on mining costs, which recognize the historical rate of technological change and its effect on costs. That’s a macro-economic approach. Micro-economic approaches that look at the effects of individual technologies are difficult to do (and I do not like to use them myself) because they require lots of assumptions in order to complete the calculation, any one of which, if wrong, turns the whole calculation topsy-turvy.
No one in the mining business or earthmoving business is forecasting a radical reduction in mining costs in the near future, just the steady, grind-it-out incremental improvement in tons per man-hour that has been typical of the business for more than a century. Equipment sizes seems to have plateaued, with the 400-ton (payload) truck, the 850-hp dozer, the 115-ton (bucket capacity) rope shovel, and the 110-160 cy (bucket capacity) dragline, becoming the apparent economic upper end for about a dozen years now. Significantly larger machines haven’t been economically successful on any generalized basis. The next wave of technology will be ways to leverage other technologies to reduce man-hours, such as robot trucks.
RWM
RWM
Thanks for your response. I’d have to agree that a forecast going out about 30 years has to take a macro approach. As I think about it, I doubt that a mining company starts to even consider extending the life of a specific mine until they get well within a decade or so of the end date of the original plan. It then follows that questions to the mining companys about the future for a mine beyond the current plan would get “Who knows?” as a response.
On getting to the west side of the railroad, shall we just move the railroad? [:D]
Recently the BNSF has opened a mine spur in southern Montana to one or two mines at the present that holds much hope for future coal production. The potential area for coal in the southern Montana area is believed to be greater than that of the PRB. Eventually the new spur could be built to a distance of about 200 miles. Like the PRB the coal is easy to reach and so far only the BNSF has built into this area. They have known of the Montana deposits for a number of years and are just now starting to mine the area. It is believed there is at least a fifty year supply of coal in the region and now that the BNSF has finally built a spur into the region it is expected to grow.The spur to the mine area is built using concrete ties and CWR. It is my understanding the spur is also built with double and triple tracking in mind for the future.
Years ago I was told by Alaskans that huge amounts of coal exist close to the Alcan highway in both the Yukon territory and Alaska. The problem of course is there is no cheap transportation to get to the coal deposits. Another reason talks keep surfacing that a RR should be built connecting the lower 48 with Alaska.
Now with all of the talk of wind generation and solar generating it is even less likely they will ever build a RR connecting the lower 48 with Alaska. If they ever do in my lifetime Amtrak can take my reservation now for a round trip. I have traveled the Alcan highway numerous times and never cease to be amazed at its wilderness beauty and marvel at the fact that when built it took only a year I believe. Of course it has been upgraded and paved since originally built but it is a marvelous piece of construction. If the Army could build the Alcan in WW II we should be able to build a RR today to connect the lower 48 with Alaska.
Al - in - Stockton
Al: The spur to which you refer is the Bull Mountain Spur, which serves the Bull Mountain #1 Mine north of Billings. The total economic reserve for this coal field is about 400 million tons, which represents about 10 months of southern PRB production at current rates. The permitted production rate is 15 million tons per year, which is less than 3 percent of southern PRB production rates. This coal is not easy to reach compared to PRB coal, as most of the reserve requires underground mining at a much higher cost than the low stripping ratio that enables the very low cost of PRB coal.
There never will be cheap transportation to move Alaskan or Northern Canadian coal to lower 48 markets, only expensive transportation. The rail transportation charges and capital cost to build an Alaska-Canada rail link would make this coal very dear. Even if someone else paid for the rail line and the coal could use it without paying a dime in capital costs, the rail transportation charges alone would be on the order of $50-60/ton to get this coal into a lower 48 coal market.
It’s rarely a question of a mineral being used up, but almost always a question of the cheap sources of the mineral being used up.
Note: the use of concrete ties and CWR means little if it’s intended to be a marker that a line is being intended for long life and heavy tonnage. Concrete ties in the western U.S. are generally less expensive installed in new construction than treated timber ties, and CWR is generally cheaper than stick rail for anything longer than a few thousand feet of new construction. Even in industrial spurs that will never see speeds higher than 10 mph, and might have 300 carloads a year across them, concrete and CWR is now often less expensive.
RWM
One technology I wonder about in the longer term is in-bed gasification i,e extracting SynGas directly from a coal seam. the gas can be burned in an onsite powerplant or upgraded to “synthetic natural gas”…of course such technology is not going to increase coal loadings for the railroads…
The Map of the Month in the November 2008 Trains (page 42) shows a coal mine named Hilight located several miles west of Reno Junction. Does this mine actually exist, or is it a mistake in the magazine?
Don’t have the magazine handy. Assume you’re talking Reno Junction, Wyoming, and not Reno Junction, Nevada?
There’s a “Hilight Loadout”, though.
Note that Belle Ayr, Caballo, and Cordero Rojo, and Antelope mines are already west of the Joint Line. The question is taking the the Coal Creek, Jacobs Ranch, Black Thunder, Black Thunder West, North Antelope, and Rochelle Mines across the Joint Line.
Also note that this is condensing about 2,000 pages of technical report into about 20 sentences, so there is a lot of generalization required on my part. I apologize for that, but listing all the nuances and exceptions turns it back into the 2,000 pages of report and then there’s no summary. The point is that the PRB has a definite economic lifespan that is principally determined by the cost effect of the increasing stripping ratio as the mines move down-dip to the west. The current location of the Joint Line effectively strands a substantial quantity of coal and creates an economic westward limit of mining for a large portion of the Gillette Field.
RWM
Yes, the Map is about the PRB in Wyoming, with Reno Junction being on the Joint Line at the start of the Reno Sub leading to the Black Thunder Mine. Sorry about the confusion.
The “Hilight Mine” is shown several miles west of the Joint Line.
By the time the PRB runs out of mine-able coal, environmental issues will have rendered using coal either immoral, illegal, or just plain stupid to use anywhere on this planet. In the 30 or so years before the coal is gone, if we as a species have not developed alternate energy sources, then our cultures and way of life will no longer exist.
Qualifying that “yes” with the statement about radical changes is important. Who knows what changes may occur in the next 30 years? AC locomotives have changed operations in the PRB during its active life so far. That’s but one small example of the type of technological change that will occur, although what it is we have no idea. What will happen with natural gas development? Oil shale? Deep water oil? These things all have a big effect on what will be feasible in 30 years.
Remember, there were cover stories on news magazines about the coming ice age about 30 years ago.
But you keep mining what is marginally the most econimical. If there is nothing that is cheaper than continuing to mine in the PRB, then mining will continue. Even if it stopped, it might start again at some point in the future. The Missabe Range was thought to be dead, until technology and economic forces made taconite feasible.
We need to be careful when predicting the future. No one has a crystal ball, especially looking out 30 years.
(Bold emphasis mine-Dan)
That makes me wonder if the RRs involved at the in the construction of the joint line knew of the scope of the Gillette Field. A forecast of the cost of recovery of the coal from that time could have missed the potential mark on the field as it dips down. As was just said, seeing far into the future is hard at best. If they did know and built anyway that sounds like that decision could become colossal miscalculation, depending on how big the field is on the other side of the line and the going price for the coal.
BN (which built the coal line) knew exactly what it was doing. It made an economic tradeoff. Had it decided to build the coal line where it would never be in the way of mining activity, then the cost of the coal line would have escalated to the point that the cost to transport the coal would have been so high that the first ton of coal never would have not moved for a number of additional years – or maybe never. Power plants need to have a firm fixed coal supply before they are constructed or even designed. All coal is not equal, and a plant designed to burn one type of coal cannot burn many other types of coal without very expensive modifications or even complete re-equipping of the combustion machinery, Had the PRB not come on line when it did, many plants would have turned instead to other coal sources or to other energy sources and the opportunity window for the PRB would have shrunk dramatically.
Economic analysis never gives you ideal solutions, it just gives you least-ugly solutions. Rarely is it possible to engineer a rail line that is perfect not only for the cash and economic reality of today, as well as that of tomorrow. You do what you can with what you have.
RWM
I would imagine that (to a point) the feasibility of the coal is a sliding scale. Hence Murph’s questions and your excellent replies. Great thread and thanks for sharing your expertise once again.
If the future economic life of PRB coal is in the 30 year range, does that put a lot of power plants in the position of making radical, expensive changes, once their favorite flavor of coal is no longer available?