Some history on Coal EROI and UK coal numbers

If you use Google Earth to look down on the village of Eglingham in Northumberland (thought they put it in Cumbria), (location 55deg28’13 N 1deg 49’38.43W at a height of 2.23 km - picture below the fold) you would rightly think that you are looking at a one of the more beautiful parts of the UK. And it was here that is as far back as my family history takes me, since back around 1700 my family lived in the street the ruins of which are now covered with gorse and moorland at the top of the lane that runs up from the bottom of the picture to the top. There are, as it happens, at least two mines whose remnants lie within the picture, and the family worked in one of them.



Back then the mines were small, the United Kingdom had 5 million inhabitants, and the coal was probably sold locally, although the village is not that far from the sea, and by 1770 the FOB price was 5s 4d per ton in Newcastle. In those times the coal was won by a hewer, who undercut the coal with a slot, using a pick, while lying on his side. He would then break the main body of the seam down into the free space in larger lumps. The coal was placed in baskets, or corves, which were dragged to the shaft by women and children, and then hoisted to the surface. (Hair’s Bottom of the Shaft, Wallbottle Colliery ) Those moving the coal were known as putters. To make it easier to move the corves they were first dragged along wooden rails, later small carts with wheels were added onto which the corves could be placed, And then, as the mines got larger, the rails were made with initially iron plate covers, and then entirely of metal, and the women and children were replaced by horses, or pit ponies as they became known.

Archeological evidence is sparse, but it looked as though the mines were relatively shallow drift mines, with the mine going into the side of the hill with a tunnel driven in the coal from the outcrop at Eglingham, rather than using a shaft. In 1865 Jevons noted that seven horses could do the work of 34 men, which allows the assumption that a man works at about 0.2 horsepower. Within a shift a hewer might mine perhaps 20 tons of coal (a ton occupies around a cubic yard), Jevons notes that in a larger colliery (South Hetton) the mine employed 140 hewers, 227 putters screeners etc, 123 employed in management and maintenance, and 39 boys. In a shallow mine the hewer would have only needed one helper, but in the deeper mines the distances would be greater, so loads would be consolidated, and there would also be need for boys to work the ventilation doors, and to bring in the support timber.

Can you spot the mines and the old house rows?

Mechanized cutting in the mines began to appear about the time that Jevons wrote his book, and a machine had been developed that would do the undercutting of the face, to take over the hardest part of the cut. The first machine was apparently introduced into West Ardsley mine and reported to reduce the efforts required to mine to coal by only 10%, which was, in that mine, some 27 men. The first attempt to mechanize had been made in 1761, but this was the first successful machine, and it was introduced in 1861. By 1881 this swinging pick machine, had been replaced by an electric rotating chain type of cutting machine which was found particularly advantageous as the mines had been switching from Room and Pillar Mining to Longwall Mining , which I have described in more detail in those posts. The undercutting of the face was carried out by a team of three men in the shift before the hewers came onto the face, and each hewer would then load the coal initially into his own tubs, but later onto a conveyor belt that ran the length of the face (and which I described in more detail in the Longwall post).

In the United States 2,739,700 tons were mined using a cutting machine in 1891, but by 1896 this had risen to 12,533,500 tons, with some 1,200 machines in operation. The machine had the advantage of cutting a 3.5 to 5.5 inch slot, as opposed to the wider slot cut by hand. Further, while a good hewer could undercut a face 5 yards long to a depth of 3 ft in a 10-hour shift, the machine could do twenty or thirty times this amount, according to Scott . The motor size used in these early machines was around 20 hp in size, so that, although the absolute production went up, the relative EROI for the face went down. Consider that while the machine cut twenty times faster than a man, it required 100 times the power.

These EROI numbers then proceeded to get worse, as the technology advanced (but also bear in mind that at least this part of the process is reversible to some degree). Why did that happen? Well if we accept Pimental’s concept that we have to consider the energy that goes into the machines and supports as part of the process, one of the changes has been the change from using wooden props and bars to hold up the roof, to the use of steel machines, which require not only power to run, but also considerable energy to make. But I really don’t want to complicate this bit of the argument, and so, for simplicity let me merely note this change, and also the transition to high-speed conveyor belts to carry the coal from the face to the main entries, where it was loaded into mine cars and then hauled around by small locomotives. In many places these tubs and locomotives have now been replaced by larger conveyor belts. (Much more energy intensive than a horse, which, depending on conditions, required more energy support than women and children). I mention the latter point not because I favor that practice in any way, but rather remind folk that there are other considerations than just EROI when considering alternative approaches.

But let me get back to the face, where the hewer, given the free undercut, can now break the coal down with a pick more effectively. And because he breaks it out in larger pieces it requires less energy than if it is ground out, the way a modern shearer will mine it. I have written about this, and its impact on EROI in an earlier post In that post I showed that if the old miner had used a pick to wedge out a 4-inch square piece of coal he would have used 800 units of energy to break free the coal. If, on the other hand a machine had ground the coal from the face in quarter-inch pieces, then it would need 540,000 similar energy units. Thus switching from manual mining to mechanical mining, requires considerably more energy input than manual means, but it does get the coal out a lot faster. But then, adding a small amount of black powder (an explosive close to gunpowder) in holes spaced 6 ft apart along the face, and firing these off at the end of the undercutting shift meant that all the hewer had to do was to load out the broken coal (and break up the odd lump that was too big), so that his “stint” became something like 15 yards of coal, undercut 6 ft deep and at a good working height of 4 ft 6 inches, to give a production of 45 tons per 7.25 hour shift (which included walking time and 20 minutes for lunch). Not bad for 0.2 hp, though I remain confused as to how you determine the EROI of using explosives.

Oops! My explanation to Gail as to why you have to be careful in deciding what the EROI of underground mining is has gone on bit longer than I had intended. As a result I haven’t given myself any room to explain why this EROI, while of some relevance, isn’t the whole picture when we get around to talking about what we consider as a reserve, and what we don’t. But I would suggest that might be possible to develop mining methods that are more efficient than some of those in use today, and perhaps get closer to that of the smart miner who was my ancestor.

So I will get to that next time, but before I go, let me give you the table I put together from Trueman on the reserves of coal in the UK as they were considered to be shortly after Nationalization.

I will chat more about how these should now be considered next time. Have a good Fourth!

And some small additional bits of information - for initial estimation purposes you might assume that a seam of coal that covers an area of a square mile to the depth of a foot represents a million tons. (after Jevons)

And with all the comment about what fraction of a horsepower a person can produce, it earlier times the draught animal of choice was the ox. Not only did it do more work for less feed, when it had reached the end of useful life it could be put into the stockpot.

And the original definition of an acre was the area that an ox could plough in a day. Twenty oxen could have been used to drag the individual blocks of the Stonehenge megalith to the site, rather than the more popular concept of 500 men.

Not only did it do more work for less feed, when it had reached the end of useful life it could be put into the stockpot.

Reminded me of the song "Timothy" by the Buoys, the only AM top 40 hit about mining and cannibalism.

Not to start and off-topic thread, but: Horses can be, were, and are put in stockpots at the end of their useful lives. And I don't know of a reason why, if cows can be eaten, horses can't. The alternative is that the horses go to waste, and more cows are raised for slaughter.

Horse remains popular in France, much to the disgust of the English. I wonder if they keep eating it just to irritate the English?

Thanks for the explanation!

I can see that at first the energy was primarily people energy, then it was supplemented by the energy of horses. Finally, mechanical energy started replacing parts of both. Using traditional EROEI calculations, the EROEI goes down, as more mechanization takes place. This is one reason why the EROEI of ethanol from Brazil sugar cane (using hand labor for harvesting) is better than from, say ethanol from US sugar cane.

Have you done any calculation of actual point-in-time numbers of EROEI using "standard" calculations, to the extent that there are such things? Energy embedded in infrastructure will have to be amortized over a suitable number of years.

"This is one reason why the EROEI of ethanol from Brazil sugar cane (using hand labor for harvesting) is better than from, say ethanol from US sugar cane."

Except from the fact that the hight EROEI areas do mechanized harvesting.

People too cheap to buy an add-on to their tractor usualy don't use state of the art refining equipment, and the hightest EROEI are from areas with hight workforce prices that, by the way, are near if not even south of the tropic (subtropical climate).

Most interesting. In the early sixyies I made a study of the economics of mechanised working versus handloading and got a peculiar result. If one wanted to maximise return on investment like a good capitalist, then hand loading was better because mechanised pit props were so expensive in a country then short of steel. But if one did a "socialist" calculation using an opportunity cost for capital in addition to depreciation, then mechanisation won easily because labour productivity was so much higher on mechanised coalfaces..

Another important factor developed later. Mechanisation permits longer coalfaces and therefore less underground roadways were needed to move coal. this "concentration" of production lead to very significant efficiency increases. Electricity consumption was a very minor cost for getting coal in the UK. Labour cost(wages, salaries, pensions, and health car were the larget single cost

"But if one did a "socialist" calculation using an opportunity cost for capital in addition to depreciation, then mechanisation won easily because labour productivity was so much higher on mechanised coalfaces.."

Did your "socialist" calculation take into acount the opportunity cost of not using that steel on places where it is more valued?

No, we just used the market price of mechanised pit-props assuming the manufacturers took account of the market price of steel. Anyway, what were the missed opportunities? An important one was that European cars generally remained small, because of steel shortages whereas , in the US with lots of steel, who bought an Edsel?

I find talk of historic coal extraction so utterly depressing from a social perspective. To think that generations of men, women, children and beasts toiled all their lives underground, sucking in Uranium enriched coal dust in dim, wet and cold mines. Life for these people was unimaginably harsh -'it sucked' hardly comes close.

I'm really not sure what lies ahead in the next 20-30 years given what I read here on TOD but can it really be as bad as this? ["Ultimate Doomers" queue up to respond.]

Regards, Nick.

Nick:
The dramatic license of some of those who have written about historic mining can make it seem much worse than it actually was. Firstly, because of the geothermal gradient, as one mines down to any significant depth the mines became comfortably warm, rather than cold. Secondly since water was (and is) an issue it is drained away so that it does not interfere with most of the mining operations, so that the working area itself was (and is) generally dry. Dim it certainly was, and walking the ways back to the shaft in the dark after my light failed is something I still remember 40-some years later, but there was a lot of cameraderie and a sense of self-worth in those who worked there that should not be forgotten. The problems of coal dust were long neglected, as were other health and safety issues, but the damage done by the dust had little to do with uranium enrichment, somewhere in the back of my mind I seem to recall some early coal roof detection equipment that worked because of the emission from the overlying shale, because the coal didn't have any.

Unfortunately society was more concerned to get cheap energy than to worry about the conditions of those who produced it. As Barbara Freese pointed out their view of the industry and its workers has more often been tinged with comtempt than, for example, the more glamorous view of oil.

One of my great-great grandfather's worked as a coalminer in Pennsylvania in the 1860's. His father died and he left home at 12, because his step-mother had young children and he had to support himself. He was from a large Mennonite family in Pennsylvania. He went to Nebraska in the middle 1870's and homesteaded, lived in a sod house on the prairie near Lincoln.
Life was just plain hard for most people in the world in the 19th century before the fossil fuel age. And it may become hard for us again, but I think its important for people to remember our roots.
EROEI isn't nearly as important as ROI. As long as people can scratch out a living mining coal, its going to be mined, just as oil production is going to continue as long as people think they can make a living at it.

Bob Ebersole

ROI is subordinate to EROEI for primary energy sources. There is no economic value in digging coal, or oil, or Uranium if you cannot get net positive energy from it. That only works for things like batteries where people will pay a premium for the energy in a convenient form.

We never thought much about ROI in energy planning. As Schumacher put it there are two basic commodities - fuel and food. All others are secondary. For fuel and food, short term market prices are a poor guide for long term planning. Overriding importance is attached to secuity of supply.

Nick,I think a example of "best case"of break-up,or powerdown in a relitive timeframe could be the collapse of the USSR....but the problem is there were functional modern societies nearby to supply consumer goods.At this next big powerdown that will not be the case.It will just keep getting worse."Where it stops,nobody knows".Make your preps as you see fit.Fruit trees are good...as are kiwi vines,grapes,a secluded residence LED lights,ect ect ect

The net energy from coal mining must have increased with mechanisation despite the need to loop back much of that energy into machines and pit props. Will a future wind and solar economy have enough spare energy to make new machines?

The next development in the coal story may be as significant as the end of the pit ponies. Using the tags I found this link in an earlier TOD article; Chinese coal production may soon peak http://www.eurotrib.com/story/2007/5/13/105158/220.
No doubt the same countries that just hosted Live Earth concerts will send their coal to China to maintain the flow of cheap manufactured goods. Obviously we'll use all the near-surface deposits of reasonable quality coal until there are none left.

More on the net energy of coal (EROEI) can be found at the following links:

http://analyst.energy.googlepages.com/TERNumber6.pdf

http://analyst.energy.googlepages.com

Larson

Thanks for the links to your analysis !
Bob Ebersole

Bob,

My pleasure! The energy field is pretty exciting and I love writing analyses.

Next week I'll be touring two coal-fired power plants and a gas fired plant. I need to do that to keep my analyses honest. It's fun, but too hot in the summer. I wish the tours could be in February.

Larson

Interesting remarks about oxen HO, besides all the rest of course. Stonehenge built entirely by hand is indeed an awkward concept.

Back in 1980 this was still a more rural than industrial country and many of the farmers worked their fields with oxen. Donkeys and hybrid crosses of mules and horses were also very popular. Now all of that is gone.

My family folk that used oxen back in the day didn’t eat them at the end of their life. Old ox meat is not that appealing, especially if you can grow a hog or two with extra turnip or beet. It is likely though that they sold them to the local butcher.

Today I question myself a lot why there were never heavy horses around here. It seems that we find them only across the Pyrenees. It could have something to do with climate, but Man has excelled in developing domestic animals according to his needs.

The problem with oxen is that they are “dumber” than horses. If go out ploughing the field with oxen you need two men, one for the plough and other to drive the oxen. With horses you just need one man for the plough.
On a smaller field were hay feed can be constrained oxen might be the option, but on a larger field I think heavy horses have the upper hand.

On that man power discussion, London lad Brad Wiggins crossed Buckingham palace on his way to Hyde Park producing 530 watts last Saturday.

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