Power station coal usage

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Andy873

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I'm just looking at the Padiham power station (near Burnely, Lancs), because of it the short Padiham to Rose Grove section was saved and used for nearly 30 years after the rest of the loop line was pulled.

And I'm wondering how many coal trains would have served it?

According to this site:
https://www.quora.com/How-much-coal-is-required-to-generate-1-MWH-of-electricity nearly half a ton of coal would be needed to produce what's called 1 mega watts of electricity for 1 hour.

In 1984, the power station was producing 15 million! MW hours of electricity (I presume over the whole year).

If I've got my calculations correct (an approx) that's roughly 7.5 millions tons of coal.

Does that sound right to you? I know they used a lot of coal - but that sound a huge amount.

And what does that mean in terms of frequency of the train deliveries? I've seen photos from the 1970s and 1980s of coal trains with at least 25+ wagons attached.

So how many trains per year do you think (or know) delivered to this (or other power stations)?

An interesting question I think.
 
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Bald Rick

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Back in the days when I was involved in such things....

Ratcliffe Power Station in Notts had a capacity of 2 GW (2000MW), and needed about 10-15 long coal trains a day, occasionally more at peak times of the year to rebuild the stockpile. Typically it would take about 5-6 million tonnes of coal a year.

Note that the power station didn’t run at full capacity all year; at least one of the four generating units would be taken off line at any one time over the summer (roughly coinciding with British Summer Time). Sometimes only one would actually be working. This was typical of coal power stations.

A quick bit of research suggests that in 1984 only Padiham ‘B’ unit was operating, which was 240MW. Eve if it ran 24/7 for a year, it would only have produced just over 2m MWh, so I suggest that the 15 million quotes is out by a factor of 10. On this basis, it would have needed one or two trains a day.
 

Andy873

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Back in the days when I was involved in such things....
so I suggest that the 15 million quotes is out by a factor of 10. On this basis, it would have needed one or two trains a day.

Thanks for that, the figure quoted did seem to be very high. So your saying probably one or two trains a day - that would make more sense.
 

RLBH

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So your saying probably one or two trains a day - that would make more sense.
Though a big station flat out certainly would burn a terrifying amount of coal - without stockpiles, you'd need sixty 32.5-ton hoppers an hour to keep pace with consumption. Fortunately there's a requirement to maintain large stockpiles - currently four months' worth, but it's varied over time. That means that you have a buffer against heavy demand.
 

RUFJAN15

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As an ex-CEGB engineer, I couldn't resist checking the numbers on this.

'Hard' coal is widely reported as having an energy density of 24 Million Joules per kg. This sounds a lot, but 1 Joule of energy will only deliver 1 Watt of power for 1 second, so you need 1000 Joules to deliver 1kW for 1 second and 3.6 Million Joules to deliver 1kW for 1 hour. This means that a kilogramme of coal contains 6.67kW hours of energy.

The next factor to consider is that the energy stored in the coal is converted to thermal energy when it is burnt and the process of converting thermal energy to electrical energy is quite inefficient. Padiham power station had two 120MW generators installed. My memory doesn't stretch to remembering the efficiency of the CEGB 120,000 kW generators, but a bit of searching suggests they were not far off the much larger 500,000 kW/660,000 kW units and could run at up to 33% overall efficiency. This means, of course, that you need to put in 3kW hours of thermal energy to get out 1kW hour of electrical power out. A kilogramme of coal will therefore only produce 2.2kW hours (i.e. units) of electricity - enough to boil a kettle continuously for an hour.

There are some useful details of Padiham power station posted on line. These suggest that Unit 1 was converted to oil firing in 1974 and was only used occasionally in the 1980's (due to the increase in oil prices relative to coal). Unit 2, however, remained as a coal burner and is reported to have generated more than 620 million 'units' (i.e. kW hours) annually during the early 1980's. Based on the calculation above, that would have required 280 million kg of coal - in other words 280,000 tonnes each year. Assuming this arrived at Padiham in old fashioned 20t mineral wagons, this would have required 14,000 wagon loads each year or 500 trains of 28 wagons each.

To draw these ramblings to a close, the figure of 15 million MW hours generated per annum is clearly wrong, the station could only generate 2.1 million MW hours if both units ran continuously (240MW x 8760 hours). With one unit (of the two) burning oil, the theoretical maximum coal consumption would be based on around 1 million MW hours of electrical output. Considering the actual output, Bald Rick's estimate of 1-2 trains per day is supported by the maths and was spot on.
 

Andy873

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Thank you for that,

Seems a comprehensive reply from someone in the know about these things.

I know the power stations did keep stock piles of coal to hand, but clearly has to be replaced as its being eaten into.

This makes me ask a related question - what would BR had charged the CEGB for using the railway line to transport coal to the power station? I guess that depends on how far the coal had to come from?

Thanks.
 

Bertie the bus

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Prior to its closure in the early 90s I think it received one train per day. A Class 60 hauled service from Lakeland Colliery. The wagons used weren't HAA mgr ones. There's a pic here of the service: https://flic.kr/p/AvgKLp
 
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