Comments on: Didcot A Power Station

By: DL

DL — Wed, 15 Aug 2012 02:26:46 +0000

On aviation kerosene : I spent a lot of time in Hong Kong in the 1970s. One of my favourite past time was plane-spotting at a park looking directly on to the old Kai Tak Airport runway. Depending on the wind direction, I could smell the exhaust from the jets. The smell was quite unlike to kerosene used in household stoves. Is there much difference to the two grades of kero?

By: danny

danny — Tue, 14 Aug 2012 20:57:01 +0000

Matthew, the black-start system is actually made up of jet engines, burning aviation fuel, and not gas turbines, at least according to this source.

"To cover black start conditions the station has four 27 MW Rolls Royce Avons. These can be at full load in less than 5 min ( just over 2 minutes is possible). They can also be used for peak lopping. Fuel is kerosene."

By: DL

DL — Mon, 23 Jul 2012 02:18:37 +0000

I am still learning, for example, I had no idea that almost 10% 0f the power generated is consumed on site. That is a big chunk. Still, it is better than the incandescent light or internal combustion which powered the family car.

By: danny

danny — Sun, 22 Jul 2012 17:55:47 +0000

The pumped storage system at Dinorwig, which we visited last year, is also a black-start system - I guess hydro is easier because you don't need power to warm up a boiler, just to operate the sluice gates and maybe power stator electromagnets. The 50MW hydro station at the bottom of Warragamba Dam only runs when the dam is full, but it is capable of black-starting the NSW grid. (Vic or Hansen could probably tell us what the power from that would be used to start next.)

By: Matthew

Matthew — Sun, 22 Jul 2012 12:17:06 +0000

'Black Start' is an issue for all large power stations - as the amount of power required by the power station itself is considerable, many 10s of MW. If the grid is unavailable 'ie black', many power stations can't be started. Presumably the 'jet' turbines (read gas turbines) can generate enough electricity that they can power all the required auxiliary systems to get one of the main steam turbines on line. And remember a 'cold' turbine may take many hours or even days to bring on-line. (They have to wind up the speed slowly to allow the sag to be 'spun' out of the turbine shafts among other things), so that 'black start' power has to be sustained for possibly several days. It's not something you could do with batteries! I seem to recall from a tour of the Eraring power station on Lake Macquarie, NSW that each 660Mw turbine there used 60Mw of it's own capacity just to keep itself running. Eraring can't black start - it requires power from the grid to boot-strap.

By: danny

danny — Sat, 21 Jul 2012 15:59:07 +0000

There is coal in Wales, but it's too expensive to extract. There are too many people - and national parks - for large-scale open-cut mining to be practical. (We went down the Big Pit coal mine at Blaenavon, which was quite an experience; we heard there about the horses that spent almost their entire lives underground.)

By: DL

DL — Sat, 21 Jul 2012 11:43:00 +0000

This is as good an introduction to coal-fired power generation as any I can get. I thought coal is simply shoved into boilers to heat water, water turns into steam and in turn drives turbines, and condenser collects the residual steam to drive other turbines, and bingo electricity. There are technical terms I don't fully understand. Jet engines for black-start? Not sure how it works.

I have never been to a thermal fire power station. Even there was an open day, the nearest coal-fired station is simply too far away. ( I visited a crematorium on an open day.) I did visit the Snowy Mts. hydroelectric plant back in 1966 or 67 on excursion. I think there was just whirring of the turbines in the housing, nothing much exciting about that. It was so long ago.

It was on a late night fishing trip to Budgewoi that I gained a little knowledge of discharged cooling water from a power station. The fishing spot at Budgewoi is next to Lake Munmorah Power Station. The cooling water is discharged into the estuary. On that particular night over thirty years ago, I could feel the seawater was pleasantly warm. But the fishing was good, and there were many, many anglers. The warm water didn't do any harm to fishing activity. Like Didcot, Munmorah is also slated for closure.

Why there is a need to ship coal from Canada and Siberia? I thought there is plenty of high grade coal to be mined in Wales. What about Newcastle? A Welsh workmate told me coal is still plentiful in Wales. His grandfather, a coal miner lived to 70, a ripe old age for a coal miner. But he was bedridden, and had tubes and tubes to help him breathe. There was no compensation. I asked him about the pit ponies. This workmate told me the ponies were taken above ground only once per year. What a dreadful lot for men and beasts down in the mine shafts.