Tidal stream

[Tim Streater]

I see in today's Times that Rolls-Royce is doing very well with their new engine - Trent replacement - due to be in service soon. So, bollocks to those who say we don't make anything in this country any longer.

The article also said that RR is going into the tidal stream generator business, using their marine engine experience. They'll make 1 Mwatt units that will operate 100ft below water but can be floated up for maintenance.

Nice thing about tidal stream is that unlike wind or harry's favourite, tides are guaranteed. And it's incremental so we don't have to spend £20 billuyn on the 7Barrage before a single watt is generated. However as my niece says neither wind nor tidal stream nor solar will solve the entire problem.

As a matter of interest, does anyone know how big the gennies are at a power station? Presumably you don't just have the one producing 1,000 Mwatts? What is the optimum size and what voltage are they producing at?

[charles]

In 1961, I was working (as a student) with a firm which made large transformers for power stations. They just completed a 120MW one for Kincardine (Coal Fired) power station. I suspect that was 'small' by modern ones. (just looked at Wiki - Drax produces nearly 4000MW)

The voltage they generate is slightly irrelevant since the output transformer will create the 132kV or 275kV that the Grid requires.

[tony sayer]

In article , Tim Streater scribeth thus

A bloke who used to work for the CEGB told me recently that they have

245 MVA transformers at largish 400 kV substations and much the same gear at the sending end..

[Phil Emmup]

The Dinorwig pumped storage hydroelectric scheme uses 6 motor/generators each delivering 300MW. Voltage at the generator terminals is 18kV at 500rpm.

[Tim Streater]

Yeah I know but was curious since what is optimum for a generator may not be optimum for transmission.

[charles]

It rarely is, which is why transformers are used. Isn't ac wonderful?

[Nightjar]

Drax has six generator sets. Each set comprises 1 x 140 MW high pressure turbine, 1 x 250MW intermediate turbine and 3 x 90MW low pressure turbines. There are also six 75MW gas turbines as backup.

They don't say what voltage the sets run at, only that their output is stepped up to 400kV before going to the national grid sub-station.

Colin Bignell

[polly filler]

I used to work at RR and they had started to send alot of work to be done abroad that we did inhouse, which wasn't of such good quality, so alot of RR stuff is outsourced and not 100% british.

[Andrew Mawson]

output

requires.

wonderful?

Well Dr Ferranti thought so, but it took a long time to convince others !!!!!

AWEM

[Harry Bloomfield]

charles formulated on Monday :

[John Bryan]

Drax has six compound steam sets (coupled on one shaft) each generating 660MW but not necessarily sending that out as each set has large motor driven fans and pumps.

The gas-turbine sets are for black start (grid failure) and peak loads.

[Tim Lamb]

In message , harry writes

What were those two women wittering on about on R4 this morning? The subject was obviously under grounding high voltage supplies. I missed the reason one claimed that putting the stuff underground would save money because of energy savings.

regards

[Tim Streater]

articles is a lack of such detail.

[Jules Richardson]

As big as a piece of string is long, or something :-)

I knew a couple of folk in NZ who looked after an old power station - the alternators there were 1250kVA, the engines 725 litre straight-8 2-stroke diesels running at 300rpm. Very small-scale in comparison to most sites! They last actively supplied power in the early '90s, after which it was all disconnected and preserved (in running order).

cheers

Jules

[Andrew Gabriel]

The UK-manufactured generators output at 11kV traditionally, but other manufacturers used different voltages, and I don't know if there are any UK manufacturers left anymore.

[Newshound]

On big coal and oil fired power stations, 500 or 660 MW. On nuclear, from 200 up to 660 MW. Not sure about gas turbine stations. ISTR that they generate at 3kV or thereabouts, but that's transformed up to 275 or

400 for transmission. Most stations have several generators, typically big coal stations have four 500s or 660s. Sizewell B (nuclear) has a single 1300 MW reactor, but two 660 MW turbine/generators. Although the Germans and others have been making 1300 MW generators for decades and most continental nuclear plant has one generator per reactor, 1300 was considered a step too far for the UK in the 90's.

[Adam Aglionby]

VA Tech who spent =A330million on the worlds most advanced and fire retardent big trafo factory in Leith, closed a few years ago.Replaced the Parsons Peebles factory in Pilton, destroyed in very big fire, Parsons had invented the steam turbine in Newcastle and Bruce Peebles was making dynamos to gas parts started making big, very big switchgear.

New aircraft carrier project at Rosyth is being built/assembled with a goliath crane made by Shenzhen Crane.

Cheers Adam

[Ron Lowe]

Yes, it was somewhat ill-informed. She said underground cables don't lose power, like pylons do. That's just plain wrong, but there is a seed of truth which she was unable to articulate.

Pylons have simple air-cooled conductors, which have normal I2R losses.

Underground cables can run too warm unless they are made of a greater x-section ( reducing the I2R losses ).

Undergrounding 400KV is a non-trivial exercise.

I came across this whilst reading up about the proposed 400KV link across scotland.

[The Natural Philosopher]

a typical aircaft engine is about 200MW and the modded up ones for CCGT uses are about 300MW, with maybe a double unit making a neat 600MW CCGT type setup.

They probably spin out at 250KV but that may be after transforming up.. you probably don't what too much voltage in the genny hall. Mind you that's still 1000A+ if I haven't gone senile.

I am dubious about tidal stream power.

Predictability doesn't help. Its the intermittency that is the problem, even when you know its going to happen. You still need to cover the gaps.

My guess is that it will work but not very well, and at large costs.

1MW is crap.

RR should be trying to get back into nuclear power - they make nuke sub reactors.

BTW I calculated that 100 jumbo jets on takeoff power could power the whole Grid.

and just two jumbo jets on takeoff power would produce more than all the wind farms in the UK do, on average.

If every house had a square meter of PV on the roof, that's about 4 jumbo jets worth.

OTOH we could save building 4000 windmills a year if we stopped all immigration.

Fun factoids.

[The Natural Philosopher]

Oh there's a big hooha because a minister or summat said it would be cheaper in the ling run, because

(a) the service costs are less (b) it wouldn't destroy the tourist industry. This is probably true - when I under-grounded my local bit of 11KV the NatGrid wonk said that 'we are not doing any more overhead 11KV for new installs and trying to undergound what we have up there' Trees are the problem.

The cost/benefit changes with power.

Not many trees up at 132KV height. But aircraft and lightning.

Also its not easy to underground such HV - get capacitative losses to ground. DC is OK for long hauls, BUT it adds even more expense and its rare to go much over 2-3GW on a single cable.

Personally I think it would be money well spent, but its certainly not cheap.