OT: 'Photon Farming' in California

g.

into how the failure happened as parts of the UK were battered by strong w inds and heavy rain."

tle Barford at 16:58. Two minutes later Hornsea Offshore wind farm seems to have disconnected."

Lol!

g.

into how the failure happened as parts of the UK were battered by strong w inds and heavy rain."

tle Barford at 16:58. Two minutes later Hornsea Offshore wind farm seems to have disconnected."

And does that happen suddenly? I think the power from a wind farm will var y much more slowly than a-ok to offline in two minutes.

I believe I read they are investigating if the first plant failure caused t he wind farm to go offline.

It also may be that they had a bit bad luck.

Good network management requires that the N-1 rule is followed. The network should survive the loss of _largest_ production unit. In practice during the first minutes the spinning reserve of other power plants are used (.i.e. overloading them). During that time quick start emergency gas turbines are started, which then takes over from the spinning reserve. When the emergency gas turbines are running, the power of existing power plants are added e.g. by burning more coal to get more steam or other slower starting power plants are starting. When these are running, the emergency gas turbines can be shut down and the N-1 criterion is restored, waiting for the loss of the next largest production unit. These emergency gas turbines are typically running for less than an hour.

However, as long as the emergency gas turbines are used, the network doesn't tolerate the loss of the next largest unit.

In this case, there was the second fault while the emergency gas turbines were running. Of course if two medium size faults occur nearly simultaneous, there should not be a problem as long as the combined lost power is less than the largest unit.

Now both units were quite big, the Little Barford 727 MW and Hornsea Project 1 of 1200 MW, however it is unclear how much of that capacity had already been installed.

Little Barford is a typical combi power plant with two gas turbines, exhaust goes through a boiler, running a single steam turbine. Even if one turbine/generator failed, the remaining turbines should still be in production, so it should be a bad case, if all 727 MW are lost at once for some reason

While one wind turbine may loose production due to loss of wind, this happens much slower in a wind farm with some geographical extent.

If the whole wind farm was lost at once, it is unlikely that it was due to loss of wind, which can be predicted quite well in advance. Since this is an offshore farm, power must be transferred to shore with cables. A total wind farm failure sounds like a problem in this cable or other farm network components, not in the turbines itself.

Then there is the question, was the wind farm loss truly independent or caused by the gas turbine fault, since it occurred during spinning reserve period. How much semiconductors were involved in the link to shore, which might have tripped due to overload.

But with a national grid and frequency being the same everywhere the substations with the more sensitive cutouts don't have to be any place special at all. So you'd almost expect random locations to trip?

piglet

That would be my /guess/.

That's plausible for this event, and I will be interested to see if it was the case.

Where the outage is marginal, that is plausible. I can think of other possibilities, but they would only be uninformed speculation.

Yes, well, that's the idea :(

I will be very interested to hear - why the *second* fault was so close in time - what the actual faults were

Considering the latter can lead to movie-plot theories.

Good questions.

No. There several days warning, and it decreases slowly.

Nonetheless, there must be sufficient conventional plant that is normally idle to take up the slack. The question is who pays for the "normally idle" plant.

The green zealots say "don't add the costs to the cost of green electricity.

The accountants say "only generating 2 days/year means the electricity is uneconomic - shut the plant down". That's just happened with another coal plant owned by RWE.

... and the result is too little margin in the available generation capacity.

I would be very interested if that wasn't the case :)

They would be negligent if they weren't doing that.

Both solar as well as wind power have a well defined maximum (100 %).

If we look at the wind turbine output power vs. wind speed, at low wind speeds the maximum available power is proportional to the cube of wind speed. At a certain wind speed, say 5 m/s and above, the output power is limited by the generator size. It remains at this constant level (100 %) up to stormy winds around 20 or 25 m/s, when the turbine must be stopped to avoid permanent damage. Variable pitch propellers can be used to limit the axial power and also in older turbines, the blade profile was such that part of the blade stalled at high winds.

In reality the output power is determined by the selection of the generator ratings. After that, the only significant parameter that can be varied is the propeller diameter. By selecting a big propeller, the nominal power is achieved at 5 m/s, but a smaller power and lower tower, up to 7 m/s is required for nominal output.

One tries to select the propeller size according to prevailing winds on a particular site. You try to select so the size that the wind is in the constant power most of the time.

The COP depends also on the prevailing winds and propeller diameter vs. generator nominal power.

One tries to avoid to operate in the say 2.5 to 5 m/s speed range, in which the generated power would vary 8 times from 12.5 % to 100 %.

It isn't really competitive, it's just benefiting from a market that's been seriously distorted by political considerations.

Try selling any other commodity on the basis that you'll supply it when it's convenient to you, and not otherwise.

Sylvia.

Why pay more for energy from a harmful source? Do you just like to toss mo ney out the window?

That's exactly what I do. My customer sends me a PO and I let them know wh en they can have the boards. In the past I have pushed to try to deliver o n their schedule, but it is never good enough and they often want earlier d elivery even after I accept the PO. I stopped worrying about it and now th ey get the boards when I tell them they can have them.

Your boards are hardly a commodity.

Sylvia.

I'm waiting for the day when solar routines displaces all the fossil fuel generation, and owners discover that when all the remaining generation has a zero marginal cost of generation, the market price collapses.

At the same time the greenies will finally realise that they cannot build any more solar farms, because there's no use for the power they generate, but the zero-carbon future still hasn't been reached, because of all the fossil fuel generation during the large part of day when solar doesn't produce.

Then the politicians will discover that nuclear power isn't so bad after all.

Sylvia.

In some ways they are. The customer actually owns the design. But for the m to make these themselves they would have to spend money to put them into production, develop testing, etc. So they go with the lower cost option ev en though they can't have them just when they want them. Same with power.

Besides, it's a false issue. Currently we can avoid releasing carbon by re placing fossil fuel with renewables. The cost is less than the other choic es, especially nuclear. As the price drops further it will be economical t o use storage with even more renewable energy. I was surprised to learn that in the UK wind power is on par with nuclear c apacity and at times equals CCGT (gas) usage. They also have significant a mount of "biomass" generation. Not sure what that is, I guess making gas f rom plants and burning that?

Nuclear isn't "bad" (except for the waste issue) it's just expensive. The North Anna reactor Dominion has received approval for will cost $19 billion ! That's $0.06 per kW just for the capital without counting the interest, operation, refueling, etc... and not counting the cost of waste handling.

How much are you willing to pay for using nuclear?

Then you seem to ignore the potential for storing energy to make renewable energy available 24/7. The UK has at least 1400 MW of pumped storage hydro for a country that uses about 30 or 40 GW peak. Obviously it can't be so expensive.

Sigh. Cherrypicking.

/Surely/ you realise by now that "MW" is only half the story.

The other half is "MWh", and that is sorely lacking in the UK.

Somehow that doesn't surprise me at all. I guess the reservoir is high, but no larger than a bathtub. 10 seconds of backup. How long does CCGT take to come online?

Poor UK.

Not typically grown explicitly to burn. Biomass is more typically a bye-product of farming, forestry, landfill and sewage waste. Biogas is sometimes included within the definition.

piglet