Grand Apagon - Electricity (not) in Spain

But grid scale batteries do - pumped hydro storage has the spinning turbines, but grid scale batteries have invereters, which can reacta lot faster than any spinning turbine, Photovoltaic power is variable so it needs energy storage of some sort to smooth out the variations.

It provides some power on gloomy days, if nothing at night. You end up installing more peak generating capacity than you need to cover the low output periods, and enough energy storage to cope with them.

Geographical averaging helps. Your denialist web-sites prefer to ignore this - they want people to keep on buying the fossil-carbon fuel that they are set up to supply, even if anthropogenic global warming makes this a very bad idea in the long term.

That is the message that your climate change denial web-sites exist to peddle. Somebody who was a better electrical engineer than you are might detect some of the fallacies in their story.

About 40% of new roof-top solar power installations in Australia include a Tesla Powerwall (or something similar) to keep the lights on at night.

It adds appreciably to the capital cost, but pays for itself in a couple of years. Australia's feed-in tariffs aren't generous.

Africa and India use this approach because nation-wide grids are expensive. Only the moderately rich can afford it. but that's still quite a few people.

Far from it. Ponzi schemes make some people a great deal of money.

Spending money on advertising is totally inefficient,but can let you make a great deal on money. Look at the fossil carbon extraction industry, which spends millions on the lying climate change denial propaganda that you re-cycle here.

Fuel-reduction burns don't stop forest fires. We do lots a of them in Australia. They can make forest fires less disastrous than they might have been, but in a dry season pretty much everything can burn

And mostly it is lightning.

Stopping digging up fossil carbon isn't going to condemn anybody to cold or hunger, even the climate change denial propaganda machine likes to complain that it will.

Except that having lots of natural gas for a while didn't make the Netherlands poor. I was living there when the natural gas was running out, and it wasn't in the least impoverished. They had the money to invest in masking better photolithography machines at ASML - I tried for work there and didn't get hired. You and Phil Hobbs seem to have done better.

Trump hasn't get the attention span to have a plan.

China is replaying Japan's me-too industrialisation, unfortunately including the enlarged co-prosperity sphere. They may get to democracy a bit faster. Replicating other people's technological advances may let them copy the poltical advances as well. The USA is still stuck with a remarkably primitive political system, so it isn't guaranteed.

In the UK air-conditioning is not common, although it is being used more as the climate heats up. On a bright day with solar power producing pretty much full output, most of it will not be used. An average house might only be using low hundreds of watts - perhaps 60W for a TV, 40W for a laptop (maybe double for a desktop), perhaps an intermittent 100W for a fridge/freezer (I have no idea what the average consumption would be as it would depend on how much the doors are opened!), a few watts for assorted wallwarts, no lighting required during the day, and cooking probably using gas. Even if a microwave is used, you're probably looking at 1.5kW for only 5 or 10 minutes.

As it happens we are currently experiencing remarkable late April weather - about 10°C above normal (it will hit 26°C today) with full sunshine all day. It will peak tomorrow with possibly 29°C expected. Currently solar is providing about 10% of the UK power requirement (about 30GW - see

Different environment. The temporal average base electricity load of a UK home in summer is somewhere around 200W mostly less unless the kettle (2 mins) or immersion heater (1 hr) is on 3kW. By late afternoon the immersion heater will not be in use as hot water will be fully hot.

Domestic aircon is virtually unknown here. Fridges and freezers come in at about 4-500W but are very intermittent so a working average power consumption for a home is somewhere between 200-300W.

As a calibration point my base load is 100W with no computers on and twice that with my main box on and idle. I have a lot of electronic gadgets running 24/7 too so most homes base load ought to be less!

It crosses my mind now you come to mention it that UK NESO might be using US figures for domestic electricity consumption which would explain why their load shedding sums went so horribly wrong.

Why? We don't have any aircon and in the daytime so the only serious loads are the fridge and the freezer for a few minutes per hour.

Key assumption was that there are never power cuts in first world countries - but when there are all hell breaks loose. Why they decided it needed an engineer to visit I really don't know.

Almost no-one in the UK has aircon. That is changing in big cities as the climate gets hotter.

In summer heating is unnecessary and immersion heaters are used by owners of solar PV arrays because it pays them to do so (crazy).

But by late morning the hot water will be at maximum get and most of the

Same in the UK although not for me since there is no gas supply here. However, British Gas sells *electricity* to our Village Hall!

It is in the UK. I might even have erred on the side of caution.

We don't have aircon, domestic walk in fridges or 2m TVs.

I thought the stabilising effect of a spinning turbine was because it

The grid frequency begins to fall so energy from the moving parts is converted to electrical power which is fed into the grid to increase. the frequency. This results in a loss of stored mechanical energy which causes the turbine to begin slowing down - which is detected by the control system and used to feed more water/gas/steam into the turbine so its speed is returned to normal.

The interface between the stored mechanical energy and the electrical energy demand has an almost instant response and is inherently stable without needing elaborate control algorithms.

I understand that the turbine doesn't actually slow down, because the generator starts working as a synchronous motor drawing energy from the network instead; this is detected by the control system and feeds more water/gas/steam, etc.

As long as the network keeps the frequency.

That doesn't sound right to me. If the frequency of the grid is dropping and the turbine is running at the correct speed, the mechanical energy will flow into the grid as electrical energy and the speed will start to drop ... but the speed can never drop below the grid frequency because when the energy flow from the turbine stops there is no longer any load on the turbine and it doesn't slow down any further.

If the turbine lost its source of mechanical power, then it would 'motor' and extract energy from the grid - but reverse current detectors would promptly disconnect it.

It doesn't slow down much, but there's no such thing as instantaneous feedback - you have to an input change before you can start correcting the output.

The "network" can't keep the frequency - it's the corrections that keep the low term frequency stable

But the stored mechanical energy in the spinning rotor can only get fed into the grid if the rotor slows down.

The generator has to have a control system to control the power being feed into the rotor to keep it spinning at the same speed while more energy is being extracted from it.

There's nothing magically stable about that kind of control system - it has to be designed to stable like any other feedback mechanism.

Actually, the grid frequency is a bit elastic. We had that in the European grid some years ago, when some Balkanese enclaves / exclaves did not care much about cos_phi correction and the grid drifted slooowly to a lower frequency. No bad consequences other than some wall clocks were a few minutes late after a week or two.

I found that easy to measure with a time interval counter. (ps resolution in a second elapsed time)

Cheers, Gerhard

I don't think we in Australia ever had the economically nonsensical net metering that the USA is only now trying to get rid of. If your electricity provider lets you use the grid as a battery for free, then there's no economic case for installing a real one.

Sylvia.

The Australian utilities don't let you use the grid as a battery for free any more .

At first they accepted excess current generated by roof-top solar and paid a reasonable price for it, but when it got popular they dropped the price and starting charging for current accepted when the grid was getting more current an it could use (and charge for).

Installing a a real battery to back up your roof-top solar became a lot more popular a that point.

One of my more distant acquaintances is a fan of "community" batteries where a bunch of people with roof-top solar pool their generated current in a single not-all-that-big-battery. The utility companies aren't all that sympathetic to the idea, and seem to make the process as difficult as an obstructive bureaucracy can, so there don't seem to be any examples around here. Or none that he knows about.

There are two mechanisms at work here:

The difference between these two shows up as a change in the speed of rotation.

Here's another perspective:

It is very unlikely that a house in th eUK with a 4kW system is exporting 4kW.

Typically PV systems are rated at by the panel output under a standard irradiance of 1000W/sqm with the panels at 25C. At noon with clear skies and the sunlight hitting the panel at 90deg the output could be slightly greater or more likely lower (especially in the UK with the longer path through the atmosphere compared to lower latitude locations).

The inverters fed from that panel are usually specified at about 80% of that panel rating or ie 3.2kW for a 4kW system. The inverters have 5-10% losses as well. It is expected that there may be some power limiting under some conditions but that energy loss is not usually worth the extra expense and idle losses of larger inverters).

At any other time than around solar noon (panel angle will affect precisely when) the panels will achieve maximum output) there will be less output.

The output will decline approximately according to the sine of the incidence angle although at lower angles the output drops off faster because of increasing path loss through the atmosphere and reflection losses at the panel.

In this example it is unlikely that there will be more than about 2kW export power once the local consumption is taken into account. Maybe