From NOT A LOT OF PEOPLE KNOW THAT

By Paul Homewood

We often tend to think that it is winter when electricity shortages are likely to occur. After all, in summer demand is lower and we have solar power as well.

With this in mind, let’s have a look at the last seven days, which have not been untypical from a weather point of view. Here is the generation mix:

Don’t pay too much attention to the individual bands at the moment. Instead focus on the four bands in the chart below.

As is often the case in summer, wind power frequently drops away close to zero. Solar power peaked at over 10 GW on some days, but on others it did not even reach 5 GW. Most important of all, of course, is gas which is always on hand, with up to 15 GW  required at times, even with I/Cs running at full blast.

In total, gas provided 33%, and nuclear a further 17%. Wind and solar came to 11% and 9% respectively.

Fast forward to 2035, when the Government hopes we’ll have 70 GW of solar power, compared to the current 16 GW.

In theory that should raise solar output from 410 GWh for the week to about 1800 GWh. However, demand is likely to rise as well, maybe from 4600 to 6000 GWh. In other words the increase in solar power will probably only be enough to cover the extra demand. Wind should add some extra output thanks to new wind farms, but not when the wind does not blow.

That means we will potentially need as much power from non-renewable sources as we do now at times during summer months.

But that’s just the tip of the iceberg.

Whereas solar power can peak at 10 GW now at midday, this figure will rise to 44 GW when there is 70 GW of capacity. This will always exceed demand, and the surplus will be wasted unless it is exported to Europe, who will have their own surplus solar power. What we manage to export will inevitably be at prices well below CfD strike prices, and it will be billpayers/taxpayers who will end up footing the bill.

There is of course the option of battery storage, both to mop up these surpluses and to supply power at night.

So how much storage would we need, simply to balance solar output throughout each 24 hour period.

Let’s look at the period from noon on the 19th to noon on the 20th:

The average hourly generation through the 24-hour period was 3289 MWh, so how much storage would we need to ensure that this amount of electricity could be fed to the grid every hour of the day and night, while mopping up the midday surplus?

The surplus begins to build up at noon, (remember that the graph starts at noon), and peaks at 27 GWh at around 5pm. By 2am the surplus is entirely used up, and the deficit accumulates to about 13 GWh at about 7.30am.

I could of course started the graph at 7.30am, which would shown a bigger surplus and no deficit. However the results are exactly the same in terms of storage – that we would need about 40 GWh of battery storage – (27 GWh + 13 GWh).

This is of course just one day, and there will probably be other days when more would be needed. We also need to factor in energy loss during the charging and discharging of the battery. Also the fact that batteries would never be charged to 100%, nor discharged to zero.

But 40 GWh is a good ball park figure, and we can multiply that up to 175 GWh when we have 70 GW of solar power. Currently we have about 2.8 GWh of battery storage around the country, so plainly this does not even start to address the needs imposed by a mass rollout of solar farms.

Looked at another way, we currently have 16 GW of solar power. If solar farms were obliged to provide a steady supply to the grid, they would need to instal 40 GW of battery storage with 1-hour discharge, the typical battery specification. Effectively for every MW of solar capacity, they would have to build 3 MW of storage.

And thjs is just to balance out daily generation, it does nothing to provide seasonal storage.