Friday, 4 June 2021

How much new capacity is needed to supply motorway charging points?


This just in from Ecotricity, my green electricity supplier. I'm delighted to see the progress the are making in their rollout of motorway charging points for EV's.

However - is National Grid letting us know the capacity and distribution implications of this activity?

One service station has a peak capacity requirement of 12x350kW=4.2 megawatts. 

There are 158 such service stations in UK, requiring 663 megawatts of peak capacity, two thirds of a Gigawatt.

And that's only enough to charge 1,896 vehicles at a time.

By 2030, several million electric vehicles will be coming on stream per year, all needing charging most days.

How much extra capacity will they need? 

Monday, 30 November 2020

Domestic electricity consumption – how can we manage it?


First, the good news. Peak UK electricity consumption is falling year-on-year.

This is for two main reasons:

·         Appliances are becoming more efficient

·         Industry and some commercial users are becoming more adept at managing their demand, particularly time-of-use.

So, what’s the bad news?

·         Domestic demand is becoming more peaky because consumers are not motivated to manage it.

·         Increases in demand will increasingly be under the control of domestic consumers, as EV’s and heat pumps are rolled out.

Unless something changes, future demand will become both bigger and more peaky, as unmotivated domestic consumers use more electricity.

This is a behavioural issue as much as a technical one.

The work to change behavioural patterns needs to happen before the mass take-up of new appliances, not after.

We are not helped in this by the almost complete absence of domestic time-of-use tariffs, which will need to become near-universal by the time EV’s and heat pumps achieve significant market penetration.

Domestic behaviour change takes time, we need to start now.


Tuesday, 20 October 2020

Can we do more to reduce peak demand caused by electric kettles?

 In 1990, there was a 2.8 GW surge on the UK grid caused by consumer switching on their electric kettles after an England vs. Germany football game.

Happily, in the 21st century, the maximum surge has been only half that, 1.4 GW after two games in July 2018.

These surges usually occur in summer and are unlikely to coincide with peak demand , so the impact on capacity requirement will be less than the surge, or possibly none at all. 

However, 1.4 GW is only half a million kettles, and there are 25 million electric kettles in UK. We are very keen on having quick access to a cup of tea.

Other research suggests that on average we heat twice as much water as we need to, perhaps with an average time of 120 seconds, which could therefore be reduced to 60 seconds simply by only heating the water we need for a cup of tea.

We drink an average of four cups of tea per day each. Each one is taking 0.1 kWh to boil if we heat twice as much water as we need. Seventy million people people consuming 0.4 kWh per day is one heck of a lot of juice! 28 Gigawatt hours to be precise. that's over a Gigawatt even if consumption is spread evenly over 24 hours. In practice of course it is likely to be at least double this at times during the day, so by reducing the kettle fill to half, a continuous Gigawatt could be saved all day. Eight billion pounds worth of nuclear capacity, even without avoiding the peak.

That's a saving worth having! 

Wednesday, 22 April 2020

Is thermal storage a serious potential contributor to electricity supply flattening?

In managing electricity demand, we are normally concerned with avoiding peak demand, in order to reduce strain on total capacity.
But with intermittent renewables, we also have a potential excess supply problem, when output from wind and solar is high, and demand is low.
Large industrial users are good at taking advantage of such situations, but the domestic sector, where peaky demand is now most prevalent, is not.
In Canada, the electricity supply companies are known to supply large water heaters to domestic consumers. The suppliers control when electricity is used to heat these stores.
Would it be worth doing the same in UK?

  • Heat generally has a lower value than electricity per kWh - except in times of potential overgeneration.
  •  Creating solar and wind capacity at a level to minimise gas generation rather than to fit within existing capacity constraints would mean long periods of oversupply, requiring storage, supply constraint,or dumping
  • ESCO's are now looking at thermal storage as a way to manage renewables, particularly in SME's.
Can it happen at scale before we have a substantially strengthened grid?

Wednesday, 8 April 2020

Is it more environmentally friendly to use electricity when the grid is showing low average carbon emissions?

The National Grid in UK has a very useful app that tells us what the carbon emissions per unit generated are. Clearly this will be at its lowest at times of high wind or solar generation, and relatively low gas generation.
The implication is that  it is better to use electricity when the average is low.
But is that actually so?
Unless we are in danger of shutting down wind or solar generation for lack of demand, which almost never happens in UK at the moment, each additional unit used comes from the supply that is responding to demand, which is currently almost always gas in UK.
Every unit of solar or wind electricty generated is always used. Switching something on at times of high renewable generation makes no difference!
So, when is the best time to use electricity?
The focus should continue to be on flattening the demand for gas, which will make gas generation more efficient, and ultimately reduce the capacity requirement for gas generation.
If you want to be sophisticated about it, track the gas power station output, for example from Kate Morley's excellent site   
Otherwise, the best thing to do is to avoid the winter peak from around 3-8pm, and try to shift non-time-sensitive consumption from the day into the night-time trough from around midnight to 6am.

Tuesday, 4 September 2018

Low Carbon Technologies set to make Peak Demand Worse!

According to BEIS (which includes what was DECC) without demand side response (DSR) we will increase peak domestic electricity demand from  24 to 31 GW, an increase of 7GW or 29% by 2030.
Note that the trough is the same, so the curve shape has got worse.
I note they are only allocating a peak of 1GW to electric vehicles, which at 3kW per vehicle is only 330,000 vehicles, or 1% of the present vehicle population.
Most of the peak increase will come, they say, from heat pumps. Storage of heat is relatively easy and cheap, all you need is a larger hot water tank. These are common in biomass heating systems.
How do we publicise the vital necessity for domestic load shifting, awareness of which needs to accelerate now to meet future demands?
At the moment it's just word of mouth, so keep on telling people about it!

Tuesday, 14 August 2018

Is the Heat Wave over?

Here's a heat wave worth looking at!
Air conditioning uses over 30% of the peak electricity on a hot day in California - and by time-shifting the cooling using stored ice, in some buildings the peak can be completely ironed out.
What's more, the air conditioning capacity needed is reduced, as it's working for longer to produce the same amount of cooling.
As air conditioning becomes more prevalent in UK and Europe, this is becoming an increasingly relevant way to avoid peaks in summer.
Conversely, in winter, if we are to use electricity for heating, it will become worthwhile to store hot water or even steam to reduce peak consumption.