Gov beta test for grid-friendly, carbon-saving smart fridges
'Dynamic demand' could save you several pounds a year!
Dynamic demand technology, in which domestic appliances adjust their drain on the national grid so as to smooth out collective spikes and dips, is to get a widespread UK trial next year.
The Guardian, reporting on the new initiative from the Department of Energy and Climate Change, says that three thousand intelligent demand-smoothing fridges will be given away free by the government in a sort of energy-policy beta test.
As any fule kno, the UK national grid's frequency rises and falls from its base level of fifty Hertz in response to demand variations against supply. As more electric power is used, the frequency changes. Once a certain limit is passed, more power stations will come on line and the frequency will move back to the nominal level.
The idea of "dynamic demand", or "intelligent" appliances is that they contain circuitry which monitors the mains frequency. A fridge normally waits until it has warmed up to a certain amount above set temperature, then runs its pumps until it is a certain amount below.
A smart fridge, though, would also take account of the grid frequency. When the grid was under strain it might not bother cooling all the way down - it might stop as soon as it reached, say, the middle of its normal temperature band. Immersion heaters and air conditioning are other examples where dynamic-demand hardware could be useful.
Dynamic demand doesn't reduce the amount of energy required over time - it merely spreads the demand out so as to make things easier on the grid. This is why the government's 2009 smart-fridges must be given away free; they won't offer any savings for their users.
But the quick-response gas turbine power stations used to iron out sudden gaps between supply and demand are dirtier than most - efficient combined-cycle kit can't be thrashed up and down the output scale the way these plants have to be. Thus the government reckons that dynamic-demand tech could could reduce UK carbon emissions, perhaps by as much as 2 million tonnes annually - a little over 1 per cent of the total. That sounds pretty high - even Friends of the Earth, great boosters of this idea, have previously suggested just half a million tonnes a year (one-third of one per cent).
And the power industry would save money on maintenance for thrashed turbines and backup plant which is left idle much of the time, so they're very much in favour of someone else paying to smooth out consumer demand for them.
Greens such as the FoE people like dynamic-demand too, as it could make life easier for renewable power. The thinking goes that the nation's fridges, aircon, immersion heaters etc could be set to take power when the wind was blowing or the sun shining and the grid was thus overpowered, rather than essentially randomly as they do now.
The idea is examined by Professor J C MacKay of Cambridge University in his book Sustainable Energy - Without the Hot Air, just published in hard copy. He says that's not really true.
Popular soap operas such as Coronation Street and EastEnders typically generate TV pick-ups of 600–800MW … automatically switching off every fridge would nearly cover these daily blips of concerted kettle boiling.
Fluctuations in wind power will be a different matter.
Re: Interesting idea, and it's been bandied around for a while
There are plenty of ways to control loads, and within certain obvious constraints (such as not suddenly turning off lights, life support systems, or Eastenders), it is a useful thing to be able to do.
An alternative system is the Radio Teleswitch, lucidly described at www.radioteleswitch.org.uk. This uses the 198kHz BBC Radio Four transmission system to signal to local units.
The principles have been around a long while. Radio Teleswitch was first considered in 1964 and has been available since 1984. There are thought to be in excess of 3 million RTS equipped meters in the field.
Another approach is to use two-way communicating meters (so-called smart meters), but this needs some sort of communications system back to the control centre. All the major meter makers offer them, e.g. Itron OpenWay, Sensus FlexNet, Cellnet Utilinet.
There’s a lot going on in the field. The IEA Demand-Side Management Programme (www.ieadsm.org) shows the scope of the ideas being developed.
But it only helps with short-term power and grid management, particularly that which comes from unpredictable sources such as wind; it doesn’t provide for the basic energy needs.
Sir, I salute you. Not many people would admit their error so graciously. What a fine example to set. I'd intended to politely correct it earlier with a link to the Gridco page as evidence, but I've been otherwise occupied.
So, now you're convinced the theory works, all we need to do is make it happen for real, perhaps using something a bit more substantial than a tiny proportion of devices which are themselves a tiny proportion of electricity demand. Maybe we could have LCD+plasma TVs switch themselves off during the commercial breaks, to compensate for the kettles which get switched on during commercial breaks? Ah, OK, never mind, I forgot that...
Earlier today when I tried the Gridco live chart, it was timing out. I wonder if they've been slightly slashdotted today?
Re: ...frequency... correction
Ooops. No, I was wrong. Should have checked! Grid frequency does change a bit in response to load. According to National Grid, who would know:
“System frequency is a continuously changing variable that is determined and controlled by the second-by-second (real time) balance between system demand and total generation. If demand is greater than generation, the frequency falls while if generation is greater than demand, the frequency rises.”
There’s a real-time graph of the variation over the last hour at http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Frequency/Freq60.htm
Lately, it’s peaked at 50.18Hz and gone down to 49.95Hz.
So there’s scope for fridges and many other devices to detect this variation and behave in a suitable pre-programmed way to shed load as necessary. Provided they have properly thought out algorithms and some randomisation, it should be possible to avoid inducing chaotic behaviour in the grid that some have suggested.