
With the greatest possible respect to Ian... the technique being discussed does NOT noticeably decrease the energy consumption in this picture. Anybody's fridge will still use roughly the same number of kilowatt-hours (aka "units of electricity") per day, per year, etc. What this technique does do is allow some control over the timing of the demand from appliances such as freezers, heaters ("furnaces"), etc, where the thermal inertia means that there won't be too much effect if the motor has to stay off for an extra few minutes. But the amount of generating capacity that we're saving, at least with fridges and freezers, is really quite small. If it was immersion heaters, maybe it would be different? Maybe?
Do some sums, based on facts not hype. Fact: a decent modern domestic freezer typically uses very roughly 200 kWh per year. Call it 0.5kWh per day. The actual power consumption is a few hundred watts when operating, but most of the time they sit idle; to make 0.5kWh a day it could be say 500 watts for 1 hour a day. So at any given time, the chances of any given freezer motor running are roughly 5% (1/24). If there are 20 million or so freezers in homes in the UK, if you could switch them all off for a while, you might actually switch off 5% of 20 million as the rest weren't running anyway. So 1 million freezers at 500W each get switched off. That's 500MW (0.5GW) of generating capacity we don't need to build, or can leave idle. Decent power stations are usually a few GW.
So is this really a worthwhile saving? It might be, e.g. if we're looking at just South East England, and the London Olympics need more power than can profitably be delivered to the South East, but in general 0.5GW across the UK is not a huge deal. The UK's actual electricity demand in the last 24 hours varied between roughly 30GW and 60GW [1].
The Yanks talked about this kind of thing a year or two back, when the Gubernator wanted Californians aircon boxes (big things, they are) to be remote controllable by the electricity supply folks. That kind of thing makes a worthwhile difference to electricity demand out there.
But fridges and freezers? They're having a laugh.
[1] http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Demand/demand24.htm