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Fairy lights put too much pressure on National Grid

by on 2014/12/23

Here we go again…

Here’s one for all you festive Scrooges out there. The National Grid is teetering on the brink of collapse, and your fairy lights could tip it over the edge:

“A TEAM of experts whose jobs are based on creating winter wonderlands are appealing for [..] residents to switch to low-energy fairy lights this Christmas. The Christmas Decorators… [are] urging the public to use energy efficiently this Christmas to ease pressure on the National Grid.” (Southern Daily Echo, 24th Nov, and others since).

The headlines are right to the extent we are experiencing some big structural changes to electricity generation in the UK, with many of the ‘super stations’ of the 1960s and 1970s being closed under the European Union’s Large Combustion Plant Directive. But are your fairy lights really the difference between a festive winter wonderland and the apocalypse? Probably not.

The dim truth about fairy lights

Back in the 1980s your fairy lights used a string of 20 tungsten filament bulbs rated at a positively wasteful 0.05 Watts (W) each. It doesn’t sound a lot compared to the 2000 Mega-Watts (MW) of installed capacity at your nearby 1970s era coal-fired power station, but then there are 20 million or so households in the UK and, like all things on the national grid, small things like fairy lights can multiply to truly daunting proportions. Don’t worry, there’s good news. We no longer use profligate 0.05 W filament bulbs in our Christmas lights; this is the 21st Century, and we use LEDs which consume a mere 0.001 W each. These days the National Grid control centre reckons fairy lights add about 750 MW to the Grid – that’s still a lot of 0.001 W LEDs – but then it does include the neighbourhood tributes to Las Vegas.

A life support machine for the modern world

750 MW is still a fair chunk of power, but then the National Grid is no ordinary bit of technology. It is like a life support machine for our modern world, and so intricately bound up in our habits and routines that we, and it, have become locked into a single system. Fairy lights are unlikely to black out the country, because that 750 MW of energy is somewhat offset by the fact most people prefer the festive glow of their Christmas tree, and will switch off their normal room lighting, making the 750 MW figure more like a net increase in electricity use of 400 MW. And anyway, we’re all on the big wind-down, making this a quiet time of year for industrial consumption, indeed, Boxing Day is the quietest time of the whole year. A mere 400 MW of additional load won’t be worrying the grid engineers too much.

There’s something else about fairy lights which makes them even more unlikely to plunge the UK into darkness: they are predictable. Most people turn them on when it’s dark, and keep them on for the evening for the full twelve days of Christmas. Much more troublesome for the National Grid are the strange and unpredictable spikes in demand, things like the Royal Wedding (2300 MW) and the episode of Dallas where we found out who shot JR (2200 MW). So troublesome are these unpredictable spikes, and so strange the behaviour of the National Grid, that in 2007, a symbolic public switch-off for a Planet Relief event was cancelled. The reason? Because it was difficult to predict, and it would require fast reacting (and much more inefficient) means of generation to cope with it. Ironically, something like that would be much more likely to cause increased carbon emissions, and maybe even blackouts, than 20 million strings of fairy lights. Happy Christmas!

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