Microwaves… electricity consumption

In one way everyone should have one of these electricity meters… in another way no one should… ever… they make you a complete energy geek. As I made coffee this morning I looked at the microwave, its green display blinked at me… and I thought… yes… I must… so here are the results

I have a 800W sharp microwave, nothing flashy.

Microwave 1

When in standby (just plugged in… waiting) it consumes 3.5 watts of electricity. When heating stuff up at full power (it’s always at full power) it consumes 1250 watts. Now I’d say I use the microwave for an average of 5 minutes a day. So that is 1435 minutes sitting waiting, and 5 minutes of action. So doing the maths bit we find that…

Microwave pie

My microwave consumes 45% of the electricity it consumes, sitting… waiting…

To put this into context, lets assume that there are 2 million microwaves in Ireland (every house, many businesses. Lets assume they are all on standby… all the time… That means that right now, microwaves on standby are consuming 7MW of electricity. If you prefer to think of it as wind turbines. Most of the wind turbines around are 1.5MW machines, and they generate an average of 1/3rd of that. So there are 14 wind turbines needed in Ireland… so we can leave our microwaves sitting… waiting…

So what can I do you might ask? Plug it out, or switch off the socket. Boom. 3watts of electricity eliminated. The clever among you will realise that this rational can be extended to a lot of other electrical equipment around the house, but hold your horses, I’ll get a post out of each one of them yet!


15 Responses to Microwaves… electricity consumption

  1. Fascinating, as always Pat. Great to catch up with you again last night at TechLudd.

  2. Tom Raftery says:

    Fascinating numbers Patrick, thanks for that.

    One thing to bear in mind though is that wind turbines generate the vast majority of their electricity at night, when the demand for electricity is at its lowest.

    As we increase the number of turbines on the grid to achieve the 30% renewables target set by the government we will very quickly reach a situation where we are trying to get rid of the excess electricity produced by those turbines.

    The most effective way to do this is to price it according to supply and demand such that in an abundance of supply electricity is negatively priced. This process is already underway. For Example, in 2007 the wholesale price for electricity in Ireland varied from 1.6c to over €1 per unit driven by demand and supply fluctuations.

    In the near future, we will potentially have a situation where on windy nights we will be paying people to leave their microwaves on (and their TVs and their dryers, etc.)!!! Smart meters, capable of controlling our appliances based on grid pricing, are already being tested.

    When people start being exposed to the actual price of electricity I believe we will see a massive change in the patterns of consumption.

  3. greennav says:

    Hi James, Tom,

    Thanks for the comments. Tom you are correct about the real time pricing, but that will only be in a wholesale basis. People will be exposed to time dependent energy prices, but real time pricing is a long way off. Truth is that people don’t want it. Most people don’t like pay by weight bins, though they are a truly great idea.

    I’d also love to see smart meters control some appliances, but again, I don’t believe that there is a public appetite for it. Well, having spoken to some of the folks who are doing the work on the smart metering testing, not among them anyway.

    Also it should be remembered that on average the value of electricity on a wholesale level is 6c. The average price for domestic electricity is about 15c (even before vat). So electricity will always have a cost to the domestic, cos most of it is handling costs.


  4. is that a small animal you’ve been cooking in there? it appears to have exploded

  5. greennav says:

    Is it too late to pretend I got the picture from Flickr?

  6. Tom Raftery says:

    I’m not sure I agree Patrick. Eirgrid (Ireland’s TSO) are certainly all in favour of Energy Demand Management and one of the most effective ways to push this out is by using real time pricing. It is already happening in parts of the US.

    Getting people to buy into it is simply a matter of education. There wouldn’t have been any great appetite for a 15c levy on plastic bags either but we can see what a fantastic success that project has been.

  7. greennav says:

    Hi Tom,

    i hope your right… I really do…


  8. Michelle says:

    I am not a math expert..but I am having difficulty understanding how you arrived at the 45/55 percent split… could you send me your method???? Thanks

  9. Ayyaz says:

    nice work

  10. Carlos says:

    Good thinking, and nice article, I was think on the same kind of stuff and google took me here, greetings from Porto, Portugal

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