Comparing wind turbine power consumption to coal and gas

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There’s a set of persistent myths that seem to imply turbines don’t generate a lot of power. It’s rubbish, of course.

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Wind turbines generate lots of energy.

Over the course of 2014, a single three megawatt turbine at Infigen’s Lake Bonney wind farm generated 7,327 megawatt hours. For comparison, an average Australian household consumes about 6.6 megawatt hours over a year.

Despite these verifiable facts, there’s a set of persistent myths that seem to imply turbines don’t generate a lot of power, including one that seems to focus heavily on the consumption of electricity by wind turbines during periods of non-generation.  You can see an example of this in this article, published in the UK’s Daily Mail.

Our Operations Control Centre (OCC) has direct access to the data collected by wind turbines, and so, we can easily take a random turbine and assess exactly how much power the machine drew from the grid, relative to how much it generated:

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The quantity of power the turbine drew from the grid over the year is so small, relative to the amount of power it output, that we had to make an incredibly long chart for the ‘consumption’ section to be even visible. After generating 7,327 megawatt hours, the turbine consumed only 12.7 megawatt hours. Broken down by month:

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For the turbine in question, consumption was around 0.1% of total generation – so next time you see a story telling you that turbines are drawing power from the grid-  stop and ask: “how much, relative to production?”. The 2009 ACIL Tasman report “Fuel resource, new entry and generation costs in the NEM” quantifies generator consumption – they refer to it as ‘auxiliary load’: “Auxiliary load is an electricity load used within a power station as part of the electricity generation process – that is, it is an electricity load used in the making of electricity”

As we saw, the turbine in question has a 0.1% auxiliary – let’s compare this to the large-scale thermal power stations discussed by ACIL:

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As we can see, even the least power-hungry thermal power stations consumes twenty times more power, as a percentage of energy sent out, than our example wind turbine. So, here’s another question to ask the skeptics: what about coal and gas? How much power do they eat up, during normal operation? Have you compared this to wind turbines?

Source: Infigen Energy. Reproduced with permission.

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8 Comments
  1. Alan Baird 4 years ago

    A good article about a seldom considered aspect of generation. Another item that goes hand-in-hand with generation is efficiency (ie things like insulation, dwelling-orientation etc) that reduce loads and hasten the tipping point into alternative energy dominance.

  2. Colin Nicholson 4 years ago
    • Ketan Joshi 4 years ago

      Wind power is generating 2.99 gigawatts at the time of clicking in, which could power South Australia’s total demand twice, with a bit left over [http://www.aemo.com.au/Electricity/Data/Price-and-Demand/Price-and-Demand-Graphs/Current-Dispatch-Interval-Price-and-Demand-Graph-SA]

  3. Henry WA 4 years ago

    Lake Bonney Wind Farm 2nd stage with 3mw turbines built 2006-2008, so probably not the latest technology. 7327 Mwh for the year for a 3 MW turbine is a capacity factor of just under 28%, which is perhaps a little disappointing. However there have been significant improvements in turbine design in just the last few years and the most modern turbines in favourable wind areas can have a capacity factor of 40% for onshore wind and 50% for off shore wind. The other points in the article are certainly well made.

    • Ketan Joshi 4 years ago

      Thanks, Henry. I’m hoping to do a follow up in the coming days that compares a few different sites – but the point was more about comparing aux consumption to generation. If the ratio is so low even with an under-generating turbine, that probably makes the point somewhat better, I suspect 🙂

  4. InsightWind 4 years ago

    @Henry. Do remember that capacity factors are extremeley malleable. It
    is very easy to install a wind turbine with the purpose of achieving a
    high capacity factor. All the project designer need do is select a
    smaller generator for a larger rotor. Hey presto, high capacity factor!

    That does not mean, however, that the wind turbine is producing as much
    electricity as it could at that particular location. That said, higher
    capacity factors can make it easier to integrate a large amount of wind
    into a smaller grid because there are fewer variations in the volume of
    energy being produced over the course of time. It is market demand
    considerations — and higher wind power penetrations — that are
    encouraging the use of wind turbine configurations that provide higher
    capacity factors, not an engineering revolution.

    The most modern wind
    turbines are of course superior to older turbines, as you so rightly point out. They generate more electricity at less cost. That trend is set to continue for a good many
    years yet with continued technology refinements.

    The article dispelling one of the age old myths of wind that sparked this debate is super, by the way. Excellently done. First time I’ve seen graphs so clearly demonstrating auxiliary load for all power plant since it first became an issue in India in the late 1980s!

  5. Albery Moray 4 years ago

    Capacity factor is nonsense.

    Let’s look at the capacity factor of a couple of power stations:

    Uranquinty: 664 MW capacity, 304.9 GWh in 2014, 5% capacity factor. Shut it down!

    Colongra: 724 MW capacity, 80.7 GWh in 2014, 1% capacity factor. Shut it down!

    Tumut 3: 1750 MW capacity, 228 GWh in 2014, approximately 0% capacity factor. Blow it up!

    Eraring: 2940 MW capacity, 14872 GWh in 2014, 58% capacity factor.
    Only 58% ? Why not 100% That’s hopeless. KNOCK IT DOWN I SAY!

    Let’s look at the capacity factor of my car. It’s got a155 kW capacity. I use it for about 1 hour per day and most of that time I’m sitting at traffic lights. Even when I drive it I rarely use the whole 155 kW. Its capacity factor is probably less than 2%. I’m even allowed to drive it and make noise within 2 km of anyone’s house!

    I repeat: capacity factor is nonsense.

    • Ketan Joshi 4 years ago

      Albery,

      Totally agree with you – it’s a terrible metric. The percentages used here are Aux consumption / output, rather than actual output / capacity, so thankfully I didn’t need to use CF in the calcs 🙂

      Incidentally, that’s also why I referred to total energy over the course of a year in my intro, rather than the capacity factor of the farm.

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