It seems that most every day a press release comes by suggesting that a new wind farm will power 30,000 or 460,000 homes. One suggested, after a simple calculation, a 1,000-Watt per home average. How could that be? Our office microwave is rated for 1,100 Watts and our home vacuum cleaner pulls 1,200W.
Yes, the releases are just trying to point out the large benefit-footprint that a wind farm provides. But to be honest, such figures are pointless and misleading. And the wind industry is not alone.
The early computer industry had a similar figure in MIPs, or Millions of Instructions Per Second. Software testers eventually recognized that some benchmark programs finished in less time on a low-MIPS computer rather than one that boasted a higher figure. Although computer builders promoted the figures, computer reviewers were soon referring to MIPS as a Meaningless Indicator of Performance. The number of homes a wind farm can power provides a similar distraction. Consider the examples in the table all collected from the last few months:
The table is sorted from lowest consumption to highest. Two things stand out: The Scots, true to their stereotype, are the most f-rrrr-ugal. And who would have thought that the Aussies are the most energy hungry? The U.S., Canada, and Brittan fall in the middle.
But don’t you wonder what you might have to do if your home were limited to about 1,600 W?
Let’s first consider the power consumption of a few household items. I read the figures off their nameplates:
You might add in clothes washer and dryer, dish washer, iron, and air conditioner. It is conceivable that many of these items would be “on” at the same time, easily exceeding the most “wasteful” Australian home. Hence, the number of average homes a wind farm will power is a meaningless figure that allows no comparisons.
However, there is something we can learn from this exercise. Is there a way to turn off appliances as we turn on another, say, to keep a consumption figure from exceeding a user-imposed value? For instance, there has been a lot of babble recently about the Internet of Things. Would it be possible to have an appliance report that “1,500 Watts are in use. Starting this device will exceed your 1,600-W limit. Identify the items I can turn off.”
Just a thought. What do you think?
- Paul Dvorak
Filed Under: News
Paul Dvorak says
Thanks to all you great people for your insight. I could’t think without you.
Jim Klessig says
I agree that it is a usless and thoughtless metric.
It is inherently impossible for any intermittent source of energy (such as these) to truely power even one home, regardless of the appliances used. This is where your measurements fail as well, and are just as meaningless.
So whatthey really should be saying is that this project, on an annual basis, can supply the average energy (not power) used by X homes on an annual basis. Doesn’t sound as sexy though, does it.
Really should say “expected” in there some where too. These projects never seem to quite deliver do they.
Dick Von Berg says
In golf, they call this creative accounting. Dick Von Berg
Dave Bryant says
Paul, I enjoyed reading your article and appreciate all the data points as well as your point of view. I think the folks that tried to put their wind farm output in perspective used some national average for power consumption of a house over a one year period. I doubt that the wind farm’s capacity factor was also considered. I build ACCC wire for a living. My wire reduced line losses on a 100 mile section of a larger 345 kV reconductor project in Texas by 30%. This translated – with a load factor of 62% into a 300,000 MWh per year savings. Using the national average CO2 emissions from all combined sources of generation in the US of 1.372 pounds of CO2 per kWh, that equals an emission reduction savings of over 200,000 metric tons per year. The EIA says that one passenger car in the US emits 4.75 metric tons per year. Thus, by replacing 100 miles of an ACSR 345 kV line (double bundled) with ACCC, the equivalent emission reduction would equate to taking 42,000 cars off the road. Does that make any sense to you? Thanks
Tom Phelps says
I am an energy engineer with 40 years experience in consulting, with much of it being heating and air-conditioning design. I am reminded of an old tongue-in-cheek saying of my trade:
“If you have one foot in the fire and the other in a block of ice, on the average, you should be comfortable, right?!”
In power use, as in heating and air conditioning, leveling out the extremes is important. While the ‘feedback mechanisms’ for reporting and correcting excursions into the ‘extreme ranges’ are well-established in heating and air conditioning, we are only now beginning to develop and adopt the economic signals and technologies needed to level out the extremes in power demand.
Martijn de Man says
Paul, In my opinion the background of the metric is a little bit different and in the press releases there is something omitted, the variable time. In the Netherlands a 177 MW windfarm might produce around 2400 hours “fullload hours” resulting in 424.800.000 kWh of electricity in a year. The average energy use of a home is 3.500 kWh / year in the Netherlands so it would be around 120.000 households. If you have more wind in a year (2730 hours) and or a lower average (3100 kWh/year) you will have a metric which is usable on a local scale. (Scotland has 2,42 million households)