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Discussion Starter · #1 · (Edited)
I've been thinking quite a bit lately about the operational costs of electric versus gas clothes dryers. I worked out some cost numbers for each and thought I'd share.

For reference, I'll use these two models which I think are pretty indicative of what's available in the wider industry as a whole:

Gas Model

Electricl Model


The relevant stats:

Cost of Gas Model: $1339
Electrical power (of gas model): 720W
Gas consumption: 22000 BTU/hr
Gas consumption in sane units: 0.60600584 cubic meters/hr

Cost of Electricl Model: $1299
Electrical power: 5600W



Assume that the cost for KWh is 4.4 cents/kWh, which is reasonable given Ontario's up-coming time-of-use programme (and assuming that you run the dryer on the weekends).

Gas prices are a bit more variable, but a good estimate (based on this link) is somewhere around $0.41 per cubic meter of gas used. (This amount accounts not just for the commodity but all of the other charges related to delivery and storage.)


Then we can define the total cost per hour to run each model:

Cost_gas(x) = 1339 + x * ( 0.044 * 0.720 + 0.41 * 0.60600584 )
Cost_electric(x) = 1299 + x * 5.6 * 0.044


This cost does not include the cost of installation, which can be much higher for gas dryers (due to venting requirements).

That said, remarkably, at these gas & electricity prices, the gas dryer is actually more expensive to run than the electric dryer! The story gets a bit different if you're running the dryers during peak power periods, in which case the gas dryer can be quite a bit cheaper than the electric one. For that case and for reference, the formulas become:

Cost_gas(x) = 1339 + x * ( 0.093 * 0.720 + 0.41 * 0.60600584 )
Cost_electric(x) = 1299 + x * 5.6 * 0.093

using, once again, Ontario's posted TOU rates. This is very interesting to me -- once the time-of-use programme comes into effect, as long as you run the electric dryer on the weekends or after 9pm in the evenings, you're probably better-off going with an electric dryer under these conditions.

But let's say that you're a rebel and intend to run your dryer during the peak times anyway (so that the gas dryer will be cheaper in the long-run than the electric). The question naturally arises: when would you break even? The answer is: around approximately 194 hours of use.


Feel free to play with the numbers; comments welcome.


K.
 

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I have adopted the following strategies to reduce the use of dryers:

- Dry on low heat setting instead of high heat. With this setting even if you increase the duration of the drying, it is still more energy efficient than running on high heat. For example, 60 mins of low heat is more efficient than 45 mins of high heat

- During summer, hang clothes out in the yard to dry (except unmentionables, that neighbors might object to).

- During winter, hang clothes to dry in the basement and only fluff in the dryer if needed. Hang clothes around the heating vents for faster drying.

I have an electric dryer and our zone is already in the time-of-use billing plan. That said, as we had discussed in the other thread on average utility bills, actual consumption forms a small portion of the hydro bill. In my case, consumption is less than 40% of the bill.
 

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I'm not actually surpised that the price difference is so narrow.

I guess the main concern for the future is price volatility. I'm less familiar with Ontario's power mix than with Quebec's, but my guess is that in the long run natural gas prices will be more volatile than electricity prices, and a gas dryer could end up costing you quite a bit more over its lifetime. Natural gas is used to produce electricity too, but not usually for baseload power.

I agree with Harold Crump's suggestions for limiting/reducing dryer use and energy consumption. I lived for 30 years without a dryer and it really wasn't inconvenient, although now that I have one I appreciate its ability to dry things like flannel sheets, which take a long time to dry on indoor racks!
 

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I've been thinking quite a bit lately about the operational costs of electric versus gas clothes dryers. I worked out some cost numbers for each and thought I'd share.
K.
Thanks for this; my wife and I were thinking about buying a gas dryer to save $ when our electric one dies! Based on your info you just saved us over $1,000+ (even if that is an expensive dryer from prices I've seen at home improvement stores).
 

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Discussion Starter · #5 ·
It's also worth emphasizing that the practical cost of the natural gas dryer is probably much more than the retail price tag alone, due to the fact that most people will probably have to hire a HVAC guy to plumb a new gas line in the house, as well as to make a new exterior vent for the gas exhaust.

In that light, a practical guess would be to "round up" that $1339 price tag to closer to $2000.


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Discussion Starter · #7 · (Edited)
I was thinking the other day that I made a critical error in my original post -- the rates that I assumed for electricity did not include all of the distribution charges, which can often double the overall (effective) cost to the consumer. Also, rates are not on the TOU pricing yet, and they have gone up quite a bit since this was last posted.

So let's see how the decisions have changed ..

Previous Formulas (for reference):
Cost_gas(x,y) = y + 1339 + x * ( 0.044 * 0.720 + 0.41 * 0.60600584 )
Cost_electric(x) = 1299 + x * 5.6 * 0.044

where "y" is the one-time cost of installing a new gas dryer (I assume that most people have electric and that it doesn't have such an overhead), and that "x" is the number of hours run.


Updated Formulas
In the mail today, I received the most recent rates for Waterloo hydro, and they are going to make things a bit more complicated. For the purposes of this email, I'm going to ignore the fixed (non-kWh) charges per month since it is assumed that you are going to pay for electricity anyway, regardless of the type of dryer that you use.

  • Electricity: $0.065 per kWh (assuming < 600 kWh used)*
  • Line: $0.0020 per kWh*
  • Network: $0.0058 per kWh*
  • Usage: $0.0132 per kWh
  • Deferral: -$0.0027 per kWh
  • Market: $0.0068725 per kWh
  • Debt retirement: $0.007 per kWh
There's a handy disclaimer in small print indicating that the "*" indicates that the kWh for those calculations are multiplied by an adjustment factor of 1.0505. (How nice.) I can ignore the effect of tax because it generally applies equally to both equations. I also assume that the cost of gas hasn't changed all that much since this was last posted, although I need to update the gas equation to reflect the new cost of electricity.

This gives the following new electricity equation:

Cost_electric(x) = 1299 + x * 5.6 * ( 1.0505 * (0.065+0.002+0.0058) + 0.0132 - 0.0027 + 0.0068725 + 0.007 )
=> Cost_electric(x) = 1299 + x * 5.6 * 0.1008489
=> Cost_electric(x) = 1299 + x * 0.56475384

Cost_gas(x,y) = y + 1339 + x * ( (0.72 * 0.1008489) + (0.41 * 0.60600584) )
=> Cost_gas(x,y) = y + 1339 + x * 0.3210736


(In other words, the effective cost of electricity is about $0.10 per kWh, prior to tax, in the Waterloo region.)


Conclusions

As you can see from the curves, the electric dryer is more expensive as a function of the number of hours that it is run. If we assume y = 0 (no overhead), then the break-even point is x = 164 hours. If you run your dryer for an hour every week, it will take you about 3 years to break even. (Note that I'm also not figuring-in the effect of investing that $40 difference into an investment vehicle at, say, 3% interest, which would slightly lengthen the break-even point.)

If the installation of a gas dryer costs money (as it would in my case), let's say, y = $300 (to run a gas line to my laundry room), then the break-even point occurs at x = 1395 hours. In practice, even if I ran my dryer for 2 hours per week, it would still take me 10+ years before I broke-even on these costs alone. (And as before, I'm not figuring-in the effect on the $340 difference if I had invested it in at ~3% interest.)

Decision: I'll continue to stick with electric.


K.
 

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Discussion Starter · #11 · (Edited)
monsieur corde à linge charges up to couple hundred bucks to install. Then you're good to go for 20 years @ zero cost.
No one would argue that clotheslines are cost effective. But for many people, the question of which automatic drying machine to purchase is quite valid for a variety of reasons (such as convenience, the legality of clotheslines in their neighbourhood, and space constraints).

As a result, my post was geared toward those people ...


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Discussion Starter · #13 ·
Why would anyone in their right mind spend $1200 on an electric dryer? Home Depot alone has three models under $400 that are large-capacity and rated 5 stars.
For the sake of modeling the problem, I picked a dryer model that came in both a gas and electric version. But you should feel free to update the equations to reflect whatever cost scenario suits you.
 

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See Office of Energy Efficiencyy for info on electric dryers http://oee.nrcan.gc.ca/residential/personal/appliances/clothes-dryers-tips.cfm?attr=4
and gas dryers http://oee.nrcan.gc.ca/residential/personal/appliances/clothes-dryers-gas.cfm?attr=4

Unfortunately there is no Energuide or Energy Star program for gas dryers, so it is hard to make objective comparisons between the two.

Hydro Quebec publishes comparative Electricity rates between major cities of Canada once a year http://www.hydroquebec.com/publications/en/comparison_prices/index.html

Natural gas prices can be found in Statistics Canada Cat. No. 57-601-XI, Energy Statistics Handbook.
 
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