I still haven’t resolved my dryer issue. One technical detail has been annoying me for a while, until I finally worked on it tonight, is whether I should buy (another) gas dryer, or go with an electric.
Conventional wisdom is a gas dryer will be cheaper to operate in the “long-term,” whatever that means. Unfortunately, gas dryers cost $50 more to purchase. To quote Consumer Reports:
Consider gas. Both gas and electric dryers perform comparably, our years of testing show. Gas dryers cost about $50 more than comparable electric models, but the likely savings in fuel costs should more than make up the difference in the long run.
I’ve emphasized “likely savings,” because I have yet to see someone do actual math. Today, I will do that math. Mwuahahaha.
My utility bill is broken out into gas and electricity components. For the last three years, the gas portion has been substantially higher than the electric. From my power company’s view, it’s doubtful it will improve:
PSE expects the near-term market price for gas to be about 17 percent higher than what is reflected in customers’current electric rates.
The only things consuming natural gas in my home are the furnace, water heater, and dryer.
Since we keep the furnace set to 66°F during the daytime, 55°F at night, and my bill peaks in January when it’s cold, dark, and rainy, it’s obvious the heater is a big chunk of that. (We turn it off completely from June through mid-October.) I don’t know how much the hot water heater and dryer use, except it’s a lot less than the furnace.
The first challenge is to determine how much gas and electricity actually cost per fomplicatron, the standard, unintuitive units of drive-by, comparative measurement.
Gas: He who smelt it, dealt it
Gas service is broken out into several different kinds of charges:
- Customer Charge — charged regardless of how much gas is used. Theoretically supports costs of meter reading (which I believe is mostly remote now), billing and fixed costs. As of August 2005, this is $6.25.
- Delivery Charge — a charge for the plumbing and maintenance that gets gas to you. This is currently $0.290620 per therm.
- Cost of Gas — actual market cost; try not to think about the Enron manipulation on this one… This is currently $0.691560 per therm.
- Gas Conservation Program Charge — pays for the weatherization and conservation programs. This is currently $0.004370 per therm
- City tax — because your city needs lovin’, too. This is probably one of the only benefits of living in unincorporated King County.
What the hell is a therm, you might wonder. It’s yet another obfuscated calculation equal to one hundred cubic feet of gas multiplied by the heat content of the natural gas, also known as the “BTU factor.” The “BTU factor” is 1.056, no units are provided.
According to a handy conversion chart I found online, 1 therm equals 100,000 BTUs.
The cost of gas per therm is $0.98655.
Electricity, e-lectricity.
Electricity is much easier to grok. The basic unit is kilowatt-hour, equivalent to running ten 100-watt light bulbs for one hour.
- Customer Charge — Same concept as above, just $5.75.
- Energy charge — for residences, there are two tiers. The first 600 kWh are $0.067933/kWh. Each additional kWh is $0.084966/kWh. I’ve yet to use more than 600 kWh, however that’s also with the conventionally wise gas dryer.
- Electric Conservation Program — $0.001154/kWh.
- Energy Exchange Credit — ($0.017400)/kWh
- Power Cost Adjustment — currently 0.
- City tax — because your city needs lovin’, too.
The cost of one kWh of electricity is thus $0.051687 for the first six hundred kWh, $0.06872 for each additional kWh. (Unless your appliance and the electric company are both enrolled in the Friends and Appliances program…)
Assumptions
For simplicity, we’ll assume the household has both sources available and therefore pays both Customer Charges. Since an electric dryer would shift the equation, we’ll use the higher electricity rate. For the sake of argument, we’ll also assume that the spot the dryer’s in is plumbed for gas. (If it wasn’t, as was the case when I moved in, expect to spend about $10/foot for a gas line.) We’ll also assume a dryer works its magic in the same time, regardless of fuel source.
How much does it use?
I looked up the specs for the electric GE Profile DPSB620EC and its evil gas-heated twin, the DPSB620GC. The E has a 5,600 Watt heating element. The G uses a 22,000 BTU/hour heating element. A standard power connection is needed to turn the drum. It appears to be a 1/3 horsepower motor drawing approximately 6 Amps at 120 Volts. That being said, we’re going to simplify life by ignoring the drum motor and assuming each dryer dries equally. Waving my hands, I calculate the per-load cost as:
Electric dryer: 5,600 w/hr * 0.06872 = $0.384832 per load
(If we used the lower rate, it’s only $0.289447 per load)Gas dryer: 22,000 BTU * 1 therm / 100,000 BTU * $0.98655/therm = $0.217041 per load.
Based on this, gas is cheaper to operate. Now, let’s figure out what the breakeven is. The cost difference is universally $50 for gas versus electric. (I think this is mostly marketing, the same way as premium unleaded is always $0.20/gallon more than regular unleaded.) The cost difference per load is: $0.384832 – $0.217041 = $0.168/load.
Conclusion
The number of loads we need to do to break even (save $50) is:
($50 + sales tax) / $0.168/load =
($50 + $4.3) / $0.168/load = 323 loads
In an average week, we do eight loads of clothes. A gas dryer would pay for itself in about ten months. Since the average lifetime of a dryer is at least five years, conventional wisdom is seems correct.
However… If I was single, it’s likely I would still be in the lower band for electricity cost. Thus the number of loads until break-even would be 750:
($0.289447 – $0.217041) = $0.072406/load
($50 + $4.3) / $0.072406/load = 750 loads
My eight loads per week assumes a family of four. For someone living alone, this might be closer to three loads per week. Assuming they’re in the lower incremental electric rate, the break-even period is 4.8 years, barely less than the average lifetime of a dryer.
December 14, 2005: Please see my update with my December billing rates and a handy-dandy spreadsheet you can use in the privacy of your own home ;-)
Keep in mind that a gas dryer’s transfer of heat from combustion to dryer is probably around 80% efficient (like a modern non-condensing furnace). (I have not, however, ever seen this listed) Resistive heat (electric), while more expensive, always transfers energy with 100% efficiency (because there is no exhaust). So in a 22,000 BTU gas dryer, probably 4400 BTU goes out the exhaust.
The burner is closer to 95%, the “flue gas” is used to heat the clothes. Think of efficiency being closer to an unvented space heater. Also consider the 22k bTU gas burner produces more heat than the 5,600W heating element 5,600w x 3.41BTU per watt = 19,096 BTU.
I am looking into buying a new dryer. How much propane does it take to run a load of laundry. I would say 80% of my laundry is dried on delicate 10% on perm press and 10% heat.
I have a gas dryer that I love so much that I took it with me when we moved out of our old house. The energy savings were great(I lived in Las Vegas so in the summer we need every break on our electric bill we can muster) plus it dries clothes twice as fast & as a new mom every second counts. Alas, now I’m moving into a new house and there is only hook-ups for an electric dryer. The house has a gas water heater so I know there is gas in the house. Does anyone know how much it will cost to run a gas line for my dryer?
Cost depends a LOT on how difficult it is to run the line and local labor rates. Typically it’s not worth doing unless you are having other work done.
I live in northern Ohio and am currently trying to decide if I want to use either an electric or gas dryer. Your analysis has actually convinced me to use electric. There are several filters that can be used to divert the (partial, or whole)heat and humidity back into the home. It is my guess that with even a 25% redirect of this otherwise lost heat, the dryers would break even. Being single, my gas dryer pay off, with the diverter use, would likely be 10+ years. Even if the dryer did last that long, it would be substantially longer before the savings would amount to anything. Thank you for the time you put into this.
In addition you can’t use a diverter with a gas dryer, it’s not safe.
Jim, that is absolutely the only article I have ever read that actually shows me the difference between gas and electric for a clothes dryer in Seattle. Thank you so much! I can sleep now. After I have a gas line installed of course.
Its the same rule of thumb as every other economic relationship.
If there was an obvious advantage, then everyone would be doing it one way.
If owning a car was always cheaper than leasing, nobody would lease.
If gas was always cheaper than electric, Sears would never sell and electric dryer.
But yet they do, so it just comes down to personal needs/preferences.
Continuing this line of reasoning it seems that home owners always choose a gas furnace and hot water heater unless they are unable. For instance, many homes in rural areas have to run all electric appliances or have a liquid propane tank. So if it makes sense to heat or homes and our water with gas would it not follow that we should heat or clothes with gas. I think we would need to look at the entire value stream, that is, how much energy is expended in getting the natural gas to our homes versus the electricity. Does it make sense for the local power plant to use natural gas to generate electricy (with significant heat losses) then trasmit that to your home (also with significant losses) and then reconvert that back into heat in your dryer? There are energy losses associated with transmitting natural gas as well but it seems like it should be more efficient since there is not a conversion to and back from electricity that has to take place.
sears sells electric because some houses dont have gas. some have gas, but not in the laundry room. some people rent to own appliances and lease their cars.
What a very informative breakdown. My neighbor was looking at his electric meter (the one the power companies install) His 220V dryer was pulling 5.5kwh while on – He ended up installing a gas dryer to save a few dollars.
Go with gas, just make sure it’s exhausted outside.
J. Mann December 2nd, 2009 at 11:29 – the exhaust (CNG, burns clean) goes directly into your clothes and then out the vent. Take one apart, it’s nothing like a Forced air furnace.
I cannot access your update or spreadsheet. We recently decided to go with electric because the sales guy STRONGLY recommended it because of the price of gas. I wanted to compare for myself. I wish I had found this before we took his advice so we could’ve made a fact-based decision.
Thanks for letting me know the link to the spreadsheet was broken. It’s fixed.
Hope your situation works out for you.
Excellent article. Just a few comments. You assume the lifespan of a dryer to be about 5 years regardless of usage. Granted it may die early, but if rather the lifespan is usage based not time based, it could still be beneficial for someone single to own. For those who have had to install a gas line and vent, what is the cost of that, and the time to recoup those costs? The other thing one should consider is the use of a high efficiency washer. Some of these now have spin cycles of up to 1400rpm almost twice the speed of older dryers. This will get the clothes very close to dry and further reduce the time in the dryer. This would further close the cost gaps in the time usage of the two dryers .
The dryer lifespan was taken from Consumer Reports’“repair or replace” articles that appear periodically.
You do make an excellent point about high-efficiency washers. Since going to one of these early last year, I’ve observed the drying time is significantly reduced because the washer has a high-speed spin. (This helps us get through laundry a lot faster!)
I have not reworked any of the numbers to account for this.
Thanks for the great spread sheet and site. I modified it a little to work with the random charges i get. I wish i would have found the spread sheet before i bought a washer/dryer- I bought a washer and electric dryer. However, since i did buy used units, i am planning on getting a gas dryer now that i see it’s cheaper. I never knew how much energy content was in a therm of gas or how to do the calcs.
I used a foolish line of reasoning- since all the appliances in my new house used nat. gas, a gas dryer would put me way over my baseline allowance(or tier 1 as you call it). I got my first partial gas bill(2 separate utilities here) and i did go over my baseline without a dryer. But the numbers don’t lie and the cost per load is still cheaper @ the higher tier on the spreadsheet; about half!
I think there is one thing you could add to the spread sheet and that is- what if your dryer dries in 1/2 hour or 45mins. I know how to figure this on my own but others might not know or think about it. just times the heating element kw rating by .5 or .75 etc. Same for therms.
Thanks for that. I’ve had my gas dryer for 10 years, so I guess it’s paid for itself plus some.
I have had my gas dryer 16 years and the dial finally went on it. Motor still goes. So I am sticking with gas. Great info!
Your calculations are misleading, a 5000 watt electric heating element does not put out 22,000 btu of heat. A gas dryer generates more heat, and will dry faster, and dry clothes quicker.
Thanks so much for the awesome info. ;o)
Glad you did all the work, I couldn’t think of what math operation I would/could use!!
Thanks for taking the time to run the numbers and share this highly accessible analysis. By far the clearest and most useful I’ve seen on this question. Will try your spreadsheet with current local figures. So far it looks like we’re going with gas (house we’re moving into has both hook ups, would that all builders were thoughtful enough to provide both). Go well.