Clothes dryers are really quite basic. There’s a big drum spun by an electric motor whereby heat is generated in one of two ways; gas vs electricity. Gas dryers tend to dry the clothes slightly faster, but only by a few minutes. So the question isn’t which is more efficient than the other, because they are both about the same. The question is operating costs.
What does make a difference is how much it costs to create the heat which drys your clothes. And that’s what we’re going to focus on. The cost of electricity and natural gas vary greatly depending on where you live, so this is where you will have to do your homework. Go get an electric bill and a gas bill. Find the cost per kilowatt (kWh) and the cost per Therm (might also be measured in CCF) and write them down. We need to find out how much energy a gas dryer uses per load (usually measured in Therms or BTUs) and how much electricity an electric dryer uses per load (measured in kWh).
My existing electric dryer, that’s about to die because it’s 12 years old and squeaks, uses 240v AC and pulls 28 amps. Volts multiplied by Amps = watts, which in this case is 6,720 watts or 6.72 kilowatts. The gas dryers I’m looking at use about 0.25 Therms per cycle and a very small amount of electricity to turn the motor. I’ll assume it takes an hour to fully dry the clothes in both the gas and electric dryers. Although gas dyers are slightly faster, they do use a bit of electricity, so we’ll call it a wash (pun intended).
Gas vs Electricity Cost per Load
Let’s look at the below cost comparison for my house based on my rates (Colorado rates as of 2012):
- Cost per kWh = $0.0998
- Cost per CCF = $0.6034 or $0.6179 per Therm (1 CCF x 1.024 = Therms)
- Electric Dryer Cost per load (1 hour) = 6.72 kWh x $0.0998 = $0.67
- Gas Dryer Cost per load (1 hour) = .25 Therms x $0.6179 = $0.16
In my location, it is way cheaper to run a gas dryer than it is an electric dryer.
Gas vs Electricity Cost per Month
When you consider we do 6 loads of laundry a week (family of 4) the numbers really start to stand out. All calculations from this point are linear, meaning, the costs for both the electric dryer and gas dryer will increase at the same rate and ratio.
- Electric Dryer = 6 loads x $0.67 = $4.02 per week
- Gas Dryer = 6 loads x $0.16 = $0.96 per week
- Electric Dryer = $4.02 per week x 4 weeks = $16.08 per month
- Gas Dryer = $0.96 per week x 4 weeks = $3.84 per month
Gas vs Electricity Conclusion
I save over $12 a month by switching to a gas dryer. One could make the argument that the gas dryer also uses electricity so it should cost more, but that is washed out by the fact gas dryers dry clothes slightly faster.
A brand new gas clothes dryer does cost slightly more than the equivalent electric model, but not by much. Maybe $50 on average. In my case, I’d pay off the cost difference with the savings in using gas over electricity in about 4 months.
When I average our monthly electric bill over the course of 12 months, we use about 750 kWh per month. The dryer alone accounts for 25% of our monthly electric bill! Here’s the math: 6.72 kWh per load X 7 loads a week X 4 weeks in a month = 188 kWh a month. If you take 750 kWh and divide it by 188 kWh, that equals 25%. (UPDATE: I was pretty close on this calculation. We’ve had our gas dryer for 6 months and my electric bill has dropped on average 145 kWh per month).
Lastly, there are other types of clothes dryers, but they usually have unwanted side-affects. Microwave dryers that dry the clothes by heating the water with microwave radiation and turning it to vapor are gaining traction in Japan, but they have drawbacks. One being, arcing can damage the clothes and two, you better make darn sure nothing metal is left in your clothes pockets (put a silver/metal spoon in the microwave oven and hit start, see what happens).
Heat pump dryers are another option, but they only operate at very high temperatures. Clothes that are sensitive to high temperature would have to be dried by other means. Lastly, there are condenser dryers. They are “passively” efficient, only because they take the hot air created during the drying process and expel it into the immediate surrounding (i.e; inside your house) so that you don’t have to run your furnace as much. This is fine in cold climates where one heats their house, but it’s bad in the summer time when it’s already hot in the house and you’re running the AC.