Image Source: Velo Steve
Dear Pablo, For boiling water what is the most efficient, an electric kettle, a pot on a stove, or a microwave?
Whether you are making tea or cooking pasta, knowing which of these three options is the most efficient way to boil water can help you become a better tree hugger and might even save you a bit of money. Through some quick measurements and calculations I hope to provide a definitive answer to this question.
A large mug is around twelve ounces, or 350 ml, so I will use 350 ml of room-temperature water (17° C). I will be using an electric kettle made by Black & Decker, an electric stove made by General Electric with a Circulon 2 quart saucepan, and a 900W microwave with a turntable. The electricity use of each will be measured using a Kill-a-watt meter until the water reaches the boiling point, or 100° C.
The Electric Kettle
Image Source: Andy Butkaj
Image Source: Ron Howard
The Microwave Oven
Image Source: Alan D
The ConclusionThe clear winner is the electric kettle, at 81% efficient, followed by the microwave, at 47% efficient, with the stove being the Hummer H2 of the bunch at 30.5% efficient. Assuming that you currently use the stove to boil water, switching to an electric kettle for your morning tea will reduce your daily electricity use from 0.11 kWh to 0.04 kWh. Over the course of a year this daily 0.07 kWh savings adds up to 25.5 kWh. Depending on where you live, you could potentially save between $2.50 and $5.00 per year. Of course most of us boil more water than just for making tea. If you extrapolate these savings out to every time you make soup, pasta, home-brew or boil a lobster it can add up.
Additional Considerations When Boiling WaterRegardless of your method for boiling water you can ensure maximum efficiency by boiling only what you need. Use your mug to measure the proper amount or get yourself an Eco Kettle. If you are in an office you might think that filling the electric kettle to the top is the most efficient but think again. Unless the water is going to be used right away a great deal of the energy is going to just end up in the air, where you HVAC system has to remove it. Besides, heating small batches of water is quicker than heating one big batch anyway.Pablo Päster is a weekly columnist for TreeHugger.com, an experienced greenhouse gas engineer and the Senior Environmental Program Manager at Hara Software. Send your questions to Pablo(at)TreeHugger.com or submit the via this form and connect to his RSS feed.
More Articles on Kettles and Boiling Water:
Brewing Change: The Guardian Keeps Its Kettle In Check
Get An Electric Kettle, Don't Overfill It
A Google Or A Cup Of Tea: Which Warms The Globe The Most?
How To Boil Water (Really, Some Folks Need Telling)