Researchers at the University of Manchester carried out the first ever comprehensive research into the environmental impacts of microwaves, considering their whole life cycle, from “cradle to grave”.
Cooking food in a microwave does not directly release carbon dioxide in the same way as a car's exhaust, but the study took into account the power the ovens use and the resources and pollution involved in every step from production to disposal.
They found that the machines are responsible for 7.7 million tonnes of carbon dioxide equivalent per year in the EU, which is the same as the annual emissions of 6.8 million cars.
Microwaves are the most used oven throughout the EU, with numbers set to reach nearly 135 million by 2020.
However, 6.8 million is only a small fraction of the number of cars being used every day in the EU.
There are at least 37.5 million cars and other motor vehicles registered for use in the UK alone. There are also at least 32 million on the roads in France, 37 million in Italy and 45 million in Germany.
And the last time the EU counted the number of cars on its roads was in 2008 when the number topped more than 256 million – which is more than 37 times the number of cars being equated to microwaves in the University of Manchester’s study.
The study also showed that microwaves across the EU consume an estimated 9.4 terawatt hours of electricity every year, which the University of Manchester claims is the equivalent to the annual electricity generated by three large gas power plants.
The researchers now say that efforts to reduce consumption should focus on improving people’s awareness and behaviour, so they use microwaves more efficiently, for example by reducing electricity use by adjusting the time of cooking to the type of food.
Waste is another major problem with low costs and ease of manufacture meaning more people are throwing away electronic equipment than ever before, including microwaves.
In 2005, across the EU, 184,000 tonnes of waste generated was from discarded microwaves. By 2025 this is estimated to rise to 195,000 tonnes, or 16 million individual units being sent for disposal.
Dr Alejandro Gallego-Schmid, from the University of Manchester’s School of Chemical Engineering and Analytical Science, said that “rapid technological developments and falling prices” were driving the purchase of electronic appliances in Europe.
“Consumers now tend to buy new appliances before the existing ones reach the end of their useful life as electronic goods have become fashionable and ‘status’ items,” he said.
“As a result, discarded electrical equipment, such as microwaves, is one of the fastest growing waste streams worldwide.”
Another major contributing factor to the waste is a reduced lifespan of microwaves.
Research shows that a microwave’s lifecycle has decreased, from around 10 to 15 years in the late Nineties to between six and eight years today.
Dr Gallego-Schmid added: “Given that microwaves account for the largest percentage of sales of all type of ovens in the EU, it is increasingly important to start addressing their impact on resource use and end-of-life waste.”
However, David Reay, professor of carbon management at the University of Edinburgh, said that comparing microwaves and cars in terms of their impact on the environment was like comparing “apples and oranges”.
“To say microwave ovens are ‘as bad for the environment as cars’ is an apples and oranges comparison, because [the microwave test] is for a full life-cycle assessment and [the cars’] is just for their direct emissions from being driven,” he said.
“The statement ‘microwaves could be as bad for the environment as cars suggests new research’ is completely incorrect in my view.
“Yes, there are a lot of microwaves in the EU and yes they use electricity. But their emissions are dwarfed by those from cars.
“The latest data shows that passenger cars in the UK emitted 69 million tonnes of CO2 equivalent in 2015.
“This is 10 times the amount this new microwave oven study estimates for annual emissions for all microwave ovens in the whole of the EU.”
“In sum, the paper does a decent job of estimating lifecycle emissions of microwaves, but to say ‘microwaves could be as bad for the environment as cars’ is very misleading, in my view.”
The University of Manchester study also suggests that existing regulations will not be sufficient to reduce the environmental impacts of microwaves, with researchers suggesting it will be necessary to look at specific regulations targetting their design.
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