Microwave appliance usage could be as bad for the environment as cars, suggests new research

Researchers at the University have carried out the first ever comprehensive study of the environmental impacts of microwave appliances, considering their whole life cycle, from 'cradle to grave'.

The study found:

• Microwave appliance usage emits 7.7 million tonnes of carbon dioxide equivalent per year in the EU. This is equivalent to the annual emissions of 6.8 million cars.
• Microwave appliance usage across the EU consumes an estimated 9.4 terawatts per hour (TWh) of electricity every year. This is equivalent to the annual electricity generated by three large gas power plants.
• Efforts to reduce consumption should focus on improving consumer awareness and behaviour to use appliances more efficiently

Microwave appliances account for the largest percentage of sales of all type of ovens in the European Union (EU), with numbers set to reach nearly 135 million by 2020. Despite this, the scale of their impacts on the environment was not known until now.

The study used life cycle assessment (LCA) to estimate the impacts of microwave appliances, taking into account their manufacture, use and end-of-life waste management. Altogether, the research team investigated 12 different environmental factors, including climate change, depletion of natural resources and ecological toxicity. They found, for example, that the microwave appliances used across the EU emit 7.7 million tonnes of carbon dioxide equivalent per year. This is equivalent to the annual emission of 6.8 million cars.

The research shows that the main environmental 'hotspots' are materials used to manufacture microwave appliances, the manufacturing process and end-of-life waste management. For example, the manufacturing process alone contributes more than 20% to depletion of natural resources and to climate change.

However, it is electricity consumption by microwave appliances that has the biggest impact on the environment, taking into account its whole life cycle, from production of fuels to generation of electricity. In total, microwave appliances across the EU consume an estimated 9.4 terawatts per hour (TWh) of electricity every year. This is equivalent to the annual electricity generation by three large gas power plants.

The study found that, on average, an individual microwave appliance uses 573 kilowatt hour (kWh) of electricity over its lifetime of eight years. That is equivalent to the electricity consumed by a 7 watt LED light bulb, left on continuously for almost nine years. This is despite the fact that microwave appliances spend more than 90% of their lifetime being idle, in the stand-by mode.

The study's authors suggest that efforts to reduce consumption should focus on improving consumer awareness and behaviour to use appliances more efficiently. For example, electricity consumption by microwave appliances can be reduced by adjusting the time of cooking to the type of food.

Waste is another major problem. Due to their relative low cost and ease of manufacture, consumers are throwing more electrical and electronic (EE) equipment away than ever before, including microwave appliances.

In 2005, across the EU, 184,000 tonnes of EE waste was generated from discarded microwave appliances. 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 School of Chemical Engineering & Analytical Science, explains: "Rapid technological developments and falling prices are driving the purchase of electrical and 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.

"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 microwave appliances. It is now nearly seven years shorter than it was almost 20 years ago. Research shows that a microwave appliance's life cycle has decreased from around 10 to 15 years in the late 90s to between six to 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."

The study also shows that existing regulation will not be sufficient to reduce the environmental impacts of microwave appliances. It recommends that it will be necessary to develop specific regulations for these devices targeting their design. This will help to reduce the amount of resources used to make microwave appliances and waste generated at the end of their lifetime.