Food waste: Reduce or recycle?

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More and more cities across the U.S. and Europe are recycling food waste to make biogas, a renewable energy source that can be burned for heating and power. The goal is to reduce carbon emissions. But a recent study in Environmental Science & Technology shows that cutting food waste could save twice as much energy as turning it into biogas.

Roughly a third of the food supply worldwide is wasted every year, according to the United Nations Environment Programme. Producing wasted food requires energy and emits greenhouse gases, as does collecting and recycling that waste. But there haven’t been efforts so far to quantify the energy-use costs and benefits of the two strategies to tackle food waste: prevention or recycling.

Researchers from the Norwegian University of Science and Technology used Norway as a case study for the analysis. They developed a multi-layer model to track the annual flow of energy through the entire Norwegian agricultural system. This included energy used in plant production, animal husbandry, food processing and consumption, waste management and biogas production. They got their data from national statistics, reports, and scientific articles.

The models showed that about 17 percent of food sold is wasted in Norway, 10 percent of that by consumers. And that doesn’t include banana peels and coffee grounds, but avoidable food waste: think restaurant leftovers or that bag of lettuce past its “best by” date.

Preventing food waste led to a 16 percent system-wide reduction in net energy use. For the food-recycling scenario, the reduction was 8 percent.

Contrary to the “reduce, reuse, recycle” mantra, Norwegian government practices currently favor food waste recycling, the researchers say. Norwegian cities have started collecting food waste in separate green bags, and the country is incentivizing biogas production because it reduces carbon emissions. The same food waste-to-biogas push is ongoing in other European countries and in the U.S. as well.

But building more biogas facilities raises the risk of making avoidable food waste a necessary commodity, the team says in the paper. Instead of focusing on end-of-life solutions, policymakers should look at the food waste problem systematically. “Our work shows that policy and incentives should prioritize food waste prevention and that most savings can be had through a combination of prevention and recycling,” said lead researcher Helen Hamilton in a press release.

They recommend that governments reconsider the economic incentives in place for recycling food waste and instead implement market-based instruments such as tax exemptions or compensation mechanisms that incentivize the prevention of food waste in all sectors from food processing to retail and consumers.

More information can also make a difference. For instance, consumers waste a lot of food because they get confused between “best by” dates, which only indicate quality reduction, and “use by” dates used for highly perishable food that can be unsafe after a certain period. – Prachi Patel | 21 January 2016

Source: Hamilton, H., M.S. Perverill, D.B. Müller and H. Bratteboe. Assessment of Food Waste Prevention and Recycling Strategies Using a Multilayer Systems Approach. Environmental Science and Technology (2015). doi: 10.1021/acs.est.5b03781

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