Sewage sandwich, anyone?

Sensemaking / Sewage sandwich, anyone?

How far will innovators go to minimise waste in the protein system?

By Fiona Harvey / 05 Apr 2016

This article was first published in The Long View 2016 chapter Crisis Catalyst. Please share your thoughts here and join the conversation on social media with #longview2016.

What would you say to a cricket canapé? A gourmet grub or a Michelin-starred maggot? Or if those fail to appeal, perhaps a sewage sandwich?

As the world’s population grows, and conventional food sources come under threat, experts are increasingly examining new ways of making more from less – and of finding new food sources. The idea that we may be eating insects in the future is now commonplace in the media, but it disguises a far bigger trend. Novel forms of protein are part of a new move that is being called ‘closed loop’, which comprises a broad range of innovations, both technical and practical, to ensure that nothing is wasted from agriculture and food processing.

In a sense, there is nothing new about closed-loop innovation in the food chain.

Since the earliest days of agriculture, waste products have been put to new uses that enhance and boost productivity. Manure is reused as fertiliser, or as fuel. Straw litter is burned for cooking fires. Skins are used for clothing as the meat is eaten. So far, so Stone Age.

Today’s innovators go further, however. The prize is protein, says Simon Billing, principal sustainability advisor at Forum for the Future. There are now more than seven billion people in the world, and our population is set to rise to more than 10 billion, and perhaps as many as 12 billion, by 2050. That will require an enormous increase in food production, but in the meantime agriculture across much of the globe is beset by the twin forces of water scarcity and climate change.

Carbohydrates such as grains and starch will be needed in abundance, but for healthy populations we will also need a massive increase in the production of protein, and that is a problem. Already, about 40% of global grain production goes to feeding livestock, and that amount is on the rise. The grain used requires fertiliser and water, and the animals produce the greenhouse gas methane – a double whammy for water scarcity and climate change.

As if that weren’t enough, our other major protein source – fish – is now under threat as stocks of commercially fished species are rapidly on their way to exhaustion.

If new ways can be found to generate sources of protein, that would go a long way to solving the coming food crisis. So, while the idea of munching on maggots may grab the headlines, in reality, says Billing, they are more likely to be used as food for animals, such as poultry, which people can then eat as a nutritious and protein-filled meal that has not cost the Earth. This is truly closed loop, as the insects that are fed to livestock are themselves fed on livestock waste. For instance, a company called AgriProtein,1 based in Cape Town, is breeding flies on waste to use as feed. Many experts now believe that poultry, such as the Giriraja chicken, and ducks raised in paddy fields – another closed-loop system, as they eat fish swimming in the fields and fertilise the rice with their manure – may be a key part of the answer to our protein crisis.

Milk and dairy products are also going to be far more in demand, and one US company has come up with a potential answer. Founded by vegans who are concerned about the inhumane practices of intensive agriculture, as well as environmental concerns, Muufri is a Californian start-up making milk from genetically engineered yeast strains. As it mimics the molecular structure of cow’s milk, it can be used in the same way as the real thing. It may take time for consumers to accept such a product, but the potential for the technology is there.

Lab-grown meat is another possibility, but while efforts to simulate animal tissue from lab-grown materials have been under way for more than a decade, progress has been slow. The first artificial steak was created several years ago, but efforts to bring the cost down have not yet paid off. Milk is an easier proposition because the texture of meat grown on artificial ‘scaffolding’ is so hard to get right.

Back to that sewage sandwich. The ultimate in closed-loop innovation might seem to be to return human waste to food. But periodic reports of researchers turning poo into edible products have come to nothing. A much simpler proposition is to use human waste as fertiliser. In Denmark, the ‘piss to Pilsner’ project last year encouraged attendees at a music festival to urinate in receptacles that collected the liquid, which was then used on barley crops, destined to be turned into beer. More prosaically, and at an earlier stage in the waste cycle, Grind2Energy installs food recyclers, called the InSinkErator, in kitchen sinks to create an energy-rich material that is subjected to anaerobic digestion, producing fertiliser, with the resulting methane captured for use as energy. This makes it much easier for waste food to be efficiently recycled into useful products.

So, if novel foods and food sources seem too outlandish for human consumption, the future may be in a return to the time-honoured traditions of our ancestors, using waste as crop fertiliser and for livestock-rearing – the modern versions of closed-loop agriculture.

Fiona Harvey is Environment Correspondent for the Guardian

Image credit: marco antonio torres / Flickr

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