Imagine if a school or hospital could deal with its own waste on-site with some planet-friendly bacteria. Well, imagine no more...
Many high school science students will remember learning about anaerobic digesters (AD). Probably something vague about how you can put things like food waste into them, and thanks to a type of composting, you can get useful solids, liquids and gases out of them.
However, few high school science students will probably remember why they were asked to learn about anaerobic digesters. This is a shame (and a reminder that science curriculums have as much learning still to do as everybody else). It’s a shame, because anaerobic digesters are brilliant.
Fed with organic and food waste materials, they are a perfect low-oxygen home for certain types of bacteria that thrive in a low-oxygen environment. The conditions in an AD foster an incredible biological process whereby bacteria essentially eat their way through the waste. Then, full up, they let off hydrocarbon gases. These gases, like their fossil counterparts, can be collected, and then used in a boiler, or put through a small engine to create electricity and heat.
AD not only contributes to our much-needed mix of clean energy, but it also helps deal with an ever-growing mountain of food waste generated in all corners of the globe. From the mismatches of supply on the farm and demand in the shops, to retailers buying too much product they can’t sell, to consumers with eyes bigger than their bellies, food ending up in our waste stream has been an ongoing problem.
In the US, a shocking 40 per cent of food is never eaten. In the UK, households chuck £13 billion worth of food in the bin every year – food that could have been eaten, according to figures calculated by the government’s advisory body Wrap.
Plus, of the 7.3 million tonnes of food thrown away in 2015, 4.4 million tonnes of it was deemed to be “avoidable” because it was perfectly edible before entering the waste stream.
Like issues with the land itself, it’s a complex problem, and it needs many connected solutions. The food industry hopes to help with a new set of ‘best before’ labels. More sustainable farming practices, and smarter choices by more savvy and better informed consumers will help too. Plus, right now, we do have AD.
However, whilst AD may have often been a staple of secondary education, the technology still hasn’t realised its full potential. Subsidy cuts have not helped the widespread acceleration of what is a well-proven system, particularly in the UK. But there has been other challenges; not least in the waste industry struggling to build the right infrastructure at the right pace to ensure that food and organic waste is mopped up wherever possible. Leftover food at supermarkets, schools, restaurants, hospitals and people’s homes needs identifying, collecting, transporting to central, large-scale AD plants and processing before any benefits are captured.
Fortunately, SEAB Energy, a Southampton-based start-up headed by CEO Sandra Sassow, has created a solution that takes that pain away by decentralising AD so that waste can be dealt with on-site, at source. “We’re turning poop into power using AD technology that fits into shipping containers, on-site, in buildings, or in remote areas around the world,” says Sassow. “Just as you can replace a mainframe computer with laptops and iPads, we’ve done the same in the waste sector – replacing a large, centralised facility with a small, portable unit.”
So, schools, hospitals, supermarkets, catering businesses – any organisation that creates plenty of food waste, and has space for a shipping container on-site – are beginning to explore the benefits of SEAB Energy’s technology. Once you start to feed, it can continuously produce electricity, unlike solar or wind which, whilst still wonderful, scaling-up, and very important, are more dependent on the time of day and/or the weather. “For every digester that we put on-site, you can run a 10 kilowatt generator full time at the back end of it,” adds a proud Sassow who has picked up a plethora of awards for her innovation, including a BusinessGreen Technology Award.
The other byproduct of the AD process is compost. When fed with food scraps, around 98 per cent of the organic material is digested, with every 1,000 kilograms of food waste leaving two kilograms of compost which can be bagged up and sold separately, making the perfect fertiliser.
But the real benefits ought to be realised by big cities, says Sassow. Depending on the current value of electricity and the cost of waste disposal, companies are able to see a mini AD unit pay back within six years – and that’s without the help of subsidies or other support mechanisms. “Cities are able to offset the huge cost of waste-disposal and improve their sustainability performance. We’re also able to help reduce traffic and make cities more liveable, plus extend the life of existing infrastructure – whether sewage treatment or current waste-processing facilities that are at capacity.”
Ultimately, more and more organisations are starting to see that waste in one area is value in another – that it’s a resource to be used for more than just putting into a landfill site. That is good news for businesses keen to extend their profit margins.
Also, more circular ways of managing waste could be good for poorer rural communities. On a recent trip to India, Sassow met with government representatives of one of the bigger states keen to install 20 AD units that would provide energy to more than 400 villages where there is currently a lack of infrastructure. “Some of these villages are currently off-grid, and most of them don’t have any kind of waste management at all right now. So, we could have a dramatic impact on the health and cleanliness of communities across places like India.”
So, why has it taken so long for what is a well-established technology to be scaled back in such a way? Sassow puts it down to the constant focus on centralised waste management systems. “I guess nobody really wanted to take on the challenge of having to decentralise this. But I’m willing to take it on,” she says, pondering her next move for the business. With both a UK and US arm of the business, a network of selling agents on every continent, interest in her mini AD plants continues to grow as the world begins to understand that it is possible to use your own waste, as your own resource, on your own site.
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