The Slow Cooker That Requires No Electricity

Wonderbags are thermal-retention cookers, technology that's been around since humans realized that wrapping up a hot pot can save precious fuel. And now one South African entrepreneur has figured out how to sell them around the globe.

Preparing hot pre-school lunch with Wonderbags.  (Wonderbag)

Sitting on my counter is my newest piece of culinary equipment: an eco-friendly Wonderbag slow cooker, the brainchild of Sarah Collins, a South African entrepreneur. She has monetized an exceedingly low-tech, old-fashioned cooking technique, marketed it with a winning Buy One Give One campaign, and closed a lot of sales. 

Wonderbags are thermal-retention cookers, technology that's been around since humans started cooking and realized that wrapping up pots, or even burying them in the ground, saves fuel. Also called fireless cookers, hayboxes, or wonderboxes, traditionally they are a large basket or box lined with a blanket or towels or sometimes stuffed with banana leaves.

After a pot of food is brought to a boil, the cook quickly tucks it into the Wonderbag, puts on the lid, and closes it up tight. The food continues cooking without added fuel. The process takes about twice as long, but I can attest to taking out a steaming, perfect pot of lentil soup a few hours later.

Wonderbags are now sold in the United States through Amazon, after successfully launching in the United Kingdom. Reviews are enthusiastic, though the Wonderbag's large size puts off a few. It arrives vacuum-packed; open it and it quickly doubles. Think dog bed.

The non-electric slow cooker is sewn in South Africa, providing jobs in a country with very high unemployment. The Wonderbags are insulated with styrene, the dreaded non-recyclable #7 foamy stuff. The company collects theirs from an upholstery factory’s leftovers, preventing it from heading to a landfill. For each bag purchased at $50, another one is donated to a low-income household.

Collins gave a new life to this old technique and turned it into something to buy rather than assemble. She realized its potential as an eco-friendly technology, sparing many trees by radically cutting fuel use—so radically that she has been able to obtain Carbon Offset Funding.

For the three billion people on the planet who cook over open fires for which they must find and chop wood, saving fuel is a big deal. The Wonderbag, like all thermal retention cookers, uses much less fuel, yielding savings in time and, often, money. 

  • Standing over a cooking fire is equivalent to smoking a few packs of cigarettes, increasingly perceived as a public health issue.  Fireless cooking eliminates most of the smoke. 
  • Food doesn’t burn, like it does over open fire, another plus.  Less waste with easier clean-up.
  • They can be left unattended, without stirring or shooing the children away from the fire. 

Those benefits make a big difference for my Wonderbag’s recipient twin.  In my kitchen, using my electric stove an hour less reduces my carbon emissions by an infinitesimal, though not insignificant, amount.  Why waste energy when there is an easy way to use it more efficiently?

And what of the Buy One Give One model, much maligned? There have been two main critiques of Tom’s Shoes, which donates a pair of shoes for each purchase. They are:

  • Shoes are not a pressing need for children in the developing world, especially compared with food, clean water, health care, and education. Shoes offer a modest benefit, at best. 
  • Dumping free shoes undercuts local shoe vendors. 

Wonderbag’s giveaways strike me as more sensible. They facilitate a useful practice, eco-friendly for the affluent world as well as in low-resource regions. Recipients realize actual savings of time and money, as well as health benefits from avoiding smoke inhalation. No local vendors sell them, so no one is being undercut. And if Wonderbags help reacquaint people with fireless cooking, there is nothing to stop local people—be they in South Africa or in South Dakota—from sewing their own. Or even wrapping up your soup pot in that old sleeping bag and sticking it in a box, a less sexy but also effective approach.