We include this initiative because it addresses the challenges of of ‘closing the food loop’. This innovative solar-thermal toilet was developed by a team led by CU-Boulder Professor Karl Linden to improve sanitation and hygiene in developing countries.
It was developed as a project in the Bill & Melinda Gates Foundation's "Reinvent the Toilet Challenge". The toilet is self-contained, waterless and can heat human waste to a high enough temperature to sterilize it and create biochar, a type of porous charcoal. The biochar can be used to both increase crop yields and sequester carbon dioxide. Biochar has good water holding capacity and it can be used in agricultural areas to hold in nutrients and bring more stability to the soils. Additionally, the biochar can be burned as charcoal and provides energy comparable to that of commercial charcoal.
Sol-char toilet, photo credit University of Colorado.
Adopting this novel technique may lead to changes in methods to capture and treat human waste, where traditional methods have been shown to result in serious health problems and death of roughly 700,000 children each year.
Read more about this research here. You can also see more resources on our website related to Biochar here. For more on the use of human sewage in the context of urban agriculture (as a means of improving nutrient use efficiency) you may be interested in this edition of the RUAF’s Urban Agriculture magazine here.