Cheaper, Safer Cooking with Biomass Briquettes

KIBERA, Kenya – When you’re required to survive on less than $1 a day you have to be resourceful. Just ask any of the estimated 1 million residents in Kibera, Kenya the biggest slum in Africa and one of the largest in the world. Kibera is on the outskirts of the Kenyan capital Nairobi and residents face a multitude of challenges including access to clean, safe drinking and cooking water as well as affordable, safe cooking fuel.

Women are primarily responsible for gathering water and preparing meals, so this burden lies with them. Unlike in the rural areas, women do not have immediate access to forests for firewood and rely on charcoal, which can be costly. A bag of charcoal costs roughly 1000 shillings (about $12) – no small price in the slum. Mary Njenga is developing a formula for a safer, cheaper and healthier charcoal briquette that has the potential to dramatically change how people in developing countries use cooking fuel. It's a continuation of research she started at the World Agroforestry Center while earning her PhD in the Management of Agroecosystems and Environment from the University of Nairobi.

Njenga’s charcoal briquette formula consists of mixing charcoal dust with water and a binding agent such as soil, paper or starch. The mixture is shaped by hand, or molded in wooden or metal presses into fist-sized units, which are then air-dried. “With charcoal briquettes it costs just 3 Kenya Shillings (US$0.04) to cook a traditional meal of maize and beans for a standard household of 5 people. This is nine times cheaper than cooking the same meal with charcoal (KSh 26 or US$0.3) and 15 times cheaper than cooking with kerosene  (KSh 45 or US$0.6). As such, households are now able to choose from a wider dietary range,” says Njenga.

We recently featured Mary's briquette formula
on our weekly Bloomberg West segment.

Njenga has been working on these complex formulas for almost a decade and has made charcoal briquettes using various binding agents, and compared their energy values. According to a recent article from the World Agroforestry Centre, “some 2.4 million tons of charcoal are traded in Kenya annually, over eighty percent of it in urban areas. Breakage during handling and transit leaves in its wake large mounds of charcoal dust at retail and wholesale outlets. This is the raw material for charcoal briquettes, which burn even cleaner than charcoal.”

Njgenga predicts that the clean burn of charcoal briquettes made with her formula drastically reduces indoor air pollution, one of the leading causes of the 400,000 deaths from respiratory diseases that occur each year in sub-Saharan Africa. 

How do you move the Planet Forward? Tweet us @planet_forward or contribute to the conversation with your own story.