A Biodigester: A Pathway for Economic and Environmental Transformation

Concern Worldwide’s Food Systems for Food Security (FS4FS) approach builds on more than a decade of integrated work in agriculture and nutrition. It recognises that food and nutrition security improves when communities are supported to strengthen farming, nutrition, local markets, and gender equality together. Since 2022, Concern has implemented FS4FS as a dedicated multi-country programme, funded through Irish Aid’s Long-Term Development support.

Across the contexts where Concern works, food insecurity is shaped by overlapping pressures, including climate shocks, conflict and fragility, weak market systems, gender inequality, and limited access to land, inputs, and services. FS4FS responds with a food systems approach, recognising that food availability, access, utilisation, and stability are interconnected and influenced by social, economic, and environmental factors.

In Malawi, the FS4FS programme (2023–2027) 'RESET' targets 14,012 subsistence farming households, including female-headed households, households that include people with disabilities, and households headed by older people. The initiative aims to increase food and nutrition security among vulnerable households by supporting income generation along food value chains.

For 75-year-old Ligness Mpoto of Mtali Village in the Kakuyu Watershed, farming has become increasingly difficult in recent years. Erratic rainfall, droughts, floods, declining soil fertility, and the rising cost of fertiliser have all contributed to reduced yields and increased pressure on household food security. Her experience reflects the wider challenges faced by many smallholder farmers in Malawi, where climate-related shocks and high input costs are making it harder for families to produce enough food.

In January 2025, Ligness was selected as one of ten pilot farmers to receive a biodigester through FS4FS, implemented in partnership with a private sector company, EcoGen Malawi. Households were selected based on access to animal waste, reliable year-round water, adequate space for installation, and the willingness and capacity to manage the system. The biodigester was introduced as a practical way to help households reduce dependence on costly inorganic fertiliser, improve soil fertility, and produce cleaner energy for cooking.A biodigester is a self-contained, eco-friendly waste management unit that uses natural microorganisms to break down organic waste, such as animal manure and food waste, in an oxygen-free environment. The process produces two useful by-products:

• Biogas: methane gas that can be captured and used for cooking and heating.
• Liquid fertiliser: nutrient-rich digestate that can be safely used to support crop production.

Before receiving the biodigester, firewood scarcity was one of Ligness’s greatest burdens. She walked long distances in search of wood, especially during the rainy season, and often returned home exhausted, only to face the smoke and heat of cooking on a traditional stove. Today, that struggle has ended.

By feeding her biodigester with around 40 litres of kitchen or animal waste, Ligness produces enough biogas to cook for three to four hours every day. The gas is reliable enough that she no longer uses firewood.

Beyond the financial relief, Ligness values the comfort of smoke-free cooking, which has improved conditions in her kitchen and allows her to prepare meals even when she feels tired. The shift away from firewood also reduces exposure to household smoke, which is associated with respiratory illness, eye problems, and other health risks. The benefits extend beyond her household: neighbours often come to boil beans using her clean energy, making the biodigester a shared asset in the community.

The system also supports around 20 households through the liquid fertiliser it produces. These households contribute waste to help feed the biodigester and receive liquid fertiliser for compost manure production without paying a fee. For households beyond this group, the fertiliser is sold or exchanged for farm labour.

What Ligness values most, however, is the liquid fertiliser produced by the biodigester. Each week, the system yields 12 buckets, or around 240 litres, of nutrient-rich organic fertiliser. Along with the other 20 households who benefit, she applies it to maize, tomatoes, onions, cabbage, rape, Chinese cabbage, and mustard greens either directly to each planting station or through spraying. As inorganic fertiliser prices have risen sharply in Malawi due to high inflation and local currency devaluation, this locally available alternative has become increasingly important for smallholder farmers. As a result, Ligness’s maize yields increased from 15 to 20 bags per acre to 40 bags last season, and she expects the same field to produce more than 60 bags this year.

For Ligness alone, using organic liquid fertiliser has translated into an estimated saving of K900,000 per year, while helping to restore soil health and improve farm productivity. The fertiliser has also become a source of additional income, as she sells it at K5,000 per 20-litre bucket or exchanges it for labour. Her experience shows how a relatively small technology can contribute to cleaner energy, stronger livelihoods, improved soil fertility, and greater resilience for households facing climate and economic pressures.