Biogas: untapped solution to rural energy

Studies and observations show that rural households continue to rely on fuelwood and animal dung as their main sources of domestic energy. It is estimated that per capita fuelwood use is 0.52 m3 in the warm plains and 0.72 m3 in the colder mountain areas of Pakistan. Therefore, a family of 10 consumes about 5.2 m3 of fuelwood in the plains and 7.2 m3 in hilly regions. This is a phenomenal burden on forests that may lead to deforestation.

Pakistan has planted billions of trees over the past decade and now a nationwide Green Pakistan initiative is underway across all provinces, including Azad Jammu and Kashmir and Gilgit-Baltistan. However, these efforts are undermined by the continuous cutting of forests for domestic fuel, which remains a persistent pressure on forestry resources. Several alternatives to fuelwood have been tried in the domestic sector, but most failed due to high prices, limited accessibility, poor supply chains, or inconsistent supply. Liquefied petroleum gas (LPG), natural gas, kerosene, and LNG are efficient energy sources, but their high costs and restricted distribution, limited mainly to urban areas, have kept them out of reach for rural communities.

Biogas offers an economically viable, socially acceptable, and environmentally friendly alternative. A rural household with one or two animals, as is common in Pakistan's villages, can easily establish a biogas plant. Being decentralised, these plants can be installed near the source of animal dung. The process, which is anaerobic digestion of organic material, can be facilitated through a biogas digester. The latest dome-shaped underground digesters are fully automatic and more efficient than the older drum-type designs. As bacteria decompose organic matter inside the digester, biogas is released as a highly effective energy source.

The composition of biogas varies depending on the raw material and operating conditions such as temperature, pH, and substrate concentration. Typically, it contains Methane (CH4) 50-75%, Carbon Dioxide (CO2) 25-50%, Nitrogen (N2) less than 5%, Hydrogen (H2) less than 1%, Oxygen (O2) less than 1%, Hydrogen Sulfide (H2S) traces under 3%, and Water Vapour (H2O) under 10%. Methane, which has a high calorific value, serves as the primary source of heating.

Biogas is socially acceptable because it offers significant health benefits. It eliminates indoor pollution caused by burning wood and dung cakes, reducing respiratory illnesses. It also minimises exposure, especially for children, to waste heaps of animal dung that attract flies and germs. For rural women, who are primarily responsible for collecting firewood and cooking multiple meals daily, biogas provides immense relief and improves quality of life, making its gender dimension particularly strong.

Economically, biogas is highly viable. Once established, a biogas plant can last more than two decades. After the initial cost is recovered, households effectively enjoy free energy. The average replacement value of biogas for fuelwood or LPG per household is around Rs15,000 per month. Additionally, the digested residue from biogas plants serves as rich organic manure, improving soil fertility and reducing dependence on chemical fertilisers. Biogas use also lowers healthcare costs by reducing sickness.

Biogas is environmentally friendly as it helps control tree cutting for fuelwood. It consists of 50-70% methane, often referred to as the "monster" of greenhouse gases (GHGs) due to its warming potential, which is nearly 80 times higher than that of other GHGs. Additionally, biogas technology reduces indoor air pollution, promotes health and hygiene by decomposing dung heaps, and qualifies for carbon credits as an anaerobic process.

This renewable source of domestic and commercial energy also reduces the consumption of fossil fuels, LPG, and kerosene oil. Therefore, biogas energy is highly sustainable over time and across regions, offering multiple benefits for both rural and national economies.

Despite its social, economic, and environmental advantages, biogas has yet to gain adequate attention from policymakers or be promoted on a large scale. Pakistan, being the world's fifth-largest livestock-producing country, must prioritise the development of biogas plants at both national and local levels.

The federal and provincial governments should actively encourage and promote biogas adoption. All relevant agencies must work to expand biogas development in rural areas. Instead of extending natural gas pipelines to these regions, decentralised biogas plants, at both household and community levels, should be promoted.

While planting trees is relatively easy, protecting them until maturity is a far greater challenge. Since the demand for fuelwood remains the main pressure on forests, this can only be addressed effectively by developing biogas systems in Pakistan's rural areas.

THE WRITER HOLDS A PHD IN FORESTRY AND HAS SERVED WITH PROVINCIAL, NATIONAL, AND INTERNATIONAL ORGANISATIONS IN FORESTRY, CLIMATE CHANGE, AND ENVIRONMENTAL MANAGEMENT