Plenty of Waste, Too Little Energy: What Is Holding Back Africa’s Biogas Boom?

Sub-Saharan Africa has no shortage of organic material that could be turned into energy. Crop residues, livestock manure and other agricultural waste are produced across a region where hundreds of millions of people still lack reliable electricity and many households continue to depend on firewood and charcoal for cooking. However, the gap between biogas potential and actual production remains stubbornly wide.

The study "Why Abundant Biomass Fails to Deliver: Machine Learning Insights into Biogas Production Constraints in Sub-Saharan Africa," published in the journal Sustainability, examines why that gap persists. Authors Zongrun Song and Zhiyuan Ma, both affiliated with China Agricultural University, analyse biogas production across ten sub-Saharan African countries from 2007 to 2023 using machine-learning models and interpretable statistical techniques.

The key finding challenges a common assumption in renewable-energy planning: Africa's biogas problem is not primarily a shortage of raw material. The bigger obstacles are weak supply chains, poor infrastructure, rural labour loss, high household costs and competition from other energy sources. Unless those constraints are addressed, the study projects that total biogas production in the countries examined could continue declining through 2030.

Biomass Is Abundant, but the Energy System Is Missing

Biogas is presented as an obvious solution to Africa's rural-energy challenge. Household or community digesters can convert animal manure and crop waste into gas for cooking, lighting or electricity generation. The residue left after digestion can also be used as fertilizer, creating potential benefits for farm productivity, waste management and household incomes.

The theoretical potential is considerable. Previous assessments cited in the study suggest that electricity produced from African crop-residue biomethane could meet a meaningful share of the continent's demand. Processing livestock manure could also generate substantial power, particularly in sub-Saharan Africa outside South Africa. But technical potential is not the same as usable energy.

The study covers Burkina Faso, Cameroon, Ethiopia, Ghana, Kenya, Nigeria, Rwanda, Senegal, Tanzania and Uganda. It combines actual biogas-production figures with indicators covering agricultural output, urbanization, rural electricity, access to clean cooking, livestock manure and charcoal consumption.

After comparing several econometric and machine-learning approaches, the researchers selected a gradient-boosting model because it performed better at identifying nonlinear relationships among the variables. Its average R² score reached 0.892 in the main model comparison, substantially outperforming conventional linear panel models.

The forces shaping biogas production do not move in simple straight lines. Greater urbanization, for example, can initially help biogas by improving access to capital, technology and services. But beyond a certain point, it may undermine production by drawing labour away from rural areas and expanding access to competing fuels.

The analysis also shows that simply producing more crops or keeping more livestock does not guarantee more biogas. Agricultural waste may be geographically dispersed, difficult to collect or already used as animal feed, fertilizer or fuel. Without transport networks, storage systems, trained technicians and dependable maintenance, biomass remains a theoretical resource rather than a functioning energy supply.

The critical question is not how much agricultural waste exists, but whether countries have the institutions and commercial systems needed to collect, process and convert it consistently.

Charcoal Dependence Reveals Where the Real Demand Lies

Among all the variables examined, charcoal consumption emerged as the strongest predictor of actual biogas production. Its mean absolute SHAP value, a measure of its contribution to the model's predictions—was 1.018, more than twice that of urbanization, the second-most influential variable. Charcoal was the dominant predictor in nine of the ten countries. Rwanda was the only exception, where total crop output ranked first.

The study does not show that charcoal consumption causes biogas production to rise. Nor does it imply that governments should preserve charcoal dependence. Instead, high charcoal use appears to signal unmet household demand for accessible cooking energy. Where charcoal use is high and clean-cooking infrastructure remains weak, households may have a stronger incentive to adopt a substitute such as biogas. In that sense, charcoal dependence functions as a marker of both energy deprivation and potential market demand.

The relationship is not linear. At relatively low levels of charcoal consumption, the model associates charcoal use with lower predicted biogas output. Once consumption passes a threshold, its predictive contribution becomes positive. The authors interpret this as evidence that strong dependence on traditional fuels can create demand for alternatives, provided biogas systems are affordable and available.

However, this creates a difficult transition challenge. As households gain access to liquefied petroleum gas, electricity or other modern cooking options, they may bypass biogas entirely. Biogas therefore competes not only with traditional fuels but also with cleaner technologies that are often easier to install and maintain.

Cost is a major disadvantage. The paper notes that a standard household biogas system can require an upfront investment of roughly USD 500–800. For many rural families, that can equal several months of income. An LPG stove may cost far less and can be used immediately without the need to collect feedstock or maintain a digester.

Biogas may produce long-term savings, but low-income households often cannot absorb the initial expense. A technology can be economically beneficial over several years and still be financially inaccessible at the moment a family must decide whether to buy it.

The affordability gap helps explain why donor-supported programmes have built thousands of digesters without always creating durable markets. Installation is only the first step. Systems require regular feeding, water, repairs, user training and access to replacement parts. Where those supporting services disappear after a project closes, digesters can quickly fall out of use.

Urban Growth, Weak Infrastructure and Abandoned Digesters

Urbanization is the study's second-most important predictor, but its relationship with biogas is complex. The analysis identifies an inverted U-shaped pattern.

At early and moderate stages, urbanization can support biogas development. Expanding towns may bring financial services, better roads, improved technical capacity and stronger markets for agricultural products and organic fertilizer. These conditions can make it easier to build and operate larger, more commercial systems.

At higher levels, however, urbanization becomes negatively associated with biogas output. Rural-to-urban migration can reduce the labour available to collect manure, feed digesters and perform routine maintenance. Urban households may also have access to electricity or LPG, while agricultural residues may be redirected to commercial processing or livestock production.

Rural electricity access shows a more consistently positive relationship. Once electricity coverage passes an apparent threshold, its contribution to predicted biogas production rises. This suggests that electricity and biogas should not always be treated as competitors.

Reliable electricity can support pumps, processing equipment, monitoring devices and small businesses that use biogas or its by-products. It may also improve the commercial viability of community-scale plants. In this sense, biogas performs better when embedded in wider rural infrastructure rather than promoted as a stand-alone substitute for electrification.

The research also highlights the importance of operational failure. Although the number of installed digesters has increased in parts of Africa, many systems constructed under earlier programmes have reportedly been abandoned. The study cites evidence indicating an abandonment rate of 27% across Kenya, Tanzania and Uganda.

The figure exposes a weakness in how renewable-energy projects are often evaluated. Donors and governments may count units installed, households reached or money disbursed. But those indicators say little about whether a digester is still operating five years later. A more meaningful measure would track gas production, maintenance frequency, user satisfaction and the availability of local repair services. Without long-term monitoring, the apparent expansion of biogas infrastructure can conceal a shrinking base of functional systems.

The study's forecasts reinforce that concern. After rapid growth from a low base, production momentum weakened after 2015, and the first negative annual growth was recorded in 2023. Under the researchers' main projection, combined production across the ten countries falls to about 51.7 million cubic metres by 2030. An alternative forecasting method produces an even lower estimate of 45.8 million cubic metres.

The authors caution that these are baseline projections. Policy reforms, subsidy programmes, technological advances or economic shocks could shift the trajectory. The model also performed far better for the relatively stable 2012–2023 period than for the full 2007–2023 series, limiting confidence in long-range extrapolation.

Africa Needs Biogas Strategies Built Around Countries, Not Continents

Sub-Saharan Africa does not have one biogas market. It has multiple national and local markets shaped by different combinations of fuel dependence, infrastructure, agricultural production and labour availability.

In countries where charcoal consumption is the dominant predictor, biogas strategies should focus on communities with clear demand for energy substitution. That means identifying where households spend heavily on charcoal, where supply is environmentally damaging and where digesters can compete on reliability and cost.

Rwanda requires a different approach because crop output emerged as its most influential predictor. Policy should therefore focus more heavily on residue collection, competing uses of agricultural waste and the efficiency with which crop residues are converted into energy.

In Ghana and Senegal, rural electricity access carries relatively high predictive importance. There, investment in power infrastructure could complement biogas development, particularly for productive uses such as agro-processing or small-scale electricity generation.

Across all countries, governments and development partners need to move away from programmes centred narrowly on equipment distribution. A sustainable biogas market requires financing, trained technicians, local spare-parts supply, feedstock aggregation, quality standards and clear ownership of maintenance responsibilities.

Innovative financing could help reduce upfront costs. Leasing arrangements, pay-as-you-go systems, cooperatively owned digesters and results-based subsidies may make biogas more accessible than conventional household purchases. Community and commercial-scale plants may also prove more durable than thousands of isolated household systems, although that question requires further research.

Businesses have opportunities in manure collection, digester servicing, fertilizer sales and decentralized energy provision. But investors will need realistic assessments of demand. Biogas must compete with charcoal, LPG, electricity and improved cookstoves, each of which offers a different combination of convenience, affordability and reliability.

Notably, the study covers only ten countries and excludes variables such as subsidies, credit availability, energy prices, governance quality and institutional capacity because comparable data were unavailable. Its SHAP analysis identifies statistical associations, not causal relationships. Charcoal consumption may be capturing broader conditions such as poverty, weak infrastructure or energy demand rather than exerting a direct influence on production.

That said, the research delivers a valuable warning for development policy. Natural-resource abundance does not automatically translate into accessible energy. The decisive factors often lie in the systems surrounding the resource: finance, logistics, infrastructure, maintenance and functioning markets.