Animal manure produced by the livestock industry has long been an environmental hazard – managing waste from over 70 billion animals results in excessive nutrients leaching into the ground and waterways. It’s also a major source of methane – a greenhouse gas with 80 times more warming potential than carbon-dioxide over a 20 year timespan.  

The industry says biogas production is the answer to this problem: install biodigesters to capture gas that is produced during the controlled decomposition of agriculture byproducts, including manure and crop residues, and use it as an alternative to natural gas in the energy system or biodiesel at the pump. 

It’s a win-win: using waste to create energy. Or is it?

Take a step back and look at the full picture of emissions from biogas production – including the cost, location of biodigesters and sustainability of feedstocks – and the benefits become less clear. 

To start, Europe and the US, installing biodigesters is expensive (around 70%-95% of total biogas costs) which means that significant subsidies are required to make projects financially feasible. A detailed geospatial analysis recently revealed that 40% of the biogas  that is technically available will still be uneconomic by 2050 without government subsidies. 

To efficiently generate biogas, bio-digesters need to be close to both large quantities of feedstock (i.e. industrial farms and their waste), as well as transportation links for the gas produced. As a result, biogas production barely exists in countries like Australia, where livestock are farmed across huge areas. It is also challenging to implement in other regions, such as Latin America, Africa or Southeast Asia. 80% of the world’s farms are small-holdings in developing countries with less than two hectares of land, that simply don’t  meet the technical and financial requirements needed to install a digester. 

In the US, livestock farms must have at least 500 head of cattle or 2,000 hogs to qualify for a biodigester, which means subsidies could end up incentivising farmers to raise more animals and in closer quarters. As a result scientists and NGOs have raised concerns that biogas production may incentivise further intensification and expansion of the livestock sector, leading to even greater environmental impacts and climate emissions – including methane emissions from the digestive processes (burps) of ruminants such as cattle and sheep. 

A closer look at the feedstocks for biogas production reveals further limitations. Manure and crop residuals make up just 29% of agricultural emissions, so their impact on overall emissions from the sector is limited. Biogas production often requires additional feedstock – from crops grown to produce energy – which has been criticised by the IPCC for causing biodiversity loss, undermining food security and excessive water use, as well as creating the potential for temperature overshoot.

On top of all these challenges, there have also been concerns raised about the safety at biogas facilities and the potential for gas leakages

The variety of risks and limitations associated with biogas production in the agricultural sector mean it’s far from the win-win solution the industry would have us believe. 

Politicians must ensure the costs of biogas implementation are carefully weighed against the benefits. Promoting healthier diets with less meat and dairy is currently the cost effective and reliable way to cut emissions from the livestock sector.  In the EU, reduction of red meat by half and dairy by a quarter would yield up to a 19% reduction in overall emissions – more than any other measure.  However it’s an approach the industry – and many governments – aren’t yet keen to back.

Read more on biogas.